Caribbean - Central America Weather

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
538 AM AST Wed Sep 25 2024

.SYNOPSIS...Increased instability and very warm to hot
temperatures with high relative humidity will bring energetic
showers and thunderstorms to the area today with frequent
lightning as well. On Thursday and Thursday night stability will
increase and this activity will be reduced, but a tropical wave
will move through on Friday and Friday night. Moisture will still
be abundant over the weekend and Monday and Tuesday, but less
shower activity will occur then.

&&

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

Overnight, some showers developed over Saint Croix and the eastern
municipalities of Puerto Rico (Humacao, Naguabo, Fajardo, and
Luquillo), as well as the island of Vieques. The rest of the islands
experienced fair weather conditions. Like previous days,
lightning activity lit the sky, particularly along the eastern,
northern, and southern coastal areas of Puerto Rico and the U.S.
Virgin Islands, as some showers and isolated to scattered
thunderstorms developed over the Atlantic and Caribbean waters as
well as the Anegada Passage. Tonight, the low temperatures
remained in the upper 60s to lower 70s in the mountains and in the
upper 70s to lower 80s in the urban/coastal areas. At the Luis
Munoz Marin International Airport, the minimum temperature stayed
at 82 degrees Fahrenheit as of 5 AM AST which will be a record
warm minimum if we can keep it through sunrise. The winds were
relatively light and variable across Puerto Rico and the U.S.
Virgin Islands.

Today, the citizens and visitors of Puerto Rico should experience
mostly fair weather through the morning hours, with some trade wind
showers filtering in from the east, particularly across the
eastern municipalities of Puerto Rico and the U.S. Virgin Islands.
However, these showers should move quickly as the winds are
slightly stronger, around 10 to 15 knots today. Each afternoon,
we anticipate the development of shower and thunderstorm activity
across the interior and western sections of Puerto Rico. In fact,
the latest guidance shows that 500 mb temperatures will be around
minus 8 degrees Celsius, meaning that there is an increased
potential for more thunderstorm development, strong wind gusts,
small hail and locally heavy rainfall that would likely cause
urban and small stream flooding and possibly flash flooding.

By late Thursday into Friday, moisture associated with a tropical
wave that will move mostly south of the islands will reach Puerto
Rico and the U.S. Virgin Islands. The latest precipitable water
(PW) models suggest values gradually increasing from the 50th
percentile (around normal PW content) to the 75th percentile
(above normal PW content). This tropical wave will increase the
potential for rainfall and thunderstorm activity across the
islands through the weekend. Some impacts associated with both this
and today's rainfall will be mudslides in steep terrains,
flooding over roads, and poorly drained areas.

Temperatures will be in the upper 70s to lower 80s over the higher
terrain, and the upper 80s to lower 90s will persist across the
lower elevations of the islands during the morning and early
afternoon hours. Therefore, excessive heat conditions can be
anticipated throughout the short-term period. Advisories and
warnings for heat have been issued again today.

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

A tropical wave will begin pushing against a weak high pressure
north of the area around 30 north and the flow behind the wave
will turn briefly east southeast after it passes. However, high
pressure at 700 mb over the Bahama Islands and a tropical cyclone
developing between 40 and 50 west and moving north through 20
north will bring flow at lower levels back to the east northeast
by Saturday morning. On Sunday a tropical wave approaches the area
but it is highly tilted and not very strong, making flow chaotic
and generally less than 12 knots Monday and Tuesday.

At upper levels on Friday high pressure is building over the
waters north of the western Bahama Islands and allowing a jet to
strengthen to 60 knots at 250 mb northwest of Puerto Rico and the
area in general. This will increase divergence over the area on
Friday enhancing activity with the wave passage. A TUTT low near
19 north and 58 west will drop rapidly southwest to tighten the
gradient even more across the area Saturday and Saturday night
adding to the ventilation across the area. High pressure at mid
levels to the north during the period will keep temperatures at
500 mb relatively high (warmer than -4 degrees C) and so
convection will not reach its full potential. Precipitable water
will be mostly below 2 inches Sunday through Tuesday with some
drying in the lower levels as well.


&&

.AVIATION...
(06Z)

VFR conditions at all Taf sites. TJSJ, TJPS, and TJBQ will
experience brief MVFR conds, particularly after 25/18Z. Winds less
than 15 kt with a few higher gusts along the coasts and near TSRA
till 25/23Z. TSRA will still be found offshore and near TJSJ, TIST,
and TISX aft 25/22Z.

&&

.MARINE...Seas will be generally benign, but the passing tropical
wave with increasing winds and a north northeast swell that will
pass through the area Friday and Saturday will cause seas to reach
4.5 to 5.5 feet then. Nevertheless, small craft advisory
conditions are not expected through the first few days of October.

&&

.BEACH FORECAST...
There will be a moderate risk of rip currents along the northern
side of the islands beginning today and continuing through
Tuesday. The risk may become high on the northwest corner of
Puerto Rico on Friday.

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
455 AM AST Thu Sep 26 2024

.SYNOPSIS...

Another day with intense heating across the islands. Therefore, a
Heat Advisory was issued for the coastal areas of Puerto Rico.
Showers and isolated thunderstorms are expected this afternoon
across portions of the interior and western Puerto Rico due to the
combination of local effects and the available moisture. Ponding of
water in poor drainage areas and urban and small stream flooding
is expected with this activity. A tropical wave is expected to
reach the islands on Friday, increasing once again the potential
for showers across the region.

&&

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

Scattered showers and isolated thunderstorms were observed overnight
across the local waters and over portions of the islands. This
activity was associated to an upper-level low that has moved south-
southwest and away of the region. Although warming of the 500 mb
temperature is expected today, shower and thunderstorm development
is still expected due to the proximity of the low and the higher
than normal moisture content across the eastern and southern
Caribbean. Ponding of water in poor drainage areas and urban and
small stream flooding is expected with this activity across PR and
the USVI. Strong gusty winds are possible with this afternoon
thunderstorms over western PR.

Furthermore, a broad tropical wave will increase moisture content
across the islands on Friday, and showers and thunderstorms will
increase in coverage and intensity. Latest model guidance suggest
precipitable water values between 2.00-2.30 inches during the peak
of afternoon convection on Friday. Therefore, urban and river
flooding can be expected across PR, as well as mudslides in areas of
steep terrain. For Saturday, a drying trend is expected as a broad
ridge develops from the western Atlantic and another upper-level low
develops over the Leeward Islands. However, typical afternoon
showers and isolated thunderstorms will develop over the western
sections of PR due to the combination of daytime heating and local
effects.

Even though showers and cloudiness are expected over land areas,
intense heating during the late morning and early afternoon hours
combined with high humidity will promote excessive heat conditions.
Therefore, a Heat Advisory(NPWSJU) was issued for the coastal areas
of PR.

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

After the passage of a weak tropical wave across the islands on
Saturday, a drier airmass is expected to quickly move into the area.
Therefore, mainly calm and stable weather conditions are anticipated
from Sunday onward. A migrating surface high pressure located over
the Bahamas and moving into the central Atlantic will promote
easterly winds until Tuesday. On Wednesday, this surface high is
expected to be located north or over the local islands promoting
winds from the northeast. Shower activity will be limited during
this period. However, passing showers dragged by the trade winds
cannot be ruled out across the eastern municipalities of Puerto Rico
and the USVI. In the afternoon hours, some localized showers are
possible due to the combination of moisture, warm temperatures and
local effects. Hot temperatures are very likely during most of the
long-term period with highs reaching the mid 90s along the coastal
and urban areas. Precipitable water will be mostly between 1.55 to
1.80 inches from Sunday through at least late Tuesday.

&&

.AVIATION...

(06Z TAFS)

SHRA and -TSRA en route from the Leeward Islands may cause brief
MVFR conds at times across TIST/TISX/TJSJ thru 26/15z. Thereafter,
SHRA/TSRA expected to spread across the interior and western
sections of PR, causing possible TEMPO MVFR conds at TJPS btw 26/18z-
22z. Elsewhere, VCTS expected. East winds expected at 10-15 kt with
locally higher gusts and sea breeze variations aft 26/14z.

&&

.MARINE...

A weak high pressure ridging over the region will maintain gentle to
moderate easterly winds over the next few days. A northerly swell
will maintain seas to around 4 to 5 feet through the weekend.
Shower and thunderstorm activity will increase from today into
Friday as a tropical wave approaches our region.


&&

.BEACH FORECAST...

There is a moderate risk of rip currents along the northern side
of most of the islands. The risk may become high for the north-
facing beaches of Puerto Rico and Culebra on Friday morning.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
524 AM AST Sat Sep 28 2024

.SYNOPSIS...Generally warm-to-hot conditions will prevail.
Conditions will continue to dry through Monday, then moisture will
build again. Showers and thunderstorms will not leave the forecast
however due to the excessive heat and humidity. Winds will be
gentle to moderate with land and sea/breeze influences.

&&

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

Mainly calm weather conditions were observed during the overnight
hours across the islands. Passing showers were seen over the U.S.
Virgin Islands and eastern Puerto Rico, leaving minor
accumulations. Minimum temperatures remained in the range from the
upper 60s to low 70s in the higher elevations, and from the mid
70s to lower 80s in the coastal and urban sectors. Winds were
calm and variable through much of the night.

For the short-term period a broad ridge will develop and dominate
the western Atlantic promoting easterly winds today. At the upper
levels, an upper-level low will develop over the Leeward Islands
bringing instability into the area. The latest precipitable water
content analysis suggests values below 2.0 inches through the next
several days.

Today, afternoon convective activity will develop across the
interior and western portions of Puerto Rico. Showers and isolated
thunderstorms may result in minor flooding and ponding of water in
low drainage areas. Therefore, there is a limited to elevated risk
to observe excessive rains across these areas. The San Juan streamer
is expected to form during the afternoon hours as well, enhancing
the potential for showers across the San Juan metropolitan area
and adjacent municipalities. On Sunday, instability is expected
to increase due to the proximity of the upper-level low to our
area. Winds will shift to northeast, therefore, afternoon
convective activity is likely across the interior and southwestern
portions of Puerto Rico. By the beginning of the next workweek,
weather conditions will turn drier and become more stable with
very limited shower activity.

In terms of heat, hot conditions are likely to continue for the next
several days into next week with an elevated to significant heat
threat. Highs will reach the upper 80s to lower 90s along the
coastal and urban areas. Residents and visitors should take
precautions to stay hydrated by drinking plenty of water, wearing
light and breathable clothing, and avoiding prolonged exposure to
the sun, especially during peak heat hours.

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

High pressure system centered about 600 miles northwest of Puerto
Rico will maintain winds coming out of the northeast for the first
couple of days of October. The pressure gradient will be very
weak too, due to the interaction of this high and a possible
tropical cyclone well east of the Caribbean. Under this flow,
moisture will mostly be trapped below the 700 and 850 mb layers.
These winds will favor showers developing over the Atlantic
waters, reaching portions of the Virgin Islands, northern and
eastern Puerto Rico at times. In the afternoon, the activity
should be mainly focused across the south-southwestern areas of
Puerto Rico. The dynamics aloft will not favor strong showers or
thunderstorms, although isolated activity cannot be ruled out in
the afternoon hours due to strong heating.

