Caribbean - Central America Weather

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
451 AM AST Sat Jul 19 2025

.KEY MESSAGES...

* Another hot day for the US Virgin Islands and Puerto Rico
today, before the formation of intense thunderstorms during the
afternoon and evening of Saturday, which could lead to flooding
rains.
* The trailing moisture from today's surface trough will
bring another round of thunderstorms on Sunday afternoon.
* The excessive heat trend is expected to persist throughout
much of the forecast period, particularly between Tuesday and
Thursday.
* If model guidance follows the correct track, a robust tropical
wave could bring a wet and unstable weather pattern around next
Friday.

&&

.SHORT TERM...Today through Monday...

Satellite and radar imagery showed partly cloudy skies and isolated
showers during the overnight period across the local waters, with
some showers reaching the northern and eastern coasts of Puerto Rico
and the U.S. Virgin Islands (USVI). Radar estimates did not indicate
significant rainfall accumulations. Temperatures ranged from the
upper 60s in the mountains to the upper 70s and low 80s in coastal
urban areas. Winds were mainly from the northeast at 10 mph or less.

The short-term forecast remains on track. Today, a TUTT low moving
north of the region will induce a surface trough that will pass near
the islands, enhancing afternoon convection and increasing the
potential for thunderstorms. Model guidance suggests that
precipitable water (PWAT) values will remain between 1.7 and 1.9
inches. Winds will shift from the northeast to the east-southeast
throughout the day. As a result, expect showers across windward
locations during the morning, followed by an active and unstable
afternoon with showers and isolated to possibly scattered
thunderstorms over interior and northwestern Puerto Rico, as
indicated by the Galvez Davison Index (GDI). The USVI also has a
good chance of experiencing occasional periods of showery weather
throughout the day. There is an elevated risk of ponding of water on
roads and in poorly drained areas, as well as localized flooding in
urban zones, roadways, and small streams. In addition, a period of
warm to hot heat indices is expected to persist. Although showers
and thunderstorms may help reduce the heat risk, high humidity will
contribute to muggy conditions in urban and coastal areas of Puerto
Rico, especially before rain develops or in places that receive
limited rainfall. As a result, a Heat Advisory is in effect between
10 a.m. and 4 p.m. AST for coastal urban areas of Puerto Rico.

Looking ahead to Sunday and Monday, expect a more typical summer
pattern for the tropics, with morning showers across the eastern
half of Puerto Rico and the USVI, followed by afternoon convection
mainly confined to the northwestern quadrant of Puerto Rico.
Rainfall should be more localized, and the flood risk will be
limited. However, warm to hot temperatures will continue. Residents
and visitors are encouraged to stay hydrated, limit outdoor activity
during peak heat hours, wear light clothing, and check on vulnerable
individuals and pets.

.LONG TERM...Tuesday through Saturday...

A mid-level high pressure will build over the northeast Caribbean
from Tuesday into next weekend, promoting dry air aloft, at least
through Friday. While a surface high-pressure will persist across
the Atlantic Ocean, promoting an increase in local winds from
around Wednesday into the end of the workweek. A weak easterly
perturbation is expected to move across the islands around
Tuesday, enhancing the potential for rain and thunderstorm
activity, especially during the afternoon hours. After Tuesday's
easterly disturbance, the local weather will be dominated by the
arrival of patches of moisture embedded in the trades, which will
promote the climatological hydrological pattern of the US Virgin
Islands and Puerto Rico on Wednesday and Thursday. Based on the
latest model guidance during this period, the primary hazard could
be excessive heat resulting from the combination of available
moisture and maximum temperatures across the islands.

A tropical wave, which currently appears to be the primary rain
and thunderstorm producer, is expected to arrive around Friday,
and its trailing moisture could persist near the region through at
least next Saturday, potentially pausing the excessive heat
trend. We are monitoring this wave, as it could increase the
potential to observe flooding rain, especially around Friday, for
both PR and the USVI. Additionally, NHC is currently monitoring
this same wave in their Tropical Weather Outlook for the Atlantic
waters, and it has a low chance of formation over the next 7 days.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
450 AM AST Sun Jul 20 2025

.KEY MESSAGES...

* The hot spell continues for the US Virgin Islands and Puerto
Rico today; thus, a Heat Advisory is in effect for the coastal
and urban areas of PR.

* One or two isolated strong thunderstorms will develop across
the northwest quadrant of PR this afternoon, which could lead to
flooding rains and intense lightning.

* Another Saharan Air Layer (SAL) with moderate to locally high
concentrations will move across the local islands from Monday
to Tuesday.

* The excessive heat trend is expected to persist throughout much
of the workweek, particularly between Tuesday and Thursday.

* There is a slight to moderate chance that a robust tropical wave
could bring a wet and unstable weather pattern around Friday.


&&

.SHORT TERM...Today through Tuesday...

Passing showers moved over the regional waters at night, with few
moving over the U.S. Virgin Islands and eastern portions of Puerto
Rico. Nevertheless, based on Doppler radar rainfall estimates,
accumulations were minimal. Minimum temperatures were slightly
cooler compared to yesterday, mainly over urban and coastal areas,
with stations reporting mid to upper 70s and isolated areas in the
lower 80s. Stations across higher elevations reported low to upper
60s, some reaching the lower 70s.

Variable weather conditions are expected for the start of the week.
The surface high pressure over the Central Atlantic will continue
promoting southeasterly/easterly winds for the next few days. Based
on the latest satellite-derived product, current Precipitable Water
(PWAT) values remain seasonal (1.5 - 1.8 inches), due to residual
humidity associated with the mid to upper level trough north of the
region. Available moisture content and marginal instability,
combined with diurnal heating and local effects, showers and
isolated thunderstorms are likely across northwestern Puerto Rico
during the afternoon. Additionally, the Galvez-Davison Index (GDI)
suggests the potential of isolated thunderstorms as well in the
afternoon. Rainfall accumulations are likely to promote ponding of
water in roadways and poorly drained areas, along with isolated
urban and small streams flooding. Another area that has potential
for shower development is the San Juan Metropolitan Area due to
local effects, but the flooding risk should remain low.

A mid to upper-level ridge over the Central Atlantic will migrate
westward, pushing the mid to upper-level low away. With the ridge
lingering north of the region during the short term, stability
should increase aloft, slightly warm 500 mb temperatures, and
inhibit deeper convection activity on Monday. Another Saharan Air
Layer (SAL) is expected to approach the local islands by Monday
afternoon and linger for the next few days. Pulses containing
moderate to high concentrations may bring hazy skies, reduced
visibility, and deteriorating air quality. Based on the latest model
guidance, a perturbation in the trades should arrive by late Monday
night into Tuesday, increasing PWAT values to near above
climatological normals (1.9 - 2.0 inches). Showers are likely to
move over windward sections Tuesday morning, with afternoon
convection over western PR, elevating the flooding risk.

Under a southeasterly windflow, warmer temperatures, and available
moisture, heat indexes are very likely to exceed 100 degrees
Fahrenheit and meet Heat Advisory criteria. Hence, a Heat Advisory
is in effect from 11 AM through 5 PM AST for urban and coastal areas
of Puerto Rico. The U.S. Virgin Islands remain under a limited heat
risk; nevertheless, warm to isolated hot heat indexes will impact
the urban and lower elevation areas. This level of heat affects
primarily those individuals extremely sensitive to heat when
outdoors without effective cooling and/or adequate hydration.

.LONG TERM...Wednesday through Sunday...

Wednesday and Thursday will be characterized by the influence of
a mid-level high-pressure system building over the northeast
Caribbean, promoting dry air aloft and reinforcing a trade wind
cap. The subtropical surface high-pressure over the Atlantic Ocean
will tighten the pressure gradient, increasing local winds around
the middle of the week. These winds will advect occasional
patches of moisture, resulting in the typical summer weather
pattern of the US Virgin Islands and Puerto Rico. This weather
pattern consists of occasional showers moving inland across the US
Virgin Islands and the windward locations of PR, followed by
strong afternoon convection across the western locations in PR.

Currently, model guidance continues to indicate the transitioning
to a wet unstable weather pattern as early as Thursday into
Friday with the arrival of tropical moisture associated with a
tropical wave being monitored by the National Hurricane Center
(and it has a low chance of formation over the next 7 days),
extending across a disorganized area of showers and thunderstorms
from around latitude 8 N, and longitude 44 W to around 10 N and 35
W. If the guidance is on track, we may observe an increase in the
potential for showers and thunderstorms from the east, beginning
over the Virgin Isles and spreading into Puerto Rico as early as
Thursday or early Friday morning, peaking the activity on Friday
with its trailing moisture over the islands through at least
Saturday. Under this weather scenario, we could pause the hot
spell, transitioning into a more unsettled weather pattern with a
risk of lightning and flooding rains. We encourage island
residents and visitors to stay updated on the latest weather
conditions, particularly from Thursday to Saturday.

After the tropical wave mentioned above leaves the area, we
expect a more typical Caribbean Tropical Weather pattern as early
as late Saturday into Sunday.

&&

.AVIATION...
(06z TAFs)

Mainly VFR conds with VCSH across most TAF sites. TSRA is xpcd
across NW PR, with VCTS and -RA/+RA over JBQ, while streamers may
also produce -RA/RA over JSJ. VIS/CIGs may be affected, with brief
MVFR conds for these terminals. Winds from the ESE-SE btwn 10 - 15kt
with few gusts up to 20 kt aftr 23/14z, becoming light to moderate
(6 - 10 kt) aft 23/23z.

&&

.MARINE...

The trailing moisture from yesterday's induced surface trough will
result in showers and thunderstorms especially during the afternoon
today. A surface high pressure over the Atlantic will mainly promote
moderate easterly winds over several days, becoming moderate to
fresh again around Tuesday next week. A weak easterly perturbation
will move across the US Virgin Islands and Puerto Rico around
Tuesday, followed by a more robust tropical wave after midweek.

&&

.BEACH FORECAST...

Beachgoers can expect a low risk of rip currents for most local
beaches in Puerto Rico and the northern US Virgin Islands.
However, there is a moderate risk of Rip Currents for Culebra and
St Croix. Regardless of the low risk, isolated stronger rip
currents may occur, especially near piers, jetties, and channels.
The risk of rip currents will spread to additional north and east-
facing beaches from Monday onward.

Thunderstorms will develop from around noon into the evening,
across northwest PR, increasing the risk of lightning strikes
along the coastal locations today. Please monitor our social media
platforms for further updates.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
458 AM AST Mon Jul 21 2025

.KEY MESSAGES...
* A low level feature will increase the showers coverage over the
eastern portions of Puerto Rico and U.S. Virgin Islands
tonight.

* Breezy to windy conditions will persist this week starting
tonight, deteriorating marine conditions and likely prompting
Small Craft Advisories around midweek.

* Moderate to high concentrations of Saharan dust are forecast to be
present, particularly from Tuesday trough Thursday. This may
result in hazy skies and reduced air quality, particularly for
individuals with sensitive health conditions.

* Warm to hot conditions will continue, remember to stay hydrated
and limit time outdoors during the hottest parts of the day.

* A robust tropical wave, currently monitored by the National
Hurricane Center, is expected to bring increased showers and
thunderstorms by the end of the week.

&&

.SHORT TERM...Today through Wednesday...

Isolated to locally scattered showers continue to affect the
eastern coastal areas of Puerto Rico and adjacent islands this
morning, though the have not produced any significant rainfall
accumulations. These showers are expected to persist
intermittently through mid morning. Later today, available
moisture combined with daytime heating and local effects will
support the development of additional showers, and possibly a
thunderstorms or two, particularly across the western interior
and northwest portions of puerto rico during the afternoon hours.
Allow level weather feature is forecast to move across the region
tonight,increasing the likelihood of showers and bringing a
noticeable uptick in winds. Following this feature, satellite
imagery indicate a plume of Saharan dust approaching the
region,expected to arrive early Tuesday, which may lead to hazier
skies, drier air and slight reduction in overall shower activity
through mid week.

.LONG TERM...Thursday through Monday...

At the beginning of the long-term period, breezy to locally windy
conditions will persist as a subtropical surface high-pressure
system over the Atlantic Ocean maintains a tightened pressure
gradient. Aloft, the mid-level high-pressure system will shift to
the western Atlantic. Moderate concentrations of Saharan dust
particles are expected to remain in the area, resulting in hazy
skies and reduced air quality, particularly affecting individuals
with sensitive health conditions.

The latest model guidance continues to indicate a transition to a
wetter pattern beginning Thursday afternoon or Friday, due to an
approaching tropical wave. This tropical wave, designated Invest
94L, is currently located about 900 miles east-southeast of the
Lesser Antilles. It is being monitored by the National Hurricane
Center and has a low chance, 20 percent, of development over both
the next 2 and 7 days. While environmental conditions are generally
favorable for some development in the short term, they are expected
to become unfavorable for further development by midweek. Regardless
of development, if the guidance holds, we can expect an increase in
the potential for showers and thunderstorms, starting over the
Virgin Islands and spreading into Puerto Rico as early as Thursday
or early Friday. Flood risk are expected to be elevated, keep in
mind that flooding in urban areas, roads, small streams, and washes
are possible and possible isolated flash floods. Residents and
visitors are encouraged to stay informed through official sources as
we continue to monitor and update the forecast.

