Caribbean - Central America Weather

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
414 AM AST Wed May 22 2024

.SYNOPSIS...
Unsettled, squally weather is expected to prevail through the end of
the workweek. The risk for flooding, rapid river rises, and
mudslides will be elevated. Conditions will gradually improve by the
weekend, but still with the risk for locally strong rains in the
afternoons for western and northern Puerto Rico. Some Saharan dust
is expected early next week, as well as an elevated heat risk.

&&

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

A significant increase of passing showers were observed across the
Caribbean and Atlantic waters as seen on the radar overnight. It
appears the trend towards unstable conditions are beginning as we
approach wetter days for the rest of the week into the weekend.

This morning an increase of passing showers across southern and
eastern Puerto Rico and also across the USVI is expected as a moist
airmass begins to lift and spread throughout the local islands. This
is associated with an approaching deep-layered trough that is
currently situated between eastern Cuba and Hispanola which will
increase instability across the local area into the weekend. As this
feature induces a surface perturbation south of Hispanola late
tonight, winds are expected to strengthen over the western coastal
waters through Thursday which can bring squally weather conditions.
Precipitable water content is likely to reach above 2.4 inches will
significantly enhance the rainfall activity across the region
through this time. Thunderstorms capable of producing strong winds,
heavy downpours, and frequent lightning remain very possible during
today through Friday.

Currently models are suggesting the heaviest congestion of rainfall
to be across the interior to eastern sections of Puerto Rico,
however elsewhere plenty of rain remains possible. The mid-level jet
segment of this trough begins to move northward into the western
Atlantic Thursday night, which is projected to then cause a surface
low to form north of the region by Friday night. This will cause
surface winds to veer through Thursday into Friday becoming
generally southerly by the end of the week. A situation like this
would bring a good chance for afternoon convection along northern
Puerto Rico, however the influence of a thick cloud layer may
disrupt diurnal heating. Nonetheless, conditions will remain
unstable through this time for Puerto Rico and the Virgin Islands
with an increased risk of flooding.

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

The islands will continue to be under the influence of a moist low
to mid weak southerly flow associated with a trough centered well
north of Puerto Rico by this time. Precipitable water values will
remain above the climatological value for late May, meaning that the
potential for showers will persist. On Sunday, the trade winds will
begin to recover and will gain an easterly component, at about 10 to
12 knots. A mid to upper level ridge centered to the east of the
Leeward islands will begin to push small pockets of drier air, along
with Saharan dust, but the moisture channel just west of Puerto Rico
will also push back, reaching the islands at times. Under this
environment, it is likely that passing showers will continue to form
around the Virgin Islands and eastern Puerto Rico, while strong
afternoon convection is anticipated for the interior and western
Puerto Rico each afternoon. In fact, the Galvez-Davison index
indicate isolated to scattered thunderstorms from Saturday through
Tuesday. The risk of flooding and mudslides will remain elevated for
these areas. Temperatures will once again warm up to the low 90s,
with heat indices above 102 degrees, mainly for the coastal and
urban areas of the islands.


&&

.AVIATION...
(06z TAFS)

VFR conditions will continue, however a rapid increase of shower
activity will bring bring periods of reduced VIS and low ceilings.
Chance of TSRA will increase through the day, worsening during the
afternoon with this activity impacting mostly all terminals. Winds
will blow from SE at 8-15 kts, with stronger wind gusts and sea
breezes variations.

&&

.MARINE...
The interaction of an induced surface trough to the west and a weakening
surface high pressure to the east will promote moderate east-southeast
winds through today. As the surface trough moves closer to the
region, expect increasing shower and thunderstorm activity across
the local waters through early in the weekend. In addition, the
proximity of an amplifying mid to upper level trough just west of
the region will enhance thunderstorm development as well as increase
winds and the potential for squally conditions across the Mona
Passage and Atlantic waters late tonight through at least Friday.
Winds are forecast to diminish once again by Friday night.


&&

.BEACH FORECAST...
Surf heights 4 to 5 increased the rip current risk for eastern St.
Croix. Elsewhere, the rip current risk is low.

&&

.HYDROLOGY...
Periods of heavy showers and thunderstorms are anticipated,
especially today through Friday. The USGS streamflows show that most
rivers are running near normal to above normal. Additionally, the
experimental Puerto Rico Landslide Forecast Network (Slides-PR) are
showing high soil saturation levels. With prolonged episodes of
heavy rain, the risk for flooding, rapid river rises, water surges
and mudslides will be elevated.

&&

.CLIMATE...
The heat spell that has been affecting the islands should appease
today and tomorrow due to abundant cloudiness brought by the deep-
layered trough. So far, for the San Juan Area climate site (LMM
Airport), eight daily warm-minimum temperatures, and three daily
maximum records have been broken for May. To date, it is also the
second warmest May in history (84.0F), after 2020 (84.1). The
month is also running 3.96 inches wetter than normal.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
330 AM AST Thu May 23 2024

.SYNOPSIS...

Unsettled, squally weather is expected to prevail through the end of
the workweek, with elevated risks for flooding, rapid river rises,
and mudslides. Wet weather conditions will persist throughout next
week as a tropical wave approaches from the southeast by Monday,
maintaining above-normal moisture across the northeastern Caribbean.
Additionally, some Saharan dust is expected by early next week,
along with an elevated heat risk.

&&

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

Numerous showers and thunderstorms continued across the eastern
Puerto Rico out to the USVI, providing a rainy night. The best
rainfall overnight was seen across St. Thomas and John with multiple
thunderstorms passing by during these early morning hours.

Unstable, wet conditions will prevail into the weekend as a deep
layered trough moves through the Caribbean basin then lifting into
the southwestern Atlantic by Saturday. As the mid to upper jet of
the trough sits over Hispaniola over the next 24 hours, a surface
induced trough begins to form to the southwest of the region
causing the veering of the surface winds to a southerly flow by
Friday. A moist airmass entered the region yesterday and as winds
veer, another plume of moisture sourced from northern South
America will move into the area, keeping precipitable water values
high in the upper 2nd percentile. This moisture, unstable
dynamics aloft due to the proximity of the mid to upper-level
jets, and moderate surface wind flow will maintain a pattern of
numerous passing showers, especially for the eastern half of the
region, including eastern mainland Puerto Rico, Vieques, Culebra,
and the USVI. Squally weather with thunderstorms are possible at
times which can bring strong winds and heavy downpours.

This afternoon convection will increase shower activity with the
eastern sections most likely to receive the bulk of rain.
Thunderstorms are also likely to spawn across northwestern Puerto
Rico, however due to cloud coverage convection over land may be
reduced. However, expect a 70 to 90 percent chance of rain for all
of the island through this afternoon. Passing showers will
continue through the night into Friday and Saturday with a similar
pattern prevailing. The greatest threat during this time is
flooding due to consecutive showers and thunderstorms capable of
producing frequent lightning and strong winds. Conditions do look
slightly less unstable Friday through Saturday, yet the previous
days of rainfall and ongoing activity will keep an elevated risk
of flooding for most of the area. Also if cloud coverage begins to
lighten on Saturday, heavy afternoon convection is very likely.

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

Model guidance indicates that the wet period will persist through
the long-term forecast. Sunday remains very moist, with precipitable
water values above 2.0 inches and ample instability aloft. A mid-
level ridge just east of the forecast area is expected to move over
us by late Sunday into early Monday, coinciding with a slight
reduction in low-level moisture, which will cause precipitable water
values to drop to almost 1.8 inches. However, this "reprieve" won't
last long as a tropical wave moves from the southeast over the
islands by late Monday, causing moisture content to surge above 2.0
inches once again, persisting through the long-term forecast.
Instability aloft will be marginal, as weak ridging will alternate
with a series of weak short-wave troughs throughout the week.
Therefore, the combination of above-normal moisture and marginal
instability will maintain the flood risk across the area.

The National Blend of Models indicates approximately a 3-in-5 (60%)
chance for thunderstorm activity and a 1-in-5 (20%) chance for 24-
hour rainfall accumulations to exceed an inch each day of the long-
term forecast, particularly across western/northwestern Puerto Rico
under an east-southeast steering flow. The Galvez-Davison Index also
suggests a similar scenario, with a high potential for observing
isolated to scattered thunderstorms capable of producing heavy
rainfall. With saturated soils and elevated streamflows from
previous rainfall, the flooding risk will remain elevated.
Therefore, we could expect urban and small stream flooding, as well
as flash flooding and landslides in areas of steep terrain.

Another hot episode is expected on Sunday and Monday, accompanied by
suspended Saharan dust particulates by early next week. Therefore,
in areas with limited showers, hot and hazy conditions will prevail.
The combination of high moisture content and high temperatures will
produce hazardous heat index values, particularly in coastal and
urban areas, possibly reaching Heat Advisory criteria once again.


&&

.AVIATION...
(06z TAFS)

SHRA/TSRA will spread across USVI, mainly TIST, and
eastern/southern PR terminals this morning. Therefore, MVFR to
brief IFR conds are possible across TIST/TISX/TJSJ. A deep layered
trough over Hispaniola will continue to cause TSRA across the
Mona Passage through the forecast period, impacting the regional
terminals with VCTS/VCSH. Low-level winds ESE up to 21 kt blo
FL080, bcmg S/SW abv and increasing with height.

&&

.MARINE...

The interaction of an induced surface trough and a surface high
pressure to the northeast will promote moderate to locally fresh
east-southeast winds. In addition, the proximity of a deep layered
trough close to the Dominican Republic will continue to enhance
thunderstorm development with the potential for squally conditions
across the regional waters and local passages through at least
Friday. Winds are forecast to diminish once again by Friday night.


&&

.BEACH FORECAST...

Low to moderate rip current risk will persist throughout the period.
In the presence of moderate rip current risk, there is still the
possibility of life-threatening rip currents in the surf zone.
Please remember to heed the advice of the local beach patrol and
flag warning systems.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
427 AM AST Fri May 24 2024


SYNOPSIS...

Cloudy conditions will the chance of showers across eastern Puerto
Rico continues through today with an increase of rain during the
afternoon hours. Wet weather conditions are expected to persist
throughout next week as a tropical wave approaches from the
southeast by Monday. In addition, hot days are expected over this
weekend with heat indices in the upper 100s mainly for coastal
sections.

&&

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

The night was tranquil for the most part over land areas, with some
isolated to scattered showers occurring over the local waters,
affecting windward coastal areas of Puerto Rico and the US Virgin
Islands at times. The strongest activity was located over the
western quarter of the offshore Atlantic waters, with heavy showers
and strong thunderstorms associated with the deep-layered trough
that had been affecting the Dominican Republic in the past few days.
This activity will gradually approach the area during the morning
hours.