The high pressure will weaken as a trough digs from the north by
the middle of the week. This trough will induce a stronger patch
of moisture that should reach the local islands by late Thursday
into Friday. Temperatures at 500 mb will cool down a little too,
so the environment will favor an increase in the coverage and
intensity of the shower activity, as well. The trough will
continue to move southward, with it axis just west of Puerto Rico
by Saturday, meaning that unsettled weather conditions will
persist.

&&

.AVIATION...

(06Z TAFS)

Mainly VFR conds expected to prevail across all terminals thru the
forecast period. Passing tradewind showers will result in VCSH at
TJSJ/TIST/TISX thru 28/14Z. Today, an increase in afternoon
SHRA/TSRA may result in brief MVFR/IFR conds at TJBQ aft
28/17-18Z. Mtn tops obscd and low cigs expected along the
Cordillera Central thru 28/22Z. East winds will increase btwn
12-14 kt with higher gusts and sea breeze variations aft 28/14z.
Pilots need to watch Density Altitude with high heat/humidity.

&&

.MARINE...Seas will continue to have swell of 4 and 5 feet from
distant tropical cyclones. Small craft will need to exercise
caution in the outer Atlantic waters. Seas will be less south of
the larger islands. Small craft advisory conditions are not
expected during the next 7 days.

&&

.BEACH FORECAST...There is a high risk of rip currents due to
north to northeast swell action today. Thereafter the risk will be
moderate on the north and east sides of the islands.

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
510 AM AST Sun Sep 29 2024

.SYNOPSIS...

An upper-level low over the eastern Caribbean will cross the local
area today from east to west over the Caribbean Sea. At lower
levels, a weak ridge over the western Atlantic will continue to
promote light east to northeast winds during the next several
days. Drier air moves in today, but above normal temperatures in
combination with the upper-low will result in strong thunderstorms
over portions of the interior and southwestern PR.


&&

.SHORT TERM...Sunday through Tuesday...

Isolated to scattered showers were observed overnight across the
local waters, over the US Virgin Islands and eastern Puerto Rico.
These showers will continue through the morning hours. Minimum
temperatures remained in the range from the upper 60s to low 70s in
the higher elevations, and from the mid 70s to lower 80s in the
coastal municipalities. Winds were light and variable overnight.

A high pressure system located over the western Atlantic, north of
The Bahamas, will maintain light winds from the east to northeast
today. A drying trend will continue today across the region with
precipitable water values falling between 1.7 to 1.8 inches.
However, the available moisture in combination with daytime heating
and local effects will result in the development of strong showers
and thunderstorms in the afternoon hours. This scenario will be
repeated each day across the interior and western municipalities of
Puerto Rico. There is also the potential to observe showers across
the San Juan metropolitan area and adjacent municipalities with the
streamer formation. For the rest of the region, expect mainly fair
weather conditions under sunny to partly cloudy skies.

Warm to hot conditions are likely to continue this week with an
elevated to significant heat threat. Highs will continue to soar
into the upper 80s to mid 90s along the coastal and urban sectors of
Puerto Rico and the US Virgin Islands. Residents and visitors should
take precautions to stay hydrated by drinking plenty of water,
wearing light and breathable clothing, and avoiding prolonged
exposure to the sun, especially during peak heat hours.

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

A drying trend is expected to continue on Wednesday as the
layered ridge over the western Atlantic sinks further into the
north-central Caribbean. Winds at the surface will remain NNE
through at least Saturday as the region remains under the
influence of the ridge to our west/northwest and a tropical
cyclone over the far Tropical Atlantic. However, a surge in low-
level moisture from the Atlantic waters is expected to move over
the area by Thu-Fri, while an upper level trough over the western
Atlantic continues to move into the northeastern Caribbean during
the weekend. Therefore, showers and thunderstorms will increase in
coverage and intensity once again later in the forecast period,
but should develop mainly over the interior and southern sections
of the islands during the afternoons. For the USVI, shower activity
will increase mainly on Thursday and Friday.

&&

.AVIATION...

(06Z TAFS)

Mainly VFR conds expected to prevail across all terminals thru the
forecast period. Passing showers will result in VCSH at TIST/TISX
thru 29/14Z. Today, an increase in afternoon SHRA/TSRA may result in
brief MVFR conds at TJBQ aft 29/17-18Z. Mtn tops obscd and low cigs
expected along the Cordillera Central thru 29/22Z. East winds will
increase btwn 10-14 kt with higher gusts and sea breeze variations
aft 29/14z.


&&

.MARINE...

NNE swell continues across the Atlantic waters and passages, but
it is expected to subside tonight. Another northerly swell will
arrive by midweek, but seas are expected to remain below Small
Craft Advisory criteria. Light east to northeasterly winds will
prevail through the workweek. Afternoon thunderstorms are expected
to develop each day over the southwestern coastal waters of PR.
Elsewhere, passing showers can be expected at times.


&&

.BEACH FORECAST...

A lingering but fading northeasterly swell(3/4ft at 11/12s) will
continue across the Atlantic waters and passages today. The
resulting breaking waves and long period energy will promote a
high risk of rip currents along the north facing beaches of Puerto
Rico. Therefore, a High Rip Current Risk (CFWSJU) is in effect
for the northeast to northwestern beaches of Puerto Rico.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
437 AM AST Mon Sep 30 2024

.SYNOPSIS...

A Heat Advisory will be in effect today for the north and west
coastal and urban areas of Puerto Rico and St. Croix through this
afternoon. Abundant moisture and above normal temperatures will
produce scattered showers early morning and over Cordillera Central
and south Puerto Rico from late morning to late afternoon most days
through the week. A dry trend early next week as a high pressure
moves and settles over the forecast area late Sunday. There's a high
rip current risk for the north-facing beaches of the islands.


&&

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

A broad upper-level low has moved south of Hispaniola, and scattered
showers were observed across the local waters with isolated
thunderstorms developing over the Mona Passage through the night. A
few showers moved over land areas, leaving mostly minor rainfall
accumulations in St. Croix and eastern Puerto Rico. Minimum
temperatures were from the upper 60s across the higher elevations of
PR to the upper 70s and low 80s across the coastal sections of the
islands.

A surface high pressure over the western Atlantic just north of the
Bahamas and Tropical Depresion Joyce near 22N well northeast of the
region will promote light winds during the next couple of days.
Winds today will have a weak easterly component as a trade wind
perturbation (likely induced by the upper-low) moves from the
Leeward Islands across the region. Thereafter, winds will gradually
turn northeast to north from Tuesday to Wednesday. Therefore, today
seems to be the rainiest day of the short-term period. Shower and
thunderstorm activity will continue to increase in general today
across the local waters as the perturbation streams across the
region, and thereafter enhance the diurnal convection cycle over the
islands, with the strongest activity developing in the afternoon
hours over the interior and western PR. Flooding is expected and
some thunderstorms could produce strong gusty winds. In addition,
hot temperatures are expected once again before the onset of
afternoon showers and a Heat Advisory (NPWSJU) is in effect for
portions of northern and western PR, and St. Croix.

The precipitable water (PWAT) content is expected to peak today
between 2.00-2.20 inches, with a drying trend expected from late
Tuesday and Wednesday as the layered ridge over Bahamas sinks
southwards over Hispaniola and into the local area. PWAT is expected
to bottom out between 1.40-1.70 inches by early Wednesday morning.

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

On Thursday, a weak mid-level high pressure over the western
Atlantic will sink further into the north-central Caribbean.
Additionally, 500 mb temperatures will warm between -3 and -4
degrees. This could potentially inhibit convective activity across
the forecast area. However, moisture content is expected to
increase. Model guidance suggests precipitable water content will
surge above 2.0 inches, even reaching up to 2.2 inches, which is
near to above the climatological normal. Therefore, expect shower
activity across interior Puerto Rico with a few very isolated
thunderstorms.

Afterwards, winds at the surface will remain light from ENE until
Saturday due to a ridge to our west/northwest and a tropical cyclone
over the far Tropical Atlantic, becoming variable by Sunday onwards.
With a surge in low-level moisture and a mid-to-high level trough
moving into the northeastern Caribbean by the end of this week into
the weekend, shower and thunderstorm activity will increase once
again mainly over the interior and southern sections of the islands
for the forecast period. Slow moving showers will enhance rainfall
accumulations across the area. Hence, a limited to elevated flooding
risk can be anticipated. Ponding of water in roadways and poorly
drained areas are likely, with urban and small stream flooding
across interior Puerto Rico during the afternoon hours.

Then, a mid-level ridge will move eastward and settles over the
forecast area by Monday inhibiting shower activity for the most
part. The combination of limited shower activity, clear skies, and
subsidence aloft will promote hot temperatures for early next
week. Limited to elevated heat risk will prevail for coastal and
urban areas of PR and USVI.


&&

.AVIATION...
(06Z TAFS)

Mainly VFR conditions expected across all terminals through the
forecast period. However, diurnally induced afternoon SHRA/TSRA
could lead to tempo MVFR to brief IFR conds at TJPS/TJBQ btw 30/18z-
22z. VCTS is possible across the rest of the terminals. Easterly
winds expected up to 12 kt with sea breeze variations aft 30/14z.

&&

.MARINE...

A high pressure system over the western Atlantic will maintain
light to gentle northeast to easterly winds. Seas will remain around
3 to 5 feet over the next few days. Showers and thunderstorms remain
possible across the regional waters through the week.


&&

.BEACH FORECAST...

Nearshore buoys are indicating breaking waves of 6-8 feet with
swell action continuing through at least this afternoon.
Therefore, a High Rip Current Risk (CFWSJU) is in effect for the
northeast to northwestern beaches of Puerto Rico, including
Culebra.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
442 AM AST Tue Oct 1 2024

.SYNOPSIS...

Variable conditions will prevail in the next few days into the
weekend. A dry trend early next week as a high pressure moves and
settles over the forecast area late Sunday. In the tropical
Atlantic, the NHC monitors the remnants of Joyce, Tropical Storm
Kirk and a tropical wave with a 90% formation chance through 7
days. Swells from these systems will deteriorate marine and
coastal conditions late this workweek and into the weekend.

&&

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

Overnight, calm weather conditions with a light northeasterly wind
prevailed. The low temperatures were warmer than normal across the
islands. The Doppler Radar detected a few showers across the local
waters, and some moved inland across the US Virgin Islands and the
windward sections of Puerto Rico.

A mid-to-upper-level ridge building across the northeast Caribbean
will produce stable weather conditions in the short term. The day
will begin with warmer temperatures, which, combined with the
available moisture, will result in moggy heat indices across the
local islands, especially in areas without rain activity. Therefore,
a Heat Advisory is in effect for St Croix.

The interaction of a surface low pressure (Joyce's remnants)
northeast of the islands and a surface high pressure to the
northwest will result in a light northeasterly to northerly wind
flow across the islands. This wind flow will bring patches of clouds
and moisture later today, resulting in some showers across the
windward sections. Then, the excessive diurnal heating, local
topography, and sea breeze fluctuations will promote the formation
of afternoon convection along the Cordillera Central and southern
slopes of PR, where we can anticipate urban and small stream
flooding due to thunderstorms.

Although a stable weather pattern will evolve in the short term due
to the presence of the mid-to the upper-level ridge, excessive
heating combined with the sea breeze variations and local topography
could promote the typical afternoon convection across portions of
the islands each afternoon. However, model guidance suggests the
arrival of a surge of moisture by Thursday that could promote
showery weather. At this time, Wednesday seems the driest day of the
short term. The hot heat indices will continue each day across the
islands.

