Caribbean - Central America Weather

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cycloneye
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Re: Caribbean - Central America Weather

#21521 Postby cycloneye » Tue Jun 11, 2024 4:36 am

Area Forecast Discussion
National Weather Service San Juan PR
456 AM AST Tue Jun 11 2024

.SYNOPSIS...

Hot conditions continue. 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. Since
dangerous hot conditions will likely continue, an Excessive Heat
Watch is now in place for Wednesday. An increase in passing
showers may occur by Wednesday night, influenced by a nearby
tropical wave, and again by Thursday night due to the approaching
surface trough. 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 Thursday...

An overnight radar and satellite imagery analysis indicated partly
to variable cloudy skies over the local islands, primarily due to a
layer of mid-to-upper level clouds moving in from the southwest. A
few light showers brushed the northeast coast of Puerto Rico, and
some moved across Culebra and the northern US Virgin Islands, but
they left minimal rainfall. Reports once again highlighted warm
overnight low temperatures above 80 degrees Fahrenheit, not only in
eastern Puerto Rico and the local islands but also in inland areas
of the San Juan-Bayamon-Caguas metropolitan area and parts of
western and southern Puerto Rico. Coastal observation sites and
local buoys have also recorded warm low temperatures, hovering
around 85 degrees Fahrenheit. This scenario offers little overnight
relief and will ultimately exacerbate the region's ongoing heatwave
situation. Winds were mainly light to calm and variable.

Weather conditions throughout the forecast period should change very
little from the persisting stable and warm pattern that has
dominated the region in recent days, mainly due to consistent mid-
level ridging and prolonged drier-than-normal periods. Driven by a
surface high pressure meandering well to the north of the local
islands, east-to-east-southeast trade winds, with peak daytime wind
speeds ranging from 15 to 20 mph, will gradually weaken and turn
east-northeasterly from Wednesday night onward, influenced by a weak
surface trough to the northeast.

Significant moisture variability will likely occur throughout the
forecast period, with precipitable water values fluctuating between
1.4 and 2.0 inches due to intermittent drier and wetter patches.
Despite these variations, with brief wet periods, showers are likely
to be sparse and highly localized, predominantly caused by daytime
heating over the far western and northwestern areas of Puerto Rico.
An increase in passing showers may occur by Wednesday night,
influenced by a nearby tropical wave, and again by Thursday night
due to the approaching surface trough. However, no flooding is
expected from the anticipated rainfall.

Dangerously hot conditions are likely again today, prompting
Excessive Heat Warnings from 9 AM to 6 PM AST for lower elevations
and coastal areas of northern and western Puerto Rico. These
conditions pose a serious risk to anyone without adequate cooling or
hydration. Heat Advisories are also in effect for the remaining
lower and coastal areas of Puerto Rico and Vieques, Culebra, and the
US Virgin Islands, indicating a significant risk for individuals
sensitive to heat. When outdoors, take extra precautions: wear
lightweight, loose-fitting clothing and limit strenuous activities
to early morning or evening. Staying hydrated and recognizing signs
of heat exhaustion are crucial. Since dangerous hot conditions will
likely continue, an Excessive Heat Watch is now in place for
Wednesday.

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

Current model guidance suggests Precipitable Water (PWAT) at normal
values to start the period with only patches of higher PWAT
values moving through the islands, remnants of a past frontal
boundary being pushed towards the region by a high pressure system
over the Atlantic, under a weak surface trough. PWAT values
remain normal, 1.6 to 2.0 in, for the weekend with another plume
of moisture related to a tropical wave, with above normal PWAT
values, possibly reaching the area by Tuesday. Most available
moisture will remain below 850 mb, with only a slight increase in
moisture through the mid-levels for Friday, Sunday and Monday. A
more notable increase in mid level moisture is forecast by
Tuesday. High pressure aloft will also strengthen over the Western
Caribbean through at least the weekend. Surface winds to start
the period are forecast to be more easterly, 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. Saharan dust particles will linger
to start the forecast period and increase on Saturday.

&&

.AVIATION...

(06Z TAFS)

VFR conditions will prevail across all terminals during the next 24
hours. Light to calm, variable winds will turn from the E-ESE at 14-
18 knots between 11/13-22Z, accompanied by higher gusts and sea
breeze variations. VCSH may develop between 11/16-22Z near TJBQ and
TJSJ, but chances are very low.

&&

.MARINE...

Surface high pressure extending from the northeastern to central
Atlantic and north of the area will continue to promote moderate to
fresh east to 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
by tomorrow. For the second half of the week, winds will be up to
moderate and become east-southeasterly by the weekend.

&&

.BEACH FORECAST...

Moderate risk of rip currents for St. Croix and SW Puerto Rico today
and tonight. Moderate risk forecast for southeastern PR tonight.
Low risk elsewhere.
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Re: Caribbean - Central America Weather

#21522 Postby cycloneye » Wed Jun 12, 2024 4:47 am

Area Forecast Discussion
National Weather Service San Juan PR
447 AM AST Wed Jun 12 2024

.SYNOPSIS...

Excessive heat continues. Excessive Heat Warnings are in effect
from 9 AM to 6 PM AST for lower elevations and coastal areas of
Puerto Rico. Heat Advisories are in effect from 9 AM to 6 PM AST
for valleys and urban areas of the eastern and western interior
sections of Puerto Rico, Vieques, Culebra, and the US Virgin
Islands. Since dangerous hot conditions will likely continue, an
Excessive Heat Watch is now in place for Thursday. A tropical
wave south of the area, frontal remnants and an upper trough are
expected to increase moisture and the potential for showers and
isolated thunderstorms. Still, this activity will remain localized
and amplified by daytime heating, especially across western
sections of Puerto Rico today and Thursday. Southeasterly winds
and saharan dust will promote a hot and hazy weekend.

&&

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

An overnight radar and satellite imagery analysis indicated mainly
clear to partly cloudy skies, with persistent mid-to-upper level
clouds moving over the eastern half of the forecast area. A few
light showers moved into eastern sections of Puerto Rico, leaving
rainfall totals up to a quarter of an inch. Reports again
highlighted warm overnight low temperatures above 80 degrees
Fahrenheit in coastal areas of the San Juan metropolitan area,
eastern and southern Puerto Rico, and the local islands. Coastal
observation sites and local buoys have also recorded warm low
temperatures, hovering around 82-84 degrees Fahrenheit. Although
slightly lower than yesterday's lows, this situation offers little
overnight relief and will exacerbate the region's ongoing heatwave
situation. Winds were mainly light to calm and variable.

Weather conditions throughout the forecast period should slightly
deviate from the persisting stable and shower-less pattern that
has dominated the region recently, primarily due to increased
instability yielded by an upper-level trough moving in from the
west and increasing moisture levels from the remnants of an old
front, steered by an approaching surface trough from the east.
Driven by a surface high pressure meandering to the north of the
local islands and the subsequent influence of the approaching
surface trough, the general steering flow will undergo some
changes. Easterly trade winds today, with peak daytime speeds
ranging from 15-20 mph, will gradually weaken to 10-15 mph and
shift from the east-northeast by tonight into early Thursday.
Winds will further diminish to 5-10 mph, gradually veering from
the east on Thursday and from the southeast on Friday.

Precipitable water values will stabilize throughout the forecast
period, rising from around 1.4 inches this morning to about 2.0
inches by Thursday afternoon and settling within typical seasonal
thresholds of around 1.8 inches on Friday. This trend and marginally
unstable conditions aloft suggest a higher probability of showers
with isolated thunderstorms. Still, this activity will remain
localized and amplified by daytime heating, especially across
western sections of Puerto Rico today and Thursday. Additionally,
expect increased passing showers with a few isolated thunderstorms
over the local waters tonight, with some moving into eastern Puerto
Rico and the local islands as remnants of an old front approach the
area. Regarding flooding impacts, ponding on roadways and poorly
drained areas, with localized urban and small stream flooding, is
likely with the heaviest and most frequent rains.

Dangerously hot conditions are likely again today, prompting
Excessive Heat Warnings for lower elevations and coastal areas of
Puerto Rico from 9 AM to 6 PM AST. These conditions pose a serious
risk to anyone without adequate cooling or hydration. Heat
Advisories are also in effect for valleys and urban areas of the
eastern and western interior sections of Puerto Rico, Vieques,
Culebra, and the US Virgin Islands, indicating a significant risk
for individuals sensitive to heat. When outdoors, take extra
precautions: wear lightweight, loose-fitting clothing and limit
strenuous activities to early morning or evening. Staying hydrated
and recognizing signs of heat exhaustion are crucial. Since
dangerous hot conditions will likely continue, an Excessive Heat
Watch is now in place for Thursday.

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

Current model guidance suggests precipitable water (PWAT) at
below normal to normal values this weekend, with only few patches
of more humid air moving through the islands, last remnants of a
past frontal boundary pushed towards the region by a high pressure
system over the Atlantic. This system will also promote
southeasterly surface windflow this weekend. This will steer
warmer tropical air towards our area and promote overall warm
conditions for the islands. Heat related products will likely be
issued for the islands later on. 925 mb temperatures are forecast
to be above normal this weekend. Saharan dust particles will
increase to start the period as well, promoting hazy skies during
the weekend at least. Most available moisture will remain below
850 mb. Although model guidance suggest some moisture over the
mid levels, a more notable increase is suggested by Tuesday and
into Friday. This increase in moisture, will lead to increasing
PWAT values Tuesday and Wednesday, in part due to the possible
passing of a tropical wave. High pressure aloft will also
strengthen over the Western Caribbean through at least the
weekend. Model guidance suggests more easterly winds to start the
workweek as the Atlantic surface high weakens, uncertainty
remains.

&&

.AVIATION...

(06Z TAFS)

VFR conditions will likely prevail across all terminals during the
next 24 hours. However, SHRA/TSRA may result in brief MVFR
conditions at TJSJ and TJBQ between 12/16-22Z and after 12/22Z at
TJSJ and USVI terminals. Light to calm and variable winds will
become more easterly and increase to 14-18 knots between 12/13-23Z,
accompanied by higher gusts and sea breeze variations.

&&

.MARINE...

Surface high pressure over the Atlantic will promote moderate to
locally fresh easterly winds. A tropical wave, frontal remnants and
an upper trough are expected to increase the potential for showers
and isolated thunderstorms. Moderate winds will back and become east
northeast tonight into early Thursday, veering to become east for
the rest of Thursday. Winds will then continue to diminish and veer,
becoming east-southeast to southeast throughout the weekend.


&&

.BEACH FORECAST...

There is a moderate risk of rip currents for St. Croix, NW to
north-central PR, and SW Puerto Rico today. Although the rip
current risk decreases to low for Puerto Rico tonight, a moderate
risk will persist for easternmost St. Croix. Low risk elsewhere
today and tonight.
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Re: Caribbean - Central America Weather

#21523 Postby cycloneye » Thu Jun 13, 2024 4:52 am

Area Forecast Discussion
National Weather Service San Juan PR
451 AM AST Thu Jun 13 2024

.SYNOPSIS...