The forecast had to be adjusted slightly to account for some of the
latest tendencies in the recent model cycles. Challenges arise due
to the forecast area being situated between the deep-layered trough
to the northwest and a mid- to upper-level ridge southeast of the
region. The TJSJ 24/00z sounding showed dry air within the 850-500
mb layer, with mid-level relative humidities at 28%. This, along
with ridging aloft, inhibited convective activity in the last 18-24
hours.

However, the 700-500 mb CIRA Layered Precipitable Water (LPW)
product shows a broad area between the Dominican Republic and Puerto
Rico with high moisture content gradually making its way towards us.
This is partly eroding the mid-level ridge while increasing mid-
level relative humidities across the region. At the same time, the
850-700 mb CIRA LPW shows a moist slot over the USVI moving
northwestward. The latest model guidance suggests increased moisture
convergence and instability as these features approach today,
promoting the development of shower and thunderstorm activity,
particularly over the northern half of Puerto Rico and smaller
islands this afternoon.

For this weekend, the mid-level ridge will continue to move eastward
as the deep-layered trough weakens and settles in. Marginal
instability aloft will persist, with precipitable water content
exceeding and remaining above the 90th percentile of the
climatological normal. Sufficient dynamics will combine with well
above normal moisture every day, potentially leading to heavy
showers and isolated thunderstorms, mostly during the afternoon
hours. A weak southeast steering flow will cause convective activity
to cluster mostly over interior and northwestern sections of Puerto
Rico, with streamers developing downwind of the smaller islands and
El Yunque into the San Juan metro area. Slow-moving showers could
enhance rainfall accumulations in flood-prone areas. Therefore, we
can expect a limited to elevated flooding threat to persist through
the weekend.

Southerly winds will persist, advecting warm temperatures over the
local islands through the short-term forecast. Extensive cloud
coverage moving in will somewhat inhibit temperatures from
increasing substantially today. However, we can still anticipate
heat index values above 100 F across coastal and urban areas. But,
for this weekend, heat index values are projected to reach Heat
Advisory Criteria in those areas during peak hours of the day before
shower activity begins. Therefore, it's important to stay hydrated
if engaging in outdoor activities.

&&

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

Model guidance indicates that a wet pattern will persist through the
long-term forecast due to a moist airmass across the region as a
tropical wave approaches from the east. As this tropical wave
moves over the islands by late Monday, causing moisture content
to rise above 2.0 inches, an increase of unstable weather is
expected to last through the long term period. Weak ridging aloft
throughout the week will help keep conditions somewhat decent,
yet the continuation of the passage of weak short-wave troughs
through Friday will maintain above-normal moisture and marginal
instability.

The National Blend of Models hints for heavier rainfall during the
afternoon hours particularly across western/northwestern Puerto Rico
under an east-southeast steering flow. The Galvez-Davison Index also
suggests a similar scenario, with a high potential for observing
isolated to scattered thunderstorms capable of producing heavy
rainfall each day. With saturated soils and elevated streamflows
from previous days of rainfall, the flooding risk will remain
elevated. Therefore, we could expect urban and small stream
flooding, as well as flash flooding and landslides in areas of steep
terrain.

Hot days are also to be expected with heat indices reaching in the
100s to 110s through the week due to the high RH values and heating
from the summer sun, therefore heat advisories or warnings may be
issued during this time. Saharan dust particulates are expected to
arrive by early in the week. Expect hot and hazy conditions to
prevail across sections with less rainfall.

&&

.AVIATION...
(06z TAFS)

Areas of SHRA and Isold TSRA over Hispaniola will move close to TJBQ
aft 24/10Z. Aft 24/16z, SHRA and VCTS could affect all remaining
terminals. These features will reduce VIS and CIG possibly producing
MVFR/IFR conds and mtn obscurations. Sfc winds ESE 10-15 kts with
higher gusts near SHRA till 24/22Z.

&&

.MARINE...

Surface high pressure across the central and northeast Atlantic and
an induced surface trough just northwest of the region will promote
moderate to fresh southeast winds through tonight. In addition, the
proximity of a deep layer trough over the Dominican Republic will
aid in enhancing thunderstorm development across portions of the
regional waters and local passages through at least today. Winds are
forecast to diminish overnight and then become more easterly over
the weekend.

&&

.BEACH FORECAST...

Low to moderate rip current risk will persist throughout the period.
In the presence of a moderate rip current risk for St. Croix,
there is still the possibility of life-threatening rip currents in
the surf zone. Please remember to heed the advice of the local
beach patrol and flag warning systems.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
440 AM AST Sat May 25 2024

.SYNOPSIS...

Expect showers and thunderstorms to develop across portions of
Puerto Rico, particularly the central, north, and west sections
each afternoon. Although a ridge aloft is expected to build during
the workweek, plenty of moisture will continue to prevail. As a
result, any prolonged period of showers and thunderstorms will
result in urban and small-stream flooding. The driest day in the
short term, Sunday. The aforementioned available moisture and the
prevailing east to east southeast winds will promote heat index
values that can affect individuals sensitive to heat today and
tomorrow.

&&

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

The broad band of cloudiness associated with the deep-layered trough
west of the area persisted overnight, with showers and isolated
thunderstorms occurring sporadically across the Caribbean waters and
Mona Passage. While some showers did penetrate inland across the
smaller islands and eastern Puerto Rico overnight, they resulted in
minimal rainfall accumulations. During the morning hours, we
anticipate a reduction in convective activity across the regional
waters, although there may still be some showers moving across
windward coastal areas at times. Additionally, there could be patchy
fog in the mountains just before sunrise, so it's important to be
prepared for sudden changes in visibility and to drive slowly.

Today, low-level moisture is anticipated to persist above 2.0 inches
across most of the forecast area, surpassing typical levels for this
time of year. This elevated low-level moisture will combine with
higher-than-normal temperatures during the day, promoting sweltering
hot conditions, particularly across coastal and urban areas.
Consequently, a limited to elevated heat risk is expected across all
coastal and urban areas as heat index values are forecast to exceed
102 degrees and, in some areas, even reach Heat Advisory criteria.
As a result, a Heat Advisory has been issued for most municipalities
across northern and eastern Puerto Rico and USVI. Aloft, instability
will be marginal as we remain situated between the almost stationary
deep-layered trough to our west and the mid-level ridge to our east.
This atmospheric setup will likely foster another active afternoon,
with shower and thunderstorm activity initially developing across
the Cordillera Central and later clustering over northwestern
portions of the island.

Sunday is expected to be the most stable day, with the deep-layered
trough continuing to weaken while the mid-level ridge remains aloft.
Additionally, a tropical wave with its axis currently positioned at
56W is approaching the area. However, before it moves in, drier air
and subsidence ahead of the wave will settle in during the peak
hours of the day. While moisture content will decrease slightly, it
will remain below normal to near-normal levels. Despite this
decrease in moisture, subsidence aloft will exacerbate warmer
temperatures across the islands, with heat index values reaching
hazardous levels. This is likely to meet Heat Warning criteria,
particularly across northern coastal municipalities. Some convective
activity is expected during the afternoon hours across northwestern
portions of Puerto Rico but is anticipated to be short-lived.

The leading edge of the tropical wave will start to approach by
Sunday evening, with the forecast area experiencing well above-
normal moisture throughout the day on Monday. This will lead to
scattered to numerous showers over eastern Puerto Rico and the
smaller islands by early Monday, as well as deep convective activity
across the region, especially across western Puerto Rico in the
afternoon. Consequently, there could be an elevated risk of flooding
in the area once again.

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

Although the ridge aloft will hold through the forecast cycle, plenty
of moisture will continue to prevail without any erosion expected
in the midterm. In fact, the latest guidance suggested precipitable
water values exceeding 2.0 inches through at least midweek.
Moisture may decrease somewhat by the end of the workweek into the
weekend and remain trapped below 700 MB.

At lower levels, easterly winds will prevail on Tuesday, becoming
more southeast Wednesday and onwards as a surface high relocates
across the central Atlantic. Under this evolving pattern, trade
wind showers will continue to affect windward locations from time
to time, with locally induced afternoon showers expected across
western Puerto Rico each day. With GDI values greater than 25
expected much of the week, diurnal heating and sea breeze
convergence, isolated to scattered thunderstorms, are expected
each afternoon. Therefore, urban and small stream flooding is
expected each afternoon, mainly across central and western areas
of Puerto Rico and the San Juan Metro Area. In addition, available
moisture and southeast winds will promote heat index values that
can affect individuals sensitive to heat.

At this time, the bulk of African Dust will remain south of the
area for much of the week. Nevertheless, some may reach the area
by midweek.

&&

.AVIATION...

(06zTAFs)
Areas of SHRA and Isold TSRA over Caribbean waters could move
close to TJPS thru 25/14z. Aft 25/17z, SHRA and VCTS could affect
TJBQ/TJPS/TJSJ. These features will reduce VIS and CIG possibly
producing MVFR/IFR conds and mtn obscurations. Sfc winds ESE 09-13
kts with higher gusts near SHRA till 25/22Z.


&&

.MARINE...

An east-to-east southeast wind flow will continue to prevail
across the local waters over the next few days. A trough west of
the area will continue to enhance shower and thunderstorm
activity. Although weather conditions are expected to improve on
Sunday, shower and thunderstorm activity is expected on Monday
with the next tropical wave passage.

&&

.BEACH FORECAST...

Seas will remain below 5 feet across much of the regional waters.
Therefore, there is a low risk of rip currents across the local
beaches of Puerto Rico and the U.S. Virgin Islands.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
530 AM AST Sun May 26 2024

.SYNOPSIS...

East to southeast winds, normal moisture content, and daytime
heating will lead to an increase in the heat indices across most
coastal and urban areas today. An Excessive Heat Warning and Heat
Advisory are in effect. Please refer to the latest heat product
(NPWSJU) for more information. A tropical wave will cross the
eastern Caribbean from later today through Monday. Shower and
thunderstorm activity will gradually increase across the local
waters and islands from around noon today. Normal to above normal
precipitable water content should persist through the long term
period, and afternoon convection is expected each day in the usual
areas.


&&

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

Fairly tranquil conditions prevailed during the overnight hours.
Doppler radar detected a few isolated showers, but mostly across the
Caribbean waters. GOES-16 Total Precipitable Water (PWAT) satellite
imagery indicates slightly drier air settling over the forecast
area, with PWAT values ranging from 1.5 to 1.6 inches. Therefore,
similar weather conditions are expected to persist through the
morning hours, with a few isolated showers over the local waters
reaching windward coastal areas at times, but resulting in minimal
rainfall accumulations.

This slot of drier air is associated with subsidence ahead of the
tropical wave currently located at 61.7W. Although moisture content
will be reduced throughout the day, model guidance suggests that
maximum temperatures will be slightly higher today compared to the
previous day. The combination of east-southeast winds, high
temperatures, and sufficient moisture could lead to heat index
values exceeding Heat Warning criteria in several locations across
the forecast area. Therefore, an Excessive Heat Warning has been
issued for most municipalities across northern Puerto Rico and St.
Croix, with a Heat Advisory in effect for the rest of the urban and
coastal areas.