&&

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

On Friday, winds at the surface will remain light from ENE until
Saturday due to a ridge to our west/northwest and current Tropical
Storm Kirk, forecast to become a major hurricane on Thursday, over
the Central Atlantic. A high level trough in the north will enhanced
thunderstorm activity. Precipitable Water (PWAT) values will range
between 2.0 to 2.1 inches, which is near to above the climatological
normal. Additionally, cold 500 mb temperatures and Galvez-Davidson
Index suggest isolated to scattered thunderstorms over the
Cordillera Central and southwest of Puerto Rico enhancing rainfall
accumulations across the area. Therefore, a limited to elevated
flooding risk can be anticipated.

On Saturday, winds will become even lighter and variable. The 500 mb
temperatures will warm again, which will inhibit thunderstorm
convective activity. But with the available moisture and light
winds, slow moving showers will enhance rainfall accumulations
across the area. Therefore, expect shower activity across interior
Puerto Rico with a few very isolated thunderstorms. Winds will
become light from the ESE on Sunday. A mid-level ridge will start to
settle over the forecast area by Monday. Additionally, relative
humidities at mid-levels will plummet below 20%. However, latest
model guidance shows a deeper layer of low-to-mid level moisture
reaching our forecast area than previous model cycle. Despite this
surge of moisture, this weather set-up will inhibit deep
convective activity for the most part. Still, isolate to scattered
showers can be expected particularly in the afternoon hours. The
925 mb temperatures will also be higher than the daily mean (21.4
degrees). The combination of limited shower activity and clear
skies in coastal areas with subsidence aloft will promote hot
temperatures for early next week. Limited to elevated heat risk
will prevail for coastal and urban areas of PR and USVI.

The National Hurricane Center public advisory #6 of
Tropical Storm Kirk suggests that the system will strengthen and
become a major hurricane and turn northward by Thursday. Although
Kirk is not expected to impact PR and the USVI, recommendations are
to keep monitoring tropical activity as the hurricane season
continues through November 30.


&&

.AVIATION...
(06Z TAFS)

VFR conditions will prevail throughout the forecast period. However,
SHRA/TSRA will develop across the interior and southern slopes of
PR, which may affect TJPS between 01/17 and 23z. Passing showers
could affect JSJ/IST at times, but we are not anticipating
significant impacts. Winds will prevail calm to light and VRB
through 01/13z, then from the NNE to N at 10-15 with gusts around 20
kt, but with sea breeze variations.

&&

.MARINE...

A high pressure system over the western Atlantic will maintain
light to gentle east to northeast winds. Seas will remain around 3
to 5 feet over the next few days. Showers with thunderstorm activity
will create locally hazardous marine conditions for small craft. A
combination of northeast to east long-period swells will reach the
regional waters this weekend bringing hazardous seas.

&&

.BEACH FORECAST...

A moderate risk of rip currents will be in effect today for the
beaches of northern PR, and northern Culebra. Low risk elsewhere.

In the tropical Atlantic, the NHC monitors the remnants of Joyce,
Tropical Storm Kirk and a tropical wave with a 90% formation
chance through 7 days. Swells from these systems will deteriorate
marine and coastal conditions late this workweek and into the
weekend.

[cycloneye]

Area Forecast Discussion...CORRECTED
National Weather Service San Juan PR
504 AM AST Wed Oct 2 2024

.SYNOPSIS...

Variable conditions will prevail through the weekend with
afternoon showers and isolated thunderstorms mainly affecting
interior to southern PR. Winds will turn with a southerly
component Sunday onwards bringing abundant moisture and warmer-
than-normal temperatures. Swells from Hurricane Kirk will
deteriorate marine and coastal conditions late this workweek and
into the weekend.

&&

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

Overnight, a dry slot promoted calm weather conditions with light
north-northeasterly winds. However, a pocket of moisture brought a
few showers across the Atlantic Oceans, moving inland across the
windward sections of PR and the northern USVI. Once again, we
observed another early morning with warmer-than-normal low
temperatures across the islands.

The mid-to-upper-level ridge over the northeast Caribbean will
continue the stable weather pattern. However, the northeasterly
winds will push a pocket of moisture over the windward sections of
PR and the northern US Virgin Islands, resulting in a mixture of
sunshine, clouds, and showers through the morning. Meanwhile, the
leeward sections of PR and St Croix can expect a mix of sun and
clouds with sweltering hot conditions throughout the morning. Then,
the diurnal heating with the local effects will promote strong
convection, resulting in periods of moderate to local rain that
could produce isolated flooding problems across the interior and
southern slopes of PR.

The local winds will continue under the influence of Kirk's
trajectory forecast, which, based on the latest NHC track forecast,
will move into the North Central Atlantic. Model guidance suggests a
Fujiwhara effect between Kirk and another surface low moving
eastward from the western Atlantic near it. As this happens, winds
will continue from the north over the northeast Caribbean.
Therefore, a similar weather pattern will continue on Thursday, with
pockets of moisture-producing passing showers across the windward
sections and afternoon convection across the interior and southern
slopes. Instability will increase by Friday as the upper-level ridge
weakens, favoring deep convection, especially in the afternoon and
evening. The hot heat indices will continue each day across the
islands.

&&

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

On Saturday, winds will remain from the northeast as Hurricane Kirk
continues moving northwest far from the region influencing the wind
flow across the northeastern Caribbean. Model guidance suggests PWAT
values between 2.0 and 2.1 inches, which are near above the
climatological normal. Colder 500 mb temperatures will also be
present indicating deep convective development. Additionally, Galvez-
Davison Index suggest isolated thunderstorms over the Cordillera
Central and southwest of Puerto Rico. Therefore, enough instability
in combination with diurnal heating and sea breeze convergence,
shower and thunderstorm activity will promote a limited to elevated
flooding risk.

Winds will then turn from the ESE and become light on Sunday, almost
two standard deviations below the climatological normal. Winds will
remain with a southerly component for the rest of the forecast
period. The latest model guidance now shows a delay in the dry
pattern that was expected for early next week as a deeper layer of
low-to-mid-level moisture reaches our forecast area. A mid-level
ridge will settle in the west Caribbean and move toward the forecast
area by Monday, inhibiting deep convection activity. Additionally,
warm 500 mb temperatures and a low Galvez-Davison Index suggest
shallow convection, however, slow-moving showers could promote
ponding of water in roads and poorly drained areas across the
northeast and metropolitan areas. Urban and small stream flooding
cannot be rule out. Southerly component winds will bring an
abundance of moisture and warmer-than-normal 925 mb temperatures for
next week. The combination of limited shower activity, clear skies
in coastal areas, and subsidence aloft will promote hot
temperatures. Therefore, limited to elevated heat risk will prevail
for coastal and urban areas of PR and USVI.

The National Hurricane Center public advisory #10 of Hurricane Kirk
suggests that the system will strengthen and become a major
hurricane and turn northward by Thursday. Although Kirk is not
expected to impact PR and the USVI, recommendations are to keep
monitoring tropical activity as the hurricane season continues
through November 30.

&&

.AVIATION...
(06Z TAFS)

VFR conditions will prevail throughout the forecast period. However,
afternoon SHRA/TSRA will develop across PR's interior and southern
slopes, which may affect TJPS between 02/17 and 23z. The northerly
winds will sometimes bring passing showers near or over JSJ/IST, but
we are not anticipating significant impacts. Winds will prevail calm
to light and VRB through 02/13z, then from the NNE to N at 10-15
with gusts around 20 kt due to sea breeze variations and near TSRA.

&&

.MARINE...

The interaction of the weak high pressure system over the western
Atlantic and Hurricane Kirk across the Central Atlantic will promote
light to gentle east to northeast winds. Additionally, the arrival
of a northeasterly swell will promote wave heights between 3 and 5
feet with wave periods around 11 seconds later today. Showers with
thunderstorm activity will create locally hazardous marine
conditions for small craft, specially during the afternoon hours
near the coastal areas of PR. A combination of northeast to east
long- period swells will reach the regional waters this weekend,
generating hazardous seas.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
449 AM AST Thu Oct 3 2024

.SYNOPSIS...

Variable conditions will prevail through the weekend with
afternoon showers and isolated thunderstorms mainly affecting
interior to southern PR. Winds will turn with a southerly
component Monday onwards bringing warmer-than-normal
temperatures. Swells from Hurricane Kirk will deteriorate marine
and coastal conditions late this workweek and into the weekend.

&&

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

The north-northeasterly wind flow promoted cool air advection,
resulting in scattered to numerous showers overnight. We noted the
showery weather over the north half of PR and the USVI. Low
temperatures were in the upper 70s or low 80s along the coastal
sections and the upper 60s or low 70s in mountain areas.

The stability promoted by the mid-to-upper-level ridge will persist
over the northeast Caribbean. Still, the near to above-normal
moisture content will continue to promote periods of showers with
moderate to heavy rain, especially across PR and USVI's windward
sections this morning. Meanwhile, the leeward sections can expect a
mix of sun and clouds with muggy temperatures throughout the
morning. Once again, the diurnal heating, local effects, and sea
breeze variations will promote strong convection, resulting in
periods of moderate to local rain that could produce isolated
flooding problems across the interior and southern slopes of PR.

Major Hurricane Kirk's track forecast (and its interaction with a
surface low pressure system across the North Atlantic) will modulate
the local weather pattern, promoting a northerly wind flow and
moisture pooling over portions of Puerto Rico and the US Virgin
Islands on Friday and Saturday. Therefore, we can anticipate a
showery weather pattern each evening and overnight hours across the
windward sections with scattered to numerous afternoon convection
each day. Additionally, the increasing instability will favor deeper
convection. The hot heat indices will continue each day across the
islands.

&&

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

On Sunday, winds will be light and variable, with near-normal
precipitable water content. This weather pattern will persist
through at least Monday, but with winds shifting more to a
southerly component. Enough instability and slow steering winds
may induce slow-moving showers and isolated thunderstorms,
particularly over the interior, gradually moving towards northern
and eastern Puerto Rico, including the San Juan metro area.
Rainfall accumulations across the area will promote ponding of
water in roads and poorly drained areas, elevating localized flood
risk for the first part of the forecast period.

The latest model guidance now shows an increase of dry air from
Tuesday onwards with a dry slot reaching the forecast area.
Overnight showers may develop over the region, but minimal
rainfall accumulations can be expected. Wednesday is expected to
be the hottest and driest day of the forecast period, with PWAT
values below the climatological normal. A surface high pressure
settling in the northwest of the region will induce southeasterly
winds. Warmer-than-normal 925 mb temperatures, limited shower
activity, clear skies in coastal areas, and subsidence aloft will
promote hot temperatures. Therefore, limited to elevated heat risk
will prevail for coastal and urban areas of PR and USVI. PWAT
values will increase again on Thursday, increasing the risk of
flooding once again.

&&

.AVIATION...

(06Z)

VFR conditions will prevail throughout the forecast period. The N-
NNE winds will push scattered to numerous showers near or across
JSJ/IST/ISX. Also, afternoon SHRA/TSRA will develop across PR's
interior and southern slopes, which may affect TJPS between 03/17
and 23z. Expect calm to light and VRB winds through 03/13z, then
from the NNE to N at 10-15 with gusts around 20 kt due to sea breeze
variations and near TSRA.


&&

.MARINE...