Moisture from a past tropical wave and frontal remnants will
reach sectors of north and east areas during the morning. Diurnal
heating and available moisture will promote localized and short-
lived showers and isolated thunderstorms in the afternoon for
western Puerto Rico. Although the heating trend will decrease
through Friday, Excessive Heat Warnings are still in effect today
from 10 AM to 6 PM for most urban and low elevation areas of the
metro area, north- central, northwestern, and western Puerto Rico.
Heat Advisories are also in effect at those same times for the
rest of the coastal areas of Puerto Rico, including Vieques and
Culebra, and St. Croix. Southeasterly winds and saharan dust will
promote a hot and hazy weekend.

&&

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

An upper level trough now extending across the northern Leeward
Islands into the eastern Caribbean will drift eastwards today
through Friday, while a mid to upper ridge is forecast to build
and then linger across the region into the upcoming weekend.
Surface high pressure extending southwards to just north of the
region and an induced trough east of the Lesser Antilles will
maintain a light to moderate east to northeast wind flow through
Friday.

Trailing low level moisture from a departed tropical wave and an
old frontal boundary will continue to be steered across the local
waters and reach portions of the north and east coastal area
during the rest of the morning. This will result in potential for
brief showers and possibly isolated thunderstorms with moderate to
locally heavy rains in isolated areas. Thereafter, a mix of good
sunshine and few clouds can be expected the rest of the day.
However the intense heating throughout the day along with
available pockets of moisture moisture will aid in the development
of some showers and isolated thunderstorms later in the
afternoon. This activity should be of short duration and prolonged
periods of heavy rainfall is not anticipated.

By late Friday and into the upcoming weekend, another surge of
Saharan dust of moderare to high concentration is forecast to
spread across the region while the local low level wind flow
becomes more southeasterly with and even drier airmass expected
through Saturday. By then with the southeasterly winds expect
another round of hotter and hazy conditions due to the combination
of suspended dust particulates and the mid to upper leve ridging,
which will favor subsidence and compression of the warm air
resulting in limited convective development across the islands.
Daytime high temperatures will be in the low 90s especially along
the north ans west coastal areas with maximum heat indices
expected to be in the low 100s once again with excessive heat
impacts probable particularly along the coastal and urban areas.

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

Hot and hazy conditions will continue to start the long term
period. Current model guidance suggests precipitable water (PWAT)
at below normal to normal values to start the period, with only
few patches of more humid air, from frontal remnants, moving
through the islands. Southeasterly surface windflow is expected to
persist on Sunday as a Surface high is present over the Atlantic.
This will steer warmer tropical air towards the islands,
promoting overall warm to hot conditions. Heat related products
will likely be issued for the islands later on. 925 mb
temperatures are forecast to be above normal to start the period.
Model guidance suggests more easterly winds to start the workweek
as the Atlantic surface high weakens. Saharan dust particles will
continue to start the period as well, promoting hazy skies at
least through Tuesday. Although model guidance suggest some
moisture over the mid levels, a more notable increase is suggested
by Wednesday. Most available moisture for the period will remain
below 850 mb, however. A decrease in PWAT values is now forecast
for Monday and most of Tuesday, with an increase by Tuesday night
and Wednesday. High pressure aloft will start to weaken as we head
into the workweek.

&&

.AVIATION...

(06Z TAFS)

VFR at all TAF sites durg prd but VCSH at TJSJ and USVI terminals
til 13/13Z. Mstly isold passing SHRA ovr regional waters en route
btw islands. Aftn VCSH/Isold TsrA psbl ovr ctrl interior and west PR
til 13/23Z...some may briefly impact areas in and around TJMZ/TJBQ.
SFC wnd fm E-NE 10-15 knots with local sea breezes accompanied by
higher gusts. Wnds bcmg less than 10 kts aft 13/23Z. Otherwise no
significant operational wx impacts.

&&

.MARINE...

Surface high pressure over the Atlantic and an induced trough east of
the area will promote light to moderate east to northeast winds
through tomorrow. Frontal remnants from the northeast and an upper
level trough are expected to increase the potential for showers and
isolated thunderstorms through tomorrow. Winds will continue to
diminish and veer, becoming east-southeast to southeast throughout
the weekend.

&&

.BEACH FORECAST...

There is a moderate risk of rip currents today for easternmost St.
Croix. For tonight, there is a moderate risk of rip currents for
SW Puerto Rico. Low risk elsewhere today and tonight.

For tomorrow, a low risk of rip currents is forecast for all
beaches. Even with a low rip current risk, life-threatening rip
currents often occur in the vicinity of groins, jetties, reefs,
and piers.
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Re: Caribbean - Central America Weather

#21524 Postby cycloneye » Fri Jun 14, 2024 4:46 am

Area Forecast Discussion
National Weather Service San Juan PR
517 AM AST Fri Jun 14 2024

.SYNOPSIS...

An induces surface trough passing through the region will promote
passing showers and afternoon convection, mainly across western
Puerto Rico. Isolated areas may experience heavy rainfall at
times, however mid to upper-level ridging will limit widespread
rainfall. A Heat Advisory will be in effect from 10 AM to 6 PM
for the metro area, north- central, northwestern and western PR. A
limited heat risk will still be present along the rest of the
lower elevation and coastal areas of the islands. Please continue
to monitor the latest forecast for possible updates. By tomorrow,
a plume of Saharan dust of moderare to high concentration is
forecast to spread across the region, causing hot and hazy
conditions that last through the second half of the weekend into
the next workweek. An Excessive Heat Watch is in effect for
tomorrow.

&&

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

A mid to upper ridge will remain anchored across Hispaniola and
the Mona passage through the weekend while an upper trough will
continue to extend southward across the northern Leeward Islands
into the eastern Caribbean. The dominant surface high pressure
will continue across the west and central Atlantic while an
induced surface trough is forecast to cross the region today
through Saturday. This will maintain a light to moderate east
northeast wind flow this morning then become east southeast later
this afternoon then more southeasterly throughout the weekend.

Fragmented low level moisture accompanying the trough and carried
by the present wind flow will bring periods of light to moderate
showers to the local waters and mainly the windward side of the
islands during the rest of the early morning. No significant rains
are anticipated. However this slight increase in moisture along
with good daytime heating will be sufficient to increase
instability across the region resulting in afternoon convection
particularly across the central interior and west sections of
Puerto Rico. Isolated areas may experience periods of locally
heavy rains with the afternoon thunderstorms, however the mid to
upper-level ridging will continue to limit widespread rainfall.
Hot and humid conditions are expected to persist today with
maximum heat indices to reach the 100 degrees along some coastal
and urban areas resulting in excessive heat impacts.

By late Saturday and through Sunday, a plume of Saharan dust of
moderare to high concentration is forecast to spread across the
region while the low level winds becomes southeasterly. With this
expected warm and humid southerly flow, expect continued hot and
hazy conditions. The combination of suspended Saharan dust
particulates and the mid to upper level ridging will favor
subsidence and good compression of the warm air in the low layer.
Daytime high temperatures will be in the low 90s especially along
the north and west coastal areas with maximum heat indices
expected to again exceed 100 degrees, resulting in excessive heat
impacts particularly along the west north and east coastal and
urban areas. Late afternoon convection will be likely each day but
excessive and widespread rainfall is not forecast for the period.

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

Although a decrease in saharan dust is forecast to start the
workweek, another pulse will continue to promote hazy conditions
through most of the long term period. Current model guidance
suggest Precipitable Water (PWAT) values at generally normal
values to start the period with a patch of below normal PWAT
values reaching the area on Tuesday. For Wednesday and Thursday,
columnar moisture will increase once again to normal to above
normal values as moisture related to a surface trough and a
possible wave, although uncertainty remains. A developing upper
level trough near the area will also increase instability. Although
model guidance suggest moisture over the mid levels, a more
notable increase is suggested by Wednesday. Most available
moisture to start the workweek will remain below 850 mb,
however. East to east- southeast surface winds should affect the
islands through Thursday, when they become more easterly and
increase. This will steer warmer tropical air towards the islands,
promoting overall warm to hot conditions. Heat related products
will possibly be issued for the islands to start the period. 925
mb temperatures are forecast to be above normal to start the
workweek.

&&

.AVIATION...

(06Z TAFS)

Prevailing VFR across the area except for SHRA/Isold TSRA dvlpg
aft 14/17Z ovr ctrl interior and wrn sections of PR till 23Z. SFC
wnd fm northeast less than 10 kts bcmg fm east northeast 10-15 kt
with gusts to nr 20kt along with sea breeze variations. Isold SHRA
mainly ovr the regional waters en route btw islands. SHRA/iSLD
TSRA psbl nr TJBQ/TJMZ/TJPS with FEW -SHRA psbl vcty of USVI
terminals fm 14/18Z- 23Z.

&&

.MARINE...

Surface high pressure over the Atlantic and an induced trough now
just east of the area will promote light to moderate east
northeast winds this morning then become more southeasterly later
this afternoon. Moisture remnants steered by the northeast
windflow and enhanced by an upper level trough just east of the
area will increase the potential for showers and isolated
thunderstorms development over portions of the local waters the
rest of today. Winds will continue to diminish and veer, becoming
east southeast then southeast through the weekend with increasing
Saharan dust expected across the region through Sunday.

&&

.BEACH FORECAST...

The risk for rip currents is low, however, life-threatening rip
currents often occur in the vicinity of groins, jetties, reefs,
and piers.
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Re: Caribbean - Central America Weather

#21525 Postby cycloneye » Sat Jun 15, 2024 4:57 am

Area Forecast Discussion
National Weather Service San Juan PR
520 AM AST Sat Jun 15 2024

.SYNOPSIS...
Another warm day is forecast for the northern and northwestern
coastal areas today, where heat indices could reach 100 to 112
degrees Fahrenheit. Given these expected conditions, an Excessive
Heat Warning is in effect from 10 AM to 6 PM and a Excessive Heat
Advisory for the same time-frame for Culebra, Vieques and the
U.S. Virgin Islands. Another warm day is forecast for tomorrow
where a Excessive heat Watch remain in place for most of the
northern coastal area. Please follow the recommendations from the
local health department to avoid heat exhaustion. Additionally,
convection is expected as plenty of moisture remains in the area,
brought in by the southeasterly wind component.


&&

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

A surface trough will continue to exit the region today with
trailing moisture expected to affect the local islands and coastal
waters during the rest of the morning hours, steered by the
prevailing southeast low level winds. Recent Doppler weather radar
VAD wind profile suggest winds veering southeast-south below 700
millibars favoring a warm moist environment in the low levels. Mid
to upper levels suggests the region remains on the subsident side of
the trough lingering east of the region, while an upper ridge will
hold just to our west. Expect this overall pattern to persist
through the weekend with a light to moderate plume of Saharan Dust
and suspended particulates expected to continue crossing the region
today through Sunday. Although the highest concentration of dust
should move just south of the region, the low level wind flow will
bring sufficient dust for slightly hazy conditions especially later
today and on Sunday. Although drier air will filter in across the
region today along with the Saharan dust, there will enough moisture
available to aid in the development of afternoon showers and
isolated thunderstorms each day. With fairly light winds and local
sea breezes, most of the expected rainfall should be focused across
eastern, central and northwest sections of Puerto Rico steered by
the southeast wind flow.

The suspended Saharan dust particulates, along with the warm
southerly flow and presence of the mid to upper level ridging will
continue to favor subsidence and support above normal daytime high
temperatures in the low 90s especially along the north and west
coastal areas. That said, maximum heat indices are expected to
exceed 100 degrees once again, resulting in excessive heat impacts
especially along the west, north and east coastal and urban areas.
These conditions will also remain likely on Sunday. Therefore
excessive heat warnings and advisories will be issued for portions
of the islands today and a Heat Watch will remain possible for
Sunday. Please refer to the latest Non-Precipitable Weather
Message(NPWSJU) issued by WFO SJU PR for additional information on
these heat impacts.