Trailing moisture will likely maintain a typical summer pattern
across the U.S. Virgin Islands and Puerto Rico over the weekend.
Beyond that, models are indicating the approach of another tropical
wave, currently located near 29 degrees west longitude and south of
17 degrees north latitude, which could increase the potential for
showers and thunderstorms early next week. Stay tuned over the
coming days for forecast updates and adjustments, as confidence
remains low at this time. Meanwhile, warm to hot temperatures will
persist. Residents and visitors are advised to stay hydrated, limit
outdoor activities during peak heat hours, wear light clothing, and
check on vulnerable individuals and pets.

&&

.AVIATION...
(06Z TAFs)

Mainly VFR conds with VCSH across most TAF sites. TSRA
is xpcd across West PR, with VCTS and -RA/+RA over JBQ, while
streamers may also produce -RA/RA over JSJ. VIS/CIGs may be
affected, with brief MVFR conds for these terminals. Winds from
the East btwn 10 and 15kt with few gusts up to 20 kt aftr 21/14z,
becoming light to moderate (6 to 10 kt) aft 21/23z.

&&

.MARINE...

Marine conditions across local waters are currently influenced by
moderate to strong east trade winds ranging from 15 to 20 knots ,
with gusts reaching up to 30 knots after mid week. Seas are
expected to range from 2 to 6 feet near shore and build up to 6 to
8 feet offshore, with occasional higher waves during heavier
showers. At this moment a Small Craft operators should exercise
caution across the Atlantic near shore areas due to this
conditions.

A tropical wave (Invest 94L)currently situated east of the Lesser
Antilles is expected to continue moving westward, bringing a
significant increase in winds across the local waves starting mid
week.. As a result, Small craft advisories will likely be issued
for most of the regional marine zones through the end of the week.

&&

.BEACH FORECAST...

Beachgoers in Puerto Rico and the US Virgin Islands should expect
breezy and unsettled conditions this week as a tropical wave
approaches, increasing winds and seas by mid week. Strong
easterly trade winds will generate choppy surf and significantly
raise the risk of dangerous rip currents. Swimming and snorkeling
conditions will be poor, and a Small Craft Advisory will be in
effect for most coastal waters. Caution is advised, beach visitors
should avoid swimming at unprotected or high risk beaches.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
448 AM AST Tue Jul 22 2025

.KEY MESSAGES...

* Moderate to high concentrations of Saharan dust are forecast to
be present, particularly from Tuesday trough Thursday. This may
result in hazy skies and reduced air quality, particularly for
individuals with sensitive health conditions.

* An increase in winds is forecast for Wednesday, resulting in
wind-driven seas across offshore Atlantic and Caribbean waters,
as well as the local passages.

* The bulk of the moisture associated with the tropical wave being
monitored by the National Hurricane Center will stay well to our
south over the Caribbean Waters.

* Another tropical wave with a better shape and plenty of moisture
will move into the islands Sunday into Monday, increasing the
potential for widespread shower activity.


&&

.SHORT TERM...Today through Thursday...

Scattered showers to numerous showers and isolated thunderstorms
affected portions of the U.S. Virgin Islands and Puerto Rico. The
are of showers and thunderstorms began impacting the U.S. Virgin
Islands during the evening hours moving over the eastern half of
Puerto Rico later in the night.In the San Juan metro are rainfall
accumulations ranged from 1 to 2 inches. Additional showers also
affected the southeastern and southern portions of PR. As this
feature continued to move westward, it produced showers and
thunderstorms along the northern coast of Puerto Rico, bringing
period of heavy rain and gusty winds to those areas.

Shower and thunderstorms activity associated with the tropical
wave in the central tropical Atlantic(Invest AL94)
remains disorganized, and further development is not longer
anticipated as it moves west-northwestward at around 15 mph.
Environment conditions are becoming increasingly unfavorable,
limiting the potential for tropical cyclone formation.

Latest models runs suggest that the bulk of moisture associated to
the tropical wave is forecasted to remain well south of the local
area, mainly over the Caribbean waters. However, increasing winds
are expected on Wednesday as the tropical wave approaches the
region, tightening the local pressure gradient. This will
resulting in wind-driven seas across the offshore Atlantic and
Caribbean waters, as well as the local passages, potentially
creating hazardous marine conditions for mariners.

.LONG TERM...Friday through Tuesday...

Variable conditions are still expected in the long-term forecast,
with a transition to a wetter and unsettled weather pattern likely
by the start of next week. Drier air will continue filtering into
the region due to a mid-to-upper level ridge lingering north of the
CWA. Based on the latest model guidance, Precipitable Water Values
(PWAT) should decrease to seasonal values (1.5 - 1.7 inches). The
most likely scenario is to expect showers embedded in the trades
moving over windward sections in the morning hours and afternoon
convection over western/northwestern Puerto Rico. Rainfall
accumulations are likely to promote ponding of water in roadways and
poorly drained areas, with isolated urban and small streams flooding
over the aforementioned areas. Another tropical wave with high
moisture content will likely approach the CWA by Saturday night
through Monday. Additionally, an upper-level low should approach the
region by Friday and linger through Sunday, increasing instability
aloft and bringing favorable conditions for deeper convection
activity. Based on deterministic guidance of the GFS and ECMWF, PWAT
values may exceed the 75th percentile (2.0 - 2.2 inches, with low
chances of reaching 2.4 inches), which is well above climatological
normal. This will enhance the shower and thunderstorm activity over
the local islands, elevating the flooding risk for most sections of
Puerto Rico and the U.S. Virgin Islands. Citizens and visitors must
pay attention to the following discussion regarding this tropical
wave. Drier air may filter once again into the region by Monday
night, bringing mostly fair conditions across the CWA.

With available moisture and warmer temperatures, heat indexes are
likely to exceed the 100 degrees Fahrenheit which may affect most
individuals sensitive to heat. Hence, the heat risk is likely to
remain limited to elevated for urban and coastal areas of Puerto
Rico and the U.S. Virgin Islands for the rest of the forecast period.


&&

.AVIATION...
(06Z TAFs)

Mainly VFR conds with VCSH across most TAF sites. RA is expected
across West PR, while streamers may also produce -RA/RA over JSJ.
VIS/CIGs may be affected, with brief MVFR conds for these terminals.
Winds from the East btwn 15 and 20kt with few gusts up to 30 kt
after 22/14z, becoming moderate (10 to 15 kt) aft 22/23z.


&&

.MARINE...A surface high pressure system over the Atlantic is
currently promoting moderate easterly winds across the region,
which are expected to strengthen to moderate to fresh levels
today through the rest of the week. A weak easterly perturbation
moved across the local waters earlier today and will be followed
by a more robust tropical wave expected to arrive during the
second half of the week. Mariners navigating across the local
waters should anticipate moderate to fresh easterly winds and
choppy seas conditions over the next several days.

For situational awareness, a series of tropical waves are expected
to move across through the region. The first wave is forecast to
reach the local area on Thursday, followed by another tropical
wave on Sunday. These system may bring periods of unsettled
weather, including increase shower and thunderstorms activity, as
well as brief gusty winds and locally higher seas. Mariners are
urged to exercise caution and stay informed with the latest
marine forecast and advisories.

&&

.BEACH FORECAST...A moderate risk of rip currents across most
local beaches today. As winds are expected to continue to
increase through Wednesday, this moderate rip current risk is
expected to expand to the eastern coast of Puerto Rico and
gradually affect other coastal areas throughout the week. These
rip currents can be strong and potentially life threatening,
especially areas not designated for swimming. Resident and
visitors are strongly urged to exercise caution when visiting the
coast, particularly on un-patrolled or remote beaches. Always
follow guidance from local authorities and heed posted warning
signs to ensure your safety.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
432 AM AST Wed Jul 23 2025

.KEY MESSAGES...

* In the near term, main hazards continue to be a moderate to
high risk of rip currents across most shorelines and choppy to
hazardous seas mainly in Caribbean waters, both associated with
breezy to windy conditions.

* Haziness associated with Saharan Dust Particles will continue to
prevail across the local area through at least midweek as well
as heat indices exceeding 100 degrees along lower elevations.

* The bulk of moisture associated with a tropical wave located
near 52W (formerly AL94) is expected to remain south of the
area. Nevertheless, an increase in shower and thunderstorm
activity, with an elevated risk of flooding, is expected on
Sunday and Monday, associated with the passage of the following
tropical wave now located near 36W.

&&

.SHORT TERM...Today through Friday...

Isolated to locally scattered showers, carried by the trade winds,
affected the eastern portions of Puerto Rico, nearby islands and
surrounding waters. Due to the their quick movement, rainfall
accumulations remained menimal.These brief passing showers are
expected to continue impacting local waters and coastal sections
of Puerto Rico trough mid-morning.

Saharan dust concetrations are expected to peak early this
afternoon, with hazy skies persisting across the region through
at least Thursday. In addition to reduced visibility and air
quality due to the dust, heat indices in lowers elevations are
forecast to exceed 100F. Residents and visitors, especially those
with respiratory conditions, should limit prolonged outdoor
activity, stay hydrated, and seek shaded or air-conditioned areas
during peak heat hours.

Strengthening mid-level ridge will dominate the forecast area
throughout the period,reinforcing stable atmospheric conditions
aloft. At the surface,, a high pressure system situated north of
the region, in combination with a tropical wave expected to pass
south of the area on Thursday. This will maintain moderate to
fresh easterly trade winds. Winds will remain on the breezy to
windy today and Thursday.

Although the tropical wave formerly known as Invest AL 94, now
localed at around 53W, carries significant moisture, the bulk it
is projected to remain south of the area. As a result, widespread
rainfall is not expected over the forecast area, however,Isolated
to scattered showers may still develop due to pockets of shallow
moisture being advected by the trade winds. Also, available
moisture will combine with diurnal local effect and generate
showers and thunderstorms along la Cordillera Central and western
portions of Puerto Rico each afternoon through Friday.

.LONG TERM...Saturday through Wednesday...

The long-term forecast remains on track, with a transition to an
unsettled and wetter pattern across the CWA. A surface high pressure
over the Central Atlantic should linger for the next few days,
promoting ESE-SE winds. The global models have consistently
suggested the approach of a tropical wave, mentioned in the previous
discussions, to the region by Saturday night into Sunday, with
moisture content lingering through early Monday. Deterministic
guidance of both GFS and ECMWF continues to highlight well-above-
normal Precipitable Water (PWAT) values (2.0 - 2.2 inches), as an
upper-level trough should also approach the CWA by Saturday. The
presence of the trough should cool mid-level temperatures ( 500 mb
temperatures around -6.5 Celsius) and increase instability aloft,
supporting deeper convection activity. Additionally, the Galvez-
Davison Index (GDI) suggests a high potential of isolated
thunderstorms, increasing chances of scattered thunderstorms across
the local area. These weather features, combined with other factors
including local effects, are likely to bring moderate to strong
showers, along with thunderstorms over the region. Rainfall
accumulations are very likely to increase the flooding potential
across most sectors of the local islands.

As the tropical wave retires from the region, a drier air mass is
likely to filter into the region. Nevertheless, the available
moisture combined with local effects and diurnal heating will
enhance afternoon convection over western/northwestern Puerto Rico,
including the San Juan Metropolitan Area, enhancing flooding
potential. The latest model solutions indicate that another tropical
wave is likely to approach the region around Tuesday, pooling high
moisture content. PWAT values may increase once again to above
climatological normal (around 2.2 inches), but uncertainty remains
high. Citizens and visitors should stay informed about the
development of these tropical waves.


&&

.AVIATION...
(06Z TAFs)

Mainly VFR conds with VCSH across most TAF sites. RA is expected
across West PR. Winds from the East btwn 15 and 25kt with few
gusts at around 30 kt after 23/14z, becoming moderate (10 to 15
kt) aft 23/23z.


&&

.MARINE...

Increased winds may lead to hazardous marine and coastal
conditions, including choppy seas and elevated rip current risk
mainly along east, north and south facing beaches. There is a
small craft advisory will be in effect early this afternoon.
During the morning hours small craft operators should exercise
caution.


&&

.BEACH FORECAST...

Beachgoers should be prepared for breezy to windy conditions,
especially on Wednesday and Thursday, due to strong easterly
trade winds.These winds will create choppy seas along most
beaches, increasing the risk of rip currents. Swimming safest at
lifeguarded beaches, and caution is advised for the inexperience
swimmers and those using flotation devices.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
430 AM AST Thu Jul 24 2025

.KEY MESSAGES...

* Breezy to windy trade winds will continue over the next several
days, creating choppy to hazardous seas for small craft and
maintaining a moderate rip current risk at many local beaches.

* Moderate to high concentrations of Saharan dust will linger
through at least tonight, leading to hazy skies, reduced
visibility.

* Warm to above-normal temperatures are expected to persist.

* Most of the moisture associated with the tropical wave moving
through the Caribbean waters today will stay south of the
region. However, a stronger tropical wave is forecast to arrive
Sunday into Monday generating a increase on showers and
thunderstorms.


&&

.SHORT TERM...Today through Saturday.

Isolated to locally scattered showers developed and moved along
the north coast of Puerto Rico, but brisk trade winds caused them
to pass quickly over the area, limiting rainfall accumulations.
Meanwhile, a band of showers associated with the leading edge of
an approaching tropical wave affected the offshore Caribbean
waters,with a few of these showers briefly reaching the southern
coastal area of Puerto Rico.

As the tropical wave move across the Caribbean waters today,the
tailing moisture will bring a slight and brief increase in
humidity late tonight into Friday. However, a dominant and drier
airmass to the north-linked to a strengthening mid level ridge,
will limit most of this moisture to the open Caribbean waters. On
Friday, an upper level low will approach from the west and a
surface trough moving in from the northeast will increase
the instability and weaken the trade wind cap. This will result
in a deeper moisture to gradually reach the region. This feature
will help raise the chances of scattered showers and isolated
thunderstorms to develop across the local forecast area.