The interaction of the weak high pressure system over the western
Atlantic and Hurricane Kirk across the Central Atlantic will promote
light to gentle north to northeast winds. Showers with thunderstorm
activity will create locally hazardous marine conditions for small
craft, specially during the afternoon hours near the coastal areas of
PR. A combination of northeast to east long-period swells will reach
the regional waters this weekend, generating hazardous seas.

&&

.BEACH FORECAST...

A high risk of rip currents will be in effect today for most
beaches of northern Puerto Rico and Culebra. Swells from
Hurricane Kirk will deteriorate marine and coastal conditions late
this workweek and into the weekend.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
452 AM AST Sat Oct 5 2024

.SYNOPSIS...

Another variable weather day will prevail for the local islands,
with passing showers across the northeastern sections of Puerto
Rico and the surrounding waters. Similar conditions will continue
for several days, with warm temperatures leading to heat indices
between 102-108°F. Hazardous marine conditions will persist due to
northeasterly and east swells generated by the distant Hurricane
Kirk in the Central Atlantic. As a result, there is a high risk of
rip currents and several small craft advisories in effect. For
more detailed information, visit www.weather.sju/marine.

&&

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

Once again, the Doppler Radar detected scattered to numerous showers
mainly across the islands' surrounding waters, with occasional
showers moving inland across the US Virgin Islands and the windward
sections of PR. Winds were calm to light and variable with a
northeasterly component. Although some stations reported lows in the
mid-70s across some urban and coastal sites, generally speaking, low
temperatures were in the upper 70s or low 80s along the coastal
sections and the upper 60s or low 70s in mountain areas.

Shower activity may reduce during the morning, and the heat indices
will slowly increase. Then, by the afternoon, we expect that the
instability provided by the proximity of an upper-level trough will
boost the effects of the sea breeze fluctuations, local effects, and
excessive diurnal heating to result in strong thunderstorms across
the interior, spreading to the rest of the coastal sites. The light
steering winds are identified as one of the principal contributors
to the elevated risk of flooding today.

A passing mid-to-upper-level trough will allow better instability
throughout the weekend as the ridges continue moving westward away
from the islands. The distant Kirk continues modulating the local
weather, as is pooling moisture over us and indirectly influencing
the local winds. Today's surface winds will be mainly light from the
northeast to north, shifting from the east-southeast on Sunday and
becoming southerly around Tuesday. As Kirk interacts with another
surface low across the Central Atlantic, a col area will position
near the Northeast Caribbean, promoting the light or calm winds
across the region. Under this weather pattern, we can expect slow-
moving showers and even more threatening afternoon thunderstorms,
which may enhance the threat of flooding each day. Additionally, the
abundant moisture combined with the afternoon maximum temperatures
will continue to promote the unpleasant hot heat indices in areas
with no rain activity, especially across the urban and coastal areas
of PR and the USVI.

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

An interesting surface pattern will dominate the first part of
the long-term period, with a weak surface low-pressure system well
to the south in the Caribbean waters and a weak surface ridge
over the Central Atlantic. The interaction between these two
features will produce a variable and light east-to-southeast wind
flow across the region through at least Friday. Under this
influence, abundant tropical moisture with PWAT near 2.0 inches is
expected from Tuesday through Wednesday. Sufficient moisture will
be present from Thursday into Sunday, though it will gradually
decrease as the week progresses. Despite tropical moisture being
trapped at the surface up to 700 MB on Tuesday and Wednesday,
widespread shower activity is not anticipated due to the lack of
instability at 250 MB and warmer temperatures at 500 MB of -4°C.
As a result, residents can expect a typical pattern of warm
morning temperatures followed by afternoon showers, especially
across the mountains. The combination of light and variable winds
with surface conditions may lead to longer periods of showers and
significant rainfall accumulations, potentially causing urban and
small stream flooding. Similar conditions will continue through
Friday, although shower activity should be less widespread.

Global model guidance for 925 MB temperatures suggests a warm
period for much of the region due to the southeasterly wind
component and the presence of tropical moisture, which will
increase relative humidity at 850-700 MB. Consequently, periods of
warm temperatures and high moisture levels could result in heat
indices near the threshold for heat advisories, increasing health
risks for vulnerable communities, particularly in coastal and
urban areas. Please follow health department recommendations to
avoid heat- related illnesses.

&&

.AVIATION...
(06z)
Expect VFR conds thru the fcst period. However, expect SHRA/-SHRA
across the local flying area, especially in the evening and early
morning hours. Also, the best period to observe MVFR or even IFR
conds will be btwn 05/17-23z when TSRA/SHRA will develop across
the interior, spreading to the coastal sites near local terminals
in PR. Expect calm to light and VRB winds thru 05/13z, then from
the NNE-NE at 10 kt with higher gusts due to sea breeze and near
TSRA. Winds will slowly shift from the E/ESE aft 05/23z.

&&

.MARINE...

Hazardous marine conditions will persist through the weekend and
into the upcoming workweek due to a combination of long-period
north-northeast to northeast swells affecting regional waters. A
weak high-pressure system over the western Atlantic, combined with
Hurricane Kirk in the Central Atlantic, will support light to
gentle north-to-northeast winds across local waters. Localized
hazardous marine conditions are expected near thunderstorm
activity, particularly during the afternoon near coastal areas of
Puerto Rico.

&&

.BEACH FORECAST...
A high risk of rip currents will be in effect this weekend for
most northern beaches of Puerto Rico, Culebra, and St. Croix.
Long-period swells from Hurricane Kirk will sustain dangerous
coastal conditions throughout the weekend, especially today and
tonight. Beachgoers and water sports enthusiasts are urged to
exercise extreme caution, as rip currents pose a significant
danger along the northern and eastern coasts of Puerto Rico and
nearby islands.

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
502 AM AST Sun Oct 6 2024

.SYNOPSIS...

Variable weather conditions will persist across the islands today
due to the divergent side of an upper-level trough and sufficient
tropical moisture in the region. Hazardous marine conditions will
continue due to northeasterly swells generated by the distant
Hurricane Kirk in the Central Atlantic, impacting most northern
Atlantic waters and the northern coastal areas of Puerto Rico. As
a result, a High Surf Advisory and a high risk of rip currents are
in effect for the exposed northern coastal areas today. A Small
Craft Advisory also remains in effect until late today, extending
into Sunday for the offshore Atlantic waters. For more detailed
information, visit www.weather.sju/marine.

&&

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

Since 8 PM AST, radar observations have detected a few showers
affecting land areas, especially the far eastern sections of Puerto
Rico and parts of the local islands, leading to minimal rainfall
accumulations. Satellite imagery and reports from trained observers
indicated that skies remained mostly clear, with only brief
interruptions from the shower activity. Most surface observing
stations reported overnight lows in the 70s, with some exceptions in
northeastern and southern Puerto Rico, as well as the US Virgin
Islands. Winds were generally light and mostly variable, as
evidenced by the nearly stationary showers developing over local
waters.

In the next 12 to 24 hours, an upper-level trough to the west,
combined with abundant moisture—with precipitable water values
peaking around 2.2 to 2.3 inches—will maintain favorable conditions
for showers and thunderstorms across the region. Initially,
scattered showers and a few isolated thunderstorms will impact local
waters and some coastal areas this morning. As the day continues and
diurnal heating, along with sea-breeze convergence, intensifies,
anticipate an increase in showers and potentially severe
thunderstorms across the islands, including the US Virgin Islands.
After sundown, the focus of the activity will shift back to the
local waters and parts of the coastal areas. Similar to previous
days, winds are expected to remain light and variable, driven by an
area of weak pressure gradient over the northeastern Caribbean,
indicating that showers will not move much, if at all, during their
duration. Additionally, in this scenario, any developing activity is
likely to favor the interior and slowly extend to nearby areas,
following the dominant steering flow. Given the anticipated nature
of these storms, expect not only excessive rainfall (flooding)
hazard risks but also risks of strong gusty winds, lightning
strikes, and possibly small hail if conditions are optimal. While
these rains may provide brief relief from the heat, overall, warm
conditions are expected to dominate today—conditions that could
particularly affect individuals who are extremely sensitive to heat,
especially when outdoors without effective cooling or adequate
hydration.

The upper-level trough is expected to weaken while drifting
southwestward by Monday, gradually making way for a mid-to-upper-
level high. However, conditions will not become completely
unfavorable for thunderstorm development. The forecast still
indicates that showers with isolated thunderstorms will persist over
the coming days—going from the local waters and coastal areas during
the night and early morning into central and downwind areas in the
afternoon, fueled by intense diurnal heating and driven by sea-
breeze convergence. Light and variable winds on Monday are expected
to produce a similar shower distribution and associated risks.
However, reduced available moisture under more southeasterly winds
on Tuesday will likely lead to fewer and more localized showers.
Warm conditions will persist, so those planning outdoor activities
or working outside should take appropriate precautions.

.LONG TERM...Wednesday through Sunday

A variable weather pattern will dominate the long-term forecast,
with a persistent mid to upper-level ridge providing stable
conditions that inhibit convective showers. Although stability
will prevail, intermittent tropical moisture will affect the
region, mainly brought by a broad surface high pressure over the
Central Atlantic. According to Global Forecast System (GFS) model
guidance, this system will push an extensive area of tropical
moisture with precipitable water values (PWAT) exceeding 2 inches
under a southeasterly wind flow. Combined with local effects, this
moisture could result in active afternoons, particularly over the
northwestern sections of Puerto Rico. The strongest showers will
likely be accompanied by isolated to scattered thunderstorms, as
suggested by the Galvez-Davison Index (GDI), especially on
Wednesday and Thursday. From Friday through Sunday, interactions
between the surface high pressure and Tropical Storm Leslie will
cause winds to shift across the forecast area. This wind shift
will lead to a more east-to-southeast wind flow, increasing
surface pressure. With higher relative humidity between 850-500 MB
and cooler temperatures at 500 MB (around -6°C), this pattern is
expected to bring showers and thunderstorms during the afternoons.

Global model guidance for 925 MB temperatures indicates a warm
period for much of the region due to the southeasterly wind
component and the presence of tropical moisture, which will
increase relative humidity at 850-700 MB. Consequently, warm
temperatures and high moisture levels could result in heat indices
near the threshold for heat advisories, posing health risks for
vulnerable communities, particularly in coastal and urban areas.
Please follow the health department’s recommendations to prevent
heat-related illnesses.

&&

.AVIATION...
( 06Z TAF )
Favorable environmental conditions will support SHRA/TSRA
development across the region. The strongest activity, resulting
in SCT-BKN around FL020-030 and reduced visibilities (MVFR
conditions) and possible impacts on operations across most
terminals, is likely between 06/14-20Z. For TJSJ and USVI
terminals, VCSH/VCTS are expected throughout the forecast cycle.
Light to calm and variable winds will prevail during the next 24
hours, peaking at 5-10 knots around 06/16-20Z.

&&

.MARINE...
Hazardous marine conditions will persist through Monday due to
northeast swells affecting regional waters, generated by Hurricane
Kirk. A weak high-pressure system over the western Atlantic and
Hurricane Kirk in the Central Atlantic will support light to
gentle north-to-northeast winds across local waters. Localized
hazardous marine conditions are expected near thunderstorms,
especially in the afternoon near coastal areas of Puerto Rico.