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

A deteriorating weather trend is forecast for the first part of
the long-term period. A trough will build just over the western
Atlantic at the upper and mid-levels. The presence of the mid- to
upper-level feature will decrease the 250 MB height and turn the
temperatures at 500 MB colder, ranging from -7 to -8 degrees. This
increases the potential for more widespread lightning activity on
Tuesday into Wednesday. According to the global model guidances
(GFS and ECMWF), surface conditions will also be favorable for
shower activity due to plenty of tropical moisture embedded in the
east-southeasterly wind flow across the region. Given the
expected conditions from Tuesday into Wednesday, the islands will
experience passing showers in the morning hours over the eastern
sections, the U.S. Virgin Islands, and the local waters, followed
by widespread shower activity across the western interior. So far
today, the rainfall threat is mostly concentrated across the
western interior, with ponding of water in roadways and poor
drainage areas. From Thursday into Saturday, plenty of surface
moisture will continue to stream across the local islands, keeping
the potential for convection in the afternoon, especially across
the mountains and the western interior. Although plenty of
moisture will remain in place, more stable conditions will be
present at the upper level, provided by an upper-level ridge.

A similar temperature pattern is expected across the islands by the
first part of the long term. According to the model guidances,
925 MB temperature, the trend calls for warmer conditions,
resulting in heat indices rounding 108 to 112 F degrees. Residents
and visitors are urged to stay informed of possible advisories or
warnings due to Excessive heat.

&&

.AVIATION...
(06Z)
SFC trough crossing the region will bring wdly SCT SHRA with SCT
ocnl BKN cld lyrs nr FL025...FL050..FL080 over regional waters and
en route btw islands. VFR conds will prevail at all terminals but
Tempo 4-5SM psbl with SHRA at TJSJ/TIST/TISX til at least 15/12Z,
Brief MVFR and Mtn top Obscr psbl ovr Eastern PR due to low clds
and -SHRA. SFC wnd calm to lgt/vrb but with a light(5-15 KTS)
southerly component in the low levels BLO FL100. SFC wnd bcmg
mainly fm the SE around 10 kts aft 15/14Z.

&&

.MARINE...

A broad surface high pressure over the eastern Atlantic extending
into the Central Atlantic interacting with an induced surface
trough just north of the CWA will continue to promote a light to
moderate south-southeasterly. Under this pattern and tropical
islands, the local waters will experiment with seas up to 5 feet
and winds up to 15 knots. Isolated to moderate showers with
thunderstorm activity would result in localized hazardous marine
conditions. There is a low risk of rip currents for all the
exposed coastal beaches in the region.
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Re: Caribbean - Central America Weather

#21526 Postby cycloneye » Sun Jun 16, 2024 4:50 am

Area Forecast Discussion
National Weather Service San Juan PR
443 AM AST Sun Jun 16 2024

.SYNOPSIS...

A more east-southeasterly wind flow will relieve the heat indices
today. Although conditions will be warmer, the heat indices will
remain near 108 to 112°F for all coastal areas and urban sections
of the vicinity of Caguas. Given the expected conditions, a heat
advisory is in effect for the abovementioned areas, and an
excessive heat watch is in effect for the same areas for Monday.
The available moisture will induce showers across the mountains
and the western interior during the afternoon hours.

&&

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

A broad surface trough with axis extending northward across
Hispaniola and the Mona passage and strong High pressure over the
central and northeast Atlantic will maintain a light east southeast
wind flow across the region. Fragments of trailing low level
moisture will continue to affect the region bringing periods of
passing showers to the coastal areas of the islands during the rest
of the morning hours. Recent Doppler weather radar VAD (Velocity
Azimuth Display) wind profile and previous ASCAT Satellite derived
winds both suggest light low level wind from east southeast below
700 millibars. Meanwhile the upper ridge will hold across the region
today into early Monday before eroding, as an upper trough is
forecast to cross the west and southwest Atlantic and settle in just
west of the region by Tuesday afternoon.

This overall local pattern suggest another day of good surface
heating with light winds and local sea breezes. Therefore good
breaks in clouds and plenty of sunshine will give way to afternoon
showers and isolated thunderstorm development over portions of the
central interior and west sections of Puerto Rico. A few late
afternoon showers will be possible in and around the San Juan metro
as well some of the USVI but mostly hot and sunny conditions should
prevail. Only traces of Saharan dust will linger across the region
today through Monday but yet another plume of dust is expected to
filter in and reach the Southeast Caribbean by late Tuesday
accompanying and trailing the next tropical wave. This tropical wave
is so far forecast to enter and cross the southeast Caribbean late
Monday through Tuesday. By then and increase in low level moisture
convergence and the erosion of the aforementioned upper ridge should
aid in enhancing early morning and afternoon convection across the
islands during the latter part of the period.

Daytime high temperatures are forecast to be in the upper 80s to low
90s especially along the north and west coastal areas. This along
with the humid conditions ans southeasterly winds will again favor
maximum heat indices to exceed 100 degrees, resulting in excessive
heat impacts especially along the west, north and east coastal and
urban areas of Puerto Rico as well as the adjacent islands including
the USVI. Please refer to the latest Non-Precipitable Weather
Message(NPWSJU) issued by WFO SJU PR for additional information on
the expected heat impacts.

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

More unstable weather conditions are expected at the beginning of
the long term due to an upper-level trough just west of the
region, with the axis over Hispaniola, leaving the CWA on the
divergent side of the TUTT. Although there are some discrepancies
in the intensity of the unstable conditions between global model
guidance, the islands should expect a deteriorating weather trend
from Wednesday into Thursday. At the surface, moisture from a
tropical wave will combine with this instability, increasing the
potential for shower and thunderstorm development. Isolated
thunderstorms are possible in the afternoon across the mountains
and over the local waters due to colder temperatures at 500 MB,
ranging from -7 to -8 degrees. According to the Gálvez-Davison
Index (GDI), there is a potential for isolated to scattered
thunderstorms from Wednesday through Friday. Therefore, the
forecast reflects afternoon showers with a limited flood threat.
Hazy skies might be possible as a big pulse of Saharan Dust Air
Layer invades the local islands.

From Saturday into Sunday, a broad surface high pressure over the
Central Atlantic extending to the Eastern Atlantic will result in
variable weather conditions. Under the east-southeasterly wind
flow, plenty of surface moisture will continue to stream across
the local islands, keeping the potential for convection in the
afternoon, especially across the mountains and the western
interior. Although plenty of moisture will remain in place, more
stable conditions will be present at the upper level, provided by
an upper-level ridge.

A similar temperature pattern is expected across the islands by
the first part of the long term. According to model guidance for
925 MB temperature, the trend calls for warmer conditions,
resulting in heat indices around 108 to 112°F. Residents and
visitors are urged to stay informed of possible advisories or
warnings due to excessive heat.

&&

.AVIATION...
(06Z)
Wdly SCT SHRA ovr regional waters and passages between PR and the
USVI til 16/12Z with Isold TSRA ovr Offshore ATL waters. SCT ocnl
BKN lyrs nr FL025...FL050..FL080. VFR conds at all terminals but
VCSH psbl at TJSJ/TIST/TISX til 15/12Z. Brief MVFR with Mtn top
Obscr psbl ovr Eastern PR due to low clds and passing SHRA. SFC calm
to lgt/vrb bcmg mainly fm the SE between 8-12 kts aft 16/14Z. No sig
operational wx impacts attm.

&&

.MARINE...
A broad surface high pressure over the Central Atlantic extending
into the Eastern Atlantic, interacting with an induced surface
trough just north of the CWA, will continue to promote light to
moderate east-southeasterly winds. Under this pattern, the local
waters will experience seas up to 4 feet and winds up to 10 knots.
Isolated to moderate showers with thunderstorm activity could
result in localized hazardous marine conditions. There is a low
risk of rip currents for all the exposed coastal beaches in the
region.
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Re: Caribbean - Central America Weather

#21527 Postby cycloneye » Mon Jun 17, 2024 4:44 am

Area Forecast Discussion
National Weather Service San Juan PR
434 AM AST Mon Jun 17 2024

.SYNOPSIS...
Surface high pressure over the central and northeast Atlantic and an
elongated area of low pressure west of the region, will induce a weak
trough over the area to promote light east southeast winds through
Tuesday. High pressure will build north and east of region thereafter
promoting an increase in the easterly winds. The upper ridge will continue
to erode as a trough deepens west of the region. Moist and unstable
condtions will continue through mid week, with showers and isolated
thunderstorm likely each day, especially over the central interior
and northwestern quadrant of Puerto Rico. Fewer showers will be possible
around the U.S. Virgin Islands during the day. Dangerously hot and
humid conditions will persist with another round of slight to moderate
concentration of Saharan dust forecast to accompany and trail a tropical
wave expected to reach the area by Wednesday.

&&

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

A variable weather pattern was observed during the early morning
hours today, with a few pockets of showers streaming across the
southeastern sections of Puerto Rico, Vieques, and the local waters.
According to estimates from the Doppler Radar, rainfall
accumulations were minimal across eastern sections of Puerto Rico.
Overnight temperatures were in the upper 70s to lower 80s across the
coastal areas and in the mid-60s to lower 70s across the interior.

For the rest of today into the short-term period, the islands are
forecast to observe a deteriorating weather pattern as an induced
surface trough from a deep upper-level trough moves just north of
the region. The instability provided by this feature and the
abundant moisture present in the area with PWAT above 2 inches, as
suggested by derived imagery from the GOES Satellite, indicate
another variable day in the morning, followed by an active afternoon
with high chances of thunderstorm activity across the interior
sections of the islands. As these surface features move and interact
with the broad surface high pressure in the Central Atlantic, the
islands will experience backing winds, which will become more
variable, especially in the afternoon. This factor will be
determinant in the movement of the showers, leaving the islands with
an elevated flood threat for today across most of the interior
sections; in the rest of the areas, the islands might experience
minor flooding with ponding of water in roadways and poor drainage
areas. In terms of temperatures, warmer minimum temperatures and the
southeasterly wind flow will provided another warm morning where
heat indices could reach 112 degrees.Given these conditions, for
today, yes again, an Excessive Heat Advisory is in effect for all
the northern, eastern, and western coastal areas of Puerto Rico,
including Culebra, Vieques, and the U.S. Virgin Islands.

By Tuesday, the surface winds will come again from the southeast,
leaving the islands under a variable pattern for the morning hours
until the next tropical wave shows up by late Tuesday into
Wednesday. Instability will be present due to the divergent side of
the upper-level trough just west of the region with the axis over
Hispaniola, resulting in enough moisture in 700-500 MB as suggested
by the RH in the model guidance and colder temperatures in the 500
MB. The Gálvez-Davison Index (GDI) shows potential for daily
isolated to scattered thunderstorm activity. Although all the
variables favor a wet pattern, the NASA Goddard Earth Observing
System Model V5 shows a decent pulse of Saharan Air Dust across the
region early Wednesday, resulting in hazy skies and muggy conditions
across the region.