The deep-layered trough over Hispaniola persists, with a weak jet at
250 mb providing ventilation aloft across the northwestern quadrant
of the CWA. Shower activity this afternoon is not expected to be
widespread; however, any strong shower development across the
interior that moves over western/northwestern Puerto Rico could tap
into favorable jet dynamics aloft, potentially promoting another
round of thunderstorm activity in that area. By late afternoon and
early Monday, the leading edge of the tropical wave will begin to
filter into the eastern portions of the forecast area, continuing
its westward movement on Monday. Trailing moisture behind the
tropical wave will persist on Tuesday, maintaining PWAT values above
2.3 inches for the remainder of the period, potentially reaching
nearly 2.5 inches at times—exceeding the climatological maximum
value for this time of year.

The GOES-16 Geostationary Lightning Mapper (GLM) currently detects a
significant amount of lightning activity over the Leeward Islands
associated with this tropical wave. Meanwhile, at upper levels, the
deep-layered trough appears to weaken in the next few days, but some
jet dynamics will persist in the vicinity, along with sufficiently
cool 500 mb temperatures, promoting marginal instability across the
area through early this week. Therefore, as the tropical wave moves
over the area, it could interact with sufficient instability at
upper levels, leading to an increased flooding risk. Continue to
monitor the forecast as the tropical wave crosses the region in the
next few days.

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

The long-term forecast remains on track. A mid-to upper-level
ridge will hold for most of the period over the eastern Caribbean,
resulting in drier air aloft and warmer 500 mb temperatures.
However, enough low-level moisture will persist through the
forecast period as the precipitable water content (PWAT) remains
around 2.00 inches or higher through Sunday. Given the expected
conditions, the combination of low-level moisture and local
diurnal effects will enhance shower and thunderstorm development,
especially in the afternoon hours over the interior and western PR.
As the surface high pressure builds over the central Atlantic,
the pressure gradient will decrease, and veering winds will focus
the shower activity over the northwestern quadrant and the San
Juan Metro area. Given the expected conditions, there is a limited
to moderate flood threat for each afternoon, and mainly over
the interior and northern half of Puerto Rico.

From Friday to Sunday, a similar weather pattern will persist as
the surface high pressure over the central Atlantic interacts
with another high building over the western Atlantic, and in
between a weak surface trough is expected to develop north of the
islands. In response, increasing moisture and southeasterly winds
will prevail across the region. Under this influence, warmer
conditions with heat indices between 102-110 degrees Fahrenheit
or higher are expected, resulting in excessive heat conditions for
the northern coastal and urban areas.


&&

.AVIATION...

(06z TAFs)

Mostly VFR conditions will prevail today. However, clouds and
mountain obscuration could develop along the interior PR this
afternoon with SHRA/VCTS possible at TJBQ thru 26/22z. The frequency
of SHRA and isold TSRA will increase near TJSJ/TIST/TISX after
26/21z due to an approaching tropical wave. Winds will be from the
ESE at 9-13 knots aft 26/13z.


&&

.MARINE...

A moderate east to southeast wind flow will prevail across the region
over the next few days. A tropical wave will move across the Caribbean
waters later today, increasing shower and thunderstorm activity
through at least Monday across the local waters.


&&

.BEACH FORECAST...

There is a low risk of rip currents today across all beaches of
Puerto Rico and the U.S. Virgin Islands. Isolated thunderstorms
are possible with the arrival of tropical wave during the
afternoon.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
421 AM AST Mon May 27 2024

.SYNOPSIS...

A tropical wave located southwest of the region will promote
shower activity throughout the day. With the expected activity,
there is an enhanced risk for minor flooding, lightning, and gusty
winds. As the wave departs the local area today, a deep southeasterly
flow will continue to bring plenty of moisture into the islands
enhancing unstable conditions until at least mid-week.

&&

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

NHC's TAFB analyses the axis of a tropical wave just southwest of
Puerto Rico this morning. Moisture associated with the wave is
evident in satellite imagery, with precipitable water values greater
than 2.2 inches, which is well above normal. At the mid levels, a
ridge is centered just of the east of the Leeward Islands. At the
upper levels, a trough over the western Caribbean is inducing a
southerly flow, bringing plenty of clouds to the area.

Since this morning, weak scattered showers have been streaming
across eastern Puerto Rico and over the northern Virgin Islands. The
islands will remain in a favorable spot for showers generation. The
high resolution guidance show that shower frequency will increase
this morning, mainly in the vicinity of the Virgin Islands and
eastern Puerto Rico. In the afternoon, especially if sunshine peeks
across western Puerto Rico, additional activity is anticipated for
the west. Enough water could be collected in the ground, increasing
the chances of urban and small stream flooding. There is the
potential for thunderstorms, producing occasional to frequent
lightning and gusty winds.

As the tropical wave departs today, a deep southeasterly flow will
continue to bring plenty of moisture into the islands. This will be
enough to generate strong thunderstorms in the afternoon, mainly for
the interior and western Puerto Rico. Additional activity is also
expected elsewhere at times. The risk for flooding will stay
elevated these days.Also, breaks of sunshine will be more frequent
tomorrow and Wednesday, allowing for temperatures and heat indices
to climb up, so it will feel muggy too.

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

No significant changes have been introduced to the long term
forecast. A mid-to-upper level ridge over the eastern Caribbean is
forecast to persist for much of the period. A drier airmass is
expected to filter into the region, promoting stable weather
conditions and warm temperatures. The general wind flow will
prevail from the southeast and will shift from the south by early
Sunday in response to a building surface high pressure in the
central Atlantic. Despite of the drier air, there is sufficient
low- level moisture from the Caribbean Sea moving into the local
area. This moisture in combination with daytime heating, and
local effects will result in afternoon convective activity across
the interior, north- central and northwestern portions of Puerto
Rico every afternoon. With the expected activity, there is a
limited to elevated risk of urban and small stream flooding in
roads and poor drainage areas. Latest precipitable water model
guidance suggest values between 1.80 to 2.00 inches between Friday
and Sunday. By Friday through Monday a relatively wet pattern is
expected to prevail across Puerto Rico and the U.S. Virgin Islands
as a weak surface trough develop between the Dominican Republic
and the local region. In response, an enhancement in shower and
thunderstorm activity is anticipated as moisture increases. By
Sunday, winds are expected to shift from the south and prevailing
from this direction until at least mid- week. With this
meteorological scenario, warmer temperatures are going to be
present with values between the upper 80s to low 90s along the
coastal and urban areas of the islands. Heat indices are
anticipated to surpass the mid 100s, and could result in
excessive heat conditions for the islands.

&&

.AVIATION...
(06z TAFs)

SHRA and isolated TSRA associated with a tropical wave will stream
across the Caribbean and Atlantic waters, reaching the USVI, TJSJ
and TJPS terminals at times. After 17Z, additional, stronger
activity is expected for NW PR, with mountain obscuration across the
Cordillera Central and TJBQ. These will result in periods of reduced
VIS and low ceilings. Winds will be from the ESE at 8-13 kts, with
stronger gusts, especially around TSRA.

&&

.MARINE...

A moderate east to southeast wind flow will prevail across the region
over the next few days. A tropical wave will move across the Caribbean
waters today, increasing shower and thunderstorm activity through at
least Tuesday across the local waters.

&&

.BEACH FORECAST...

There is a low risk of rip currents today across all beaches of Puerto
Rico and the U.S. Virgin Islands. Moderate to heavy showers and isolated
thunderstorms are possible with the influence of a tropical wave
just southwest of the region.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
336 AM AST Tue May 28 2024

.SYNOPSIS...

Marginally unstable weather conditions are expected to persist
across the region through the next several days. A southeasterly
wind flow will continue to bring plenty of tropical moisture from
the warmer Caribbean waters, enhancing the potential for strong
showers and thunderstorms over the interior and northwestern
Puerto Rico each afternoon.A relatively drier airmass is expected
to filter into the region by the end of the workweek, promoting
stable weather conditions and warm to hot temperatures.

&&

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

Overnight observations from satellite and radar have indicated
persistent variable to mostly cloudy skies across the region.
Scattered showers with isolated thunderstorms and areas of
persistent light rains were observed across the local waters, with
some moving over the US Virgin Islands, Vieques, Culebra, and Eastern
Puerto Rico. So far, the highest rainfall totals of up to three
quarters of an inch were observed over western Saint Thomas.
Overnight low temperatures ranged from the upper 60s across higher
elevations to the lower 80s across eastern and southern Puerto Rico
and the local islands. Winds were generally light and variable in
Puerto Rico, influenced by land breezes, and from the east-northeast
across the US Virgin Islands.

As the tropical wave moves away from the region, moisture levels
will gradually decrease over the next few days. However, persistent
moisture will keep precipitable water (PWAT) values well above the
climatological thresholds, exceeding 2.0 inches through at least
late Wednesday night. By Thursday, PWAT values are expected to drop
to more typical levels, around 1.8 inches. Meanwhile, the upper-
level trough will start lifting northward and weakening. Still, it
will remain close enough to hold a mid-to-upper-level ridge to the
south-southeast, maintaining marginally unstable conditions. Jet
dynamics aloft and 500 mb temperatures between -6 to -7 degrees
Celsius support this instability. As the ridge moves closer,
conditions will likely become less conducive to deep convective
development by midweek due to the entrainment of drier air and
higher-than-normal 500 mb temperatures. East to east-southeast winds
at 5-15 mph will continue, resulting in a relatively weak steering
flow.

Weather conditions will gradually transition to a more typical
seasonal shower pattern, driven by diurnal heating and local
effects, with enhanced afternoon convective development over the
interior and west to northwestern Puerto Rico each day. Afternoon
convection is also possible elsewhere, and similar to the potential
impacts from overnight and early morning showers affecting eastern
Puerto Rico and the U.S. Virgin Islands, the expected flooding risk
is minimal. Recent GOES-16 Geostationary Lightning Mapper (GLM)
data, along with the Galvez-Davidson Index and the latest model
guidance, indicate the potential for scattered thunderstorms, some
capable of producing heavy rain or scattered shallow convection with
isolated thunderstorms. This scenario raises concerns about elevated
flooding risks in urban areas, roads, small streams, and washes.
Given the current soil saturation levels between 90-100%, isolated
flash floods and mudslides in steep terrain are also possible.
Although the intensity and spread of the expected activity may
decrease, the flood risk will persist throughout the forecast
period.

Despite persistent cloud cover and high rain probabilities, warmer-
than-normal conditions will continue. Coastal and urban areas are
expected to have lows in the lower 80s, while higher elevations may
see lows in the upper 60s to around 70 degrees. In contrast, highs
will range from the lower 90s in lower elevations to the upper 70s
in higher elevations. With ample moisture present, heat indices may
exceed 108 degrees Fahrenheit in many coastal and urban areas, with
some locations experiencing brief periods of 112 degrees or higher.
These warm conditions pose a significant health risk, prompting the
issuance of Excessive Heat Warnings/Advisories. Residents and
visitors should take necessary precautions, particularly those
engaging in outdoor activities.