&&

.BEACH FORECAST...
Today, another pulse of northeasterly swell will reach the
Atlantic coastal waters this morning, resulting in breaking waves
up to 12 feet. These conditions will generate very dangerous
marine conditions across the northern and northeastern exposed
beaches, where a High Surf Advisory remains in effect until 6 PM
tonight. Additionally, the high risk of rip currents continues
throughout the weekend for most northern beaches of Puerto Rico,
Culebra, and St. Croix. Beachgoers are urged to exercise extreme
caution, as the breaking waves pose significant dangers along the
northern and eastern coasts of Puerto Rico and nearby islands.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
433 AM AST Mon Oct 7 2024

.SYNOPSIS...

Light winds will become southeasterly today onwards. Warm-to-hot
conditions will continue over the next few days. Thunderstorm
activity, particularly in the afternoon, could produce strong
gusty winds, frequent lightning, and flooding impacts each day.
Swells from distant storms will generate life-threatening rip
currents and hazardous marine conditions by the end of the
workweek into the weekend.


&&

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

Since 8 PM AST, radar observations have shown scattered to numerous
showers and a few isolated thunderstorms developing over the local
waters, especially the waters around eastern Puerto Rico, Vieques,
Culebra, and the U.S. Virgin Islands. Some of the activity moved
over land areas. While surface observing stations have reported
rainfall accumulations of up to a quarter of an inch, radar
estimates suggest isolated areas in Culebra and the northern U.S.
Virgin Islands have received over an inch. Most surface observing
stations reported overnight lows in the 70s, with upper 60s in
higher elevations. Winds have generally been light but are beginning
to trend southeasterly, as reflected by the showers forming over the
region.

Marginally unstable conditions, driven by a weakening upper-level
trough and abundant tropical moisture, with precipitable water
values around 2.0 to 2.2 inches, will maintain favorable conditions
for showers and thunderstorms today. Scattered showers and possibly
isolated thunderstorms are expected to affect the local waters this
morning, with some impacting coastal areas and the local islands. As
the day progresses and diurnal heating combined with sea-breeze
convergence matures, anticipate another stormy afternoon with
scattered to numerous showers and potentially severe thunderstorms.
After sunset, the activity will focus on the local waters and
coastal areas, particularly in southerly-exposed areas.

Winds are expected to remain light, but unlike previous days, there
will be a more noticeable southeasterly steering flow today. As a
result, developing storms will likely initiate over the interior and
gradually move north to northwest, following the steering flow. If
conditions are ideal, these storms pose risks for excessive rainfall
(flooding), strong gusty winds, lightning strikes, and possibly
small hail. While the rain may provide brief relief from the heat,
overall warm-to-hot conditions are expected. Consequently, a Heat
Advisory is in effect for northern Puerto Rico and Saint Croix, as
this level of heat may significantly impact those who are
particularly sensitive to heat, especially if they are outdoors
without adequate cooling or hydration.

The forecast indicates calm mornings and evenings, with warm-to-hot
and stormy afternoons expected over the next few days. On Tuesday,
reduced moisture levels will likely result in fewer and more
localized showers. However, as instability and moisture levels rise
by Wednesday—well above typical October threshold values—expect an
increase in showers and thunderstorms, with a heightened flooding
risk. Warm-to-hot conditions will continue, so individuals planning
outdoor activities or working outside should take necessary
precautions. Winds are expected to pick up, but they won't be strong
enough to pose any threats. For updates on excessive heat, heavy
rainfall, or other potential hazards in the days ahead, visit the
Experimental Graphical Hazard Weather Outlook at
https://www.weather.gov/erh/ghwo?wfo=sju.

&&

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

Variable weather is expected for the long-term period. Thursday will
be the wettest day, as precipitable water (PWAT) values are expected
to exceed the climatological normal. Additionally, the Gálvez-
Davison Index suggest deep convection activity, promoting
isolated-to-scattered thunderstorms in the interior and
northwestern sections of PR. Therefore, a limited to elevated
flooding risk can be anticipated each day. Ponding of water in
roadways and poorly drained areas is very likely, with urban and
small stream flooding across interior Puerto Rico during the
afternoon hours.

The latest model guidance shows a dry air mass expected to reach the
region by Friday through Saturday morning as a weak mid-level high
pressure over the western Atlantic moves westward and remains over
the central Atlantic. A surface high pressure north to the region
will continue pushing moisture, increasing shower and thunderstorm
activity in the afternoon hours for the rest of the forecast period.
Winds with a southerly component, abundant tropical moisture, and
warmer-than-normal 925 mb temperatures will promote limited to
elevated heat risk for coastal and urban areas of PR and USVI.

&&

.AVIATION...
(06Z TAFS)

Abundant moisture and favorable conditions will boost SHRA/TSRA
development, bringing MVFR to brief IFR conditions due to reduced
visibility and BKN-OVC skies below FL020-030 across most terminals.
TJUA and USVI terminals may experience operational impacts over the
next 24 hours, with TJBQ and TJPS affected between 07/16-22Z. Light
to calm and variable winds, increasing to 5-10 knots from the ESE
after 07/13Z, with sea breeze variations and higher gusts,
especially near SHRA/TSRA.

&&

.MARINE...

Light east to southeast winds will prevail through next week as a
weak surface high pressure develops northeast of the region. Swells
from Hurricane Kirk over the north-central Atlantic will slowly
subside today onwards. However, additional long-period northerly
swells will arrive across the local Atlantic waters and passages by
the end of the week from distant storms.

&&

.BEACH FORECAST...

A high risk of rip currents continues in effect for the northern
beaches of PR and a moderate risk for some of the northwestern and
northeastern beaches of PR, Vieques, Culebra, and the USVI. Low
risk elsewhere. Additional long-period northerly swells are
expected to deteriorate once again marine and coastal conditions
late this workweek and into the weekend.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
438 AM AST Tue Oct 8 2024

.SYNOPSIS...

An unstable and wet weather pattern will persist through mid-week,
accompanied by dangerously hot and humid conditions lasting for
several days. Thunderstorm activity, particularly in the
afternoon, could produce strong gusty winds, frequent lightning,
and flooding impacts each day. Swells from distant storms will
generate life-threatening rip currents and hazardous marine
conditions by the end of the week into the weekend.

&&

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

Radar observations have shown areas with scattered showers and a few
isolated thunderstorms developing over the local waters, especially
the Caribbean waters and passages. Some have moved over southern
Puerto Rico and the local islands. While surface observation
stations have reported rainfall accumulations below half an inch
since 6 PM AST, radar estimates suggest an area centered over
Humacao with around three-quarters of an inch. Overnight lows ranged
from the upper 60s across higher elevations to around 82-84 degrees
across lower and coastal elevations of northeastern and southern
Puerto Rico, with upper 60s in higher elevations. Winds have
generally been light but are beginning to trend southeasterly, as
reflected by the showers forming over local waters.

Aside from slightly lower moisture levels, with precipitable water
ranging from 1.9 to 2.1 inches, today's weather is expected to
mirror yesterday's pattern. A lingering weak trough will maintain
marginally unstable conditions for thunderstorms. However, intense
daytime heating and sea-breeze convergence will become the primary
forces once fully established. Since the steering flow will remain
light and mostly southeasterly, showers and thunderstorms will
likely develop over the southern slopes and the interior between the
late morning and late afternoon hours, gradually spreading north-to-
northwestward as the day progresses, heightening the risks of
flooding, lightning, and gusty winds. While rain may temporarily
relieve the heat, warm-to-hot conditions are anticipated. A Heat
Advisory has been issued for northern Puerto Rico and Saint Croix,
valid between 10 AM and 5 PM AST, as these heat levels could
significantly affect those particularly sensitive to heat,
especially outdoors, without proper cooling or hydration.

The forecast suggests that instability from a surface-induced trough
and increasing moisture levels between Wednesday and
Thursday—significantly above typical October levels—will promote the
likelihood of thunderstorm formation, as shown by the Galvez-
Davidson Index (GDI). Additionally, Thursday will be a transition
day as a drier-than-usual air mass moves into the northeastern
Caribbean, generating a more stable weather pattern. Warm-to-hot
conditions will persist, so those planning outdoor activities or
working outside should take appropriate precautions. Winds are
expected to increase by midweek but not strong enough to cause any
threats. For updates on excessive heat, excessive rainfall, or other
potential hazards in the days ahead, visit the Experimental
Graphical Hazard Weather Outlook at
https://www.weather.gov/erh/ghwo?wfo=sju.

&&

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

A variable weather pattern is expected for the forecast period. The
latest model guidance shows a dry air mass reaching the islands by
Friday, as a mid-level ridge moves westward and remains over the
central Atlantic. The Precipitable Water (PWAT) values will
gradually increase to typical values for the season from Saturday
onwards. Additionally, the Gálvez-Davison Index indicates shallow
convection with very few isolated thunderstorms. Diurnal heating,
sea breeze convergence, and local effects will promote shower and
thunderstorm activity over the interior and west to northwest
sections of PR over the weekend.

The start of the next workweek will be wet and unstable as high-
level troughs in the Central Atlantic move westward towards the
Caribbean, and a surface of high pressure north to the region
continues pushing moisture. The latest model guidance shows PWAT
values near the above climatological normal, enhancing rainfall
accumulations across the interior and west/northwest PR. Therefore,
flooding of urban areas, roads, small streams, and washes, including
isolated flash floods, can be anticipated.

Winds with a southerly component, abundant tropical moisture, and
warmer-than-normal 925 mb temperatures will promote limited to
elevated heat risk for coastal and urban areas of PR and USVI.

&&

.AVIATION...
(06Z TAFS)

VCSH/SHRA will affect USVI terminals, TJSJ, and TJPS through
08/14Z. Then, SHRA/TSRA are expected to affect most terminals
between 08/14-22Z, potentially bringing MVFR to brief IFR
conditions due to reduced visibility and BKN-OVC skies below
FL020- 030. Light to calm and variable winds, increasing to 5-10
knots from the ESE after 08/13Z, with sea breeze variations and
higher gusts, especially near SHRA/TSRA.

&&

.MARINE...

Light east to southeast winds will prevail through the end of the
workweek as a weak surface high pressure develops northeast of the
region. Swells generated from Post-Tropical Cyclone Kirk over the
far north-central Atlantic will continue to subside today. However,
additional long-period northerly swells from distant storms, will
arrive across the local Atlantic waters and passages by the end of
the week into the weekend.

&&

.BEACH FORECAST...

Atlantic nearshore buoys continue to report breaking waves above 6
feet. Therefore, the Rip Current Statement will remain in effect
through this afternoon for all beaches along the north coastline of
Puerto Rico. For more information and details, please refer to the
latest Surf Zone Forecast (SRFSJU) and the Coastal Hazard Message
(CFWSJU).

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
518 AM AST Thu Oct 10 2024

.SYNOPSIS...

A drier-than-normal airmass will limit rain chances through the
end of the week. Hazardous seas and coastal conditions will
persist over the next days as long period swells arrive to the
local Atlantic waters and passages. Sweltering hot temperatures
will persist, with the potential for Heat Advisories and Warnings
today and are anticipated to probably continue over the next few
days.

&&

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

Radar observations have identified isolated to scattered showers
and a few thunderstorms developing over the local waters,
particularly in the Caribbean and its passages. Some have moved
into southern and eastern Puerto Rico and nearby islands. Surface
observation stations report rainfall accumulations of about three-
quarters of an inch in Ponce and around an inch in St. Croix since
8 PM AST. At the same time, radar estimates indicate various
isolated southern and eastern Puerto Rico areas have received
between half an inch and an inch of rain. Overnight temperatures
ranged from the lower 70s in higher elevations to around 82-84
degrees in lower and coastal areas, including southern, eastern,
and northeastern Puerto Rico and the San Juan metropolitan area.
Winds have generally been light from the southeast, reflected in
the showers' formation over the local waters.