Given the expected conditions, residents should prepare for a
variable weather pattern for Tuesday morning, followed by afternoon
and evening showers across the eastern sections of Puerto Rico,
Culebra, Vieques, and the U.S. Virgin Islands in the early morning
hours of Wednesday when the tropical wave arrives in the CWA.

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

Moist and unstable weather conditions are expected to continue
through at least the early part of the period as a deepening
upper- level trough with the axis over Hispaniola west of the
region,will linger and provide good ventilation and a divergent
pattern aloft. This along with good tropical moisture convergence
produced by the prevailing and moderate east to southeast and a
passing tropical wave, will maintain good potential for shower and
thunderstorms development at least through Friday and moisture
trailing the wave will combine with the instability aloft and good
daytime heating to maintain moderate to high potential for
afternoon and early evening convection. Based on the most recent
guidance and Gálvez-Davison Index (GDI)product, the potential for
isolated to scattered thunderstorm will continue through Friday.
Overnight and afternoon showers will be likely with a limited
flood threats across portions of the islands each day. Hazy skies
will continue at least through Thursday due to some lingering
Saharan Dust with improving conditions by Friday and into the
weekend.

Over the following weekend and through Monday, a broad surface
high pressure will again spread across the Central Atlantic and
Eastern Atlantic result in increasing east to southeast trade
winds and variable weather conditions. Under the expected low
level wind flow, plenty of surface moisture will continue to stream
across the islands and coastal waters, thus maintaining the potential
for passing showers overnight and afternoon convection each day.
This expected activity should be focused particularly across the
central interior and west sections of Puerto Rico,while the U.S.
Virgin Island can expect afternoon showers mainly on the west-end
and downwind of the islands with fewer shower activity elsewhere
from time to time.

A similar and slightly above normal temperature pattern is expected
to continue across the islands at least through the early part of
the long term. Model guidance remains persistent in maintaining overall
hot and humid conditions although the easterly are expected to increase
during the latter part of the period. Residents and visitors are
urged to stay informed of possible advisories or warnings due to
excessive heat conditions.

&&

.AVIATION...
(06Z TAFS)

VFR conditions will persist for all the morning hours across all the
TAF sites. By 17/17Z, brief MVFR conditions are forecast across TJSJ,
TJBQ, and TJPS due to t-storm activity developing across the interior
and the San Juan Metro area. This activity will affect VIS and ceilings
across the mountain area as well. Winds will become more light from
the E-SE, and more VRB after 17/22z.

&&

.MARINE...
Surface high pressure over the Atlantic and the proximity of an
induced trough across the region will promote light to moderate
east to southeast winds today through Tuesday. Passing showers
and isolated thunderstorms will continue to affect the coastal
waters and local passages resulting in localized hazardous marine
conditions especially over the offshore Atlantic and Caribbean
waters and between eastern Puerto Rico and the U.S. Virgin Islands
during the early morning hours and on the west coastal areas Turin
the afternoon hours. The easterly winds are forecast to increase
to moderate to locally fresh by late Wednesday and through the
rest of the work week.
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Re: Caribbean - Central America Weather

#21528 Postby cycloneye » Tue Jun 18, 2024 5:01 am

Area Forecast Discussion
National Weather Service San Juan PR
445 AM AST Tue Jun 18 2024

.SYNOPSIS...
A broad surface high pressure extends southwest into the central
Atlantic while an elongated area of low pressure extends across
Hispaniola into the eastern Caribbean. A tropical wave with axis
now south of Puerto Rico continues to cross the region. This will
aid in promoting light east southeast winds today. High pressure
is forecast to build north and east of region thereafter and promote
an increase in the easterly winds. The upper trough and area of low
pressure continues to become amplified west of the region through
Wednesday. This along with the tropical wave will maintain moist
and unstable conditions through mid week resulting in periods of
developing showers and isolated thunderstorms each day. A slight
to moderate concentration of Saharan dust is forecast to spread
across the area Wednesday into Thursday.

&&

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

Isolated to scattered showers were observed all night into the early
morning across the eastern sections of Puerto Rico and the U.S.
Virgin Islands. According to radar estimates, rainfall accumulations
were between 1 to 2 inches over some Humacao, Yabucoa, Ceiba, and
Fajardo coastal areas. Several pockets of showers also affected most
of the local waters, causing localized higher seas and gusty winds.
The islands registered minimum temperatures in the upper 70s to
lower 80s across the coastal areas and in the mid to upper 70s
across the interior sections.

A deteriorated weather pattern will persist at least until late
Wednesday across the region. At the surface, the islands will be
mostly influenced by the interaction between a broad surface high
pressure over the Central Atlantic and an induced surface trough
just northwest, resulting in a light southeast wind flow over the
region. This wind flow will bring plenty of tropical moisture, with
rainfall amounts exceeding 2 inches from the upcoming tropical wave.
In the mid-to-upper levels, a trough will continue to deepen over
Hispaniola, placing the islands under the divergent side of this
TUTT. This instability will enhance colder temperatures at 500 MB
and higher RH values at 750-500 MB. According to the Gálvez-Davison
Index (GDI), a good indicator of thunderstorm activity, there is a
high chance for isolated to scattered thunderstorm activity across
the interior. Ample deep-layer moisture will persist through
Wednesday as the tropical wave moves over the region. The available
moisture, saturated soils, and instability aloft will trigger early
afternoon showers, affecting the interior and the San Juan Metro
area. On Thursday, as the induced surface trough moves westward,
building surface high pressure over the North-Central Atlantic will
tighten the pressure gradient and create backing winds. A wet
pattern will continue due to abundant moisture over the CWA, but the
focus of the showers will shift more to the interior and western
sections due to the easterly winds across the area.

Due to the significant rainfall observed over the past two days,
soils are already saturated, leading to urban and small-stream
floods in some areas across the islands. Therefore, it's crucial for
residents and visitors to be aware of these conditions for safety
and operational reasons and to check weather conditions during the
day for possible advisories or warnings.

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

Conditions are so far forecast to improve by Friday with increasing
stability aloft, as the previously mentioned upper trough west of
the area weakens and high pressure builds across the area from the
central and eastern Caribbean. Low level moisture transport will
also erode as the easterly winds increase resulting in less frequent
passing late evening and early morning shower activity. The
potential for afternoon shower development and isolated
thunderstorms will continue on Friday but mainly due to local
effects and good daytime heating. Shower activity should be more
localized and focused over the interior and west section of Puerto
Rico steered by the moderate trade winds. Overall improving
condtions is expected elsewhere on Friday and into Saturday with
plenty of sunshine and near seasonal temperatures expected.

For the rest of the following weekend prevailing easterly winds are
forecast with periods of passing early morning showers affecting the
windward side of the islands. This will be followed by afternoon
convection limited to mainly parts of the central interior and west
sections of Puerto Rico. Plenty of sunshine and mostly pleasant
summertime weather is expected elsewhere although a weakly induced
easterly perturbation will cross the region late Saturday into
Sunday followed by the next topical wave so far forecast to enter
the eastern Caribbean late Sunday then cross the region Monday
through Tuesday. That said expect lesser showers and thunderstorm
activity across during the early part of the period with the best
potential for increasing instability and convection so far
forecast for the latter part of the period on Monday and Tuesday
due to the approaching tropical wave and associated moisture
field.

&&

.AVIATION...
(06z)

VCTS and -RA will persist through 18/15Z, followed by SHRA & TSRA,
which are forecast from 18/16Z for TJSJ, TJPS, and TJBQ due to
strong showers across the region. These conditions will result in
MVFR and brief IFR conditions across the major TAF sites of the
island. Lower ceilings and limited VIS are expected over the
mountains as well. Winds will continue light and VRB, increasing at
18/15Z from the E-SE at 12 knots with gusty winds near the showers.

&&

.MARINE...
Surface high pressure over the Atlantic and a tropical wave crossing
the region will promote light east to southeast winds today, then
becoming more easterly and increasing to moderate to locally fresh
by Wednesday and through the rest of the week. Passing showers and
isolated thunderstorms will continue to affect the coastal waters
and local passages resulting in localized hazardous marine conditions.

&&

.BEACH AND RIVER FORECAST...

The risk of rip currents is low for all beaches today through
Wednesday morning, however life threatening rip currents may
still occur especially near groins, jetties, reefs, and piers.

Local rivers and streams are at normal levels however expected
afternoon showers and thunderstorm development across the interior
and west sections of Puerto Rico may produce locally heavy rains
at the headwaters and this may cause sudden surges of water along
rivers and streams across theses areas. Please monitor the weather
conditions throughout the day and always take time to look
upstream.
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Re: Caribbean - Central America Weather

#21529 Postby cycloneye » Wed Jun 19, 2024 4:59 am

Area Forecast Discussion
National Weather Service San Juan PR
349 AM AST Wed Jun 19 2024

.SYNOPSIS...
An elevated risk of flooding, with thunderstorms is expected for
today and Thursday. Conditions will become more seasonal this
weekend, but still with enough moisture to generate showers and
isolated thunderstorms. Hot conditions will persist each
afternoon, with little relief for areas with the lowest cloud
coverage.

&&

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

Isolated to scattered showers were observed all night into the early
morning across some coastal sections of St. Thomas. According to
radar estimates, rainfall accumulations were minimal. Several
pockets of showers with thunderstorms affected most of the local
waters, causing localized higher seas and gusty winds. Due to these
conditions, a marine weather statement was issued for most of the
local waters. The islands registered minimum temperatures in the
upper 70s to lower 80s across the coastal areas and in the mid to
upper 70s across the interior sections.

A similar weather pattern will persist today into Thursday across
the region. At the surface, the islands will continue to be
influenced by the interaction between a broad surface high pressure
over the Central Atlantic and an induced surface trough just
northwest, resulting in a light southeast wind flow over the region.
This wind flow will continue to bring plenty of tropical moisture,
with PWAT values exceeding 2 inches from the previous tropical wave
now located over Hispaniola. A similar pattern will prevail in the
mid-to-upper levels; a deep trough will continue to increase
instability, enhancing colder temperatures at 500 MB and divergence
aloft. These conditions will enrich vertical development, and deep
afternoon convection is forecast again across the interior sections
of the island. According to the Galvez-Davison Index (GDI), a good
indicator of thunderstorm activity, there is a good chance to
observe scattered thunderstorms with the heaviest activity today.
Since the surface winds remain light, resulting from the relaxation
in the pressure gradient, slow-moving showers could result in
significant rainfall accumulations. That is why there is an elevated
risk of flood threats across most of the CWA today. Residents are
urged to check weather conditions for further updates.
The forecast remains on track for Thursday. As the induced surface
trough moves westward, building surface high pressure over the North-
Central Atlantic will tighten the pressure gradient and create
backing winds. This wind flow will continue to drag moisture across
the region, resulting in a persistent wet pattern. The prevailing
winds will focus the showers more on the interior and western
sections. By Friday, the available moisture will diminish, resulting
only in localized showers for the afternoon hours.


Due to the significant rainfall observed over the past few days,
soils are already saturated, leading to urban and small-stream
flooding in some areas across the islands. Therefore, it's crucial
for residents and visitors to be aware of these conditions for
safety and operational reasons and to check weather conditions
during the day for possible advisories or warnings.

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

A surface high pressure centered over the eastern Atlantic will
drive the trade winds from the east during the weekend, bringing
occasional showers across eastern Puerto Rico and the Virgin
Islands, and followed by afternoon convection across western Puerto
Rico.