Saharan dust levels reached their peak last night and will slowly
decrease throughout the day. However, the particulate is not
expected to clear entirely, with residuals concentrations likely
to persist across the region into the incoming weekend.

.LONG TERM....Sunday through Thursday...

Variable conditions are expected early next week, with tropical
waves pooling high moisture content into the region. The first one,
arriving late Saturday night, is expected to linger through Monday.
From the latest global model solutions, PWAT values continue above
climatological normal (2.0 - 2.2 inches), with low to medium chances
of reaching 2.4 inches. With an upper-level low approaching the CWA
by Saturday as well, mid-level temperatures should cool to seasonal
values (- 6.0 to -6.5 Celsius) and increase instability aloft. The
latest solution of the Galvez-Davison Index now increases the
potential of isolated to scattered thunderstorms across the CWA.
Based on the latest NASA GMAP Dust Detection product, another
Saharan Dust Layer (SAL) may accompany the tropical waves, filtering
low to moderate concentrations into the region. Nevertheless,
there's uncertainty regarding the concentrations, time of arrival,
and the interaction between the tropical wave and the SAL. The
second tropical wave is likely to arrive by early Tuesday, with the
best moisture content remaining south of the local islands. Based on
deterministic guidance of the GFS and ECMWF, PWAT values will
increase but remain seasonal to near above normal (1.8 - 2.0 inches)
due to the influence of a mid to upper level ridge moving and
lingering over the CWA, warming 500 mb temperatures (around -4.5
Celsius) and promoting stability aloft. Nevertheless, the
combination of the tropical wave features, local effects, and
diurnal heating is likely to bring showers and isolated
thunderstorms across the local area.

The flood threat during this period (Sunday through Tuesday) will
remain limited to elevated for most portions of Puerto Rico and the
U.S. Virgin Islands since the most likely scenario shows the
potential of rainfall accumulations enhancing urban and small stream
flooding, with isolated flash floods.

For the rest of the forecast period (Wednesday and Thursday), PWAT
value should remain seasonal, with patches of moisture moving from
time to time. Afternoon convection is likely to develop, but the
flood threat should remain limited.


&&

.AVIATION...
(06Z TAFs)

Mainly VFR conds with VCSH across most TAF sites. RA is expected
across West PR in the afternoon hours. Winds from the East btwn
15 and 25kt with few gusts at around 30 kt after 24/14z, becoming
moderate (10 to 15 kt) aft 24/23z.


&&

.MARINE...

A surface high pressure over the western Atlantic, combined with
the passage of tropical waves, will continue to support moderate
to fresh trade winds through the remainder of the week. These
persistent winds will keep seas choppy to hazardous, with Small
Craft Advisories in effect for most local waters through late
tonight, posing dangers to small craft vessels and inexperience
boaters. Low visibilities due to saharan dust will continue
through at least tonight.

Choppy conditions will prevail for the next several days but for
the boaters knowledge waves are due the interaction between
strong local winds and the ocean. A wave is a local disturbance on
the water surface caused primarily by wind, while a swell is a
series of long, rolling waves that have traveled away from their
wind source and continue moving through the ocean with a more
uniform height and direction.

&&

.BEACH FORECAST...

Breezy to windy conditions will continue to generate choppy to
hazardous seas across the region, maintaining a moderate rip
current risk at many local beaches tonight. While the risk may
vary between low and moderate over the next few days, isolated
strong rip currents can still develop, especially near piers,
jetties and channels, even in areas with a lower risk level. These
conditions pose a threat to swimmers and small watercraft. For
safety, swimming is recommended only at lifeguarded beaches, and
caution is urged for inexperienced swimmers and using floatation
devices.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
433 AM AST Fri Jul 25 2025

.KEY MESSAGES...

* Moderate to fresh trade winds will maintain choppy and locally
hazardous marine conditions for small craft and sustain a
moderate rip current risk at most local beaches through early
next week. Mariners and beachgoers should exercise caution.

* Temperatures will remain above normal, with indices potentially
prompting additional Extreme Heat products.Take proper
precautions to avoid heat related illness.

* A through moving through on Saturday, followed by a strong
tropical wave sunday into Monday, will increase the coverage of
showers and thunderstorms. This will elevate the risk of urban
and small stream flooding.


&&

.SHORT TERM...Today through Sunday...

Isolated to locally scattered showers developed over the
surrounding waters, and due to a slght shift of to wind to the
north, this allowed some of them to move into portions of the
east and north coastal areas of Puerto Rico.

Today...a high pressure system over the western Atlantic will
keep breezy to occasionally windy eat- northeasterly winds in
place through Friday. These winds will continue into early
Saturday as a weak weather disturbance moves from the northeast,
before shifting more from the east with another high pressure.
Starting today and continuing through Saturday, an upper- level
system will increase instability and allow more moisture to move
in. By late Saturday night, a strong tropical wave is expected to
approach the region. This feature will bring a noticeable increase
in tropical moisture and raising the chances for showers and
thunderstorms.

.LONG TERM....Monday through Friday...

Variable conditions are likely to persist during the long-term
forecast, with tropical waves moving over the region during the
first part of the workweek, and patches of moisture moving from time
to time through Friday. But small changes were introduced to the
forecast for Monday and Tuesday. From the latest global model runs,
it seems that the leading edge of the second tropical wave may
approach the region earlier than expected (Monday afternoon instead
of early Tuesday), but uncertainty remains. In terms of impacts,
this tropical wave with PWAT values above normal (2.0 - 2.2 inches)
is expected to bring showers and thunderstorms across the forecast
area. The combination of local effects and the influence of an upper-
level trough northwest of the CWA should enhance deeper convection
activity. Additionally, the Galvez-Davison Index continues to
suggest the potential of isolated to scattered thunderstorms moving
over the local islands. Given these factors, an elevated flooding
risk is expected across most sectors of Puerto Rico and the U.S.
Virgin Islands, especially poorly drained and flood-prone areas.

As the tropical wave retires from the area, a drier air mass should
filter into the region due to the presence of a mid to upper-level
ridge moving north of the region and lingering through early
Thursday. Additionally, as mentioned in the previous discussion, a
Saharan Dust Layer (SAL) may filter into the region as well. Based
on the latest model guidance cross-section, mid-level moisture
should plummet to 10 - 20%. The combination of these weather
features should limit deeper convection activity from Wednesday
onwards. Nevertheless, due to diurnal heating, sea breeze
convergence, and local effects, showers are likely to develop mainly
over western/northwestern Puerto Rico and northeastern Puerto Rico,
including the San Juan Metropolitan Area. Rainfall accumulations are
likely to promote ponding of water over roadways and urban and
poorly drained areas.


&&

.AVIATION...
(06Z TAFs)

Mainly VFR conditions are expected to prevail across all TAF
sites during the next 24 hours. However, trade wind SHRA may
affect TJSJ, TJBQ, and TIST between 25/06Z and 25/14Z. Breezy to
windy conditions will persist, Winds will increase again to 16–20
knots with higher gusts after 25/13Z...becoming moderate (10 to
15 kt) aft 25/23z.

&&

.MARINE...

A surface high pressure over the western Atlantic will continue to
generate moderate to fresh east-northeast trade winds today,
shifting to a more easterly flow by Saturday as another high
develops over the north-central Atlantic. In combination with
passing tropical waves, these winds will lead to choppy seas and
potentially hazardous conditions for small craft. Afternoon
thunderstorms are expected daily across western Puerto Rico and
nearby waters, with showers and thunderstorms activity forecast to
increase on Sunday and into next week as a strong tropical wave
approaches the region.

&&

.BEACH FORECAST...Although winds are slowly decreasing, breezy to
locally windy conditions will continue to produce choppy to
occasionally hazardous seas cross the region, contributing to a
moderate rip currents at many local beaches this morning. Although
the overall risk will vary between low and moderate over the next
few days, isolated stronger rip currents may still develop.
Particularly near piers, jetties, and channels, even in areas
with a lowers risk classifications. For safety, swimming is
recommended only at lifeguarded beaches. Extra caution is advised
for inexperience swimmers and those using flotation devices.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
350 AM AST Sat Jul 26 2025

.KEY MESSAGES...

* An increased risk of urban and small stream flooding is
expected across the local islands on Sunday and Monday as
tropical waves move through the area.

* Heat indices exceeding 100 degrees will continue to prevail
across the forecast area during the next several days.

* There is a moderate risk of rip currents along the northwest
coast of Puerto Rico and Saint Croix.

&&

.SHORT TERM...Today through Monday...

A few high clouds were observed in the sky during the night hours.
Some showers managed to move across the local waters, but impacts to
land were minimal. Temperatures remained a little warm in coastal
areas, in the mid-70s, but managed to cool down to the 60s in the
mountain. In the big picture, there is a high pressure driving the
trade winds from the east, and breezy too, with speeds of 15 to 20
mph. In the flow, some Saharan dust is embedded, so hazy skies are
expected again today. With strong heating, showers and thunderstorms
are expected to fire up in the interior and west, where the risk of
urban and small stream flooding is elevated. Streamers are also
expected to develop from the Virgin Islands, Vieques and Culebra.
These lines of showers will reach eastern Puerto Rico too, but
accumulations are not expected to be too significant.

The pattern will shift for Sunday, as a tropical wave reaches the
region. The envelope of moisture observed in satellite-derived
product show precipitable water values around 2.2 inches, and some
intermittent thunderstorms are also observed by GOES-19 Flash Extent
Density products. As the wave progresses, periods of showers are
expected to first increase in the vicinity of the Virgin Islands in
the overnight hours, gradually moving into Puerto Rico in the
morning and afternoon hours. Rainfall accumulations are expected to
range from 1 to 3 inches, so some localized urban and small stream
flooding can be anticipated, as well as gusty winds within the
thunderstorms. The areas with the highest risk of flooding are the
east-southeat, and the west-northwest.

On Monday, yet another waves will move in. This one does not look as
concentrate as the one for Sunday, but still, showers will manage to
reach portions of eastern Puerto Rico and the Virgin Islands through
the day. Also, with enough sunshine, stronger showers and
thunderstorms are anticipated in the afternoon along the Cordillera
Central, eastern and western Puerto Rico.

The temperature forecast is a little trickier, since it will depend
on how dense the cloud deck of the tropical waves will be. Since the
lowest chances of rain are today, then temperatures should warm up
more, with heat indices surpassing 100 degrees in urban and low-
elevated areas. This level of heat affects primarily those
individuals extremely sensitive to heat, especially when outdoors
without effective cooling or adequate hydration.

.LONG TERM...Tuesday through Saturday...

A mid-level ridge pattern is expected to prevail across the local
islands throughout the forecast period, with some weakening
anticipated on Wednesday and Thursday. At lower levels, a surface
high-pressure northeast of the region will continue to yield
easterly winds for much of the cycle, with a tropical wave moving
across the eastern Caribbean during the weekend. In terms of
precipitable water, lingering moisture is expected on Tuesday,
with a sharp decrease on Wednesday. Although the trades will
continue to bring patches of moisture from time to time on
Thursday and Friday, deep tropical moisture advection is expected
from Saturday night into Sunday, associated with the passage of
the aforementioned tropical wave. Overall, Monday through at least
Friday, moisture will be confined below 850 mb. As a result,
Tuesday is expected to be a transitional day with afternoon
showers and thunderstorms developing across much of central and
western Puerto Rico. Once a drier airmass encompasses the area,
expect a seasonal weather pattern with afternoon showers and
isolated thunderstorms, mainly focused across west Puerto Rico on
Wednesday and Thursday. The intensity and areal coverage of
showers and thunderstorms are expected to increase once again over
the upcoming weekend, associated with the passage of the tropical
wave.

Having said this, the risk for urban and small stream flooding
is expected to increase by the end of the forecast cycle. Warm to
hot temperatures will continue to prevail with heat indices
exceeding 100 degrees each day. The hottest days are likely to be
Wednesday and Thursday. Some haziness is anticipated on Tuesday.

&&

.AVIATION...
(06Z TAFs)

Mainly VFR conditions expected to prevail through the forecast
period. VCSH are expected in the Caribbean Sea and Atlantic
waters, but with no impacts to operations. SHRA and TSRA are
expected for the western Cordillera Central from 17-22Z, with
mountain obscuration expected. After 27/05Z, a tropical wave will
reach TISX terminal, with periods of reduced VIS and low ceilings.
Winds will be from the E at 15-20 kts, with stronger gusts and
sea breeze variations.

&&

.MARINE...

A moderate to locally fresh easterly wind flow will continue to
prevail across the local waters during the weekend into early next
week. A tropical wave will reach the area late tonight into
Sunday, increasing the chance for showers and thunderstorms,
particularly across the Caribbean waters and local passages. A
second tropical wave is forecast to arrive early next week.

&&

.BEACH FORECAST...

Beachgoers can expect a moderate risk of observing life-threatening
rip currents along the exposed beaches in the northwest coast of
Puerto Rico and Saint Croix. In contrast, elsewhere, can expect a
low risk of rip currents. Regardless of the low risk, isolated
stronger rip currents may occur, especially near piers, jetties,
and channels. A tropical wave will reach the area late tonight into
Sunday, increasing the chance for showers and thunderstorms,

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
404 AM AST Sun Jul 27 2025

.KEY MESSAGES...

* A tropical wave will continue to produce showers and
thunderstorms across the region through tonight. The risk of
urban and small stream flooding is elevated across all the
islands. Localized flash flooding and mudslides in areas of
steep terrain cannot be ruled out.