The short-term forecast will be predominantly influenced by a drier-
than-normal airmass associated with a surface high pressure system
anticipated to drift just east-northeast of the region.
Concurrently, mid-level ridging to the north will enhance dry air
entrainment and subsidence, creating unfavorable conditions for
thunderstorm development. GOES-16 Total Precipitable Water (PWAT)
imagery indicates that this transition to lower PWAT values is
already in progress, with estimates expected to fall below the
typical October range, potentially reaching 1.2-1.4 inches, as the
airmass continues to advance across the area today. This airmass is
projected to persist until Saturday, when the proximity of a
Tropical Upper Tropospheric Trough (TUTT) will initiate a gradual
shift toward a wetter and more unstable weather pattern, as
suggested by the Galvez-Davison Index (GDI). At the surface, winds
are forecasted to maintain an east-southeast to southeast direction
at speeds of 10-15 mph throughout this period, contributing to
warmer 925 temperatures and directing any shower activity toward the
west-northwest.

Despite the anticipated drying conditions, the forecast still calls
for limited and highly localized showers, along with one or two
isolated thunderstorms, primarily over northwestern Puerto Rico and
areas downwind from the local islands and the Sierra de Luquillo
each afternoon. The expected rains could result in minor flooding
impacts on roadways and poorly drained areas today and Saturday.
Friday is expected to be the driest and most favorable day for
outdoor activities. However, warm-to-hot conditions will persist, so
those planning outdoor events or working outside should take
necessary precautions and plan accordingly. For updates on excessive
heat, heavy rainfall, or other potential hazards in the coming days,
please visit the Experimental Graphical Hazard Weather Outlook at
https://www.weather.gov/erh/ghwo?wfo=sju.

&&

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

During the long-term period, we will transition to a wetter and more
unstable pattern. Based on the latest precipitable water (PWAT)
models, values are anticipated to gradually exceed climatological
normal starting Sunday into Monday. A TUTT low will sweep close to
our area, and deep-layer moisture should be in place, enhancing
rainfall accumulations across the islands. Additionally, the
potential for thunderstorm development will increase as 500 mb
temperatures decrease to around -6 degrees Celsius. As a result,
flooding in urban areas, on roads, in small streams, and in
washes—including isolated flash floods—can be expected from Sunday
into the start of next week. On Tuesday and Wednesday, moisture
content will decrease to around normal climatological values for
this time of year, leading to a more typical pattern with morning
showers across the eastern sectors of Puerto Rico and local islands,
and afternoon convection across the interior and west due to
southeasterly winds. While cloud cover should help keep temperatures
a few degrees lower at the beginning of the period, southerly winds,
combined with ample tropical moisture and warmer-than-normal
temperatures at the 925 mb level, will contribute to a heat risk
ranging from limited to elevated for low-elevation and urban areas
of Puerto Rico and the U.S. Virgin Islands for most of the period.

&&

.AVIATION...
(06Z TAFS)

VFR conds to prevail. SHRA will continue to affect TJPS and USVI
terminals through 10/14Z. Then, SHRA/TSRA possible across NW PR,
with brief MVFR conds possible across TJBQ and TJSJ between 10/16-
22Z. Light and variable winds, increasing to 5-10 knots and turning
from the ESE after 10/14Z.

&&

.MARINE...

Gentle to moderate southeast winds will prevail through the end
of the workweek as a weak surface high pressure develops northeast
of the region. Long-period northerly swells generated from
Hurricane Leslie and distant storms will continue to arrive to the
local Atlantic waters and passages over the next few days,
promoting hazardous seas.

&&

.BEACH FORECAST...

A High Surf Advisory continues in effect for the beaches from
Rincon, the northern coastline of Puerto Rico through Fajardo,
Culebra, and the U.S. Virgin Islands through 6 AM AST Friday.
These large breaking waves will result in life-threatening rip
currents and cause minor beach erosion. For more details, please
refer to the latest Surf Zone Forecast (SRFSJU) and Coastal Hazard
Message (CFWSJU).

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
527 AM AST Fri Oct 11 2024

.SYNOPSIS...

Limited showers and hot conditions will persist through today,
with shower and thunderstorm activity gradually increasing this
weekend into early next week. Hazardous marine and coastal
conditions are expected to continue through at least this weekend.
Warm to hot conditions are anticipated throughout this period.

&&

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

Skies were mostly clear during the overnight hours with only a few
light showers noted over the offshore coastal waters. Overnight low
temperatures were in the upper 70s to low 80s along the coastal
areas and in the upper 60s to low 70s n higher elevations. Winds
were calm to light and variable. Extremely hot conditions are
expected to continue today with daytime high expected to reach the
low to mid 90s especially along parts of the north coastal areas
under a light southerly wind flow. The dominant light southerly wind
flow and strong mid to upper level ridging will maintain a subsident
weather pattern and thus promote above normal heat conditions across
the region. This pattern is expected to persist through Saturday,
with the local wind flow gradually becoming more east-southeasterly
over the rest of the weekend.

Limited shower activity is expected today under overall dry and
stable weather pattern. However the intense daytime heating along
with local sea breezes and local effects may lead to late afternoon
convection over parts of the west central and northwest Puerto Rico.

By Saturday afternoon, an slight increase in low-level moisture is so
far expected with model guidance suggesting PWAT values to be around
1.7 inches. This will increase the potential for scattered showers
and isolated thunderstorms during the afternoon but mainly focused
over the central interior and west to northwest sections of Puerto
Rico. Lesser activity is forecast for the U.S. Virgin Islands
where mostly hot and sunny conditions are expected.

As the upper ridge is to erode by Sunday with the approach of a Tutt
from the east, a transition to a wetter and more unstable pattern is
forecast. Latest guidance continued to suggest precipitable water
(PWAT) values to increase to between 1.80 to 2.13 inches by Sunday
afternoon thus exceeding the climatological normals. This expected
scenario will then favor enhanced overnight and afternoon convection
across the islands. Additionally, the potential for thunderstorm
development will increase as the suggested 500 mb temperatures
decrease to between -6 and -7 degrees Celsius by Sunday afternoon.
Consequently the forecast continues to support best chance for
enhanced afternoon showers and thunderstorm development with
possible flooding in urban areas and small streams, including
isolated flash floods possible during that time especially across
portions of central and northwest to north central Puerto Rico
including parts of the San Juan metro area.

&&

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

At the beginning of next week, a wet pattern is expected to
persist, accompanied by easterly winds. According to the latest
precipitable water (PWAT) models, values on Monday are projected
to range from 1.8 to 2 inches, which falls within the normal
range. At the upper levels, the axis of the TUTT low is
anticipated to be near our area, enhancing rainfall development
across the islands. Furthermore, the potential for thunderstorm
activity is likely to increase, as 500 mb temperatures are
expected to remain around -6 degrees Celsius. While winds may
increase slightly, helping to expedite the movement of showers,
some flooding in urban areas, on roads, and in small streams
cannot be ruled out, particularly during the afternoon hours.

Variable conditions are expected to continue through mid-week. On
Tuesday and Wednesday, mixed patches of moisture and dry pockets
will shift within the easterly wind flow, creating a more typical
weather pattern with morning showers across the eastern sectors of
Puerto Rico and local islands, and afternoon convection in the
interior and western regions. By Thursday, models indicate an
increase in moisture, further enhancing rainfall development
across the islands. Throughout this period, warm to hot conditions
are anticipated.

&&

.AVIATION...
(06Z TAFS)

VFR conds at all local terminals and en route btw islands. Few SHRA
mainly over the offshore regional waters and local passages btw PR
and the USVI, mstly SKC. SFC wnd calm to lgt/vrb bcmg S-SE 5-10 kts
with sea breeze variations aft 11/14Z. SCT SHRA/ Isold TSRA psbl
mainly over the Cordillera Central and NW PR fm 11/18-11/22Z. Lgt
l/lvl wnds 5-10 kts with srly component BLO FL100...then backing
bcmg fm E and incr w/ht ABV.

&&

.MARINE...

Gentle to moderate southeast winds will prevail through the weekend
as a weak surface high pressure pattern continues northeast of the
region. Long-period northeasterly swells generated by Hurricane
Leslie and distant storms and northwesterly swells from Hurricane
Milton will continue to arrive to the local Atlantic waters and
passages over the next few days, promoting hazardous seas.

&&

.BEACH FORECAST...

Buoy 41044 is indicating additional long-period northeasterly
swells reaching the northern coastal waters today. As a result,
the High Surf Advisory was extended through 6 PM AST this
afternoon due to large breaking waves up to 10 feet. These large
breaking waves will create dangerous swimming conditions and may
cause minor beach erosion. A High Rip Current Risk remains in
effect for the northwestern, northern, and eastern beaches of
Puerto Rico, as well in Culebra and all the U.S. Virgin Islands.
For more details, please refer to the latest Surf Zone Forecast
(SRFSJU) and Coastal Hazard Message (CFWSJU).

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
354 AM AST Sat Oct 12 2024

.SYNOPSIS...
Weak high pressure ridge extending southwards from the northeast
Atlantic along with a series of low pressure and Tropical storm
Leslie across the west and central Atlantic respectively, will
help maintain light southeast winds the remainder of the holiday
weekend. Hazardous marine and coastal conditions will persist as
long period swells from the distant storms arrive across the
local waters. Hot conditions will continue for the next several
days. Overall dry and stable conditions will prevail today,however
by Sunday an increase in moisture will promote better chance for
showers and isolated thunderstorm development mainly across the
interior and northwestern Puerto Rico.

&&

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

Surface observations and satellite imagery showed calm weather
conditions overnight across the islands, with mostly clear skies and
only a few clouds drifting in from the east. Minimum temperatures
are ranging from the upper 70s to low 80s along the coasts and
valleys, including the U.S. Virgin Islands, while higher elevations
are experiencing temperatures in the upper 60s to mid-70s.

A mid-to-upper ridge and a drier air mass continues to dominate the
region, with precipitable water levels hovering around the 25th
percentile, below the normal for this time of year. This will
maintain stable conditions throughout the morning. As the day
progresses, humidity will increase slightly from the east,
potentially leading to the development of some scattered showers
across the Cordillera Central of Puerto Rico and interior western
municipalities during the afternoon. Isolated and brief rain showers
are also expected in the vicinity of the U.S. Virgin Islands. For
the rest of the area, conditions will remain predominantly stable
and sunny, but hot conditions are expected.

From Sunday onwards, the upper ridge is expected to erode, leading
to more favorable weather conditions for shower development due to
increasing moisture content and the influence of a Tropical Upper
Tropospheric Trough (TUTT) low moving in from the east. According to
the latest precipitable water (PWAT) models, values are projected to
gradually rise to around 2.0–2.1 inches, which is at the high end of
the normal range for this period. On Monday, values are expected to
range from 1.8 to 2.0 inches, also within the normal range. The
potential for thunderstorm development will increase as 500 mb
temperatures decrease to around -6 and -7 degrees Celsius.
Consequently, the forecast continues to indicate best chances for
enhanced afternoon showers and thunderstorms, with the possibility
of flooding in urban areas and small streams, especially across
portions of central and northwest to north-central Puerto Rico,
including parts of the San Juan metro area. Additionally, warm to
hot conditions are likely to persist for the next several days, with
925 mb temperatures expected to remain two standard deviations above
the normal range. Highs are projected to reach the low to mid-90s in
coastal, lower-elevation, and urban areas of the islands, with heat
indices exceeding 100°F. Residents and visitors should take
precautions to stay hydrated by drinking plenty of water, wearing
light and breathable clothing, and avoiding prolonged exposure to
the sun.