Early next week, a mid level ridge will build north of the
region, and the surface high pressure will strengthen as it moves
westward. At this time, an induced surface trough will approach the
area, and a tropical wave will cross the eastern Caribbean. The
moisture from these surface features will bring an increase in
showers to the area, mainly for the Virgin Islands, local waters and
eastern Puerto Rico. Accumulations are not expected to be too
significant because the low level steering flow will be enhanced.
Saharan dust will follow on Tuesday, lasting through Wednesday. Then
on Wednesday, another trough will dig from the northeast, shifting
the winds from this direction. All these days, afternoon convection
is anticipated, mainly for the interior and western Puerto Rico. The
activity could be strong, with possible lightning, and urban and
small stream flooding developing.

The heat risk will be elevated all these days, impacting outdoor
activities, and those without effective cooling or poorly hydrated.


&&

.AVIATION...
(06z)

Briefly, VFR conditions will persist for most of the TAF sites until
SHRA and TSRA develop from 19/Z across the islands. These conditions
will result in MVFR and brief IFR conditions across the major TAF
sites of the island where TSRA ceiling in the FL020 & FL030 are
forecasted. Lower ceilings and limited VIS are expected over the
mountains as well. Winds will continue light and VRB, increasing at
19/15Z from the E-SE at 12 knots with gusty winds near the showers.

&&

.MARINE...
Surface high pressure over the Atlantic will promote moderate to
locally fresh easterly winds through the rest of the week. Passing
showers and isolated thunderstorms accompanying and trailing a
tropical wave will continue to affect the coastal waters and local
passages resulting in localized hazardous marine conditions.

&&
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Re: Caribbean - Central America Weather

#21530 Postby cycloneye » Thu Jun 20, 2024 4:48 am

Area Forecast Discussion
National Weather Service San Juan PR
420 AM AST Thu Jun 20 2024

.SYNOPSIS...

The interaction between a broad surface high over the Central
Atlantic and an induced surface trough northwest of the local
islands has promoted southeasterly winds today. For tonight,
remnant afternoon showers will continue lingering and gradually
dissipating while showers and possible thunderstorms move towards
the eastern and southern coastal areas from the waters. A wet
pattern will continue into next week as moist air lingers across
the region from the arrival of tropical waves.

&&

.SHORT TERM...Tonight through Friday...

Afternoon shower and thunderstorm activity was observed across
most of the area with the strongest activity over western and
northern municipalities. These showers and thunderstorms were fast
moving, finally moving offshore and or dissipating. The highest
rainfall amounts were reported around Manati, Barceloneta and
Arecibo, peaking at around 4.18 inches in Barceloneta. High heat
indices above 106 degrees were reported in several coastal areas,
before generalized afternoon convection and cloudiness was able
to provide relief in that aspect to most areas. Precipitable water
(PWAT) values are above normal (above 2.0 inches) over the
region. Current model guidance has the bulk of PWAT leaving the
area during the overnight hours. For Thursday and Friday, columnar
moisture will remain normal to above normal as as patches of
moisture move across the region. The interaction between a broad
surface high over the Central Atlantic and an induced surface
trough northwest of the local islands has promoted southeasterly
winds today. For tonight, remnant afternoon showers will continue
lingering and gradually dissipating while showers and possible
thunderstorms move towards the eastern and southern coastal areas
from the waters. As we head into the second half of the weekend
the surface trough will move westward and the surface high will
build, due to this winds are forecast to back and become more
easterly while increasing to moderate and locally fresh speeds.
Under these easterly winds and patches of moisture, afternoon
shower and thunderstorm activity should concentrate more on
interior to western PR and downwind of the local islands. Lows
tonight up to upper 70s and around 80 across lower elevation
areas. 925 mb temperatures should remain at normal to above normal
values.

&&

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

A surface high stretched across the central Atlantic will bring a
pattern of trade wind showers followed by afternoon convection
across the islands on Sunday into the early of next week. Plenty of
moisture remains over the area with consistent high precipitable
water values which will yield in an abundance of showers at times.
By Tuesday, a tropical wave begins to move across the area,
bringing unstable conditions across the the lower levels and
continuing the trend of moist conditions. Generally relatively
high pressure will remain across the mid to upper-levels during
this time, however with the instability caused by the tropical
wave and a continued east to southeasterly flow, rain may be
persistent and heavy a few time throughout this period. Afternoon
convection due to local effects and diurnal heating will play a
big role in allowing thunderstorms to form, with western Puerto
Rico most likely to receive the bulk of rain and the greatest risk
of excessive rainfall.

&&

.AVIATION...
(06Z)
Mainly VFR conditions expected to prevail. SHRA will move at
times across the waters, and after 17Z, will form in the western
half of the Cordillera Central, causing mountain obscuration.
Winds will increase today, out of the east at 15-20 kts, with
gusts up to 25 knots, mostly from 14-22Z.

&&

.MARINE..
Surface high pressure over the Atlantic will promote moderate to
locally fresh easterly winds through the rest of the week. Passing
showers and isolated thunderstorms associated with a tropical wave
will continue to affect the coastal waters and local passages
resulting in localized hazardous marine conditions.
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Re: Caribbean - Central America Weather

#21531 Postby cycloneye » Fri Jun 21, 2024 4:48 am

Area Forecast Discussion
National Weather Service San Juan PR
419 AM AST Fri Jun 21 2024

.SYNOPSIS...

A typical weather pattern with passing windward showers and
active afternoon convection over the interior and western Puerto
Rico is to be expected through the next week. A series of
tropical waves will approach the area starting early next week,
furthering this pattern.

&&

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

Showery conditions has been observed across the islands during the
night hours, but rainfall estimates from the NEXRAD in Cayey did not
show any significant accumulations. Recent infrared satellite
imagery shows some lingering high clouds coming from the west, from
a developing system over Mexico and Central America. Close to home,
satellite-derived precipitable water shows a patch of enhanced
moisture approaching the islands from the southeast. The high
resolution and global models show an increase in shower activity for
the region today, first moving over portions of eastern Puerto Rico
and the Virgin Islands, and reaching the west in the afternoon
hours. Conditions aloft are not really favorable for strong
thunderstorms, but strong heating should be enough to fire up some
thunderstorms this afternoon. The risk for flooding will be elevated
for the west, and limited for the rest of the area.

A surface to mid level high pressure will drive the trade winds from
the east southeast this weekend, with speeds at around 15 to 20
knots today through Sunday. In this flow, induced patches of
moisture will reach the islands at times. The Galvez-Davison Index
show a better chance for thunderstorms in the afternoon for the
interior and western Puerto Rico. There will be some Saharan dust at
the low levels too, turning skies hazy, but also enhancing the
lightning activity each afternoon.

Temperatures will remain above normal these days too, with highs
reaching the low 90s at coastal areas, and lows close to 80. Heat
indices will be elevated too, with a limited heat risk anticipated.

&&

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

A robust surface high stretched across the central Atlantic will
maintain a pattern of trade wind showers followed by afternoon
convection across the islands throughout the week. Plenty of
moisture remains over the area with constantly high precipitable
water values which will yield in an abundance of showers at
times. On Monday, a tropical wave begins to move across the area,
bringing unstable conditions across the the lower levels that will
aid in thunderstorm development across the area. Generally
relatively high pressure will remain across the mid to upper-
levels during this time, however with the instability caused by
the tropical wave and a continued east to southeasterly flow, rain
may be persistent and heavy a few time throughout this period.

The movement of an area of low pressure north of the region by
mid-week will help maintain high precipitable water values as
easterly flow pushes a moist airmass over the region. Afternoon
convection due to local effects and diurnal heating will play a
big role in allowing thunderstorms to form, with western Puerto
Rico most likely to receive the bulk of rain and the greatest
risk of excessive rainfall.

&&

.AVIATION...

(06Z TAFs)

Mainly VFR conditions expected to prevail through the forecast
period. SHRA will continue across the region, impacting the USVI
terminals and TJSJ through the day. Widespread SHRA and isolated
TSRA expected after 15Z, reaching also TJPS and TJBQ. Periods of
reduced VIS and low ceilings are anticipated, as well as mountain
obscuration for the Cordillera Central. Winds will be out of the E
at 14-18 kts, with gusts around 25 kts from 13-22z.

&&

.MARINE...

A surface high pressure over the central Atlantic will promote
moderate to locally fresh easterly winds through the rest of the
week. Trade wind showers will move across the regional waters from
time to time. The next tropical wave will approach the local islands
by the beginning of the next workweek.

.BEACH FORECAST...

A moderate risk of rip currents is present for the northern,
eastern and southwestern exposed beaches of Puerto Rico, Vieques,
Culebra and St. Croix. Remember, life-threatening rip currents are
possible in the surf zone.
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Re: Caribbean - Central America Weather

#21532 Postby cycloneye » Sat Jun 22, 2024 4:53 am

Area Forecast Discussion
National Weather Service San Juan PR
356 AM AST Sat Jun 22 2024

.SYNOPSIS...
A summer-like pattern will persist for the weekend across the
islands, with passing showers early in the day, and afternoon
convection for the interior and western Puerto Rico each day. A
tropical wave will approach the area on Monday, followed by
Saharan dust. Hot temperatures will prevail for the forecast
period.

&&

.SHORT TERM...Saturday through Monday...

Surface ridging continues to dominate the Atlantic Basin, allowing
moderate easterly flow to prevail across the lower levels through
Sunday. This trade wind pattern will stream humid air masses
across the region, allowing windward showers and afternoon
convection to occur. Under a weak ridge across the mid to upper-
levels, local effects and diurnal heating will provide enough
instability to bring heavy rainfall during the afternoon hours for
western Puerto Rico where flooding and strong thunderstorms
remain possible.

On Sunday, lower level winds start to veer, becoming southeasterly
as the surface high in the Atlantic becomes more centered at about
45W longitude and as a tropical wave begins to move into eastern
Caribbean Basin. Weather conditions are likely to deteriorate
Sunday Afternoon onward as this tropical wave moves through the
area on Monday. Expect a rapid increase of passing showers Sunday
night into Monday morning, then heavy convection during Monday
afternoon for multiple sections of the islands. Breezy conditions
are forecast to occur as well, which will bring squally weather at
times with strong thunderstorms. Northwestern Puerto Rico may see
the heaviest rainfall during Monday afternoon, however
southeastern PR may see some impressive thunderstorms capable of
bringing lots of rain.

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

After the tropical wave departs, a surface high pressure will take
control of the atmospheric conditions. First, this feature will
drive the trade winds from the southeast, and will tighten the
pressure gradient, with surface speeds around 20 knots. Also, a
trade wind cap inversion will form at around 800 mb, trapping all
the available moisture below this level. Moderate to strong
concentrations of Saharan dust may arrive too, with hazy skies and
little precipitation expected through at least early Thursday. This
conditions, however, will make temperature soar, with very hot
conditions expected to return these days.