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

A mid-to-upper level ridge moving from the south-southeast into the
local area will promote relatively drier weather conditions and
warmer temperatures. Nonetheless, light wind flow from the southeast
in combination with daytime heating and local effects will enhance
showers and thunderstorm development across the northwestern
portions of Puerto Rico each afternoon. Despite of the presence of
the ridge, tropical moisture being pulled from the warm Caribbean
Waters will approach the local area by late Saturday. The latest
Precipitable Water Content Analysis suggest values from 1.9 to 2.45
through the period. Due to the expected conditions, there is a
limited to elevated risk of urban and small stream flooding and
isolated flash flooding mainly for central, northern and
northwestern Puerto Rico. By Sunday into Tuesday a weak surface
trough is forecast to develop west of our area, increasing once
again the potential for moderate to heavy rainfall across the
islands. Warmer temperatures are expected to persist through the
entire period with values between the upper 80s to low 90s along the
coastal and urban areas of the islands. Heat indices are likely to
surpass the mid 100s, resulting in excessive heat conditions for the
islands.

&&

.AVIATION...

(06z TAFs)

SHRA/TSRA will result in brief MVFR conds at TJSJ/USVI terminals
through 28/14Z. Afternoon SHRA/TSRA will generate MVFR to brief IFR
conditions across TJSJ/TJBQ between 28/16-22Z, followed by VCTS
after 28/22Z. VCSH possible across USVI terminals throughout the
period. Light and variable winds across PR terminals and E-ENE winds
at 5-10 knots across USVI terminals. Winds will increase to 10-15
knots after 28/14Z, with sea breeze variations and higher gusts near
SHRA/TSRA.

&&

.MARINE...

A moderate east to southeast wind flow will prevail across the region
over the next few days. Showers and isolated thunderstorms associated
with the trailing moisture of a departing tropical wave and a surface
trough east of us will continue to affect the regional waters and
local passages overnight. So far, the next tropical wave, located in
the central tropical Atlantic near 47W, is forecast to approach the
regional waters by mid-week, with its bulk of moisture well to the
south across the Caribbean Sea.

&&

.BEACH FORECAST...

There is a low risk of rip currents across all beaches of Puerto
Rico and the U.S. Virgin Islands tonight. Moderate to heavy
showers and isolated thunderstorms are possible each afternoon
mainly across the northwestern waters of Puerto Rico.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
506 AM AST Wed May 29 2024

.SYNOPSIS...

Warm to hot conditions will persist today across the region. A
Heat Advisory will be in effect today for the north and west coast
of Puerto Rico, including St. Croix. Moisture content is expected
to remain normal to above normal, enhancing the potential for
afternoon convective activity across northwest Puerto Rico. A
tropical wave is expected to approach the region by Thursday,
however, the bulk of moisture should remain over the Caribbean
waters. Drier air is expected to filter into the area by the end
of the workweek, accompanied by Saharan dust particles.

&&

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

Satellite and radar data indicated thunderstorms developing across
the Atlantic and Caribbean waters through early morning hours. Some
of this activity moved over eastern PR, and the Doppler radar
estimated over an inch of rain across el Yunque area. Minimum
temperatures were from the mid 60s across the higher elevations to
the upper 70s and low 80s across the lower elevations of the
islands. A Saharan Air Layer is weakening and this should allow for
moisture to increase slightly across the region today, but hazy
conditions should return once again on Friday.

Moisture content is expected to remain at normal to above normal
levels through Thursday, when a tropical wave moves across the
Caribbean waters. This will aid in the development of showers and
thunderstorms across the region. A drier air mass with suspended
Saharan dust will follow on Friday, but the local effects combined
with the available low level moisture will trigger afternoon showers
and isolated thunderstorms once again across western PR.

In addition, warm to hot temperatures are expected through the short
term period under moist east to southeasterly winds. Heat indices
are expected to range from 104 to 112 degrees Fahrenheit, mainly
along the lower elevations of western and northern Puerto Rico, and
St. Croix. Therefore, there is a Heat Advisory (NPWSJU) in effect
for today across these areas.

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

A surface high pressure in the central Atlantic will promote south
southeasterly winds through much of the long-term-period. Plenty of
abundant tropical moisture moving into the local area will help
to maintain a wet and unstable pattern across the islands. The
latest Precipitable Water Content analysis (PWAT) suggest values
of 2.3 to 2.5 inches between Sunday through Monday. This is in
response of the development of a surface trough west of the region
that will enhance the shower and thunderstorm potential across
Puerto Rico and the U.S. Virgin Islands. Sufficient moisture in
combination with daytime heating and local effects, will lead to
convective activity across the central interior and northwestern
portions of Puerto Rico during the afternoon hours. Therefore,
there is a limited to elevated risk of isolated flash flooding,
urban and small stream flooding, river rises, and mudslides. By
Tuesday into Wednesday as the surface trough lingers north of the
area, moisture from the Caribbean waters will continue to be
lifted and moved over the islands. Winds are expected to veer from
the south by Tuesday in response to the combination of the
surface trough and a approaching tropical wave. With this scenario
the potential for moderate to heavy rainfall and isolated
thunderstorms remains high. Despite the anticipated weather
scenario, warmer to hot temperatures are expected each day.
Daytime temperatures are expected to reach the upper 80s to low
90s. Meanwhile, overnight temperatures will remain in the upper
70s to low 80s along the coastal and urban areas of the islands.
Heat indices may reach the mid to upper 100s during the period,
especially during the mid-morning to early afternoon hours.

&&

.AVIATION...
(06z TAFs)

Mainly VFR conditions expected. However, SHRA en route
from the Leeward Islands could move at times thru 29/12 across
TIST/TISX. Also, diurnally induced afternoon SHRA/TSRA may cause
tempo MVFR conds at TJSJ/TJBQ btw 29/17z-21z. Winds will increase
from the east at 10-15 kt with higher gusts and sea breeze
variations after 29/14z.

&&

.MARINE...

A moderate east to southeast wind flow will prevail across the region
over the next few days. Showers and isolated thunderstorms associated
with the trailing moisture from a tropical wave which exited the region
and a surface trough just east of the area us will continue to affect
the regional waters and local passages. The next tropical wave,
located near the Lesser Antilles, is forecast to approach the
regional waters later today, with the bulk of associated moisture
expected to remain well to the south across the Caribbean Sea.

&&

.BEACH FORECAST...

There is a moderate risk of rip currents across the northwestern
beaches of Puerto Rico, and the beaches of St. Croix. Elsewhere,
there is a low risk. Moderate to heavy showers and isolated
thunderstorms are possible each afternoon mainly across the
northwestern waters of Puerto Rico.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
455 AM AST Thu May 30 2024

.SYNOPSIS...

A tropical wave will pass mainly south of the region today. A
Saharan Ar Layer will bring hazy skies on Friday. Diurnally
induced afternoon showers and thunderstorms are expected each day,
mainly across the interior and western Puerto Rico. Another
tropical wave is expected to cross the local area late in the
weekend. A wetter pattern is forecast for next week. Warm to hot
conditions expected across most lower elevations of the islands
during the next several days.


&&

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

Overnight observations from satellite and radar indicated moderate
shower activity over the local Atlantic and Caribbean waters. Some
of this activity moved inland over the eastern municipalities of
Puerto Rico, and Vieques. Doppler radar estimated rainfall
accumulations between 0.5 to 1.0 inches in Naguabo, Ceiba, Fajardo
and Vieques. Minimum temperatures were observed in the upper 70s to
low 80s along the coastal and urban areas, and in the mid to upper
60s across the mountains. East to southeasterly winds of less than
10 mph prevailed through most of the night.

Variable weather conditions are expected today due to the proximity
of a tropical wave and its associated moisture field. The latest
precipitable water content guidance continues to suggest normal to
above normal values around 2.0 inches. As the wave passes south of
the region over the Caribbean waters, an increase in moisture will
enhance the development of showers and thunderstorms in the
afternoon hours. The northwestern municipalities of Puerto Rico can
expect the most activity in the afternoon through early evening, due
to the southeasterly wind flow in combination with daytime heating
and local effects. Conditions will gradually improve as the evening
comes by. A mass of drier air is expected to filter into the region
by Friday. However, this airmass will come accompanied by moderate
concentration of Saharan dust that will last through Sunday. On
Saturday, similar weather conditions are expected with limited
shower activity.

Despite of the presence of the drier airmass, active afternoons are
expected to persist each afternoon across the interior and
northwestern portions of Puerto Rico. The risk of excessive rainfall
and lightning remains limited for the weekend. However, minor
flooding is possible with the heaviest rains.

Warm to hot temperatures will continue for the next several days
under moist east to southeasterly winds. Heat indices are expected
to range from 104 to 111 degrees Fahrenheit along the northern and
western portions of Puerto Rico and St. Croix. Therefore, a Heat
Advisory will be in effect starting at 10 AM AST today for the
mentioned areas.

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

There will still be some Saharan dust over the region as the
Saharan Air Layer weakens during the weekend. A tropical wave is
forecast to cross the islands on Sunday. This will bring an
increase in shower activity first across the U.S. Virgin Islands,
then spreading across Puerto Rico during the peak time of
afternoon convection. Some thunderstorms could be strong over
western PR.

For next week, a mid-to upper-level trough is expected to move
from the western Atlantic into the northeastern Caribbean, while a
deep layered ridge builds and hold just east of the Leeward
Islands. This will promote divergence aloft and a south to
southwesterly wind flow at lower levels. In addition, a surface
front associated to the upper trough will sink southwards but
should remain above 20N. However, pooling of moisture is expected
in general across the northeastern Caribbean through the long term
period with global models suggesting between 2.10-2.40 inches of
precipitable water content over the local area, peaking by
midweek.

The southerly winds and high humidity content will also promote
warm to hot conditions across the islands, particularly across St.
Croix and most coastal municipalities of PR.


&&

.AVIATION...

(06z TAFs)

Mainly VFR conds expected across all terminals. SHRA will continue
to move into from the Caribbean waters and Anegada passage and VCSH
expected at TJSJ/TIST/TISX thru 30/14z. Aftn SHRA/TSRA may cause
tempo MVFR conds at TJSJ/TJBQ btw 30/17-23z. Winds will prevail from
the ESE at 10-15 kts with higher gusts and sea breeze variations aft
30/14z.


&&

.MARINE...

A moderate east to southeast wind flow will prevail across the region
over the next few days. The next tropical wave will move far to the
south of Puerto Rico and the U.S. Virgin Islands between today and
early Friday. Thunderstorms are expected to develop once again
today, between the late afternoon and evening hours across the
western waters of Puerto Rico.


&&

.BEACH FORECAST...