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

At least through Tuesday, good moisture convergence accompanying an
induced surface trough is forecast to persist under a light east to
southeast low level wind flow. The proximity of a mid to upper
trough (TUTT) and associated low will help maintain unstable conditions
aloft. The latest layered precipitable water (PWAT) products suggest
values ranging between 1.75 to 2.05 inches at least until Wednesday.
The aforementioned Tutt low is forecast to reposition over or just
southwest of Puerto Rico by then. Consequently this should aid in
enhancing overnight and afternoon shower development in and around
the islands. Additionally,the potential for thunderstorm activity
will be likely as 500 mb temperatures are also expected to remain
between -6 and -7 degrees Celsius through Tuesday. Surface winds
are forecast to increase and become more easterly by mid week.
This will aid in quickly moving the shower activity across the
islands and coastal waters. However, afternoon convection may lead
to some isolated flooding in urban areas, on roads, and in small
streams.

Variable conditions are expected to continue through mid-week with a
mix of sunshine and clouds each day steered by the light to moderate
easterly winds. Passing overnight and early morning showers will remain
possible along parts of the east coastal sections of the islands. The
driest period so far appears to be late Wednesday through Thursday
when a more typical weather pattern is expected with only brief
morning showers possible on the east coastal sections. This will
be followed by limited afternoon convection focused mainly over
the interior and western Puerto Rico. By late Thursday or early
Friday and the rest of the period, model guidance continued to
suggest an increase in moisture due to the approach of a vigorous
tropical wave. This forecast scenario should increase moisture
convergence and instability, and further enhance showers and
thunderstorms development across the islands and coastal waters.
Throughout this period, warm to hot and humid conditions are
expected to persist.

&&

.AVIATION...
(06Z TAFS)

VFR conditions are expected to continue most of the period. Light
and variable winds becoming 5 to 10 knots and sea breeze variations
around mid morning into the afternoon. VCSH are possible across the
USVI TAF sites around 12/14-15Z with sct clouds, then some VCTS are
possible after 18Z across TJBQ with sct to bkn skies. Winds becoming
light and variable overnight.

&&

.MARINE...
Gentle to moderate east southeast winds will prevail through the rest
of the weekend as a weak surface high pressure pattern will continue
northeast of the region. Slowly decaying Long-period northerly swells
generated from Tropical Storm Leslie and distant storms over the west
Atlantic will continue to arrive to the local Atlantic waters and
passages at least into early next week, promoting hazardous seas.

&&

.BEACH FORECAST...
Slowly decaying long-period north northeasterly swells will
continue to reach the local waters from distant storms over the
Atlantic. A High Rip Current Risk remains in effect for the
northwestern, northern, and eastern beaches of Puerto Rico, as
well in Culebra and St. Croix. There is a moderate risk of rip
currents for the north facing beaches of St Thomas and St John.
For more details, please refer to the latest Surf Zone Forecast
(SRFSJU) and Coastal Hazard Message (CFWSJU).

[cycloneye]

Area Forecast Discussion...CORRECTED
National Weather Service San Juan PR
537 AM AST Sun Oct 13 2024

.SYNOPSIS...
Hazardous marine and coastal conditions will persist the rest today
as long-period northerly swells arrive into our local waters. Hot and
humid conditions will continue for the next several days across the
region. An increase in tropical moisture is expected today into the
early part of the upcoming week due to the approach of an upper- level
trough and an induce surface trough crossing the region. This pattern
will increase the chance for showers and isolated thunderstorm development
across the coastal waters and U.S. Virgin Islands the rest of the morning
hours, then spreading over the interior and northwestern to northern
sections of Puerto Rico during the afternoon hours.

&&

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

Satellite and radar imagery indicated partly cloudy conditions overnight,
with isolated to scattered showers moving across the Caribbean local
waters, the U.S. Virgin Islands, and the eastern sectors of Puerto
Rico. Surface observations showed overnight temperatures ranging
from the upper 70s to low 80s along the coasts and valleys, including
the U.S. Virgin Islands, while higher elevations experienced slightly
cooler temperatures in the upper 60s to mid-70s.

During the short-term forecast period, we will have a more conducive
atmosphere for the development of showers and thunderstorms. At the
surface, a weak high-pressure pattern will maintain predominantly
southeast winds, with variations of sea breezes developing each day.
Aloft, the upper ridge is expected to erode as a Tropical Upper
Tropospheric Trough (TUTT) low moves into the local area from the
east. According to the latest precipitable water (PWAT) models,
values are projected to gradually rise today to around 2.0 to 2.1
inches, which is at the high end of the normal range. Therefore,
expect the development of scattered to numerous showers and isolated
thunderstorms today, particularly over the southern slopes and
interior between late morning and late afternoon, gradually
spreading north to northwest as the day progresses, heightening the
risks of flooding, lightning, and gusty winds. Across the U.S.
Virgin Islands, expect the showery weather to continue throughout
the morning hours.

On Monday, patches of drier air are expected to move into the area,
and PWAT values are projected to decrease slightly, ranging from 1.7
to 1.9 inches. Overall, this may somewhat limit the development of
showers; however, daytime heat, local effects, and existing humidity
could still lead to some trade wind showers, with additional
afternoon rain focused on the northwest quadrant of Puerto Rico. On
Tuesday, moisture content is anticipated to increase again to around
2 inches, which should enhance shower and thunderstorm development
early morning hours over the waters and in the afternoon across the
islands. This could lead to flooding in urban areas and small
streams. The potential for thunderstorm development with the
afternoon showers and over the waters will persist throughout this
period, as 500 mb temperatures decrease to around -6 to -7 degrees
Celsius today and remain at that temperature over the next several
days. According to the Galvez-Davidson Index (GDI), we have a
higher chance of observing thunderstorm development today and
Tuesday.

Despite any rain, warm to hot conditions are likely to persist over
the next several days. The 925 mb temperatures are expected to
remain two standard deviations above the normal range today. Highs
are projected to reach the low to mid-90s in coastal, lower-
elevation, and urban areas of the islands, with heat indices
exceeding 100°F.
&&

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

Based on recent model guidance and the overall weather pattern,
the easterly winds will increase while low level moisture will
continue to erode Wednesday through Thursday. By Friday and
through at least late Saturday or early Sunday, moisture pooling
and low level convergence and instability will increase due to
the approach of a vigorous tropical wave and broad low level
moisture field so far forecast to spread across the region. The
latest layered precipitable water (PWAT) products suggest overall
values to diminish and range between 1.65 to 1.80 inches Wednesday
through Thursday but significantly increasing to between 2.0 to
2.5 inches Friday through Saturday. This along with good ventilation
aloft, will aid in enhancing overnight and afternoon shower development
across the islands and coastal waters during the latter portion of
the period and at least until early Sunday. Overall weather
conditions are expected to improve thereafter with a return of
light to moderate east to southeast winds. The increasing chance
for overnight and afternoon convection Friday through Saturday
will also increase the potential for localized flooding impacts in
urban areas, on roads, and along some rivers and small streams
across Puerto Rico and the U.S. Virgin Islands Friday through
Saturday.

Mostly sunny to partly cloudy skies area expected through Thursday
becoming variably cloudy with a mix of sunshine and clouds by Friday
into the weekend, due to increasing moisture and the approach of the
aforementioned tropical wave. Passing overnight and early morning
showers will remain possible along parts of the east coastal sections
of the islands with afternoon convection expected but mainly focused
across the central interior and west sections of Puerto Rico each
afternoon through Thursday. There is however increasing chance
for more widespread showers across the coastal waters and portions
of the islands Friday through Saturday when the overall weather
conditions are expected to be the most active part of the period.
Meanwhile the driest and hottest period will be Wednesday through
Thursday when a more typical weather pattern is expected with limited
showers and isolated thunderstorms focused mainly over the east coastal
sections, and across the interior and western Puerto Rico during
the afternoon.

&&

.AVIATION...
Mainly VFR conditions expected to prevail through the morning
period. SHRA will increase in frequency across the Anegada Passage,
reaching the USVI terminals at times. Periods of reduced VIS and low
ceilings are possible. Around 13/17Z onwards, SHRA and TSRA are
expected over the western Cordillera Central, with some impacts to
operations across TJBQ. General wind flow will remain from the SE at
10 knots or less, stronger gusts may occur near rain and t-storm
activity.

&&

.MARINE...
Gentle to moderate east southeast winds will prevail through the
holiday weekend as a weak surface high pressure pattern continues
northeast of the region. Slowly decaying long-period northerly
swells generated from distant storms and areas of low pressure
will continue to affect the local Atlantic waters and passages
over the next few days, promoting hazardous seas.

&&

.BEACH FORECAST...
Slowly decaying long-period north northeasterly swells will
continue to reach the local waters from distant storms over the
Atlantic. A High Rip Current Risk remains in effect for the
northwestern, northern, and eastern beaches of Puerto Rico and
Culebra. There is a moderate risk of rip currents for the north
facing beaches of St Thomas and St John and Vieques. For more
details, please refer to the latest Surf Zone Forecast (SRFSJU)
and Coastal Hazard Message (CFWSJU).

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
501 AM AST Mon Oct 14 2024

.SYNOPSIS...

A fairly moist and unstable weather pattern will continue across
the islands today due to the proximity of an upper level trough
(TUTT) and associated low pressure crossing the region and now
just west and southwest of Puerto Rico. An induced low level
trough and a weak tropical wave will also maintain unstable
conditions through midweek. The National Hurricane Center is
monitoring a well- defined area of low pressure Invest 94L,
located several hundred miles west of the Cabo Verde Islands. The
system has a medium (40%) formation chance through 7 days and
could approach the area to end the workweek. Residents and
visitors should continue to monitor future updates regarding this
system.

Small craft should exercise caution over the Atlantic waters and
local Passages. A High Rip Current Risk is in effect for the
northwestern, northern, and eastern beaches of Puerto Rico, and
Culebra through this afternoon. A Heat Advisory will be in effect
for the coastal areas of Puerto Rico, & St. Croix from 10 AM to 4
PM.

&&

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

Fairly moist and unstable weather pattern will continue across the
islands today due to the proximity of an upper level Trough (TUTT)
and associated low pressure crossing the region and now just west
and southwest of Puerto Rico. This along with an induced low level
trough and weak tropical wave will maintain unstable conditions
during the period. For the rest of the early morning hours, isolated
to scattered showers can be expected around the USVI, over the
Caribbean waters and Mona passages as well as over the offshore
Atlantic waters. Brief passing showers may also brush the northeast-
and southeast sections of Puerto Rico but rainfall accumulations
should be minor. During the afternoon, good daytime heating and the
instability in place along with localized convergence will favor
showers and isolated thunderstorm development over the central and
northwest sections of Puerto Rico as well as around portion of the
San Juan metro area. As a result minor urban and small stream
flooding, ponding of water on roads and quick rises of water level
along rivers in these areas will again be possible. A hot and humid
trend will persist and for this reason a heat Advisory will be
likely for some areas at least into the early afternoon hours before
the start of afternoon convection.