By Thursday, as an induced surface trough (more evident in the 700
mb pressure field) approaches, the winds are expected to shift from
the northeast at these heights, and the trade wind cap will weaken.
Instability should be enough to fire up showers and thunderstorms
for the interior and western portions of Puerto Rico, with an
elevated risk for urban and small stream flooding, and lightning.
Also, by the end of the week, an upper level trough will approach
the Leeward Islands. This trough is not expected to affect the local
islands directly, but it will allow for better shower and
thunderstorm production each afternoon across the usual interior and
western Puerto Rico. Shower activity will become more frequent too
for eastern Puerto Rico and for the Virgin Islands. Saharan dust
will not completely go away, but concentrations are expected to be
lower. This low concentrations of dust could contribute to enhance
the frequency of the lightning activity within the thunderstorms.


&&

.AVIATION...
(06Z TAFs)

Mainly VFR conditions expected to prevail through the forecast
period with periods of reduced VIS and low ceilings possible during
the afternoon. SHRA will continue across the region, impacting the
USVI terminals and TJSJ through the day. Widespread SHRA and
isolated TSRA expected after 15Z, effecting also TJPS and TJBQ.
Winds will be out of the E at 14-18 kts, with gusts around 25 kts
from 13-22z.

&&

.MARINE...
A surface high pressure over the central Atlantic will promote
moderate to locally fresh easterly winds through the rest of the
week. Trade wind showers will move across the regional waters from
time to time. The next tropical wave will approach the local islands
by the beginning of the next workweek.
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Re: Caribbean - Central America Weather

#21533 Postby cycloneye » Sun Jun 23, 2024 5:08 am

Area Forecast Discussion
National Weather Service San Juan PR
425 AM AST Sun Jun 23 2024

.SYNOPSIS...

There is a Heat Advisory in effect for most urban areas and lower
elevations of the islands. A weak upper-level trough and the
available low-level moisture will promote shower and thunderstorm
development across the area today. A tropical wave will increase
shower activity on Monday. A strong Saharan Air Layer with a
dense area of dust is expected to move over the islands by
midweek.


&&

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

Advective showers and isolated thunderstorms will continue to effect
windward sections throughout the morning hours as relatively drier
air filters into the region under a surface easterly to
southeasterly flow. High pressure continues to dominate the Atlantic
Basin and as it shifts towards the eastern Atlantic and a tropical
wave moves into the eastern Caribbean, winds will begin to veer
slightly remaining from a southeasterly direction through the short
term. Afternoon convection later on today is expected to bring heavy
thunderstorms across the western section of Puerto Rico, mainly in
the center of the western part of the island as sea breezes keep
most of the rain inland. Streamer formation downwind of El Yunque
and the smaller islands may bring some good showers are well.
Flooding is possible with the heaviest activity and thunderstorms
capable of producing frequent lightning are possible.

The tropical wave is forecast to move across the region on Monday
afternoon, bringing a moist airmass that will elevate the chance of
passing showers and overall cloudy, muggy conditions. Winds may
increase to strong values at times, which may result in squally
weather conditions especially across the southeastern sections of
Puerto Rico and the USVI. A drier airmass with high concentrations
of Saharan Dust is forecast to replace this airmass as the tropical
wave exits to the northwest of the region on Tuesday morning. Hazy,
dry conditions are forecast on Tuesday as a result of this. Monday
night may see a good amount of thunderstorms as the interaction of
the saharan dust causes somewhat of dryline effect on the moisture
in front of it. Yet as mentioned, Tuesday appears to be quite dry
with high maximum temperatures which may yield for a heat advisory
or warning, stay tuned.

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

The NASA Dust Aerosol Optical Thickness model shows a dense Saharan
Air Layer (SAL) lingering over the local islands through Thursday.
In addition, there will be a mid-to upper-level ridge across the
northeastern Caribbean, resulting in drier conditions aloft and
inducing a very stable weather pattern with hazy skies, sunny
mornings, and some afternoon showers across the western sections of
Puerto Rico. Instability will slightly increase from late Thursday
and Friday as an induced low-level trade wind perturbation streams
across the local area. Moisture content will increase once again and
isolated thunderstorms are expected to develop over portions of the
waters and across the islands.

Later in the period, as the SAL exits the region, the islands will
be influenced by the easterly winds resulting from the interaction
between a surface high pressure over the central Atlantic and an
induced surface trough just northwest of the region over the Western
Atlantic. This wind pattern will drag tropical moisture into the
islands. According to global model guidance, PWAT values will
fluctuate from 1.70 to 2.10 inches, just above climatology for the
region. That moisture, along with diurnal heating, will promote the
development of afternoon showers and isolated thunderstorms each day
across the western interior sections of Puerto Rico. Winds will
return from the southeast by Saturday into Sunday, increasing the
potential to observe heat indices near 108 to 112°F across the
coastal and urban areas of the islands.


&&

.AVIATION...

(06Z TAFs)

Mainly VFR conditions expected to prevail through the forecast
period with periods of reduced VIS and low ceilings possible during
the afternoon. SHRA will continue across the region, impacting the
USVI terminals and TJSJ through the day. Widespread SHRA and
isolated TSRA expected after 15Z, mainly effecting TJPS and TJBQ.
Winds will be out of the E at 14-18 kts, with gusts around 25 kts
from 13-22z.


&&

.MARINE...

A surface high pressure over the central Atlantic will promote
light to moderate easterly winds through the rest of the weekend.
Trade wind showers will move across the regional waters from time to
time. The next tropical wave will approach the local islands from
late tonight through Monday. Increasing winds and showers with
thunderstorms are expected through Monday across the local
waters. Hazy skies are expected from Tuesday through Thursday due
to Saharan dust.
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Re: Caribbean - Central America Weather

#21534 Postby cycloneye » Mon Jun 24, 2024 4:46 am

Area Forecast Discussion
National Weather Service San Juan PR
439 AM AST Mon Jun 24 2024

.SYNOPSIS...
The arrival of a tropical wave today will bring showers and
thunderstorms across the area, especially during the afternoon. A
thick plume of Saharan dust will bring hot and hazy conditions
from tomorrow through Thursday morning, then a trade wind pattern
with advection showers and afternoon convection will prevail. Hot
temperatures are expected through the week with a Heat Advisory in
effect for northern and western Puerto Rico and a watch for
tomorrow afternoon for all the coastal sections of PR and the
USVI.

&&

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

Passing showers have been moving across Puerto Rico and the United
States Virgin Islands during the night hours. The strongest activity
was observed early in the night, across northeastern Puerto Rico,
with lightning detected. All this rain is related to a tropical wave
near the Lesser Antilles. The field moisture is evident in the
satellite-derived precipitable water product.

As the wave progresses today, moisture value will remain well above
the climatological value for this time of year, meaning that
conditions will be favorable for showers and thunderstorms. It will
be gusty too, with a southeast breeze at 15 to 25 mph. The risk for
flooding will be elevated, with lightning and gusty winds
anticipated with the thunderstorms.

Once the wave departs, a dense Saharan Air Layer follows, so
conditions will dry out later this evening. Hazy skies and hot
temperatures are anticipated for Tuesday and Wednesday, with only a
few showers reaching the islands at times. Afternoon convection will
remain possible for western Puerto Rico, but conditions aloft will
not favor widespread nor strong rainfall accumulation.

&&

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

Through early in the weekend, there will be a mid-to upper-level
ridge across the northeastern Caribbean. Its still possible that
afternoon showers will form across the western sections of Puerto
Rico. Instability will slightly increase from late Thursday and
Friday as an induced low-level trade wind perturbation streams
across the local area raising moisture content that will increase
the chance of isolated thunderstorms and showers.

A trade wind pattern due to an established surface high across the
Atlantic basin will drag tropical moisture into the islands through
the weekend into next week. According to global model guidance, PWAT
values will fluctuate from 1.70 to 2.10 inches, just above seasonal
climatological values for the region. That moisture, along with
diurnal heating, will promote the development of afternoon showers
and isolated thunderstorms each day across the western interior
sections of Puerto Rico. The arrival of drier air on Monday may
reduce the chance of showers, however do still expect a typical
seasonal pattern of passing showers and afternoon convection for the
start of the following week.

&&

.AVIATION...

(06Z TAFs) SHRA and isolated TSRA from a tropical wave will move
across the area today, reaching the terminals at times. The activity
will be strongest after 15Z, with periods of reduced VIS and low
ceilings expected. Winds will be from the southeast from the
surface through FL150, at 14-24 kts.

&&

.MARINE...

A surface high pressure over the central Atlantic will promote
light to moderate southeasterly winds. Trade wind showers will move
across the regional waters from time to time. The next tropical wave
will approach the local islands from late tonight through Monday.
Increasing winds and showers with thunderstorms are expected through
tonight across the local waters. Hazy skies are expected from
Tuesday through Thursday due to Saharan dust.

&&

BEACH FORECAST...

There is a low to moderate risk of rip currents across PR and the
USVI. Showers and isolated thunderstorms are possible across the
coastal areas of the USVI and eastern PR during the morning hours,
and across the west/northwest coast of PR during the afternoon.
The afternoon thunderstorms could produce frequent lightning and
gusty winds.
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Re: Caribbean - Central America Weather

#21535 Postby cycloneye » Tue Jun 25, 2024 5:23 am

Area Forecast Discussion
National Weather Service San Juan PR
526 AM AST Tue Jun 25 2024

.SYNOPSIS...

As mentioned in previous discussions, a dense plume of Saharan
dust is expected to arrive on today along with a dry airmass.
These conditions will promote hazy skies and hot temperatures from
Tuesday through Thursday. Significant rainfall activity is not
anticipated due to the presence of the dust particles.

&&

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

Calm weather conditions prevailed overnight, with warmer-than-normal
low temperatures across Puerto Rico and the U.S. Virgin Islands. In
the satellite imagery, a mid-to-upper-level cloud deck was observed
moving over the islands, limiting nighttime cooling overnight. The
winds were mainly from the east-southeast at 10 mph or less.
Additionally, the Saharan Air Layer began to produce hazy skies
across the region.

Due to the warmer-than-normal low temperatures, we can expect
maximum temperatures to rise to near or above-normal values today
and tomorrow. The arrival of a Saharan Air Layer will reduce the
available moisture, but the high low-level humidity will still lead
to warm and hot heat indices. This has prompted an Excessive Heat
Warning for most of the coastal areas and western interior urban
sections of Puerto Rico, Culebra, and all of the U.S. Virgin
Islands. The rest of mainland PR and Vieques are under a Heat
Advisory, indicating the potential hazards of these weather
conditions.

We cannot rule out some showers arriving while steering by the winds
across the windward sections, but it should be minimal today. During
the afternoon, some showers will develop across PR's mountain and
western sections.

Due to similar weather conditions, an Excessive Heat Watch will be
in effect tomorrow. Additionally, the hazy skies will remain across
the islands throughout the short term. The heat spell may extend
through at least Thursday when a trade wind perturbation will
increase humidity, increasing the potential for showery weather and
some isolated afternoon strong convection.

&&

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

The inherited forecast remains unchanged. The latest model
guidance continues to suggest a slight increase in instability
through the end of the workweek into the early weekend as an induced
low-level trade wind perturbation streams across the local area.
This perturbation will allow the moisture content to increase
through the mid-levels of the atmosphere, increasing the chance of
isolated thunderstorms and showers. Precipitable water models
show values ranging from normal to slightly above normal
climatological levels. By the weekend, the surface high-pressure
system will position across the Atlantic basin, dragging tropical
moisture into the islands through next week. At this time, we
anticipate that this moisture, along with the diurnal heating,
will promote the development of afternoon showers and isolated
thunderstorms each day, particularly across the western interior
sections of Puerto Rico, as mostly easterly winds will dominate
the forecast area.