A low to moderate risk of rip currents will continue today across
most beaches of the U.S. Virgin Islands and Puerto Rico. Isolated
thunderstorms are expected this afternoon across the northwest
coast of Puerto Rico.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
501 AM AST Fri May 31 2024

.SYNOPSIS...

Short-term concerns include continued heat through the weekend,
daily afternoon showers and thunderstorms mainly across the interior
and western Puerto Rico, and the arrival of Saharan dust, contributing
to hazy skies and elevated to moderate heat risk. Wet and unstable
conditions are expected early next week.


&&

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

Calm weather conditions prevailed overnight under clear to partly
cloudy skies. Satellite and radar observations indicated showers and
isolated thunderstorms over the Caribbean waters south of Puerto
Rico. Fast moving passing showers were also observed over the
Anegada Passage, some of this showers moved inland over eastern
Puerto Rico leaving minimal accumulations. Minimum temperatures were
observed in the upper 70s to low 80s across the coastal and urban
areas, and un the upper 60s in the higher elevations.

For today, typical weather conditions will persist across Puerto
Rico and the U.S. Virgin Islands. A slight decrease in moisture
content is expected today into Saturday, with precipitable water
values between 1.75 to 1.90 inches. However, an increase in moisture
content is expected by late Saturday into Sunday due to the arrival
of another tropical wave located at 45W.

A moderate east to southeast wind flow will prevail across the
region for the next few days. Showers will continue to move over the
eastern and southeastern portions of Puerto Rico, and the U.S.
Virgin Islands during the morning hours. Then, convective activity
is once again anticipated over the northwestern quadrant of Puerto
Rico during the afternoon hours. Moderate to heavy rainfall across
these areas may result in urban and small stream flooding, river
rises, and potential mudslides. From Friday onward, a Saharan dust
plume is expected to reach the local area until at least Sunday. The
presence of this particles may suppress shower development in some
areas, bringing hazy skies across the northeastern Caribbean.

A warm temperature trend will continue for the next few days due to
temperatures well above normal in the 925 mb. Therefore, high
temperatures in combination with above-normal moisture will result in
heat indices between 104 to 111 degrees Fahrenheit along the
northern and western portions of Puerto Rico and St. Croix.
Therefore, a Heat Advisory will be in effect starting at 10 AM AST
today for the mentioned areas.

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

The lingering moisture from a departing tropical wave is set to
continue promoting shower and thunderstorm activity across the
region on Monday, with some thunderstorms potentially being strong
over western PR. Following this, a wet weather pattern is expected
to unfold across the northeastern Caribbean as a mid-to-upper-
level trough moves from the northwestern to the north-central
Caribbean, while a deep layered ridge builds and holds just east
of the Leeward Islands. This will promote divergence aloft and
south-to-southwesterly wind flow at lower levels. Furthermore,
global models are indicating the development of an elongated area
of low pressure to our north/northwest through the first part of
the week. In response, moisture pooling is generally expected
across the local area through most of the long-term period, with
guidance suggesting 2.00-2.50 inches of precipitable water
content, peaking by midweek. Therefore, the risk of flooding rains
will significantly increase across all the islands.

As the southerly winds and high humidity persist, we can expect
warm to hot conditions across the islands, particularly across St.
Croix and most coastal municipalities of PR, on Monday. Afterward,
it will depend on how much cloud cover and rainfall materialize
over the islands. A drying trend is expected by Friday as the
broad surface ridge becomes the dominant weather feature.


&&

.AVIATION...

(06z TAFs)

Mainly VFR conds expected across all local terminals. Trade wind
showers will continue to move into the area during the morning
hours. VCSH expected at TJSJ/TIST/TISX thru 31/14z. A SAL will arrive
today, causing hazy skies and lowering VIS at times. Aftn SHRA/TSRA
may cause brief tempo MVFR conds at TJBQ btw 31/17-23z. Winds will
prevail from the ESE at 10-15 kts with higher gusts and sea breeze
variations aft 31/14z.


&&

.MARINE...

A moderate to locally fresh east to southeast wind flow will
prevail across the region through Saturday, becoming easterly
briefly on Sunday, and with a dominant southerly component through
midweek next week. A tropical wave will continue to move westward
across the offshore Caribbean waters and the Mona Passage today.
Increasing winds and seas are expected across the Caribbean
offshore waters. Thunderstorms are expected to develop once again
between the late afternoon and evening hours across the western
waters of Puerto Rico.


&&

.BEACH FORECAST...

A low risk of rip currents will continue today across most
beaches of Puerto Rico, St. Thomas, and St. John while a moderate
risk is expected across southwestern Puerto Rico, Vieques, and
St. Croix. The risk of rip currents is expected to remain between
low and moderate throughout the upcoming weekend.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
448 AM AST Sat Jun 1 2024

.SYNOPSIS...

Expect the hazy skies and warm weather conditions to prevail
through the weekend and early next week. We anticipate the
typical afternoon across western and northwestern Puerto Rico.
Wet and unstable conditions are expected early next week due to
an approaching tropical wave. Improving conditions are foreseen
from Friday onwards.

&&

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

Hot temperatures are expected to continue through the rest of the
short term period. Heat indices are expected to range from 104 to
112 degrees Fahrenheit, mainly along the lower elevations of western
and northern Puerto Rico, and St. Croix. Therefore, another Heat
Advisory (NPWSJU) was issued across these areas, and will likely be
issued once again on Sunday and Monday. Hazy skies will continue
today and through at least early Sunday as the area remains under
the influence of a Saharan Air Layer with moderate to high
concentrations of Saharan dust. This drier air mass will limit
shower activity in general, but diurnally induced streamers
developing off the USVI and smaller islands and possible isolated
thunderstorms could still develop once again this afternoon over
western PR.

On Sunday and Monday, a gradual increase in moisture content is
expected as a tropical wave streams across the islands and a broad
surface trough develops west of the region. The precipitable water
content is forecast to increase from around 1.50 inches today to
near 2.50 inches by late Sunday into Monday morning under a moist
southeast wind flow. Therefore, the risk for flooding rains will
increase across the USVI and most areas of Puerto Rico. Residents
and visitors in PR should avoid activities in small streams and
waterfalls due to the risk of sudden water rises across the area
rivers.

&&

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

The inherited forecast remains unchanged. The latest model
guidance suggests Precipitable Water(PW) values staying in the
75th percentile or above normal values for this time of the year
as lingering moisture from a departing tropical wave continues to
promote showers and thunderstorm activity across Puerto Rico and
the U.S. Virgin Islands with some thunderstorms potentially being
strong over western PR. We foresee a wet weather pattern unfolding
across the northeastern Caribbean as a mid-to-upper-level trough
moves from the northwestern to the north-central Caribbean while a
deep layered ridge builds and holds just east of the Leeward
Islands. This weather pattern will promote divergence aloft and
south-to-southwesterly wind flow at the surface. As mentioned in
previous discussions, an elongated area of low pressure will
develop to our north/northwest, particularly by the first part of
the week. In response, moisture pooling is generally expected
across the local area through most of the long-term period, with
guidance suggesting 2.00-2.50 inches of precipitable water
content, peaking from Tuesday into midweek. Therefore, the risk of
flooding rains will significantly increase across all the
islands. Nonetheless, with the persistent southerly winds and high
humidity, we can expect warm to hot conditions across the
islands. However, it will depend on how much cloud cover and
rainfall materialize over the islands.

A drying trend is expected by the end of the workweek and early
in the weekend as a broad surface ridge becomes the dominant
weather feature. Overall, expect wet and somehow unstable weather
conditions to prevail through Thursday and improve weather
conditions from Friday onwards.

&&

.AVIATION...

(06Z TAFS)

Mainly VFR conditions are expected to prevail across all terminals
during the next 24 hours. However, SHRA/TSRA is expected to develop
btw 01/17z-21z in and around TJBQ, causing tempo MVFR conds. HZ due
to Saharan dust will continue through early Sunday, this is causing
false cigs at TISX. ESE winds expected at 10-15 kt with higher gusts
and sea breeze variations aft 01/14z.

&&

.MARINE...

A moderate east to southeast wind flow will prevail across the
region today, becoming easterly briefly on Sunday, and with a
dominant southerly component through midweek next week. Thunderstorms
are expected to develop during the weekend between the late
afternoon and evening hours across the western waters of Puerto Rico.
A wetter pattern is anticipated by Sunday into early next week as
the next tropical wave will approach the region.

&&

.BEACH FORECAST...

A low risk of rip currents will continue today across most
beaches of Puerto Rico, Culebra, St. Thomas, and St. John while a
moderate risk is expected across southwestern Puerto Rico,
Vieques, and St. Croix. The risk of rip currents is expected to
remain between low and moderate throughout the upcoming weekend. A
high risk of rip current is possible across the beaches in Saint
Croix.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
500 AM AST Sun Jun 2 2024

.SYNOPSIS...

A mixture of hazy skies along with an increase in moisture is
expected today. We anticipate the typical afternoon across
western Puerto Rico. Wet and unstable conditions are expected
early next week due to an approaching tropical wave. Improving
conditions are foreseen from next Friday onwards.

&&

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

As a tropical wave approaches the islands from the southeast and a
broad surface trough develops west of the region, we can expect a
gradual increase in moisture content for the rest of the short-term
period. According to the latest model guidance, the precipitable
water content will rise to above-normal levels, approximately 2.20
to 2.50 inches, by late today into Monday due to the synoptic
scenario and a moist southeast wind flow. This will heighten the
risk of flooding rains across most of the forecast area, potentially
leading to flooding in urban areas, roads, and small streams, as
well as isolated flash floods in the upcoming week. It is advisable
for residents and visitors to avoid activities near small streams
and waterfalls due to the risk of sudden water rises in the area's
rivers. Thunderstorms today could produce frequent cloud to ground
lightning.

Additionally, a weak Saharan Air Layer remains over the area,
leading to a combination of haze and increasing humidity. This
weather pattern will contribute to warm to hot temperatures, and
heat indices are expected to reach heat advisory criteria along the
southern, western, and northern coastal and urban areas of Puerto
Rico and St. Croix. Therefore, a Heat Advisory (NPWSJU) is in effect
for these areas.

&&

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

Most recent model guidance suggests Precipitable Water(PW) values
ranging from the 75th percentile (above normal values) to above
the 2-standard deviation for this time of the year as lingering
moisture from a departing tropical wave continues to promote
showers and thunderstorm activity across Puerto Rico and the U.S.
Virgin Islands. We forecast the thunderstorm activity to be
stronger over western PR, particularly by the afternoon hours.
However, the stronger or more convective part of the tropical wave
will remain well to the south of the islands. The persistent mid-
to upper-level trough across the northwestern Caribbean will
favor periods of heavy rainfall and thunderstorms near the
forecast area, particularly over the Hispaniola, and potentially
reach some areas of western Puerto Rico through mid-week. At this
time, models suggest Wednesday as the most unstable day of the
long-term period. Therefore, the risk of flooding rains will stay
elevated across all the islands.