* Another tropical wave, but weaker will stream across the area on
Monday. Regardless, the risk for urban and small stream flooding
will remain elevated due to the expected saturated soils.

* An elevated heat risk will prevail across most coastal and urban
areas of the islands through the workweek. Particularly on
Monday before the onset of afternoon convection and again
on Tuesday.


&&

.SHORT TERM...Tonight through Monday...

The most recent satellite imagery shows the axis of a tropical wave
just to the southeast of Saint Croix, while a second tropical wave
is located a couple hundred of miles to the east of the Lesser
Antilles. Shower activity associated with the first wave has been
increasing in frequency since midnight. The showers have been
moderate to locally strong, but are moving quickly and rainfall
accumulations were not too significant. However, as the wave
advances into the region, showers and thunderstorms will continue to
stream into the Virgin Islands, Vieques, Culebra and the eastern and
southern halves of Puerto Rico in the morning, and into the west in
the afternoon hours. Since it is hard to pinpoint the exact location
that will receive the highest rainfall accumulations, the elevated
risk of flooding was assigned for the whole area. The risk does not
means that it will be raining all day long or that the rain will be
heavy at all times, rather it means that some urban and small stream
flooding, rapid river rises and some mudslides can be anticipated
today. Isolated flash floods cannot be ruled out. Gusty winds are
expected as well.

A second, weaker, tropical wave is anticipated on Monday too. This
wave will bring additional showers for eastern Puerto Rico and the
Virgin Islands in the morning, followed by stronger activity in the
afternoon across the Cordillera Central and western Puerto Rico.
Once again, the likelihood of urban and small stream flooding will
be elevated, but only for these localized areas in west and east
Puerto Rico. Since the cloud deck is expected to be less dense than
today, the heat risk is going to be elevated.

By Tuesday, a mid level ridge builds in, and as the moisture
departs, a drier air mass, with light to moderate concentrations of
Saharan dust will filter in. A trade wind cap inversion will develop
at around 800 mb, so rainfall activity is expected to be more
limited to afternoon convection along the interior and western
Puerto Rico. Winds will pick up too, coming out of the southeast at
15 to 20 mph. With southeast winds, temperatures will be on the
rise, with heat indices above 100 degrees in urban and coastal
areas, and across the valleys of the eastern interior. The expected
level of heat will affect most individuals sensitive to heat,
especially those without effective cooling or adequate hydration.

.LONG TERM...Wednesday through Sunday...

A drier air mass will linger on Wednesday under the influence of a
mid-level ridge extending from the southwestern Atlantic. This
will promote warmer 500 mb temperatures of near -3C, and the
precipitable water content is expected to drop near 1.50 inches.
Therefore, fair weather conditions are anticipated across the
islands, with limited shower development over western PR in the
afternoon hours. Thereafter, the main weather features will be two
tropical waves. The first one on Thursday, with global models
suggesting a weak and disorganized wave that can still bring an
increase in passing showers across the USVI and windward areas of
PR during the morning hours. Then, as the wave moves across the
region during the peak of daytime heating, this will enhance the
diurnal cycle of afternoon convection with showers and isolated
thunderstorms developing over western PR and downwind from el
Yunque into portions of Bayamon, Toa Baja, Dorado and nearby
municipalities. On Friday, a quick drying pattern is expected as
drier air with minor concentrations of Saharan dust filters over
the area. Then, between Saturday and Sunday, model guidance
continues to indicate the passage of the second tropical wave
across the local area. This wave is expected to bring better
tropical moisture with precipitable water content peaking once
again over 2.00 inches. Therefore, increasing the threat for urban
and small stream flooding across all islands.

From Thursday through Sunday, southeasterly trades and higher
dewpoints will increase the heat risk once again across the
northern and western coastal municipalities of Puerto Rico, with
heat indices ranging between 105F-110F in general across these
areas, and particularly from the late morning hours until the
development of afternoon showers.


&&

.AVIATION...

(06Z TAFS)

A tropical wave will move into the islands today, bringing periods
of SHRA and TSRA. Periods of reduced VIS and low ceilings are
expected. SHRA will decrease over the PR terminals around 22-00Z,
but with linger in the vicinity of USVI. The winds will be from the
E at 14-22 kts, but stronger near thunderstorms.


&&

.MARINE...

A tropical wave will continue to produce showers and thunderstorms
across the regional waters through late tonight. These thunderstorms
can produce squalls and locally higher seas. Another tropical wave,
but weaker is forecast to stream across the region on Monday
afternoon. Choppy wind driven seas are expected with the wave
passages. From mid-week onward, moderate to locally fresh east to
southeasterly winds are expected to return as a broad surface high
pressure builds over the far northeastern Atlantic.


&&

.BEACH FORECAST...

Shower and thunderstorm activity will increase across most coastal
areas of the islands today. Periods of moderate to locally heavy
rainfall and occasional lightning strikes are anticipated with
this activity. The risk of rip currents is low, however, life-
threatening rip currents often occur in the vicinity of groins,
jetties, reefs, and piers.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
433 AM AST Mon Jul 28 2025

.KEY MESSAGES...

* Very hot temperatures are expected today and tomorrow today,
especially for areas not receiving rain in the afternoon.

* Moisture from another tropical wave will trigger some passing
showers this morning, followed by stronger showers and
thunderstorms in the afternoon for the interior and west Puerto
Rico.

* Another, stronger, tropical wave could approach during the
weekend, with another round of showers and thunderstorms
expected.


&&

.SHORT TERM...Today through Wednesday...

Most showers and thunderstorms associated with the departing
tropical wave remained over the waters, though some moved inland
over eastern Puerto Rico overnight. The most vigorous activity
affected coastal areas of northeastern Puerto Rico and the
metropolitan area, where radar-estimated rainfall totals since 8 PM
peaked at nearly half an inch. Low temperatures dropped into the 70s
across most areas, with low 80s persisting over far eastern Puerto
Rico, Culebra, and the US Virgin Islands. Winds were generally light
to calm and variable, with gusts of 15–20 mph reported with the
thunderstorms.

A tropical wave will cross the region today, maintaining abundant
moisture and supporting increased showers and thunderstorms through
late tonight. A weak wind surge and drier air will follow, with
sustained low-level winds briefly increasing to 15–20 mph by Tuesday
night. Tuesday into Tuesday night will mark a transition, not only
in moisture levels but also in the overall pattern, as a mid-level
ridge builds north of the area and merges with a broader high-
pressure system over the western Atlantic by Wednesday. This
evolving setup will promote drier air entrainment, subsidence, and
the development of a stronger trade wind cap.

Precipitable water values remain near to well above normal today
(1.9–2.1 inches), supporting scattered to locally numerous showers
and thunderstorms. Southeasterly low-level flow will steer activity
toward northern and western municipalities, including parts of the
San Juan metropolitan area, enhanced by orographic lifting over the
Sierra de Luquillo. Moisture and instability will decrease tonight
into Tuesday but remain sufficient for some afternoon showers and
isolated thunderstorms. By Wednesday, drier air will limit
convection to brief, trade wind–driven showers along coastal areas
and isolated to locally scattered afternoon showers over the west.

Excessive heat is the primary hazard today, particularly in lower
elevations and urban centers, where an Extreme Heat Warning is in
effect. This heat can affect those without adequate cooling or
hydration, impacting vulnerable populations and infrastructure. The
secondary hazard is excessive rainfall and localized flooding,
primarily in the western interior and northwestern Puerto Rico, as
well as the San Juan metro area. Lightning and wind hazards will be
minimal and localized. Overall, except for heat and breezy winds,
most hazards should diminish through midweek as drier, more stable
air prevails.

.LONG TERM...Thursday through Monday...

Surface high pressure over the eastern Atlantic will maintain the
trade wind enhanced for most of the forecast period, with speeds
of 15 to 20 knots. In the flow, there are pockets of Saharan dust
but also weak perturbations that will move at times into the
region. The first perturbation will move across the region on
Thursday, with more Saharan dust coming in on Friday.

The forecast for the weekend is a little uncertain. There is a
stronger tropical wave that should move across the region.
However, the ECMWF solution has the wave crossing the islands on
Saturday, while the GFS shows the wave moving south of the region
on Saturday. For now, the Saturday solution was preferred, with
the highest chances of rain shown. Gusty winds can be anticipated
too with the passage of the wave. Lingering moisture is expected
on Sunday and Monday, although more dust will come into the
islands on Monday.

It is also worth noting that the hot streak will persist,
especially for those days with only localized rainfall, such as
Thursday and Friday. At least Heat Advisories are possible on
these dates, meaning a level of heat that affects most individuals
sensitive to heat.


&&

.AVIATION...
(06Z TAFs)

VFR conditions will generally prevail across all terminals through
the next 24 hours. However, trade wind showers and afternoon
convection may intermittently affect TJSJ and USVI terminals. At
TJBQ, SHRA/TSRA are likely this afternoon, with brief MVFR to IFR
conditions possible between 28/16-22Z. Winds will remain light to
calm and variable overnight, increasing to 10–15 kt after 28/13Z,
then diminishing to 5–10 kt after 28/23Z. Gusty winds expected near
SHRA/TSRA.

&&

.MARINE...
Another tropical wave, will move across the region today, with some
showers and thunderstorms streaming along the local waters. Choppy
wind driven seas are expected with the wave passages. From mid-week
onward, moderate to locally fresh east to southeasterly winds are
expected to return as a broad surface high pressure builds over the
far northeastern Atlantic.

&&

.BEACH FORECAST...

Rip current risk is low today, however, life-threatening rip
current risk can still occur near groins, jetties, reefs, and
piers. Keep in mind that thunderstorms will develop again today,
meaning that there is a risk of lightning within these storms.
Seek shelter if you hear thunder immediately.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
435 AM AST Tue Jul 29 2025

.KEY MESSAGES...


* Another warm day is forecast for the urban and coastal areas
today, with heat indices leading to a limited to elevated heat
threat from 10 AM to 5 PM. Therefore, a Heat Advisory is in
effect.

* Another active afternoon is expected today, with the potential
for showers and isolated thunderstorms across western Puerto
Rico.

* By the upcoming weekend, a tropical wave is expected to
increase the frequency of showers and thunderstorms.


&&

.SHORT TERM...Today through Thursday...

Most showers and thunderstorms associated with a departing tropical
wave remained over the waters overnight, though some moved inland
over eastern Puerto Rico. The most vigorous activity affected
coastal areas of northeastern Puerto Rico and the metropolitan area,
where radar-estimated rainfall totals since 8 PM peaked between half
and three-quarters of an inch. Low temperatures dropped into the 70s
across most areas, with warm lows in the low 80s persisting across
coastal and urban areas of eastern Puerto Rico, Vieques, Culebra,
and the U.S. Virgin Islands. Winds were generally light to calm and
variable but gusty near the thunderstorms.

Trailing moisture from the wave will continue to support showers and
thunderstorms across the region today. In its wake, a drier air mass
accompanied by low to moderate Saharan Dust concentrations will
filter in, steered by gentle to moderate trade winds. This marks a
transition toward more stable conditions, as mid-level ridging
promotes dry air entrainment, increased subsidence, and a
strengthening trade wind inversion over the next day or so. A weaker
tropical wave is forecast to enter the eastern Caribbean by
Wednesday night, bringing a patchy moisture environment and east-
northeasterly winds ahead of its axis. More significant trailing
moisture, driven by moderate to fresh east-southeasterly trades, is
expected to reach the region from Thursday into Thursday night
before the wave dissipates.

Scattered to locally numerous showers and isolated thunderstorms are
expected today, particularly across northern and western
municipalities, including portions of the San Juan metropolitan area
in the afternoon. As hostile conditions set in, convection on
Wednesday will be limited to brief, trade wind–driven showers along
windward areas and isolated to locally scattered afternoon showers
over western Puerto Rico. With a rebound in PWAT values to near-
normal levels, along with cooling mid-level temperatures, a gradual
increase in showers is expected on Thursday.

Excessive heat and rainfall are the primary hazards today. Lower
elevations and urban centers are most susceptible to heat levels
that can impact heat-sensitive individuals, especially those without
effective cooling or adequate hydration. A Heat Advisory is in
effect due to the expected heat indices. In contrast, ponding of
water to localized flooding is likely across the western interior,
northwestern Puerto Rico, and parts of the San Juan metro, where the
heaviest and most frequent rains are expected. Reduced visibility
and air quality due to Saharan dust will affect much of the region.
Lightning hazards are expected to be minimal and localized. While
heat concerns are expected to continue Wednesday, excessive rainfall
and wind-related hazards are likely to return on Thursday.


.LONG TERM... Friday through Tuesday...

An interesting weather pattern is expected across the islands for the
weekend. At the beginning of the period, both the GFS and ECMWF
global models agree that high pressure will dominate the region at
the surface, mostly resulting in an east-southeast wind flow on
Friday. For Saturday and Sunday, the global models presented a
significant discrepancy regarding the timing of the arrival of
abundant tropical moisture associated with an approaching tropical
wave. The ECMWF indicated that the bulk of the moisture would
move westward into the region starting Saturday morning,
surrounding the islands. In the other hand, the GFS shows the
moisture associated with the tropical wave that is moving
westward by Sunday, keeping the deepest moisture over the
Caribbean waters to the south of the CWA. Based on recent latest
model outputs, the forecast suggests a wet and unstable pattern
for the upcoming weekend, with increased showers and
thunderstorms, particularly across the eastern sections, western
interior, and northwestern quadrant. In addition to this pattern,
some Saharan dust intrusion is also forecast, contributing to hazy
skies in areas without rainfall activity.