A slight change in weather conditions is foreseen as drier air will
filter across Puerto Rico and the U.S. Virgin Islands on Monday,
which may reduce the chance of showers. Nevertheless, a typical
seasonal weather pattern of passing showers and afternoon
convection is expected.

&&

.AVIATION...

(06Z TAFs)

Hazy skies will limit VIS btwn 4 and 6 SM or less. The winds will
remain mainly from the east to east-southeast at 10-20 kt with gusts
between 20 and 30 kt. Some showers will develop across the interior
and western PR between 25/18-23z.

&&

.MARINE...

A surface high pressure over the central Atlantic will promote
moderate to fresh east-southeasterly winds. Trade wind showers
will move across the regional waters from time to time. Hazy skies
are expected through Thursday due to Saharan dust.

&&

.BEACH FORECAST...

There is a moderate risk of rip currents across PR and the U.S.
Virgin Islands. A low risk is forecast for western PR.
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Re: Caribbean - Central America Weather

#21536 Postby cycloneye » Wed Jun 26, 2024 10:28 am

Area Forecast Discussion
National Weather Service San Juan PR
404 AM AST Wed Jun 26 2024

.SYNOPSIS...

The dense plume of Saharan Dust will continue to affect the local
islands through Thursday. This plume will continue to promote
hazy skies, lower visibilities and hot temperatures across the
area. Expect warmer than normal temperatures each day, resulting
in excessive heat warnings and heat advisories across Puerto Rico
and the USVI.

&&

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

Saharan dust and warmer than normal temperatures are expected to
continue through at least Thursday across the U.S. Virgin Islands
and Puerto Rico. An Excessive Heat Warning and a Heat Advisory are
in effect for all coastal counties, please refer to the latest heat
product NPWSJU for more information. Heat indices higher than 112
degrees Fahrenheit are expected. Hazy skies will continue today as
the area remains under the influence of a strong 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 are possible,
in addition to isolated thunderstorms developing this afternoon over
west/northwest PR.

On Thursday and Friday, a gradual increase in moisture content is
expected as an induced perturbation on the trade winds moves from
the east. A 700-500MB ridge north of the region will promote
northeasterly steering winds, while mainly easterly trades prevail
at the surface due to the Azores High. This will cause showers and
thunderstorms to develop over the interior and south/southwestern
quadrant of Puerto Rico, while an advective pattern with passing
showers persists across the USVI and the east/northeast sections of
PR.

&&

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

The latest precipitable water guidance suggests values ranging
around normal climatological levels across Puerto Rico and the U.S.
Virgin Islands during the weekend. Nonetheless, as a surface
high-pressure system positions across the Atlantic basin, we
anticipate the introduction of tropical moisture into the islands
through at least the upcoming workweek. This weather pattern will
allow moisture to filter over the islands from time to time, and
this, combined with the diurnal heating, will promote the
development of afternoon showers and isolated thunderstorms,
particularly across the western interior sections of Puerto Rico,
as mostly easterly winds will dominate the forecast area. As
mentioned in previous discussions, the tourists and citizens of
Puerto Rico and the U.S. Virgin Islands will experience a slight
change in weather conditions as drier air will filter across the
region on Monday, reducing the chance of showers through Tuesday.
Nevertheless, a typical seasonal weather pattern of passing
showers and afternoon convection is expected.

On Wednesday, expect a gradual increase in shower and possible
thunderstorm activity across the forecast area, particularly over
the Caribbean waters, as a tropical wave now being monitored by
the National Hurricane Center moves south of us. However, we
encourage people to stay updated with any changes in the forecast.

&&

.AVIATION...

(06Z TAFS)

Mainly VFR conditions are expected to prevail across all terminals
during the next 24 hours. HZ due to Saharan dust could drop VSBY
around 6 miles. SHRA/TSRA is expected to develop btw 26/18z-22z in
and around TJBQ, causing tempo MVFR conds. ESE winds expected at 12-
16 kt with stronger gusts and sea breeze variations aft 26/14z.

&&

.MARINE...

A surface high pressure over the central Atlantic will promote light
to moderate east-southeasterly winds. Trade wind showers will move
across the regional waters from time to time due to a tropical wave
moving south over the Caribbean Waters. Hazy skies are expected
through Thursday due to Saharan dust.

&&

.BEACH FORECAST...

There is a moderate risk of rip currents across southern PR and
St. Croix. A low risk is forecast elsewhere.
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Re: Caribbean - Central America Weather

#21537 Postby cycloneye » Thu Jun 27, 2024 4:42 am

Area Forecast Discussion
National Weather Service San Juan PR
418 AM AST Thu Jun 27 2024

.SYNOPSIS...
A low to mid -level trough will enhance moisture
levels, leading to increased shower coverage across the local
area. this will result in a few showers affecting the coastal
region of Puerto Rico and the U.S. Virgin islands. On Thursday
night, a high pressure system over the mid -Atlantic will
strengthen over the local region, creating dry and stable
conditions across the area through at least Saturday, until the
next Wave moves in. Moisture associated to this tropical wave
will increase the shower and cloud coverage through Sunday. At
this moment the National Hurricane Center is monitoring a vigorous
tropical wave with a moderate to high chance chance of formation
in the long term. Residents in Puerto Rico and the U.S. Virgin
Islands should always stay tuned with the latest information using
official sources.

&&

.SHORT TERM...
Passing showers were noted across portions of the islands during the
overnight hours. Minimum temperatures were from the upper 60s to mid
70s across the higher elevations, and from the upper 70s to low 80s
across coastal areas. Winds were light from the east to northeast.
Scattered showers and isolated thunderstorms were increasing over
the offshore Atlantic waters after 3 AM.

A gradual increase in moisture content is expected through the short-
term period as a low-to mid-level trough moves across the
northeastern Caribbean today and a tropical wave on Saturday. A 700-
500MB ridge north of the region will promote northeasterly steering
winds, while mainly easterly trades prevail at the surface due to
the broad surface high pressure over the central Atlantic. This will
cause showers and thunderstorms to develop mainly over the interior
and south/southwestern sections of Puerto Rico through Friday, and
an advective pattern will prevail with passing showers across the
USVI and the east/northeast sections of PR each day, with increasing
shower and thunderstorm activity on Saturday. Urban and small stream
flooding is possible each afternoon over western PR.

Saharan dust will diminish today across the area, but hazy skies can
still be expected. It will be hot again across the islands and a
Heat Advisory (NPWSJU) was issued for Puerto Rico and the U.S.
Virgin Islands once again. Maximum temperatures should reach the low
90s across most coastal municipalities with heat indices reaching or
exceeding 110F. Easterly winds around 15 mph with stronger gusts are
expected during the day.

.LONG TERM...

The long term forecast is based on the forecast trajectory of a
couple of tropical disturbance that area expected to move south
of the local area. We are currently monitoring two tropical weather
systems. The first system has a higher potential for development,
however, a high pressure area will keep it positioned well to the
south of our region. The second tropical wave is not forecasted
to develop as significantly,but models suggest it will be located
somewhat closer to the local region. While it might initially
appear that neither of these systems will have a direct impact on
our area, they will indeed indirectly affect us. Both systems
will lead to increased cloudiness and higher likelihood of rain.
Our primary concern, however, is the hazardous marine conditions
anticipated, particularly in the Caribbean Sea, due to the
forecasttrack of both systems. The first wave now Invest 95L is
forecast between late Monday and Tuesday and the second wave is
forecast to move south of the area between Wednesday and Thursday.


&&

.AVIATION...Mainly VFR conditions are expected to prevail across all terminals
during the next 24 hours. However, MVFR conds are possible across
the area terminals btw 27/15z-22z as a trough streams over the area
from the east. East winds expected at 12-16 kt with stronger gusts
and sea breeze variations aft 27/14z.


&&

.MARINE...A surface high pressure over the central Atlantic, extending all
the way to the Caribbean, will hold a moderate easterly wind
pattern across the region. Therefore, seas will remain between 3
and 4 feet, even less for the coastal waters. By the beginning of
the upcoming workweek, building seas are forecast as a vigorous
tropical wave, now monitored by the National Hurricane Center,
moving over the Caribbean Waters, increasing the seas to 8 feet.
Mariners should keep track of the tropical forecast for further
updates on the expected conditions. Also, regarding the moisture
field that accompanied the tropical wave, the forecast calls for
thunderstorm activity, which could lead to even more localized
hazardous conditions. For the coastal areas, the risk of rip
currents will continue to moderate for some areas and low for the
rest of the areas.
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Re: Caribbean - Central America Weather

#21538 Postby cycloneye » Fri Jun 28, 2024 4:33 am

Area Forecast Discussion
National Weather Service San Juan PR
459 AM AST Fri Jun 28 2024

.SYNOPSIS...

The primary concern for the short-term period will continue to be
heat, at least through this weekend. Additionally, some suspended
Saharan dust particulate is expected by tomorrow and will persist
through early next week, contributing to hazy skies and a
moderate to localized high heat risk. Afternoon convection is
likely every day, mostly over western Puerto Rico. Invest 95L
will start to impact the local area from late Monday night through
Tuesday as it moves south over the Caribbean waters. Continue to
monitor the forecast as this event unfolds.

&&

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

Trade wind showers increased overnight across the regional waters
and over portions of the islands. The Doppler radar estimated around
a tenth of an inch in St. John and half an inch over northeastern
Puerto Rico. Minimum temperatures were from the upper 60s to mid 70s
across the higher elevations, and from the upper 70s to low 80s
across coastal municipalities. Winds were light from the east to
northeast.

A gradual increase in moisture content is expected through Saturday.
Today, a trade wind perturbation will continue to induce scattered
showers across the local waters and enhance afternoon shower and
thunderstorm activity mainly across the interior and western
sections of Puerto Rico. A northeasterly component in the winds in
combination with the sea breeze convergence and daytime heating will
favor showers over the SW quadrant of PR. Urban and small stream
flooding is expected with this activity. It will be hot again across
the islands and a Heat Advisory (NPWSJU) was issued for St. Croix,
and for the north, south, and western coastal counties of Puerto
Rico. Maximum temperatures should reach the low 90s across the lower
elevations with heat indices ranging between 108F-112F before the
onset of afternoon convection.

A wind shift from the east to southeast is expected on Saturday as a
tropical wave moves across the eastern Caribbean. Shower activity
will increase in coverage as well as thunderstorms across the local
waters. Urban and small stream flooding will remain as the main
weather hazard, particularly across the NW quadrant of PR on
Saturday afternoon. Trailing the wave there is a Saharan Air Layer
with moderate amounts of Saharan dust that should cause hazy skies
across the USVI by Saturday evening, spreading across the rest of
the area through Sunday. Therefore, a decrease in shower activity is
expected on Sunday in general. However, afternoon convection will
still develop over western PR.

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

By early next week, drier air will filter across the islands, with
suspended Saharan dust particulate engulfing the area. This will
promote hazy skies and limit the potential for shower activity
throughout most of the day. Although isolated to localized scattered
showers cannot be ruled out, particularly during the afternoon
hours, excessive heat threat will continue as southeasterly winds
prevail, advecting warm temperatures across the northeastern
Caribbean and combining with the Saharan Air Layer.