As this pattern unfolds, a deep layered ridge will build and hold
just east of the Leeward Islands. The interactions of these
weather features will promote divergence aloft and south-to-
southwesterly wind flow at the surface. That being said, we
foresee warm to hot conditions across the islands. However, it
will depend on how much cloud cover and rainfall materialize over
the islands.

A drying trend is still expected by the end of the workweek into the
weekend as a broad surface ridge becomes the dominant weather
feature.

&&

.AVIATION...


(06z TAFs)

A tropical wave will likely bring VCSH/VCTS across the local area
today. Therefore, areas of MVFR conds and mtn tops obscd can be
expected as the day progresses. Winds will prevail from the east to
southeast at 10-15 kts with higher gusts and sea breeze variations.

&&

.MARINE...

Moderate to fresh easterly winds will prevail today. The rest of the
week expect a dominant southerly to southeasterly component. A
wetter pattern is anticipated from today through at least mid-week
as a tropical wave approaches the region from the southeast
increasing moisture, seas, and winds.

&&

.BEACH FORECAST...

A moderate risk is expected across most of the beaches in Puerto
Rico and the U.S. Virgin Islands. While, a low risk is anticipated
for western and south central Puerto Rico. The risk of rip
currents is expected to remain between low and moderate through at
least midweek, then return to low by the end of next week.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
505 AM AST Mon Jun 3 2024

.SYNOPSIS...

A wetter and unstable pattern is anticipated through at least
mid- week as a tropical wave continues to affect the region
maintaining high moisture content across the area. Therefore,
the risk of flooding rains will remain elevated across most of
the forecast area. Improving conditions are foreseen by the second
part of the workweek into the weekend.

&&

.SHORT TERM...TOday through Wednesday...

The weather conditions prevailed variably cloudy, and the winds were
from the east-southeast. The minimum temperatures ranged from the
upper 70s along the coast to the upper 60s across mountains and
valleys. The Doppler Radar detected some showers moving from the
Caribbean Sea across St Croix and the south and southeast coast of
Puerto Rico, making their way into the eastern interior, northeast,
and the San Juan Metro Area. Ponding of water in roads and poorly
drained areas was likely with the periods of heavy rain.

An unstable weather pattern will prevail today due to abundant
tropical moisture from a tropical wave and the proximity of an upper-
level trough. The available moisture with the expected maximum air
temperature will produce muggy heat index values in the upper 90s
and surpass 100 degrees Fahrenheit today, especially when rain
activity is absent or after brief showers. We are also anticipating
unsettled weather conditions today, especially by the afternoon,
which means that flooding of urban areas, roads, and small streams
is likely, and flash floods are possible.

On Tuesday, as the surface high pressure (north of the region across
the Western Atlantic) migrates further east into the Central
Atlantic, a surface-low pressure will follow it, inducing a
southerly wind flow and pooling plenty of tropical moisture over the
Northeast Caribbean. GFS total precipitable water suggested values
near or above 2.25 inches, above the normal values for the San Juan
area's local climatology for June.

Although this wet and unstable weather pattern will persist through
Wednesday as the surface-low pressure promoted additional tropical
moisture to pool over PR and the USVI, the NASA Dust Extinction
(Aerosol Optical Thickness) guidance suggested the presence of
traces of African Desert Particles filtering across the region,
especially Wednesday into the second part of the work week.

&&

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

Currently, Thursday looks like the transition day as we will
gradually/slowly move from a wet and unstable weather pattern to
dry and mostly fair weather conditions. The Dust Aerosol models
indicate the arrival of Saharan Dust particles reaching the
forecast area, with concentrations potentially reaching 0.20 on
Thursday. These concentrations across Puerto Rico and the U.S.
Virgin Islands will lead to a slight to moderate dust event.
Therefore, we added it to the forecast for Thursday. Nevertheless,
climatological Precipitable Water(PW) models still suggest values
ranging above the 75th percentile or around 2.00 inches as
lingering moisture from the past tropical wave and the mid-upper
level trough across the northwestern Caribbean remains.

From Friday onwards, the latest model guidance shows a deep layered
ridge building and holding just east of the Leeward Islands. We
foresee, mostly fair typical weather conditions with warm
temperatures across the islands as mostly southeasterly winds
will dominate through at least Monday.

&&

.AVIATION...

(06z TAFs)

Expect an unstable weather pattern today with the arrival of
SHRA/TSRA across the local flying area. Therefore, occasional
periods of MVFR or brief IFR conditions at local terminals
(especially 03/10-14z and 03/16-20z) are expected. Winds will
prevail from the ESE at 5 to 10 kt, then between 10-15 kt after
03/13z, with higher gusts and sea breeze variations.

&&

.MARINE...

A surface front stalled in front of a sub tropical high pressure
across the Western Atlantic north of the islands will promote a
south to southeasterly wind flow across the islands. A wetter pattern
is anticipated through at least mid-week as a tropical wave
continues to affect the region maintaining high moisture content
across the area with increasing seas and winds, as a result small
craft should exercise caution across most of the regional waters and
local passages.

&&

.BEACH FORECAST...

A High Rip Current Risk is in effect from this morning to this
afternoon for beaches of St Croix. A moderate risk is expected
across most southern and eastern facing beaches of Puerto Rico,
Vieques, Culebra, St Thomas, and St John, while a low risk is
anticipated for the northern and western beaches of Puerto Rico.
The risk of rip currents is expected to remain between low and
moderate through at least midweek, then return to low by the end
of next week.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
513 AM AST Tue Jun 4 2024

.SYNOPSIS...

The wetter pattern is still forecast through at least mid-week as
a tropical wave continues to affect the region maintaining high
moisture content across the area. Therefore, the risk of flooding
rains will range from limited to elevated across most of the
forecast area. Improving conditions are foreseen by the end of the
workweek into the weekend.

&&

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

The weather conditions prevailed variably cloudy, and the east-
southeast winds pushed additional moisture across PR and the USVI.
The minimum temperatures ranged from the upper 70s to low 80s along
the coast to the upper 60s and low 70s across mountains and valleys.
The Doppler radar detected showers and thunderstorms moving from the
Caribbean Sea across the USVI and PR's windward sections, making
their way further inland. Gusty winds and ponding of water in roads
and poorly drained areas were likely due to the thunderstorms.
Hazardous marine conditions due to a cluster of strong thunderstorms
affected the USVI's eastern surrounding waters. Thus, a Special
Marine Warning was issued.

A surface trough north of the islands induces a southeasterly wind
flow, pooling plenty of tropical moisture from the Caribbean Sea,
creating an unstable weather pattern. This could lead to potentially
hazardous conditions, with flooding of urban areas, roads, and small
streams likely, and flash and river floods possible. Additionally,
the available moisture combined with the expected maximum air
temperature will produce muggy heat index values in the upper 90s
and surpass 100 degrees Fahrenheit again today, especially when rain
activity is absent or after brief showers.

The model guidance consistently suggested values near or above 2.25
inches, above the normal values for the San Juan area's local
climatology for June, extending into the middle of the week.
Wednesday will be the wettest day with the more favorable conditions
to observe flooding.

Our latest guidance, based on the GFS model, indicates a slower
drying out of the region than the previous runs, with plenty of
moisture expected through the late Thursday night hours or early
Friday morning. This aligns with the NASA Dust Extinction (Aerosol
Optical Thickness) guidance, which suggests the arrival of more
pronounced African Desert Particles filtering across the region.

&&

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

By the end of the work week, we will gradually reach the
anticipated drying and stable weather pattern across Puerto Rico
and the U.S. Virgin Islands as a deeply layered ridge builds and
holds just east of the Leeward Islands. The NASA Dust Aerosol
Optical Thickness model indicates the presence of Saharan Dust
particles over the area from Friday into the weekend. Currently,
the concentrations do not surpass 0.20 on those days. Therefore,
it was not added to our forecast grids, particularly because it
is not be considered a slight to moderate dust event. Nevertheless,
people will experience hazy skies, and the ones with respiratory
illnesses could still be affected.

The latest climatological Precipitable Water(PW) models continue to
suggest values above the 75th percentile and dry air at the mid-
levels with 500 mb temperatures around -4 to -5 degrees Celsius.
This means that there will be sufficient surface moisture across
the region, but conditions at the mid-levels of the atmosphere
will not be favorable to the vertical development of any shower
activity that does develop. At this time, we anticipate showers
forming along the northwestern quadrant of Puerto Rico,
particularly during the afternoon hours.

On Monday and Tuesday, we foresee a slight increase in moisture as
the Saharan Dust moves out of the area and patches of moisture
associated with another tropical wave over South
America/southeastern Caribbean waters are brought into the
region.

During the long-term period, southeasterly winds will prevail across
the islands, meaning that warm temperatures will prevail mostly
across the islands. With the warm temperatures and the available
moisture, we anticipate the issue of heat advisories in low and
urban areas.

&&

.AVIATION...

(06z TAFs)

The unstable weather pattern will continue today and tomorrow with
the arrival of SHRA/TSRA across the local flying area. Therefore, we
can expect brief periods of MVFR or brief IFR conditions at local
terminals (mainly through 04/12z and later in the afternoon 04/16-
22z). Winds will prevail from the SE/ESE at 5 to 10 kt, then between
10-15 kt after 04/13z, with higher gusts (especially near TSRA) and
sea breeze variations.

&&

.MARINE...

A stationary front and a sub tropical high pressure across the
Western Atlantic will promote a moderate to locally fresh south to
southeasterly wind flow. A wetter pattern is anticipated through at
least mid-week as a tropical wave continues to affect the region
maintaining high moisture content across the area with increasing
seas and winds, as a result small craft should exercise caution,
especially across the Caribbean Waters and local passages.

&&

.BEACH FORECAST...

There is a moderate risk for most beaches from western, southern,
and southeastern Puerto Rico, Vieques, Culebra, and USVI. The northern
beaches of Puerto Rico have a low risk of rip currents. The risk
of rip currents is expected to remain between low and moderate
through at least midweek, then return to low by the end of the
workweek into the weekend.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
516 AM AST Wed Jun 5 2024

.SYNOPSIS...

Today looks like the wettest day of the period. A wet pattern
will continue through at least Thursday morning, as southerly
winds continue to steer warm and available moist air over the
area. The risk of flooding rains is elevated across the islands
today. Improving conditions are forecast by the end of the
workweek into the weekend.

&&

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

Showers and thunderstorms were detected across the local waters
overnight. The Doppler radar detected rainfall accumulation along
the south, southeast, east, and northeast PR and the USVI. However,
the Atlantic Offshore waters had the strongest thunderstorms. Skies
were variably cloudy, and the winds were mainly from south to
southeast. The San Juan Area had two records yesterday. The first
ties the old record of 94 degrees Fahrenheit for the maximum
temperatures set in 2022 and 2023, and the second was another tie
but for the warmest low temperature of 82 degrees Fahrenheit.