From Monday through Tuesday, the GFS global model shows a
significant increase in tropical moisture reaching the islands,
leading to a significant increase in moisture and consequently
elevating the heat index from late Sunday through Tuesday.
Therefore, residents can expect warmer and muggy conditions with heat
index values that exceed the threshold for heat- related risks and
an increase the potential of showers across most of the eastern
side of the CWA.

&&

.AVIATION...
(06Z TAFs)

VFR conditions will generally prevail across all terminals through
the next 24 hours. However, trade wind SHRA may intermittently
affect TJSJ through 29/13Z and the USVI terminals through 29/22Z. At
TJSJ and TJBQ, SHRA/TSRA are likely in the afternoon, with brief
MVFR to IFR conditions possible between 28/16Z and 28/22Z. Winds
will remain light to calm and variable, increasing to 10–15 kt after
29/13Z, then diminishing to 5–10 kt after 29/23Z. Gusty winds are
expected near SHRA/TSRA. Saharan dust may also result in reduced
visibilities at times.

&&

.MARINE...

Moisture trailing behind the tropical wave will continue to move
across the islands. A surface high pressure over the central
Atlantic, combined with an induced surface trough, will maintain
east-southeasterly winds, supporting a gradual improvement in
weather conditions. From midweek into the latter part of the
workweek, moderate to locally fresh east to southeasterly winds
are expected to return as a broad surface high pressure builds
over the far northeastern Atlantic.

&&

.BEACH FORECAST...

There is a low risk of rip current across all the coastal areas of
Puerto Rico and the U.S. Virgin Islands today. The risk will
increase to moderate tomorrow in northern areas; therefore,
beachgoers are urged to stay away from non-designated beach areas.

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
432 AM AST Wed Jul 30 2025

.KEY MESSAGES...

* Warm conditions will persist today; therefore, a heat advisory is
in effect from 10 AM to 5 PM for all coastal areas, including
the vicinity of Caguas.

* WET PATTERN EXPECTED FROM LATE FRIDAY INTO THE UPCOMING WEEKEND:
A tropical wave will increase moisture and enhance the potential
for showers and thunderstorms across the islands.

* Today, a low concentration of Saharan dust particles will
remain in place. However, a typical summer pattern is expected,
with afternoon showers likely across the southwestern quadrant.

&&

.SHORT TERM...Today through Friday...

Despite radar Doppler and satellite imagery detecting pockets of
isolated to scattered showers and low-level clouds across the
region, weather conditions over Puerto Rico and the US Virgin
Islands were significantly quiet under mostly clear skies and light
to calm and variable winds. Low temperatures ranged from the lower
60s across the highest elevations of the Cordillera Central to warm
lower 80s persisting across coastal areas of northeastern, eastern,
and southern Puerto Rico, Culebra, and the US Virgin Islands.

A drier air mass, featuring precipitable water values as low as 1.2
inches and low Saharan Dust concentrations, will continue to move
into the region today, steered by moderate trade winds. At the same
time, mid-level ridging will persist, promoting dry air entrainment,
increased subsidence, and a strengthening trade wind inversion
through late tonight. However, a low-to mid-level trough will then
move into the eastern Caribbean, bringing more favorable conditions
and a patchy moisture environment. Winds will be out of the east-
northeast tonight, shifting to a more east-southeasterly direction
on Thursday and continuing into Thursday night before the trough
dissipates. More persistent tropical moisture, associated with the
leading edge of an approaching tropical wave and steered by moderate
to fresh east-northeasterly winds, is anticipated to reach the
region Friday night.

As hostile conditions persist today, convection will be limited
primarily to brief, trade wind–driven showers along windward areas
in the morning. However, diurnal heating and local effects will
prompt shallow, scattered to locally numerous afternoon showers over
southwestern Puerto Rico this afternoon. As conditions become less
hostile, expect increased trade wind shower activity linked to
patches of moisture tonight into Thursday morning, followed by
showers and possible isolated thunderstorms by Thursday afternoon
and evening. A patchy weather scenario is expected again Thursday
night, but with abundant tropical moisture moving in on Friday into
Friday night, along with slightly cooler mid-level temperatures, a
gradual increase in shower and thunderstorm activity is anticipated.

Excessive heat remains the primary hazard today, with a Heat
Advisory in effect for lower elevations and urban centers of Puerto
Rico, which are most susceptible to heat levels that can impact heat-
sensitive individuals, particularly those without access to
effective cooling or adequate hydration. In contrast, flooding is a
secondary hazard today, indicated by ponding of water in roads and
poorly drained areas, as well as a low likelihood of urban and small
streams flooding, primarily in southwestern Puerto Rico. Wind
hazards are expected to be minimal and localized to exposed coastal
areas. While heat will likely remain the primary concern over the
next few days, excessive rainfall and wind-related hazards are
expected to continue, with lightning risks likely to return by
Thursday.


.LONG TERM...Saturday through Wednesday...

A vigorous tropical wave will bring an unstable weather pattern
across Puerto Rico and the U.S. Virgin Islands from Saturday
through Sunday. Abundant moisture associated with this wave will
support a wet pattern, with increased cloudiness and a higher
frequency of showers and thunderstorms. While there remain
discrepancies between the GFS and ECMWF models regarding the exact
timing of the wave’s axis passage, both agree on the potential
for widespread rainfall. The most significant impacts are expected
on Sunday, supported by favorable instability from an upper-level
low just northwest of the region, with 500 mb temperatures
ranging from -6 to -7°C, as shown by the Gálvez-Davison Index
values. The flood threat will be elevated, particularly across the
eastern slopes, western interior, and northwestern and
northeastern Puerto Rico due to persistent shower activity and
saturated soils. The U.S. Virgin Islands will mostly observe
showers early on Saturday and Sunday. Therefore, for the islands,
the flood risk will remain limited.

Trailing moisture will linger into Monday, keeping conditions
humid and favorable for showers across parts of the islands. These
conditions will lead to mostly warm and muggy conditions, leading
heat indices to surpass 100 degrees in most of the coastal and
urban areas. However, a drier and more stable air mass with
Saharan dust is forecast to arrive by Tuesday, leading to
improving conditions. This will result in hazy skies and reduced
shower activity through midweek. By Wednesday, as the Saharan dust
moves out of the area, a more seasonal weather pattern is
expected to resume, characterized by typical afternoon convection
mainly across the interior and western sections of Puerto Rico
under light to moderate easterly trade winds.

&&

.AVIATION...
(06Z TAFs)

VFR conditions will generally prevail across all terminals through
the next 24 hours. However, trade wind SHRA may intermittently
affect TJSJ and USVI terminals after 30/13Z. At TJBQ and TJPS,
afternoon SHRA/TSRA may result in brief MVFR conditions between
30/16Z and 30/23Z. Winds will remain light to calm and variable,
increasing to 10 to 15 kt with occasional higher gusts after 30/13Z,
then diminishing to 5 to 10 kt after 30/23Z.

&&

.MARINE...

A surface high pressure over the central Atlantic, in combination
with an induced surface trough, will continue to promote gentle to
moderate east-southeasterly winds. Today, portions of the
Caribbean waters may experience moderate to locally fresh winds,
leading to slightly choppy marine conditions. By Friday, an
approaching tropical wave and its leading edge will increase winds
across the local waters, enhancing the potential for thunderstorms
and resulting in localized hazardous marine conditions.

&&

.BEACH FORECAST...

There is a low risk of rip currents across all coastal areas of
Puerto Rico, including Culebra, Vieques, and the U.S. Virgin
Islands. A slight to moderate increase in risk is forecast for St.
Croix tomorrow. Although coastal conditions remain generally
favorable, residents and visitors are urged to exercise caution,
especially along the north-facing beaches of Puerto Rico, where
rip currents are more likely. Additionally, thunderstorms are
possible again today across some coastal areas. Residents are
advised to seek shelter if a thunderstorm approaches the coastline
or moves over nearby waters.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
400 AM AST Thu Jul 31 2025

.KEY MESSAGES...

* A weak tropical wave will increase shower activity today.

* Breezy winds will create choppy seas and a moderate rip current
risk along north- and east-exposed beaches over the next few
days.

* A Saharan Air Layer with minor to moderate dust concentrations
will bring hazy skies and deteriorate air quality on Friday.

* A wetter pattern is expected over the weekend into early next
week with the passage of a vigorous tropical wave, increasing
the potential for flooding.


&&

.SHORT TERM...Today through Saturday...

Doppler radar and satellite imagery detected lingering afternoon
showers over southwestern Puerto Rico during the evening, along
with pockets of isolated to scattered showers and low-level clouds
drifting inland over windward areas from the surrounding waters
overnight. Despite this activity, overall weather conditions
across Puerto Rico and the US Virgin Islands remained generally
quiet, with mostly clear skies and light to calm, variable winds.
Minimum temperatures ranged from the lower 60s across the highest
elevations of the Cordillera Central to the lower 80s along
exposed coastal areas of northeastern, eastern, and southern
Puerto Rico, as well as across Culebra and the US Virgin Islands.

A disturbance will move into the northeastern Caribbean today and
cross the area through tonight, creating more favorable
conditions for convection within a patchy moisture field. A robust
tropical wave will follow, with its axis crossing the region
Saturday morning. Winds will be from the east- southeast today and
tonight, shifting from the east on Friday, then gradually
aligning with the wave’s flow on Saturday. Moisture levels will
range from near- normal today to below-normal tonight, then
increase gradually, peaking well above normal by Saturday morning.
Meanwhile, a Saharan Air Layer with low to moderate dust
concentrations is expected to bring hazy skies and deteriorate air
quality on Friday. Abundant tropical moisture, along with cooler
mid-level temperatures, is expected to spread across the region
Saturday into Saturday night.

Today, expect trade wind showers this morning across windward
areas, followed by scattered to locally numerous showers and
isolated thunderstorms this afternoon, mainly across northwestern
Puerto Rico. A similar pattern is expected tonight into Friday
afternoon, with activity suppressed in some areas by Saharan
dust. Showers and thunderstorms will increase thereafter, with
more widespread and organized rainfall likely on Saturday as
conditions become most favorable for deep convection. Flood risk
will also increase—from minor ponding and localized flooding today
to a higher potential for urban and small stream flooding on
Saturday. Isolated flash flooding is possible, particularly in
areas experiencing persistent heavy rainfall.

Excessive heat remains the main hazard today, with a Heat Advisory
in effect for lower elevations and urban centers of Puerto Rico.
While flooding is a secondary concern today, it is expected to
become more significant later in the period with the passage of
the tropical wave. Lightning and wind hazards will remain
minimal, mainly limited to isolated thunderstorms and exposed
coastal areas, respectively.

.LONG TERM...Sunday through Thursday...

The wet and unsettled weather pattern is expected to continue
early next week through at least Wednesday, becoming variable on
Thursday. High moisture content associated with a vigorous
tropical wave should linger through at least Monday, enhancing
shower and thunderstorm activity across the area. Based on the 12z
deterministic guidance of the GFS and ECMWF, PWAT values are
likely (50 - 60%) to exceed the 75% percentile (2.0 - 2.2 inches),
with a low chance of reaching 2.4 inches. From the latest model
guidance, high moisture content in the low to mid levels will
increase lapse rates (700 mb) to above climatological values
(around 6.5 C/km). Additionally, an upper-level trough approaching
the region and lingering through Tuesday could cool mid-level
temperatures (between -7 and -8 Celsius), promote instability
aloft, and enhance deeper convection activity. From the latest
Galvez-Davison Index (GDI) run, there's potential of observing
isolated to scattered thunderstorms across the CWA from Sunday
through Tuesday. Nevertheless, the latest NASA GEOS-5 GMAO Dust
Extinction product shows a dense Saharan Air Layer (SAL) that may
move over the local area by Monday. The interaction of these
particles with the tropical wave introduces uncertainty to the
forecast; nevertheless, the flooding risk will remain elevated on
Sunday through Wednesday.

By late Wednesday into Thursday, a drier air mass should filter
into the region, reducing PWAT to season values (1.5 - 1.7
inches). Nevertheless, patches of moisture may arrive from time to
time over the CWA and, combined with diurnal heating and local
effects, will likely enhance shower and thunderstorm activity,
mainly over northwestern Puerto Rico. Rainfall accumulations may
promote mostly ponding of water over roadways, urban, and poorly
drained areas, along with urban and small streams flooding.


&&

.AVIATION...
(06Z TAFs)

VFR conditions will prevail across all terminals during the next
24 hours. However, passing trade winds SHRA may intermittently
affect the USVI terminals throughout the period, and TJSJ after
31/23Z. At PR terminals, afternoon SHRA/TSRA could result in brief
MVFR conditions between 31/16Z and 31/23Z. Winds will remain light
and variable overnight, increasing to 10–15 kt with occasional
higher gusts after 31/13Z, then diminishing to 5–10 kt after
31/23Z.


&&

.MARINE...

A surface high-pressure system over the central Atlantic, combined
with a vigorous tropical wave, will promote moderate to locally
fresh winds over the next few days, maintaining choppy marine
conditions across portions of the local waters. From Friday into the
weekend, the wave will increase the potential for thunderstorms and
contribute to localized hazardous marine conditions.


&&

.BEACH FORECAST...

Breezy conditions will also sustain a moderate rip current risk at
selected beaches of northwestern Puerto Rico, Culebra, and Saint
Croix. While this moderate risk is expected to spread across most
local beaches over the next few days, isolated stronger rip
currents may still occur in areas currently at low risk—especially
near piers, jetties, and channels. Swimming is safest at
lifeguarded beaches, and caution is advised for inexperienced
swimmers and anyone using flotation devices.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
328 AM AST Fri Aug 1 2025

.KEY MESSAGES...