The rest of the long-term forecast continues to appear active. A
tropical wave (Invest 95L or AL95) located several hundred miles
west-southwest of the Cabo Verde Islands is being monitored by the
National Hurricane Center (NHC), with a high potential of developing
into a tropical depression or tropical storm in the next day or so.
However, model guidance suggests that this system will stay south of
the local islands, crossing the Caribbean Sea by late Monday night
through Tuesday. Despite the expected system remaining over the
Caribbean waters, the broad moisture field will engulf the forecast
area, increasing the potential for squally weather. Therefore, as
AL95 approaches, expect increased cloudiness and deteriorating
conditions with heavy showers and gusty winds. A limited to elevated
flooding threat can be anticipated, particularly as it interacts
with the Cordillera Central in Puerto Rico.

Another tropical wave behind AL95, centered a few hundred miles
south-southwest of the Cabo Verde Islands, is also being monitored
by the NHC. Although significant development of this system is not
anticipated at the moment. Model guidance suggests this tropical
wave will also move south of the islands. Similarly, although a
direct impact is not anticipated, the moisture field will again
cover the forecast area, maintaining wet and unstable weather
conditions from Thursday through the end of the workweek.

Forecast confidence is low to moderate regarding the impact of both
tropical waves on the forecast area by next week. Therefore,
continue to monitor the forecast, as slight deviations in the tracks
of AL95 and the tropical wave behind it could change the expected
impacts across the local islands.


&&

.AVIATION...
(06Z TAFS)

Mainly VFR conditions are expected to prevail across all terminals
during the next 24 hours. However, SHRA/TSRA expected to develop
over the interior of PR, which may cause MVFR conds in and around
TJPS/TJSJ/TJBQ btw 28/17z-22z. Across the USVI terminals, mostly
VCSH with brief periods of -SHRA can be expected. E-ENE winds at 12-
16 kt with stronger gusts and sea breeze variations aft 28/14z.

&&

.MARINE...

A surface high pressure over the central Atlantic will promote light
to moderate east-southeasterly winds. Trade wind showers will move
across the regional waters from time to time due to a tropical wave
moving south over the Caribbean Waters by Saturday. Another tropical
wave with a high potential of developing into a tropical cyclone,
according to the National Hurricane Center, will move into the
Caribbean Sea by late Monday night into Tuesday, likely deteriorating
marine conditions.


&&

.BEACH FORECAST...

There is moderate risk for the island of St. Croix. Elsewhere, the
risk is low. Deteriorating conditions is expected by early next
week, particularly across south-facing beaches as Invest 95L
approaches and moves south of the area across the Caribbean Sea.
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Re: Caribbean - Central America Weather

#21539 Postby cycloneye » Sat Jun 29, 2024 5:00 am

Area Forecast Discussion
National Weather Service San Juan PR
418 AM AST Sat Jun 29 2024

.SYNOPSIS...

A tropical wave is expected to move across the local area today
promoting afternoon convective activity over western Puerto Rico
and downwind of the smaller islands. Hot conditions are also
expected today across the region, and a Heat Advisory is in effect
for most of the coastal and urban areas of Puerto Rico and St.
Croix. Tropical activity is anticipated next week, with the
passage of Tropical Storm Beryl and a tropical wave south of the
area and over the Caribbean Waters.

&&

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

Trade wind showers and isolated thunderstorms increased throughout
the night across the regional waters and over portions of the
islands. The Doppler radar estimated around half an inch of rain
over eastern Puerto Rico. Minimum temperatures ranged from the upper
60s to mid-70s across the higher elevations and from the upper 70s
to low 80s across coastal municipalities. Winds were around 10 mph
from the east.

It will be hot again across the islands, and a Heat Advisory
(NPWSJU) was issued for St. Croix and the north, south, and western
coastal counties of Puerto Rico. Maximum temperatures should reach
the low 90s across the lower elevations, with heat indices ranging
between 108F and 112F.

Although mainly east winds prevail at the surface, an east-to-
southeast steering wind flow is expected today as a tropical wave
moves across the eastern Caribbean. Shower activity will continue to
increase in coverage, as will thunderstorms across the local waters.
Urban and small stream flooding is expected, particularly across
western PR during the afternoon. Trailing the wave, a Saharan Air
Layer with moderate amounts of Saharan dust should cause hazy skies
across the USVI by this afternoon. On Sunday and Monday, drier air
will continue to filter across the islands, with suspended Saharan
dust, causing hazy skies and limiting the potential for shower
activity throughout most of the period. Although isolated to
localized scattered showers cannot be ruled out, particularly during
the afternoon, excessive heat threat will continue as warm
temperatures prevail across the northeastern Caribbean and combine
with the Saharan Air Layer.

Weather conditions will quickly deteriorate during the night as the
outer bands from TC Beryl bring showers and thunderstorms across the
local area. Squally weather with strong gusty winds is possible
across portions of the Caribbean waters, the USVI, and east/southern
PR through early Tuesday.

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

Tropical activity will dominate much of the long term period with
the presence of Tropical Storm Beryl and a vigorous tropical wave in
the Eastern Tropical Atlantic.

The National Hurricane Center (NHC) is monitoring Tropical Storm
Beryl located in the Central Atlantic that it is forecast to
become a hurricane before reaching the Lesser Antilles. Latest
model guidance suggest that Beryl will stay well south of the
local islands as a category 2 hurricane. At this moment, the
closest point to Puerto Rico and the U.S. Virgin Islands will be
on Tuesday. Despite this system staying south of the islands over
the Caribbean waters, a broad field of moisture and external
bands could reach the local area. Therefore, an increase in
showers and thunderstorm activity associated to this system is
anticipated. With the expected conditions, some potential hazards
are: flooding, mudslides, and river rises.

A drier airmass will quickly follow Beryl as it moves away from the
region towards The Hispaniola. This drier airmass will bring some
Saharan Dust particles promoting slightly hazy skies. However,
this dry weather pattern will not last long due to the fast
approach of a tropical wave behind Beryl with the potential of
becoming a tropical cyclone. Model guidance suggest the
development of this wave, and moving this system close to the
local area by Thursday. Similarly to Beryl, this wave is nor
expected to have direct impacts over Puerto Rico and the U.S.
Virgin Islands. However, it is expected to bring shower activity
over the region.

Residents and visitors of Puerto Rico and the U.S. Virgin Islands
should continue to monitor the progress of both systems as they
move towards the Caribbean over the next few days.

&&

.AVIATION...

(06Z TAFS)

SHRA/TSRA expected to increase across the local area due to a
tropical wave passage across the Caribbean Sea. Tempo MVFR
conditions are possible in and around TJPS/TJSJ/TJBQ btw 29/15z-21z.
Across the USVI terminals, mostly VFR conditions are expected with
VCSH prevailing thru the mid afternoon hours. HZ due to Saharan dust
will gradually increase across the USVI terminals into eastern PR
before sunset. East winds at 12-16 kt with stronger gusts and sea
breeze variations aft 29/14z.

&&

.MARINE...

A surface high pressure over the central Atlantic will promote light
to moderate easterly winds. Trade wind showers will move across the
regional waters from time to time due to a tropical wave moving south
over the Caribbean Waters today. Tropical Storm Beryl is forecast to
strengthen as it approaches the Caribbean waters late Monday night
into Tuesday, deteriorating marine and coastal conditions
considerably for the Caribbean and local passages.
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Re: Caribbean - Central America Weather

#21540 Postby cycloneye » Sun Jun 30, 2024 4:29 am

Area Forecast Discussion
National Weather Service San Juan PR
503 AM AST Sun Jun 30 2024

.SYNOPSIS...

Lingering moisture from a tropical wave combined with Saharan Dust
will promote thunderstorm activity over western Puerto Rico during
the afternoon hours. Hurricane Beryl is forecast to rapidly
intensify today as it approaches the Caribbean waters. Marine and
coastal conditions will start to gradually deteriorate across the
Caribbean and local passages as Beryl approaches the area. Stay
tuned for updates associated with this storm.

&&

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

Scattered showers and isolated thunderstorms were noted across the
local waters and over portions of the islands during the night. The
Doppler radar estimated around half an inch of rain over Juncos and
Las Piedras and around a quarter of an inch across St. Thomas and
St. John. Minimum temperatures ranged from the upper 60s to mid-70s
across the higher elevations and from the upper 70s to low 80s
across coastal municipalities. Winds were up to 15 mph from the
east, with gusts around 25 mph across coastal areas.

For today, the lingering moisture from a tropical wave, combined
with the influence of a Saharan Air Layer carrying moderate amounts
of Saharan dust, will promote shower and thunderstorm activity,
mainly across PR throughout the day, with drier conditions expected
across the USVI. The hazy skies and low-level southeasterly winds
will also contribute to hot temperatures across the islands, and a
Heat Advisory (NPWSJU) is in effect for all coastal municipalities
of PR and St. Croix. Maximum temperatures should reach the low 90s
across the lower elevations, with general heat indices ranging
between 106F and 112F.

There haven't been significant changes in the forecast track for
Beryl, which is expected to pass about 200 miles south of the
islands. However, weather conditions will quickly deteriorate
between Monday afternoon and Tuesday as the outer bands from
Tropical Cyclone Beryl bring showers and thunderstorms to the local
area. Squally weather with strong gusty winds is possible across
portions of the Caribbean waters, the US Virgin Islands, and
eastern/southern Puerto Rico through Tuesday.

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

After the passage of Hurricane Beryl south of the local area, a
drier airmass will quickly move over the islands. This drier airmass
will promote stable conditions on Wednesday with limited shower
activity. However, by Thursday onwards tropical activity is expected
once again.

The National Hurricane Center (NHC) is currently monitoring an area
of low pressure located over the eastern Atlantic with a medium to
high formation chance over the next 7 days. Latest model guidance
suggest that this system will develop as a tropical storm or
hurricane before reaching the Lesser Antilles. Nonetheless, this
system should remain south of the islands and over the Caribbean
waters. At this moment some of the potential indirect impacts
associated to this low are: localized flooding, gusty winds,
squally weather, and deteriorated marine and coastal conditions.
It is too early at this moment to determine the amount of expected
rain. Therefore, residents and visitors of Puerto Rico and the
U.S. Virgin Islands may continue to monitor the progress of this
system as it moves towards the Caribbean. A vast moisture field of
this low will persist across the region once it departs on
Saturday, promoting afternoon convective activity across the
western portions of Puerto Rico. Following the system, more drier
air and Saharan Dust particles will take over, enhancing stable
and dry conditions for few days. Despite of the expected weather,
high temperatures will remain between the upper 80s to low 90s
across the islands with heat indices surpassing the mid 100s.

&&

.AVIATION...

(06Z TAFS)

Mainly VFR conditions expected across all terminals. However,
SHRA/TSRA expected to develop due to a departing tropical wave may
cause tempo MVFR conds at TJSJ/TJBQ btw 30/16-22z. HZ due to Saharan
dust expected but VSBY should remain P6SM. East winds at 12-16 kt
with stronger gusts and sea breeze variations aft 30/14z.

&&

.MARINE...

A surface high pressure over the central Atlantic will promote
moderate to locally fresh easterly winds over the next few days,
bringing trade wind showers. Hurricane Beryl is forecast to
strengthen as it approaches the Caribbean waters late Monday night
into Tuesday, deteriorating marine and coastal conditions
considerably for the Caribbean and local passages.
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