Expect afternoon shower activity and cloudiness to gradually
diminish and dissipate before sunset, leaving mostly fair weather
conditions for the rest of early evening and overnight. However few
passing showers may continue across the coastal waters and between
eastern Puerto Rico and the U.S. Virgin Islands. By Tuesday and at
least through Wednesday, latest model guidance continued to suggest
a drier pattern, as the TUTT weakens/ fills and pulls away from the
region. Moisture content across the area will also erode with
layered precipitable water values (PWAT) expected to diminish and
range between 1.5 to 1.7 inches. Nonetheless, shower development and
isolated thunderstorms are expected across the interior and western
Puerto Rico during the afternoon hours due to the combination of
daytime heating and local effects. This activity may lead to minor
flooding in urban areas and small streams but mainly in isolated
areas. Daytime highs are expected to reach the low 90s each day with
elevated maximum heat indices possible for portions of the coastal
and urban areas through the rest of the period.

The National Hurricane Center continues to monitor a well defined
area of low pressure and tropical wave, Invest 94L, which is located
several hundred miles west of the Cabo Verde Islands. The short term
potential for development is low at this time, but the system may
encounter conditions more favorable for development for the middle
or latter part of the week when there is a medium potential for
formation at the moment. Since the system is still several days away
from the islands, uncertainty remains very high as far as impacts,
but users should stay tuned for further updates.

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

Model guidance indicates patches of moisture on Thursday, with
precipitable water (PWAT) values only locally reaching 2 inches. A
typical weather pattern is forecast for Thursday, including passing
overnight and early morning showers steered by easterly winds along
parts of the east coastal sections of the islands with afternoon
convection expected but mainly focused across the central interior
and west sections of Puerto Rico. High heat indices will continue.
The National Hurricane Center (NHC) monitors a well defined area of
low pressure several hundred miles west of the Cabo Verde Islands.
Designated as Invest 94L, the NHC forecasts that environmental
conditions could become more favorable during the start of the long
term period. This system currently has a 40 percent formation chance
through 7 days. GFS model guidance has the system nearing the
islands on Friday, while the ECMWF has the system more north of the
local islands. It is still to early to know any specific impacts, if
any, that this system could bring. An increase in overall moisture
is still forecast even if the system doesn't form, as a broad
moisture field engulfs the region, with PWAT values increasing to
above 2 inches possibly through the end of the forecast period. With
the forecast to end the workweek and to start the weekend more
closely linked to the future of Invest 94L, uncertainty remains.
However, with increased moisture and overall more unstable
conditions, the chance for overnight and afternoon convection Friday
through Saturday will increase along with the potential for
localized flooding impacts in urban areas, on roads, and along some
rivers and small streams across Puerto Rico and the U.S. Virgin
Islands. More typical weather conditions, albeit with more moisture
are forecast by next week under light to moderate east to southeast
winds. For more information regarding Invest 94L, please refer to
the latest Tropical Weather Outlook (TWOAT & TWOSAT) issued by the
NHC.

&&

.AVIATION...

(06Z TAFS)

Tutt low crossing the forecast area today along with an induced low
level trough and tropical wave will enhance SHRA/iSOLD TSRA en route
btw islands, especially over the Caribbean waters and the Mona
Passage. VCSH will remain psbl at TJSJ/TISX/TIST til 14/14Z with
brief mtn top obscr psbl ovr E interior of PR til 14/12Z. Fm 14/17Z-
22Z SHRA/Isold TSRA psbl at TJBQ and ovr NW PR, with brief MVFR in
aftn convection. VCSH psbl at TJSJ/TISX/TIST fm 14/19Z-22Z. SFC Wnd
calm to lgt/vrb, bcmg fm ESE at 10-15 kts with hir gusts and sea
breeze variations aft 14/14Z.

&&

.MARINE...

Gentle to moderate east southeast winds will prevail into mid-week
as a weak surface high pressure pattern will continue northeast of
the region. Slowly decaying long-period northerly swells generated
by distant storms will continue to affect to the local Atlantic
waters and passages through at least today. Small craft should
exercise caution over the Atlantic waters and local Passages.

&&

.BEACH FORECAST...

A High Rip Current Risk was kept in effect for the northwestern,
northern, and eastern beaches of Puerto Rico, and Culebra through
this afternoon. A slowly decaying long-period north northeasterly
swells will continue to reach the local waters today. A moderate
rip current risk is in effect for western PR, southeastern PR,
Vieques and the USVI. Low risk elsewhere. For more details,
please refer to the latest Surf Zone Forecast (SRFSJU) and Coastal
Hazard Message (CFWSJU).

[underthwx]

I read the SanJuan forecast discussion everyday....hurricane season or not....usually if a storm is brewing out in the atlantic...you can bet there will be a discussion about it there....I hope 94L does not cause problems in the region...or anywhere else...these systems seem to keep popping up this season...for whatever reason...94L is evidence of that...

[cycloneye]

I read the SanJuan forecast discussion everyday....hurricane season or not....usually if a storm is brewing out in the atlantic...you can bet there will be a discussion about it there....I hope 94L does not cause problems in the region...or anywhere else...these systems seem to keep popping up this season...for whatever reason...94L is evidence of that...

Hopefully it moves north of the islands but we could get plenty or not much rain depending how close it moves.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
458 AM AST Tue Oct 15 2024

.SYNOPSIS...

Through midweek, a drying trend with low concentrations of
Saharan dust and increasing east to southeast winds, as a surface
ridge builds in across the region from the east. A Heat Advisory
will be in effect for the coastal areas of Puerto Rico, & St.
Croix from 10 AM to 4 PM. The National Hurricane Center continues
to monitor an area of low pressure (Invest 94L) located in the
central tropical Atlantic. The system has a medium (60%) formation
chance through 7 days and could approach the area by Friday into
Saturday. Residents and visitors should continue to monitor future
updates regarding this system.

&&

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

A Tutt low continued to shift farther west of Puerto Rico while a
weak upper ridge nudges southwest across the region from the central
Atlantic. Moisture with areas of enhanced showers and isolated
thunderstorms trailing a tropical wave now crossing Hispaniola will
continue to exit the region this morning while affecting portions of
the Mona passages and the offshore Atlantic and Caribbean waters.
While most of the thunderstorms remained offshore, some showers
reached portions of the south and east sections of Puerto Rico
producing periods of light to moderate showers at times. So far
lesser activity was observed in and around the U.S. Virgin islands
as a slot of drier air continued to filter in from the east.

For the rest of the day and through the period a gradual drying
trend trend and increasing east to southeast winds is expected, as a
surface ridge will build in across the region from the east.
However, available moisture along with local effects and good
daytime heating will lead to isolated to scattered showers with
isolated thunderstorms mainly over portions of central and northwest
Puerto Rico. Mostly sunny and slightly hazy conditions are expected
elsewhere as a low concentration of Saharan dust will linger across
the region through Wednesday. As far as impacts these is a chance
for minor urban and small stream flooding, ponding of water on
roads with the late afternoon convection but so far overall drier
conditions and no widespread weather impacts are forecast for the
period. Hot and humid conditions will persist and for this reason
a heat Advisory will be required for some areas at least into the
early afternoon hours.

Recent model guidance continue to suggest erosion of moisture across
the region through Wednesday with layered precipitable water (PWAT)
values across the area to range between 1.08 to 1.70 inches at least
into early Wednesday. A gradual increase is expected thereafter into
Thursday as the trade winds increase and a moisture surge/easterly
perturbation crosses the region in advance of a vigorous tropical
wave and area of low pressure (AL94)(which is still forecast to
approach the Lesser Antilles by late Thursday night. During the
daytime afternoon shower development and isolated thunderstorms
are however expected across the interior and western Puerto Rico
mainly due to good daytime heating and local effects. So far
limited impacts of minor flooding in urban areas and small streams
is expected over Puerto Rico while the USVI should expect mostly
hot and sunny conditions with limited shower activity most of the
period. Daytime highs will reach the low 90s each day with
elevated maximum heat indices possible for portions of the coastal
and urban areas through the period.

The National Hurricane Center continues to monitor the
aforementioned area of low pressure and tropical wave, Invest 94L,
located over the Central Tropical Atlantic. The short term potential
for development remains low at this time, but the system may
encounter conditions more favorable for development for the middle
or latter part of the week when there is medium potential (60
percent) for formation at the moment. Since the system is still
several days away from the islands, uncertainty remains very high as
far as impacts, but users should stay tuned for further updates.

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

Model guidance indicates gradually increasing moisture on Friday to
start the long term period. The National Hurricane Center (NHC)
continues to monitors a well defined area of low pressure (Invest
94L) over the central tropical Atlantic. Environmental conditions
are expected to become more favorable for gradual development by the
middle to latter part of this week. This system currently has a 60
percent formation chance through 7 days. Model guidance has the
system nearing the local islands Friday into Saturday. It is still
to early to know any direct impacts, that this system could bring.
An increase in overall moisture is still forecast even if the system
doesn't form, as the system would still pass as a tropical wave and
a broad moisture field would engulf the region, with PWAT values
increasing to above 2 inches possibly through the end of the
forecast period. With the forecast to start the period closely
linked to the future of Invest 94L, uncertainty remains. However,
with increased moisture and overall more unstable conditions, the
chance for overnight and afternoon convection Friday through
Saturday will increase along with the potential for localized
flooding impacts in urban areas, on roads, and along some rivers and
small streams across Puerto Rico and the U.S. Virgin Islands. More
typical weather conditions, albeit with more moisture are forecast
by next week under light to moderate east to southeast winds,
including passing overnight and early morning showers steered by
easterly winds along parts of the east coastal sections of the
islands with afternoon convection expected but mainly focused across
the central interior and northern sections of Puerto Rico. High heat
indices will continue. For more information regarding Invest 94L,
please refer to the latest Tropical Weather Outlook (TWOAT & TWOSAT)
issued by the NHC.

&&

.AVIATION...

(06Z TAFS)

Tutt low west of the region and a tropical wave with trailing
moisture between western PR and Hispaniola will aid in promoting
shower and thunderstorms across the Caribbean waters and offshore
Atlantic waters and the Mona passage. SCT-BKN lyrs nr FL025...
FL040..FL090. SHRA/Isold TSRA ovr regional waters en route towards
PR and the USVI. VCSH will remain psbl at TJPS/TJSJ/TISX/TIST til
15/12Z with brief mtn top obscr psbl ovr E interior of PR due to
SHRA/low clds. Fm 14/17Z-21Z SHRA/Isold TSRA psbl at TJBQ and NW
interior of PR with brief MVFR in aftn convection. VCSH at
TJSJ/TISX/TIST fm 15/18Z-23Z. SFC wnd calm to lgt/vrb, bcmg mainly
fm ESE at 12-15 kts with ocnl hir gusts and sea breeze variations
aft 15/14Z.

&&

.MARINE...

Gentle to moderate east southeast winds will prevail into mid-week
as a weak surface high pressure pattern will continue northeast of
the region. Showers and isolated thunderstorms will move across the
waters under this windflow. Afternoon convection can move over the
waters from northwest of Puerto Rico. Seas up to 4 to 5 feet are
forecast for today, locally higher near strong showers and
thunderstorms. The NHC is monitoring Invest 94L over the central
tropical Atlantic, which could increase seas and winds by the end of
the workweek.