GOES-East suggests an elongated surface trough extending from the
Northeast Caribbean into the Atlantic Ocean. This trough will create
variably cloudy skies, lifting abundant tropical moisture over
Puerto Rico and the U.S. Virgin Islands. Although the available
humidity combined with the expected maximum air temperature will
produce muggy heat index values in the upper 90s and surpass 100
degrees Fahrenheit, we can expect showery weather with some strong
thunderstorms across the region today. Today will be the wettest day
with favorable conditions to observe flooding, leading to
potentially hazardous situations, with flooding of urban areas,
roads, and small streams likely, and flash and river floods
possible.

Thursday will be a transition day. Model guidance suggests above-
normal moisture lingering over the region due to the surface low
north of the area and an approaching tropical wave crossing across
the Caribbean. However, a Saharan Air Layer, suggested by NASA Dust
Extinction (Aerosol Optical Thickness) (and observed by the
Satellite imagery), may arrive, limiting rainfall activity across
the region and resulting in hazy conditions. On Friday, the
lingering drier air mass will extend the haziness but with less
concentration of suspended dust particles. The typical rain pattern
can be expected for Friday.

&&

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

The latest model guidance continues to suggest a dryer and more stable
weather pattern across Puerto Rico and the U.S. Virgin Islands as
a deeply layered ridge prevails just east of the Leeward Islands
through the weekend. The NASA Dust Aerosol Optical Thickness model
indicates the presence of Saharan Dust particles over the area.
Currently, the concentrations do not surpass 0.20. Therefore, it
is not considered as a slight to moderate dust event, and we did
not add it to our forecast grids. Nevertheless, people will
experience hazy skies, and sensible people with respiratory
illnesses could still be affected. The latest Precipitable Water
(PW) models suggest values decreasing to normal, even below normal
climatological levels for this time of the year. Most recent
guidance also shows dry air at the mid-levels of the atmosphere
and the 500 mb temperatures around -5 degrees Celsius, meaning
that if any rainfall activity does develop, it will not grow much
vertically. Therefore, we do not anticipate unstable conditions
through the weekend. However, we cannot rule out the typical
afternoon convection across the islands.

By Tuesday into midweek, we foresee a slight increase in moisture as
the Saharan Dust moves out of the area and patches of moisture
associated with another tropical wave reach the island.

Overall, during the long term, we forecast mostly stable weather
conditions across the islands, with southeasterly to east-
southeasterly winds. With this weather pattern, we anticipate warm
temperatures, and we cannot rule out the possibility that heat
products like advisories and warnings will be issued along the
lower elevations and urban areas. We encourage citizens and
visitors/tourists to stay updated with our latest weather
forecasts.

&&

.AVIATION...

The unstable weather pattern will continue today with the arrival of
SHRA/TSRA across the local flying area. Therefore, we can expect
brief periods of MVFR or brief IFR conditions at local terminals.
Winds will prevail from the SE/ESE at 5 to 10 kt, then between 10-15
kt after 05/13z, with higher gusts (especially near TSRA) and sea
breeze variations.

&&

.MARINE...

The strong sub-tropical high pressure across the central and northeast
Atlantic along with a broad and elongated trough extending northwards
across the region from the central and eastern Caribbean will promote
a light to moderate south to southeasterly wind flow. The moist
southerly flow will maintain the potential for showers and isolated
thunderstorms across the regional waters especially during the
overnight and afternoon hours. This will also aid in increasing winds
and seas, especially across the Caribbean Waters and local passages
each day. As a result small craft should exercise caution.

&&

.BEACH FORECAST...

There is a moderate risk for beaches along southwestern Puerto
Rico and St. Croix. The northern and eastern beaches of Puerto
Rico, Vieques,Culebra, St. Thomas, and St. John will remain with a
low risk of rip currents. The rip current risk is expected to
remain between low and moderate through the weekend.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
523 AM AST Thu Jun 6 2024

.SYNOPSIS...

Troughiness at different levels across the northeastern Caribbean
will continue to enhance shower and thunderstorms development
across the regional waters and portions of the islands through
today. A Saharan Air Layer will bring a drier airmass and dust
across the local area leading to hazy skies, mainly today and
Friday. Hot temperatures are expected throughout the weekend. The
next tropical wave with better potential of rain is expected by
next Tuesday into Wednesday.

&&

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

An elongated surface trough north of the islands extending into the
Central Atlantic combined with plenty of tropical moisture promoted
showers and thunderstorms across the local waters overnight. These
thunderstorms moved inland across portions of PR and the USVI,
producing periods of moderate to locally heavy rain. Skies were
variably cloudy, and the winds were mainly from south to southeast.

From now until this afternoon, a southerly wind flow will bring an
abundance of moisture over the islands. This, combined with an
elongated surface trough to the north, will likely result in showers
and thunderstorms near the islands. These conditions may sometimes
lead to heavy downpours, potentially causing ponding water in roads
and poorly drained areas and even urban or river flooding.

The high humidity combined with the expected maximum air temperature
will create heat levels that could affect most individuals sensitive
to heat, especially those without effective cooling and/or adequate
hydration. Therefore, a Heat Advisory is effective today, especially
between 10 AM and 5 PM AST. Additionally, a Saharan Air Layer will
spread from the east into the islands by mid-morning into the
evening, creating hazy conditions and slowly limiting rain activity.
However, the arrival of these suspended air particles may promote
the formation of robust thunderstorms, especially when the
concentrations are not high enough to suppress cloud development.

A more typical weather pattern with a combination of sunshine and
clouds may evolve from Friday into the weekend as moisture content
returns to typical values and the surface trough moves far from the
northeast Caribbean. However, the above-normal temperatures will
continue under the southeast winds, which may extend the heat spell.
Strong afternoon convection may also develop due to local effects,
excessive heat, and fluctuations in sea breeze. Additionally, the
warmer-than-normal sea surface temperatures will promote nighttime
convection across the surrounding waters, moving inland
occasionally.

&&

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

A dryer and more stable weather pattern is expected to prevail
across Puerto Rico and the U.S. Virgin Islands during the
beginning of the long-term period as a deeply layered ridge sets
just east of the Leeward Islands and some Saharan Dust particles
will remain over the area. People will experience hazy skies and
sensible people with respiratory illnesses could still be
affected. The latest Precipitable Water (PW) models suggest values
decreasing to normal and even below normal climatological levels
for this time of the year, around 1.4 to 1.7 inches. Recent
guidance also shows dry air at the mid-levels of the atmosphere
and the 500 mb temperatures around -5 degrees Celsius, meaning
that if any rainfall activity does develop, it will not grow much
vertically, however, we cannot rule out the typical afternoon
convection across the islands, mainly over the western quadrant of
Puerto Rico during the afternoon hours due to diurnal heating and
local effects.

By Tuesday afternoon into Wednesday, a slight change in the weather
pattern is anticipated as patches of moisture associated with our
next tropical wave reach the island. That will result in better
chances of rain by midweek. On Thursday, a patch of dry air should
reach the islands again.

Overall, during the long term, we forecast mostly stable weather
conditions across the islands, with southeasterly to east-
southeasterly winds and moisture returning by Tuesday afternoon
into Wednesday. With this weather pattern, we anticipate warm
temperatures with the possibility that heat products like
advisories and warnings will be issued along the lower elevations
and urban areas. We encourage residents and visitors to stay
hydrated and updated with our latest weather forecasts.

&&

.AVIATION...

(06z TAFs)

We expect the arrival of SHRA/TSRA across the local flying area.
This could lead to brief periods of MVFR or brief IFR conditions
at local terminals, especially through this aft. Winds will be
predominantly from the SE/ESE at 5 to 10 kt, then between 10-15 kt
after 06/13z, with higher gusts (especially near TSRA) and sea
breeze variations. Hazy skies will be possible, especially by this
afternoon, as suspended dust particles from the Sahara desert
filter from the east over the region, but with P6SM.

&&

.MARINE...

A surface high pressure north of the area will slowly move
eastwards and build into the central Atlantic by the weekend. A
surface trough will remain mainly north and west of the area. In
response, light to moderate east to southeast winds will prevail
across the local waters. Isolated thunderstorms across the waters
and local passages are possible through today, then more stable
conditions are anticipated throughout the weekend. The next
tropical wave with better potential for squally weather is
expected by early next week.

&&

.BEACH FORECAST...

Today, mainly low risk of rip currents across Puerto Rico,
Vieques, Culebra, St Thomas, and St John, while a moderate risk
across beaches of St Croix. Mainly low risk should prevail throughout
the weekend. For more information and details about the latest
forecast please refer to the Surf Zone Forecast (SRFSJU).

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
500 AM AST Fri Jun 7 2024

.SYNOPSIS...

A Saharan Air Layer and drier airmass will continue to promote
hazy skies throughout the weekend. Generally, fair weather
conditions are expected, however shower activity and some
thunderstorms may develop across northwestern portions of Puerto
Rico during the afternoon hours due to local effects. Warm to hot
temperatures will continue to persist across the region with heat
indices surpassing the mid 100 degrees Fahrenheit. The next
tropical wave with better potential of rain is anticipated by next
Tuesday into Wednesday.

&&

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

A Saharan Air Layer and a mid-level ridge promoted stable weather
conditions across the islands overnight. Mid to upper-level clouds
moved across the islands, dissipating early this morning. The
minimum temperatures were warmer than the climatological values of
PR and the USVI, while surface winds continued from the southeast.

Today will begin warmer than normal. The available moisture and the
southeasterly wind flow will result in warm to hot conditions across
Puerto Rico and the U.S. Virgin Islands. This stable weather pattern
with little or no rain will intensify the hot spell, potentially
extending into the weekend. It's crucial to note that an Excessive
Heat Warning (NPWSJU) is in effect for the urban and coastal areas
of mainland PR and St Croix, while Culebra, Vieques, St John, and St
Thomas have a Heat Advisory today. This information is vital for
your safety and well-being, especially for the most vulnerable
communities like pregnant, newborns, children, elderly, chronic
illness patients, and pets. An Excessive Heat Watch is also in
effect for Saturday, between 9 AM AST and 6 PM AST, due to the high
chance of observing dangerous hot heat indices across the urban and
coastal areas.

Even though the ridge pattern in the upper atmosphere and the
presence of a Saharan Air Layer will restrict rain activity, local
factors could lead to isolated to scattered afternoon convection
each day. Additionally, patches of clouds moving in along the
windward areas may bring brief passing showers during the day.
Nighttime showers could form over the nearby waters, occasionally
moving inland due to the warmer-than-usual sea surface temperatures.

The bulk of a tropical wave's moisture is forecast to move far to
the south across the Caribbean Sea late Sunday night into Monday.
However, its perispheric moisture field could increase the frequency
or intensity of the showers across the regional waters from late
Sunday night into early Monday morning.