* A tropical wave will cross the islands late Friday and on
Saturday, increasing the frequency of showers and thunderstorms.
Urban and small stream flooding and lightning is expected to be
the main hazard associated with this wave.

* Hot summer temperatures are expected to continue each day, with
heat indices above 100 degrees each afternoon along urban and
coastal areas in the islands.

* Saharan dust is expected on Monday, resulting in hazy skies.

&&

.SHORT TERM...Today through Sunday...

Isolated to scattered showers over the waters moved onshore at times
during the night hours. An area of stronger showers and increased
cloudiness, associated with a surface perturbation, began moving
near or over St. Thomas and St. John by 02/05z. However, only
minimal rainfall accumulations were detected with this activity.
Similar weather conditions will persist through the morning hours,
with variably cloudy skies and isolated showers passing over
windward coastal areas as the surface perturbation continues to
move westward. Trace amounts of suspended Saharan dust
particulates will also contribute to hazy skies, particularly in
areas with limited shower activity. During the afternoon hours,
above-normal moisture associated with the surface perturbation,
combined with diurnal heating, is expected to enhance
orographically driven convection, primarily across the interior
and northwestern parts of Puerto Rico, resulting in periods of
heavy showers and isolated thunderstorms across that
region.

Additionally, hot temperatures combined with humid conditions
will once again result in high heat index values, increasing the
heat threat across coastal and urban areas. Therefore, a Heat
Advisory has been issued for Puerto Rico. Although Heat Advisories
are not in effect for Vieques, Culebra, and the U.S. Virgin
Islands, heat index values above 100F can still be expected,
resulting in a limited heat threat for those areas. Residents and
visitors are urged to stay hydrated, avoid prolonged exposure to
the sun, and limit strenuous outdoor activities during the hottest
parts of the day.

For the remainder of the short-term forecast, weather conditions are
expected to deteriorate as a tropical wave with a broad moisture
field, with axis currently located near 52.7W, engulfs the
forecast area. Columnar moisture is forecast to surge, with
precipitable water values potentially exceeding 2.25 inches by
Saturday morning. Model guidance also suggests cold air advection
at mid to upper levels, along with a reduction in 250 mb height
fields, which will enhance dynamical instability throughout the
weekend. The 700–500 mb lapse rate is expected to steepen
significantly by Sunday night, reaching well above normal
climatological values. This pronounced instability will further
support the development of deep convection. As a result, the areal
coverage of strong showers and thunderstorms is expected to
increase across the region.

Given the expected unstable and wet weather conditions, the risk of
flooding will increase across the region over the coming days.
Localized urban and small stream flooding, as well as isolated flash
flooding events, will become increasingly likely, with the potential
for rapid river rises and minor landslides in steep terrain.
However, some uncertainty remains regarding the extent of afternoon
convection, as it will depend largely on cloud coverage. Increased
cloudiness could suppress surface heating and, consequently, limit
convective development over interior and western Puerto Rico. If
this scenario materializes, the greatest flooding threat would
likely be confined to eastern Puerto Rico, including Vieques,
Culebra, along with the U.S. Virgin Islands. Residents in flood-
prone areas should remain alert and prepared for sudden changes in
weather.

.LONG TERM...Monday through Friday...

After the moisture field from the tropical wave departs on Monday, a
low to mid-level ridge builds, with a deep southeasterly wind flow
established. This will cause temperatures to soar, with elevated to
significant heat indices across the local islands. Saharan dust will
move in too, so hazy skies are anticipated too. Then, on Tuesday,
the winds will turn from the northeast as a trough moves north of
the region. This trough will not have too much moisture to work
with, but shallow patches of moisture will stream from the Atlantic
waters in to the local islands, while afternoon convection is
anticipated for the western Cordillera Central and southwestern
Puerto Rico.

By the middle and latter part of the week, the surface high will
reform across the western Atlantic, maintaining the trade winds out
of the or east-southeast at 15 to 20 mph. Moisture will be limited
to the lowest levels of the atmosphere, as dry air filter in at the
mid levels. In general, the weather will be typical, with passing
showers moving over the east of Puerto Rico and the Virgin Islands
in the morning, and showers and thunderstorms anticipated each
afternoon along the interior and western Puerto Rico. Heat indices
are likely to remain elevated for most of the period, with potential
heat advisories each day. With these high temperatures, individuals
sensitive to heat, especially those without effective cooling or
adequate hydration could be the most affected.


&&

.AVIATION...

Mostly VFR conds expected through the forecast period. SCT SHRA will
cause VCSH across the local terminals through 01/15Z. Thereafter,
SHRA/ ISOL TSRA could affect areas near the vicinity of TJBQ though
01/22z. Some HZ Winds will be increasing this morning, at around
15kt and gusty by 01/14Z, from the ESE, with some sea breeze
variations. HZ due to Saharan dust, but VSBY will remain above 6SM.
A tropical wave moving to the area will result in SHRA and VCTS for
TIST, TISX, TJSJ, causing some briefly MVFR conditions with the
heaviest activity, mostly aft 02/00z.

&&

.MARINE...

A surface high-pressure system over the central Atlantic, combined
with a vigorous tropical wave, will promote moderate to locally
fresh winds over the next few days, maintaining choppy marine
conditions across portions of the local waters. Starting late today
into the weekend, the tropical wave will increase the potential for
thunderstorms and contribute to localized hazardous marine
conditions.

&&

.BEACH FORECAST...

Winds out of the east at 15 to 20 mph will maintain a moderate rip
current risk for the beaches facing the northern coast of Puerto
Rico, Vieques, Culebra, and Saint Croix.

As a tropical wave approaches this weekend, the risk of lightning
strikes will increase, since thunderstorms will stream at times
across the local beaches.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
310 AM AST Sat Aug 2 2025

.KEY MESSAGES...

* A vigorous tropical wave will cross the region today, bringing
periods of heavy showers and thunderstorms to the islands. Stay
alert for lightning, sudden downpours, and the potential for
localized flooding.

* Normal to above-normal temperatures, combined with high humidity,
will result in persistently elevated heat index values, especially
on Sunday. The heat threat could reach significant levels at times
across lower elevations and urban areas, posing a concern for
vulnerable populations such as the elderly, children, and those
with pre-existing health conditions.

* Low to moderate concentrations of Saharan dust are expected to
return from Sunday night into Monday, leading to hazy skies and
deteriorating air quality.

&&

.SHORT TERM...Today through Monday...

As of tonight, the frequency of passing showers increased across the
local islands as a tropical wave continued to approach the region.
Rainfall accumulations from the initial bands of moisture ranged
between 0.05 and 0.15 inches, mainly across the U.S. Virgin Islands
and eastern Puerto Rico. The most intense rainfall and thunderstorm
activity developed over the Anegada Passage, prompting the issuance
of a Marine Weather Statement. Besides that, the minimum
temperatures ranged from the upper 70s to low 80s in coastal and
urban areas, and from the upper 60s to low 70s in rural and
mountainous regions. Winds were generally from the northeast at 5 to
10 mph, with occasional higher gusts near heavier showers.

As the tropical wave continues to move westward, deep tropical
moisture will persist across the region, with precipitable water
values expected to peak between 2.00 and 2.40 inches. This will
support frequent showers and isolated thunderstorms across the U.S.
Virgin Islands and eastern Puerto Rico through the early morning
hours. By the afternoon, additional convection is expected to
develop across central and northwestern Puerto Rico due to the
available moisture from the tropical wave, daytime heating, and
local effects. At this time, the ELEVATED flooding concerns with
urban and small stream flooding are likely, particularly in areas
with poor drainage or already saturated soils, for Puerto Rico,
Vieques, Culebra, and Saint Thomas. While, Saint Croix and
southwestern Puerto Rico has a limited flooding risk, with ponding
of water and minor flooding possible in low-lying or poorly drained
areas. Residents and visitors are advised to stay informed and plan
accordingly, especially when participating in outdoor activities
today. Additionally, conditions should remain hot and humid through
the weekend, with near to above-normal 925 mb temperatures. Daytime
highs will range from the upper 80s to low 90s in coastal and urban
areas, with heat indices reaching dangerous levels due to the
combination of high temperatures, moisture, and easterly winds.

By Monday, as the tropical wave exits the region, a strengthening
low- to mid-level ridge will establish a deep southeasterly wind
flow. This pattern will lead to even hotter conditions across the
local islands, with elevated to significant heat indices. In
addition, a plume of Saharan dust is expected to arrive, resulting
in hazy skies and drier conditions to start the workweek.

.LONG TERM...Tuesday through Saturday...

The long-term forecast begins with lingering instability aloft as an
upper-level low continues to exit the forecast area. Although cooler
500 mb temperatures will lead to steeper lapse rates, below-normal
moisture levels will somewhat limit shower activity across the
region. Nevertheless, surface heating, sea breeze convergence, and
orographic lifting will be sufficient to compensate for the reduced
moisture, resulting in afternoon convection over interior and
western portions of Puerto Rico. Elsewhere, lingering suspended
Saharan dust will lead to hazy skies and limited shower activity.

Dynamic instability will persist on Wednesday as an induced surface
trough moves westward and crosses the northeastern Caribbean. The
areal coverage of showers and thunderstorms is expected to increase
during this period, aided by near-normal moisture converging in the
region.

For the remainder of the long-term forecast, weather conditions will
be variable, with marginal instability. This will be due to a series
of weak troughs crossing the region, combined with below-to-near-
normal moisture content. Alternating periods of fair weather,
showers, and thunderstorm activity will follow the typical seasonal
weather pattern. Showers will move onshore at times over windward
coastal areas during the night and morning hours, while shower and
thunderstorm development is expected over the interior and western
portions of Puerto Rico during the afternoon. The southern coastal
areas of Puerto Rico are likely to continue experiencing abnormally
dry conditions throughout the period, with only occasional, isolated
showers, which are likely to be insufficient to bring significant
relief to the region.

The forecast period will also be characterized by hot temperatures,
as 925 mb temperatures fluctuate between near-normal and above
climatological normals. These above-normal temperatures, combined
with humid conditions, will result in persistently high heat index
values. As a result, Heat Advisories, or even Warnings, cannot be
ruled out throughout the period. Residents and visitors are advised
to stay hydrated, limit outdoor activities during peak heat hours,
and monitor official updates for potential heat-related alerts.


&&

.AVIATION...
[06Z TAF]

With the passage of the tropical wave, TSRA is anticipated to affect
TIST and TJSJ through at least 02/15, causing a brief period of MVFR
conditions with the heaviest Tstorm from time to time. Aft 02/17
SHRA/ ISOL TSRA could affect areas near the vicinity of TJBQ and
TJPS through 02/23z. Winds will gradually shift from the ENE to the
ESE as the wave moves across the islands.

&&

.MARINE...

A surface high-pressure over the central Atlantic, combined with a
vigorous tropical wave, will promote moderate to locally fresh winds
through the weekend. Seas of up to 7 ft are likely for the offshore
Atlantic waters where a Small Craft Advisory is in effect through
this evening. The tropical wave will continue to affect the regional
waters today, with lingering effects expected into tomorrow,
increasing the frequency of showers and thunderstorms throughout the
weekend. Hazy skies due to the arrival of Saharan dust are
anticipated on Monday.

&&

.BEACH FORECAST...

Shower and thunderstorm activity due to a tropical wave will
continue to affect some coastal areas of the islands on occasion
today. Periods of moderate to locally heavy rainfall and occasional
lightning strikes remain possible with this activity. Winds out of
the east northeast at 17 to 23 mph will maintain a moderate rip
current risk for the beaches facing the northern coast of Puerto
Rico, Culebra, and Saint Croix.

Given the potential for thunderstorms, beachgoers are advised to
take appropriate lightning safety precautions. Lightning can strike
with little warning, particularly near open water or along the
shoreline. At the first sign of thunder or lightning, all beach and
water activities should be stopped immediately. Seek shelter in a
well-constructed building or a hard-topped vehicle, and wait at
least 30 minutes after the last sound of thunder before resuming
outdoor activities.

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
329 AM AST Mon Aug 4 2025

.KEY MESSAGES...

* Hazy skies associated with the arrival of Saharan dust will
lead to reduced visibility and deteriorated air quality, today.

* Once again, high heat indices will prevail today.

* We encourage citizen and visitors to continue to monitor the
long-term forecast as the National Hurricane Center is
monitoring a tropical wave across the Central Tropical Atlantic
with a 50 percent chance of development in the next 7 days.

&&

.SHORT TERM...Today through Wednesday...

Satellite and Doppler radar data indicated clear to partly cloudy
skies over the islands, with occasional passing showers over eastern
Puerto Rico during the nighttime hours. Overnight low temperatures
were one or two degrees warmer than in previous days, with
temperatures above 80 degrees Fahrenheit in coastal areas of the San
Juan metropolitan area, eastern and southern Puerto Rico, and the
local islands. Coastal observation sites and local buoys have also
recorded warm low temperatures, hovering around 83-84 degrees. Winds
were mainly light to calm and variable.

Satellite-derived precipitable water imagery shows a gradient of
moisture, with a moist air mass over Puerto Rico and a drier one
east of the Virgin Islands. This drier air mass will continue moving
westward over the local islands. The GEOS-5 dust extinction model
indicates a low to moderate Saharan Air Layer also reaching the
area, resulting in hazy skies. This dust is expected to linger into
tonight. With fewer clouds and less rain activity than yesterday,
temperatures are expected to soar once again, with hazardous heat
indices anticipated. A Heat Advisory has been issued for coastal and
urban areas of Puerto Rico. A limited heat risk will persist for
Vieques, Culebra, and the U.S. Virgin Islands. Residents are advised
to stay hydrated and take breaks from the sun, especially as air
quality deteriorates due to the Saharan dust.

A surface high-pressure centered north of the islands will also
enhance the steering flow, with winds from the east-southeast at 17
to 22 mph and occasional stronger gusts. Despite the presence of a
drier air mass, some showers will still move through at times, and
additional activity could develop in the afternoon. Strong daytime
heating may lead to isolated thunderstorms, mainly across
northwestern Puerto Rico this afternoon.

For the remainder of the short-term forecast period, as the Saharan
dust departs, some moisture is expected to filter in from the east.
Precipitable water values will increase from below-normal to near-
normal levels. Additionally, weak troughing aloft and a surface-
induced perturbation crossing the area by Wednesday could result in
a slight uptick in shower activity. Low-level winds will weaken
slightly but remain from the east at around 15 mph. As is typical
with the diurnal pattern of shower development, morning showers will
favor eastern Puerto Rico and the Virgin Islands, while stronger
convection is expected to develop over the interior and western
portions of Puerto Rico during the afternoon hours. This could lead
to an elevated risk of urban and small stream flooding.


.LONG TERM...Thursday through Monday...

The inherited forecast remains on track, with improving weather
conditions expected by Thursday. Mid-level dry air will dominate,
and low-level moisture will drop to below-normal levels,
increasing overall atmospheric stability. Despite this, isolated
to scattered showers are forecast from time to time, particularly
across the windward areas and western sections of Puerto Rico
during the afternoon hours, driven by diurnal heating and sea
breeze convergence. Through Friday, model guidance continues to
suggest 925 mb temperatures near or above climatological normals.
This indicates that hot daytime temperatures will persist.
Combined with sufficient low-level moisture, heat index values
exceeding 100°F are likely. As a result, a limited to elevated
heat risk is expected for coastal and urban areas, especially
during peak afternoon hours. A localized significant heat threat
cannot be ruled out.

From Saturday into Monday, forecast confidence decreases slightly,
but there is general agreement on a gradual increase in moisture and
atmospheric instability. This trend is associated with the approach
of a Tropical Upper Tropospheric Trough (TUTT) north of the area. By
Monday, global models diverge in their solutions as the Global
Forecast System (GFS) depicts a vigorous tropical wave
approaching the northeastern Caribbean, combining with the TUTT to
enhance instability and increase rainfall potential, and the
European Centre for Medium Range Weather Forecast(ECMWF), on the
other hand, suggests possible tropical development, with the
system steering northward before reaching the region and weakening
rapidly.

At this time, the forecast leans slightly toward the GFS scenario,
which implies a transition into a wetter pattern late in the weekend
into early next week. This would bring a gradual deterioration in
weather conditions and a rising flood threat across Puerto Rico and
the U.S. Virgin Islands. The National Hurricane Center is now
monitoring this tropical wave over the Central Tropical Atlantic and
is giving it a 50 percent chance of development in the next 7
days. However, due to ongoing uncertainty in model guidance, it
remains too early to specify exact impacts. Residents are strongly
encouraged to stay informed and monitor future forecasts as we
move closer to early next week.

&&

.AVIATION...
(06Z TAFS)

Mainly VFR conditions across the terminals. Winds will be mainly
from the ESE at up to 12 to 18 kts aft 4/13Z with sea breeze
variations and higher gusts. Afternoon TSRA/SHRA are forecast for NW
PR, which can affect TJBQ, at around 4/17Z-22Z. This can promote
brief MVFR conditions. Brief VCSH across other terminals possible
during the period. HZ across the terminals with increasing Saharan
Dust today may reduce VIS.

&&

.MARINE...

A surface high pressure over the central Atlantic will promote
moderate to locally fresh winds through early this week. Hazy
skies are anticipated today due to the arrival of Saharan dust.

&&

.BEACH FORECAST...

The moderate risk of rip currents along the norther coast and St.
Croix will continue through at least tomorrow, with a low risk
elsewhere. The north- central to northwestern PR are forecast to
remain under a moderate chance of rip currents through early
Tuesday. Even if the risk for rip currents is low, life-
threatening rip currents often occur in the vicinity of groins,
jetties, reefs, and piers. Deteriorated air quality is forecast
today as a plume of saharan dust affects the islands.

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
423 AM AST Tue Aug 5 2025

.KEY MESSAGES...

* Today, afternoon convection is expected to develop across the
interior and southwestern portions of Puerto Rico, resulting in
showers and isolated thunderstorms.

* Winds will be from the east-northeasterly today due to weak
trough aloft and a surface-induced perturbation. This could
promote somewhat lower temperatures today.

* A tropical wave over the eastern tropical Atlantic continues to
have a 50 percent formation chance in the next 7 days. We
encourage citizens and visitors to continue to monitor updates
from the National Hurricane Center (TWOAT) and from NWS San
Juan.

&&

.SHORT TERM...Today through Thursday...

Mostly fair weather prevailed through the night, with clear to
partly cloudy skies. A few passing showers moved onshore at times
from the local waters across the eastern and northeastern coastal
areas of the islands, but rainfall accumulations were minimal to
none. A similar weather pattern is expected to persist throughout
the remainder of the morning hours. Temperatures across north-
central, western, and southwestern Puerto Rico have remained in the
upper 70s. In contrast, slightly warmer-than-normal temperatures
persisted across eastern Puerto Rico and the smaller islands during
night hours, holding in the low 80s. A surface-induced trough
located northeast of the forecast area has shifted winds to a more
northeasterly direction. This, combined with reduced cloud cover, is
expected to bring slightly lower temperatures before sunset.

Today, the aforementioned surface trough, induced by an upper-level
shortwave trough, will dominate weather conditions across the
region. Precipitable water (PWAT) values are expected to rise from
below-normal levels to near climatological normals, reaching close
to 1.9 inches, as the surface trough moves over the area from the
northeast. Under an east-northeasterly steering wind flow, afternoon
convection is expected to develop across the interior and
southwestern portions of Puerto Rico, resulting in showers and
isolated thunderstorms.

On Wednesday, as the shortwave trough exits the region, some mid-to-
upper-level ridging is expected to build in, bringing slightly more
stable conditions aloft. Temperatures at 500 mb are forecast to warm
from around -7C today to -4C by midday tomorrow. However, sufficient
columnar moisture will likely offset the increasing mid-level
stability, allowing for continued convective development. Steering
flow is also expected to shift more easterly by tomorrow, focusing
afternoon convection mainly across the interior and western sections
of Puerto Rico. Both afternoons may see localized urban and small
stream flooding in these areas. Elsewhere, a few passing showers may
affect eastern Puerto Rico and the U.S. Virgin Islands, but impacts
should be minimal, mainly limited to ponding on roadways and poor
drainage areas. Thursday is expected to be the least active day, as
stability aloft persists and trade winds bring a dry slot over the
northeastern Caribbean. However, diurnal heating and sea breeze
convergence may still trigger localized afternoon convection over
western Puerto Rico, though any activity should be short-lived
overall.

In terms of heat, the northeasterly wind flow will result in near-
normal temperatures today, with some limited heat impacts still
possible across urban and coastal areas. However, shifting winds
tomorrow and through the remainder of the short-term forecast period
could bring hotter conditions once again, potentially prompting the
issuance of Heat Advisories or even Extreme Heat Warnings if
warranted. Stay tuned for further updates.


.LONG TERM...Friday through Tuesday...

The latest model guidance continues to suggest Friday as the warmest
day of the long-term period with 925 mb temperatures in the 75th
percentile or above climatological normals with heat index values
exceeding 100°F. As a result, a limited to elevated heat risk is
expected for coastal and urban areas, especially during peak
afternoon hours. A localized significant heat threat cannot be
ruled out. The 500mb temperatures should remain around -4 to -2
degrees Celsius, and the overall precipitation values below normal
for this time of the year, allowing the stable and fair weather
conditions to prevail.

Heading into the weekend, conditions will gradually become wet and
unstable as a Tropical Upper Tropospheric Trough (TUTT) begins to
establish to the northeast of the forecast area by Saturday. This
feature will enhance moisture and instability, leading to
occasional showers across the windward sectors of Puerto Rico and
the US Virgin Islands, with isolated afternoon showers and
thunderstorms over western Puerto Rico through Sunday.

Looking into early next week, model solutions continue to disagree
regarding the position, development, and timing of the tropical
wave now over the eastern tropical Atlantic. The Global Forecast
System (GFS) depicts a vigorous tropical wave approaching the
northeastern Caribbean, combining with the TUTT to enhance
instability and increase rainfall potential, while the European
Center for Medium Range Weather Forecasts (ECMWF) does not support
tropical development. The National Hurricane Center currently
gives the system a 50% chance of tropical development within the
next 7 days as it moves west-northwestward across the central
Atlantic.

Our forecast currently leans toward the GFS scenario, which
favors a transition to a wetter pattern early next week,
increasing the potential for deteriorating weather and rising
flood threats across Puerto Rico and the US Virgin Islands.
However, uncertainty remains high, and it is still too early to
specify exact impacts. Residents and visitors are strongly
encouraged to stay informed and monitor the latest forecast
updates as forecast confidence is expected to increase in the
coming days.

&&

.AVIATION...
(06Z TAFS)

VFR conditions expected bfr 05/17Z today. Then, SHRA and TSRA are
expected to develop along the Cordillera Central, spreading toward
the SW coastal areas. This could lead to periods of reduced VIS and
low ceilings along TJPS. Winds will be 13-17 kts from the ENE, but
with variations due to sea breezes and outflows from TS.

&&

.MARINE...

A surface high pressure over the central Atlantic will continue to promote
gentle to moderate winds. Winds will turn slightly to the east-
northeast on Tuesday as an induce surface perturbation move into the
islands.

&&

.BEACH FORECAST...

The risk of rip current should remain moderate along the
northwestern beaches of PR through tonight. There is a low risk
elsewhere. Even if the risk for rip currents is low, life-
threatening rip currents often occur in the vicinity of groins,
jetties, reefs, and piers. Deteriorated air quality is forecast to
continue tonight as a plume of saharan dust affects the islands.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
458 AM AST Wed Aug 6 2025

.KEY MESSAGES...

* Passing showers will continue to filter across eastern Puerto
Rico and the U.S. Virgin Island through the morning hours. There
is an elevated risk of flooding (urban and small stream
flooding) across western Puerto Rico, particularly for the
afternoon hours.

* Once again, temperatures will be warm, with heat indices
exceeding 100 degrees across Puerto Rico and the US Virgin
Islands.

* The tropical wave over the eastern tropical Atlantic remains
with a 50 percent chance of formation chance in the next 7 days
and a 10 percent in the next 48 hours. We encourage citizens and
visitors to continue to monitor updates from the National
Hurricane Center (TWOAT) and from us, NWS San Juan, your local
forecast office.

&&

.SHORT TERM...Today through Friday...

A northeasterly steering flow, driven by a surface perturbation with
its axis just east of the area, promoted showery weather across the
northern and northeastern coastal areas of the islands. However,
most locations received less than half an inch of rainfall.
Satellite imagery shows that, despite the passing showers, skies
remained generally light to moderately cloudy, with no significant
or sustained cloud deck. A similar weather pattern is expected, with
passing showers over the waters frequently moving onshore through
the rest of the morning hours. Winds will gradually shift more
easterly by 09Z and east-southeasterly by 12Z as the surface
perturbation moves across the forecast area. Afternoon convection
will now be confined to the interior and western/northwestern
Puerto Rico, with showers and thunderstorms increasing the
potential for urban and small stream flooding, frequent lightning,
and gusty winds in that region.

Moisture levels will fluctuate between below-normal and near-normal
values for the remainder of the short-term period. At upper levels,
a ridge aloft will dominate, leading to increased dynamical
stability through at least Friday. A warming trend at mid-levels
will result in 500 mb temperatures rising to about two standard
deviations above climatological normals for this time of year,
reaching around -3.5 C. Thursday is expected to be the least active
day, as mid-level drying reduces relative humidity to below 15%
before rebounding by the evening. Despite this trend, model guidance
indicates that diurnal heating and sea breeze convergence will still
be sufficient to support the development of showers and possibly a
few very short-lived thunderstorms over western and northwestern
Puerto Rico.

On Friday, the areal coverage of showers and thunderstorms during
the afternoon will be slightly broader than on Thursday across the
same region. This is due to increasing moisture between 700-500 mb,
which will enhance vertical mixing across the area. Overall, expect
a limited flooding threat during the afternoon hours, with Thursday
being the least active day in terms of convection.

With the southeasterly wind component, temperatures today are
expected to rise to above-normal levels. Combined with near-to-
slightly above-normal moisture, this will lead to soaring heat index
values throughout the day. However, by 18Z, a narrow dry slot is
forecast to move over the area, potentially bringing some relief
from the high heat indices during the afternoon hours. Nevertheless,
a Heat Advisory has been issued for urban and coastal areas of
Puerto Rico, with a limited heat threat for Vieques, Culebra, and
the U.S. Virgin Islands. Similar heat conditions are expected to
persist through the rest of the week, as above-normal temperatures
and sufficient low-level moisture continue to support a limited to
elevated heat threat. Residents and visitors are urged to stay
hydrated, avoid prolonged exposure to the sun during peak heating
hours, and take frequent breaks in shaded or air-conditioned areas.
Vulnerable groups, such as the elderly, children, and those with
chronic health conditions, should take extra precautions.


.LONG TERM...Saturday through Wednesday...