&&

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

The drier and more stable weather pattern is expected to prevail
across Puerto Rico and the U.S. Virgin Islands during the
beginning of the work week due to the presence of a drier airmass
and a mid to upper level high-pressure ridging over the area. The
latest Precipitable Water (PW) models suggest values decreasing
to around 1.4 to 1.7 inches on Monday, which is normal to even
below normal climatological levels for this time of the year.
Recent guidance also shows dry air at the mid-levels of the
atmosphere and the 500 mb temperatures around -5 degrees Celsius,
meaning that if any rainfall activity does develop, it will not
grow much vertically. We cannot rule out the typical afternoon
convection across the islands, mainly over the western quadrant of
Puerto Rico during the afternoon hours due to diurnal heating and
local effects. The 925 mb temperatures should remain well above
normal through early next week. That could promote hazardous heat
conditions, particularly across coastal and urban areas. Therefore,
heat products will likely need to be issued until next week. We
encourage residents and visitors to stay hydrated and updated with
our latest weather forecasts.

We foresee a change in the weather pattern to begin next Tuesday
into Wednesday as patches of moisture associated with a tropical
wave that will move to our south reach the island. That will
result in better chances of rain by midweek onwards. At the end of
the week, models agree that additional moisture from another
surface disturbance will also reach the island and further enhance
the chance of showers.

&&

.AVIATION...
(06TAFs)

VFR conditions will prevail today with traces of suspended
Saharan desert particles. Winds will continue from the SE at 6 kt
or less through 7/13z when they range around 10-15 kt, but with
higher gusts due to sea breeze variations. Strong SHRA could
develop during the afternoon near the vicinity of JBQ, especially
7/20z-8/00z.

&&

.MARINE...

A surface high pressure north of the area will continue to move
eastwards into the central Atlantic promoting light to moderate east
to southeast through most of the forecast period. More stable
conditions are anticipated throughout the weekend, then the next
tropical wave with better potential for showers and isolated
thunderstorms possible across the waters and local passages is
expected by early next week.

&&

BEACH FORECAST...

A low risk of rip currents across most beaches of Puerto Rico and
the U.S. Virgin Islands through early next week, then low to
moderate risk is anticipated with an approaching tropical wave by
midweek onwards. For more information and details about the
latest forecast please refer to the Surf Zone Forecast (SRFSJU).

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
530 AM AST Sun Jun 9 2024

.SYNOPSIS...High pressure extends out of the central Atlantic and
across the Atlantic waters just north of the local area. With
limited moisture this is bringing warmer than usual temperatures
that will gradually cool through Friday. Some limited showers will
be possible, with a tropical wave passing to our south and
moisture from an old frontal boundary entering into the area on
Thursday.


&&

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

An overnight radar and satellite imagery analysis indicated areas of
clear to partly cloudy skies as some high clouds moved across the
region. Some showers generated variable cloudy skies and rainfall
accumulations of up to a tenth of an inch across portions of eastern
Puerto Rico, Vieques, and the local waters. Overnight minimum
temperatures stayed in the lower 80s across coastal areas of the
metro area, northeastern, and southwestern Puerto Rico. Across the
mountains, temperatures dropped to the upper 60s.

Today we are expecting another day with warm to hot temperatures.
Note that an Excessive Heat Warning (NPWSJU) is in effect today for
the lower elevations and coastal areas of mainland PR, while eastern
PR, Culebra, Vieques, St Croix, St Thomas, and St John have a Heat
Advisory. An Excessive Heat Watch is also in effect for Monday,
between 9 AM AST and 6 PM AST, as hot conditions will likely
return.

The general weather pattern will continue to be dominated today by
the presence of a ridge at the mid to upper levels and a surface
high pressure extending from the eastern Atlantic to the Central
Atlantic. This will continue to provide subsidence, inducing stable
weather conditions and drier air aloft, mostly resulting in
a drying pattern with minimal to no rain activity. The latest
Precipitable Water (PW) models suggest values around normal to
below normal climatological levels, around 1.5 to 1.9 inches
during the short-term period. Tonight into Monday, model guidance
continues to suggest the passage of a tropical wave well south of
the islands, leaving the bulk of the moisture over the Caribbean
Sea. As a result, every day of the period, isolated to scattered
afternoon convection may occur due to local effects, especially
across northwestern Puerto Rico during the afternoon hours.
Furthermore, patches of clouds moving in along the windward areas
may bring brief passing showers. Also, due to the warm sea surface
temperatures, nighttime showers may form over the adjacent waters
and occasionally move inland like the last few days.

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

A tropical wave will pass just south of the area Tuesday night and
Wednesday and will be enhanced somewhat by the passage of a weak
upper level trough to the north Tuesday night. Then high pressure
aloft intensifies over the Western Caribbean and pushes the
remnants of an old frontal boundary into the area from the
northeast with its accompanying moisture. Temperatures will
rebound on Saturday as surface winds return to a southeasterly
flow. Thunderstorms will again become possible Wednesday and
Friday over portions of the area and especially the western
interior. The influx of Saharan dust will continue through the
period bringing hazy skies and visibilities of 8 to 15 miles.

&&

.AVIATION...
(06Z TAFs)

Mainly VFR conditions prevail across all terminals during the
period although TJNR will have some MVFR in the morning. TJBQ may
experience some VCSH around 18Z. Light to calm and variable winds
will turn from the E-ESE at 10-15 knots between 09/13-22Z,
accompanied by higher gusts and sea breeze variations.

&&

.MARINE...Seas will generally run 2 to 4 feet in the open waters
around the island and less than 2 feet in protected waters. The
wave passage on Tuesday night will boost seas up to 6 feet in the
southwest corner of the forecast area.


&&

.CLIMATE...Very warm temperatures have continued with the high of
95 and the low of 81 on Sunday both being the second warmest on
record.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
436 AM AST Mon Jun 10 2024

.SYNOPSIS...

Hot conditions return today. Excessive Heat Warnings are in
effect from 9 AM to 6 PM AST for all lower elevations and coastal
areas of Puerto Rico. Heat Advisories are in effect from 9 AM to 6
PM AST for Vieques, Culebra, and the US Virgin Islands.Due to the
likelihood of these extreme heat conditions continuing, an
Excessive Heat Watch is now in place for Tuesday. Weather
conditions remain relatively stable before an increased moisture
reaches the area by Wednesday due to the proximity of a tropical
wave. Small craft should exercise caution today for areas of the
nearshore and offshore Atlantic waters due to increasing winds.
Seas up to 4 feet, occasionally up to 5 feet. Saharan dust
particles also promoting hazy conditions.

&&

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

An overnight radar and satellite imagery analysis indicated that
clear to partly cloudy skies dominated the region. A few light
passing showers moved inland over the US Virgin Islands, Vieques,
Culebra, and eastern Puerto Rico, leaving minimal rainfall totals.
Reports from official sites indicate that overnight minimum
temperatures stayed above 80 degrees across coastal areas of the San
Juan metropolitan area, northeastern and southwestern Puerto Rico,
and the local islands. In higher elevations, temperatures dropped to
around 67-69 degrees. Winds were mainly light to calm and variable.

Weather conditions throughout the short-term forecast should remain
relatively stable, mainly due to consistent mid-level ridging across
the region and prolonged drier-than-normal periods. East-to-east-
southeast trade winds will persist throughout most of the forecast
period, with peak daytime wind speeds ranging from 15 to 20 mph,
driven by a high-pressure system over the central Atlantic. Winds
will begin to weaken and slowly turn from the east-northeast by
Wednesday night. Intermittent patches of drier- and wetter-than-
normal patches will cause precipitable water levels to fluctuate
between 1.6 and 2.0 inches today, followed by an abrupt drop to
around 1.3 inches on Tuesday afternoon and back to typical values on
Wednesday. Despite these moisture fluctuations, limited shower
activity is likely throughout the forecast period, primarily
generated by daytime heating over the far western-to-northwestern
sections of Puerto Rico. Passing shower frequency may increase by
Wednesday due to the proximity of a tropical wave. However, no
flooding impacts are anticipated with any of the expected rains.

In terms of temperatures, dangerously hot conditions will return
today. As a result, Excessive Heat Warnings are in effect from 9 AM
to 6 PM AST for all lower elevations and coastal areas of Puerto
Rico, posing a threat to anyone without effective cooling and/or
adequate hydration. Meanwhile, Heat Advisories have been issued for
Vieques, Culebra, and the US Virgin Islands, posing a risk to most
individuals sensitive to heat. Remember to take extra precautions
when outside. Wear lightweight and loose-fitting clothing. Try to
limit strenuous activities to early morning or evening. It is
essential to stay hydrated and watch for signs of heat exhaustion.
Due to the likelihood of these extreme heat conditions continuing,
an Excessive Heat Watch is now in place for Tuesday.

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

Current model guidance suggests normal to below normal Precipitable
Water (PWAT) values as a tropical wave will be southwest of the
area to start the period. However, an area of normal to above
normal PWAT will start to approach the islands from the northeast
increasing PWAT values through Friday. This is due to the remnants
of a past frontal boundary being pushed towards the area by a
high pressure system over the Atlantic. High pressure aloft will
also strengthen over the Western Caribbean through the period.
Winds through Friday are forecast to be more east to east
northeasterly, which could bring some slight relief in terms of
warm temperatures although model guidance continues to suggest
above normal 925 mb temperatures. Winds are forecast, however, to
become more southeasterly by the weekend and through the rest of
the period. This will help promote warm temperatures once again.
PWAT values return to normal for the weekend with another plume of
moisture with above normal to normal values possibly reaching the
area by next week. Most available moisture will remain below 850
mb, with only a slight increase in moisture through the mid-levels
for the weekend. Saharan dust particles will linger to start the
forecast period.

&&

.AVIATION...

(06Z TAFS)

VFR conditions will likely prevail across all terminals during
the next 24 hours. Between 10/13 and 22Z, afternoon VCSH/SHRA may
briefly impact operations across TJSJ, TJBQ, and the USVI
terminals. Light to calm, variable winds will turn from the E-ESE
at 12-16 knots between 10/13-22Z, accompanied by higher gusts and
sea breeze variations.

&&

.MARINE...

A mid to upper level ridge is promoting generally stable conditions
across the local waters. Surface high pressure extending from the
northeastern to central Atlantic and north of the area will continue
to promote up to moderate to fresh east-southeasterly winds through
midweek. A tropical wave is expected to increase the potential for
showers and isolated thunderstorms mainly across the Caribbean waters
and local passages on Wednesday.

&&

.BEACH FORECAST...

Moderate risk of rip currents for most of St. Croix's coasts
today and tonight. Moderate risk forecast for southwestern and
southeastern PR tonight. Low risk elsewhere.

[Iceresistance]

In the Trinidad and Tobago of all places

 https://twitter.com/TTWeatherCenter/status/1800227407401558158