As we head into the weekend, variable conditions are expected across
the region, with the Tropical Upper Tropospheric Trough (TUTT)
persisting northeast of the forecast area. This upper-level
feature will enhance moisture and instability, supporting
occasional showers across windward areas of Puerto Rico and the US
Virgin Islands, and isolated to scattered afternoon convection
over western Puerto Rico through Sunday. Model guidance indicates
925 mb temperatures in the 75th percentile, above climatological
normals, particularly during the weekend. Combined with high
moisture levels, heat index values may exceed 100°F, especially in
coastal and urban areas during peak afternoon hours. As a result,
a limited to elevated heat risk is anticipated, and a localized
significant heat threat cannot be ruled out.

Looking ahead into early next week, forecast uncertainty increases
due to inconsistency within model solutions regarding the
tropical wave currently located over the eastern tropical
Atlantic. The Global Forecast System (GFS) remains consistent in
depicting a system progressing toward the northeastern Caribbean,
with possible interaction with the TUTT on Monday, followed by the
passage of its remnants or trailing moisture across the local
area by Tuesday. In contrast, the European Center for Medium Range
Weather Forecasts (ECMWF) continues to favor tropical development
well east of the region, specifically in the Atlantic waters,
keeping the system distant and of limited local impact. As of the
latest update, the National Hurricane Center continues to give a
50% probability of development over the next 7 days, and a 10%
chance within 48 hours, as the tropical wave moves west-
northwestward across the subtropical Atlantic.

Given current trends, the long-term forecast leans toward the GFS
solution, which supports a deterioration in weather conditions
after Monday, with increasing moisture, instability, and a rising
flood risk across Puerto Rico and the US Virgin Islands through at
least Tuesday. That said, forecast confidence remains low, and it
is too early to specify exact impacts for the region.

Residents, visitors, and emergency managers are strongly encouraged
to closely monitor the forecasts from official agencies,
particularly from the National Hurricane Center and us, your local
forecast office, as confidence is expected to improve in the
coming days.

&&

.AVIATION...
(06Z TAFS)

Mostly VFR conds expected through the forecast period. SCT SHRA will
cause VCSH across the local terminals through 06/15Z. Thereafter,
SHRA/ ISOL TSRA could affect areas near the vicinity of
TJBQ/TJPS/TJSJ through 06/22z. Winds will increase at around 15kt
and gusty by 06/14Z, shifting from ENE to ESE, with some sea breeze
variations.

&&

.MARINE...

A surface high pressure over the central Atlantic will continue to
promote gentle to moderate winds. Easterly winds should prevail
across the region through at least Friday.

&&

.BEACH FORECAST...

There is low rip current risk across all beaches in Puerto Rico
and the U.S. Virgin Islands, today. However, even if the risk for
rip currents is low, life- threatening rip currents often occur
in the vicinity of groins, jetties, reefs, and piers. The low risk
across beaches in Puerto Rico should remain through Friday, when
the moderate risk returns along the northern coast.

[cycloneye]

AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
425 AM AST Thu Aug 7 2025

.KEY MESSAGES...

* Seasonal weather conditions will prevail today with passing
showers moving into the local area this morning, followed by
afternoon showers and isolated thunderstorms across western
Puerto Rico.

* Warm to hot temperatures are expected, once again, across all
islands with heat indices exceeding the 100 degrees Fahrenheit
along the coastal and urban areas.

* The tropical wave over the central tropical Atlantic remains
with a 60% chance of formation chance in the next 7 days and a
20% in the next 48 hours. We encourage citizens and visitors to
continue to monitor updates from the National Hurricane Center
(TWOAT) and from us, NWS San Juan, your local forecast office.

&&

.SHORT TERM...Today through Saturday...

Current satellite derived precipitable water (PWAT) values show a
patch of moisture (with values at 1.55 in, below normal) moving over
the USVI, Vieques, Culebra and reaching eastern PR. This has
resulted in shower activity over the waters, steered by easterly
flow, and reaching windward sectors. Patches of drier air and low
level moisture will continue to reach the islands, with most
available moisture remaining below 800 mb. PWAT values over 2 inches
will likely be limited to afternoon convection during the period.
The most notable advective patch of moisture (with PWAT values
around 1.85 in) is forecast to arrive by Saturday night and into the
long term period. At upper levels, a ridge aloft will dominate
today, bringing more stable conditions, however model guidance
suggests and upper low developing over the region on Friday and
persisting to start the weekend. This upper level low can enhance
moisture and instability, supporting a boost in the diurnal pattern
of showers across windward areas of Puerto Rico and the US Virgin
Islands, and isolated to scattered afternoon convection, mainly over
western Puerto Rico. Sea breeze convergence, local effects, and
diurnal heating will still help promote shower and t-storm activity
over western PR each afternoon, with conditions more favorable for
more widespread activity tomorrow and Saturday. Overall the risk of
excessive rainfall will be limited to elevated. Varying steering
flow during the period can promote convective activity over more NW
or SW municipalities during the period, with current model guidance
supporting activity over more W-SW PR tomorrow and W-NW PR on
Saturday. A plume of Saharan Dust will also affect the islands
during the short term period. As the saharan air layer (SAL) moves
in from the east, concentrations will gradually increase today,
become locally moderate by tomorrow and persist through the end of
the week. This can deteriorate air quality and promote hazy skies.

Highs will be in the upper 80s to low 90s over urban and coastal
areas of the islands, with heat indices surpassing 105°F. Lows will
be in the the upper 70s to low 80s at coastal and urban areas, and
the upper 50s to low 70s at higher elevations. A Heat Advisory has
been issued from 10 AM to 5 PM AST for urban and coastal areas of
Puerto Rico, with a limited heat threat also present today for the
U.S. Virgin Islands, Vieques and Culebra. Similar heat conditions
are forecast for the rest of the week, with a limited to elevated
heat risk.

.LONG TERM...Sunday through Thursday...

A strong tropical wave is anticipated to move south of the area from
Sunday into Monday. Moisture associated with this wave will increase
the potential to observe showers across the islands in the morning
hours. Then, followed by afternoon convective activity across
portions of western Puerto Rico with moderate to heavy rainfall and
thunderstorms. Another tropical system, Invest 96L, located in the
central Atlantic is currently being monitored by the National
Hurricane Center with a 60% formation chance over the next 7 days,
and a 20% chance within 48 hours. Model guidances have been very
inconsistent in the last few days with the track of this system.
However, there is a trend for this tropical system to remain
northeast and away from the Northeastern Caribbean region. At
this time the forecast confidence remains low, and it is too early
to determine impacts associated with the systems for the region.
Despite of the model trends for early next week, an increase in
moisture over the area is anticipated on Monday, followed by much
drier air and Saharan dust on Tuesday.

By Wednesday onwards, trailing moisture associated with the Invest
96L will reach portions of the local islands as it moves north and
away from the area, resulting in a increased potential for showers
across the region. A t this time, residents, visitors, and emergency
managers are strongly encouraged to closely monitor the forecasts
from official agencies, particularly from the National Hurricane
Center and us, your local forecast office, as confidence is expected
to improve in the coming days.

&&

.AVIATION...

(06Z TAFS)

Mainly VFR conditions through the forecast period. SHRA will
continue to move through the region, moving over the VCTY of the
eastern terminals during the morning hours. Varying E flow up to 15
to 20 kts with higher gusts will steer these SHRA and promote
SHRA/ISOL TSRA mainly near the vicinity of TJBQ at around 07/17z to
07/22z. Winds decreasing after 07/22Z.

&&

.MARINE...

A surface high pressure over the central Atlantic will continue to
promote gentle to moderate winds from the east for the next few
days. In addition, showers and thunderstorms will form each
afternoon along western Puerto Rico, potentially reaching the waters
of western Puerto Rico.

&&

.BEACH FORECAST...

There is low rip current risk across all beaches in Puerto Rico
and the U.S. Virgin Islands, today. However, even if the risk for
rip currents is low, life- threatening rip currents often occur
in the vicinity of groins, jetties, reefs, and piers. The low
risk will persist through Sunday, when a moderate risk is expected
to return along the north-central coast of Puerto Rico.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
507 AM AST Fri Aug 8 2025

.KEY MESSAGES...

* Another warm day is expected across the U.S. Virgin Islands and
Puerto Rico with highs reaching the upper 80s to low 90s over
urban and coastal areas.

* Low to moderate concetrations of Saharan dust particles will
promote hazy skies and deteriorated air quality across the
region.

* Afternoon showers and thunderstorms are expected each day across
portions of central and western Puerto Rico.

* The U.S. Virgin Islands can expect a mix of sunshine and passing
showers, mainly during the morning hours.

&&

.SHORT TERM...Today through Sunday...

Current satellite derived precipitable water (PWAT) values indicate
below normal moisture over the islands (1.34 to 1.51 in) with the
lowest values over the SW quadrant of Puerto Rico and the highest
values over eastern Puerto Rico, including Vieques and Culebra, and
the U.S. Virgin Islands. Since midnight, radar estimated
accumulations over land have been minimal to locally low, mainly
over St. Thomas, St. John, Vieques and north-central to eastern
Puerto Rico. This was due to overnight passing showers under ENE
steering flow. Patches of drier air and low level moisture will
continue to reach the islands during the period, under ENE flow
today and ESE flow on Saturday and Sunday, with most available
moisture remaining below 800 mb. PWAT values over 2 inches will
likely be limited to afternoon convection during the period. Notable
advective patches of moistures (with PWAT values around 1.85 in) are
forecast to arrive by tonight into early tomorrow and by late Sunday
night and into the long term period. An upper low will continue over
the region to end the week, moving away on Sunday, leaving ridging
aloft. In general the diurnal pattern of morning and night passing
showers across windward areas of Puerto Rico and the US Virgin
Islands, and isolated to scattered afternoon convection, mainly over
western Puerto Rico, will continue. Sea breeze convergence, local
effects, and diurnal heating will promote this afternoon shower and
t-storm activity over western PR each afternoon with the risk of
excessive rainfall being limited to elevated. Steering flow during
the period can promote convective activity over more W-SW PR today
and W-NW PR on Saturday and Sunday, with lines of showers also
forming downwind of El Yunque and the USVI. A plume of Saharan Dust
will continue to affect the islands during the next couple of days
bringing up to locally moderate concentrations during the weekend.
This can deteriorate air quality and promote hazy skies.

Maximum temperatures will still reach the upper 80s to low 90s over
urban and coastal areas of the islands, with heat indices surpassing
105°F. A Heat Advisory is in effect today from 10 AM to 5 PM AST for
urban and coastal areas of Puerto Rico. A limited heat threat is
also present today for the U.S. Virgin Islands, Vieques and Culebra.
Minimum temperatures will be in the upper 70s and low 80s at coastal
and urban areas, and the upper 50s to low 70s at higher elevations.
Similar heat conditions are forecast for the rest of the short term
period, with a limited to elevated heat risk.

.LONG TERM...Monday through Friday...

The uncertainty for the long term forecast continues regards the
development of a tropical wave, Invest 96L, located over the central
tropical Atlantic with a formation chance of 60% in the next 7 days.
The latest model guidances continues to suggest the passage of the
wave to the northeast of the region and away over the open Atlantic
waters on Monday. However, trailing moisture associated with this
system will reach the islands by early Tuesday. Therefore,
enhancing the potential to observe showers and isolated
thunderstorms across the U.S. Virgin Islands and Puerto Rico.

By Wednesday, a mid-to-upper level ridge will place over the
northeastern Caribbean promoting drier and stable conditions aloft.
A dense Saharan Air Layer (SAL) is expected to arrive into the
region from mid-week onwards, with moderate to high concentrations
of Saharan dust particles. Under the aforementioned conditions,
limited shower activity is anticipated during this period.

The 925 mb temperatures will remain at normal to above-normal
climatological values for next week. Highs will remain in the upper
80s to low 90s along the coastal and urban areas, and from the low
to mid 80s in the higher elevations. Heat indices will continue over
the 100 degrees Fahrenheit each day. Plan accordingly if planning to
do outdoor activities under sun exposure.

By the end of the workweek, model guidances are suggesting a
strong tropical wave to move into the central Atlantic. However,
there is a lot of uncertainty regarding the future of this system
as it is too early to specify possible impacts, if any, to our
region. Residents and visitors are strongly encouraged to stay
informed and monitor future forecasts as we move into next week.

&&

.AVIATION...
(06Z TAFS)

Mainly VFR conditions through the forecast period. Passing SHRA will
continue to move through the region, moving over the VCTY of TIST,
TISX, TJSJ and TJBQ during the morning hours. ENE flow up to 15 to
20 kts with higher gusts will steer these SHRA and promote SHRA/ISOL
TSRA mainly near the vicinity of TJBQ and possibly TJPS at around
08/17z to 08/22z. Winds decreasing after 08/22Z while gradually
veering to become more ESE.

&&

.MARINE...

Mariners can expect a moderate to fresh easterly wind flow
generating moderate chops across the local waters. Afternoon
convective activity will produce showers and thunderstorms across
the Mona Passage each day. An induced surface trough will move near
the region by Saturday or Sunday, increasing the available moisture
and the potential for showers and thunderstorms across the local
waters.

&&

.BEACH FORECAST...

Today, there is a low risk of rip currents at all beaches in
Puerto Rico and the U.S. Virgin Islands. However, it's important
to note that even with a low risk, life-threatening rip currents
can still occur near groins, jetties, reefs, and piers. This low
risk is expected to continue until early Sunday, when a moderate
risk of rip currents is anticipated to return along the north-
central coast of Puerto Rico.