Caribbean - Central America Weather

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
510 AM AST Fri Mar 1 2024

.SYNOPSIS...

Northeasterly winds will continue to steer shallow shower activity
over windward sectors through the weekend, with limited afternoon
shower development over portions of southwest Puerto Rico. Another
increase in moisture is forecast for Sunday onwards. Marine and
coastal conditions will deteriorate and become hazardous due
increasing northeast winds and a northerly swell tonight through
the first half of the next workweek.

&&

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

Partly cloudy skies prevailed through the overnight hours across the
islands. Passing showers under northeasterly winds moved over the
northern and northeastern half of Puerto Rico through the early
morning hours. The Doppler radar estimated between 0.25-0.40 inches
of rain between Arecibo and Luquillo. Minimum temperatures were from
the low 60s across the higher elevations to the mid 70s across the
coastal areas. Wind gusts were up to 30 mph in St. Thomas, and up to
29 mph in Carolina.

For today, increasing winds will continue to bring showers at times
across portions of northern and eastern PR, and as well across the
USVI. Partly cloudy skies should prevail in general across the
islands. Shallow convection could develop late this afternoon over
the southwestern portions of PR, with minor rainfall accumulations.
A strong surface high pressure will move into the western Atlantic
later today and move over the north central Atlantic by Sunday. This
will increase winds across the northeastern Caribbean, with 20-25 kt
winds expected from this evening through Saturday across portions of
the local waters. Therefore, breezy conditions are anticipated and
showers could move further inland over central PR during the night.

However, a drying trend is expected for Saturday and mostly sunny to
partly cloudy skies should prevail across all the islands. Then, an
increase in moisture content is expected on Sunday as a surface
trough moves from the east across the local area. Precipitable water
is expected to increase from less than an inch on Saturday to 1.50
inches by Sunday afternoon. Therefore, an increase in shower
coverage is expected across the islands in diurnal activity and in
nighttime showers across the windward areas of the islands.

&&

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

Broad surface high pressure in the north-central Atlantic will
maintain mainly east to northeasterly winds across the local area
throughout the period. The latest guidance is still suggesting a
surface trough approaching the northeast Caribbean on Monday,
resulting in moisture increase across the local area. The
Precipitable Water content (PWAT) should range between 1.4 and
1.6 inches which is around normal to above normal for this time of
the year. This pattern accompanied by an upper jet axis moving
over the region could result in an increased chance of rain early
next week. Expect scattered to numerous showers, mainly across
eastern sections of PR and the U.S. Virgin Islands during the
morning hours, with areas of afternoon convection across the
western and southwest quadrant of Puerto Rico. Through the rest of
the forecast period, the broad surface high pressure will
continue to slowly move and remain stretched and centered across
the northern Atlantic driving additional a tropical airmass from
the south to our area. That moist airmass should remain with us
through the end of the week. As a result, Precipitable Water
values are anticipated to remain, with values up to 1.8 - 1.9
inches. Rainfall accumulations of around 0.5 - 1.0 inches during
these periods, generated by a higher frequency of showers moving
inland may lead to limited flooding impacts. Ponding of water on
roadways and poorly drained areas is likely, with possible
localized urban and small stream flooding through at least
Tuesday. We will continue to closely monitor the forecast for any
updates.

&&

.AVIATION...
(06Z TAFS)
Issued at 500 AM AST Fri Mar 1 2024

Mainly VFR conditions are expected to prevail across all terminals
during the next 24 hours. However, showers embedded in the northeast
trades should cause mostly VCSH and brief -SHRA with MVFR cigs at
times across TJSJ/TJBQ and the USVI terminals. ENE winds at 13-17 kt
with gusts at 24-28 kt.

&&

.MARINE...

Moderate to fresh northeasterly winds are forecast through the
weekend as a broad surface high pressure will move northeastward
across the western Atlantic during the next several days and spread
into the north central Atlantic. Confused seas and generally hazardous
marine and coastal conditions are anticipated due to these increasing
northeast winds and a northerly swell arriving by Friday through
the first half of the next workweek. A Small Craft Advisory will
be in effect for the offshore Atlantic waters by tomorrow morning
through at least Tuesday afternoon.

&&

.BEACH FORECAST...

For beachgoers, a high risk of rip currents is in effect through
the weekend for most north-facing beaches of Puerto Rico and
Culebra as seas and a small northerly swell begin to grow tonight.
Remember that life-threatening rip currents are likely across
these areas.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
521 AM AST Sat Mar 2 2024

.SYNOPSIS...

Breezy conditions expected today. Shower activity is expected to
decrease through early Sunday. Then, a surface trough is expected
to move across the local area later on Sunday into Monday,
increasing showers in general across the islands. Moisture content
will then be dominated by patches of low-level moisture content
through mid-week. Later in the period, an upper level trough and
associated frontal system moving over the western Atlantic in
combination with southeasterly trades should promote an increase
in moisture content across the northeastern Caribbean. Life-
threatening rip currents will continue across the north and east
facing beaches of PR and Culebra during the next few days.


&&

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

Partly cloudy skies prevailed through the overnight hours across the
forecast region. Passing showers under northeasterly winds moved
over the northern half of Puerto Rico through the early morning
hours. Doppler Radar rainfall estimates generally show between 0.01
and 0.05 inches. Higher values of 0.30 inches were registered in
some areas such as Quebradillas, Corozal, Naranjito, and Río Grande.
Overnight temperatures ranged from the mid-70s near coastal areas to
and 60s over the mountains.

Surface high pressures over the Atlantic are dominating the general
wind flow supporting northeasterly winds to prevail through the
weekend. A strong surface high pressure will continue to move into
the western Atlantic and over the north-central Atlantic by Sunday.
Under this pattern, the pressure gradient over the local area will
remain tightened and will promote breezy conditions; especially over
sections of the local waters, but over land we can have breezy and
gusty periods as well.

Today, mostly sunny to partly cloudy skies should prevail across all
the islands as it should be the driest day of the short-term period.
GOES-16 Satellite-Derived Imagery shows a slot of drier airmass
moving towards our region with Precipitable Water (PWAT) values
around 0.8 to 0.9 inches. Based on model guidance, PWAT values
should decrease to below-normal values today promoting a decrease in
rain chances and coverage. Some shallow shower activity will still
be possible over windward sectors but remain limited.

The chances and coverage of showers increase from Sunday onward.
Current model guidance indicates an increase in moisture on Sunday
due to a surface trough moving in from the east across. PWAT values
are expected to increase and reach above-normal values by Monday.
This will promote an increase in shower activity across the region,
affecting windward sectors during the night and mornings, and help
promote convective activity over the SW quadrant of PR during the
afternoon. Additionally, an upper-level jet is expected to move over
Puerto Rico and the U.S. Virgin Islands early next week. This
synoptic pattern accompanied by the increase in moisture would
enhance the chances of showers and thunderstorms over the local
Islands. We will continue to closely monitor the model guidance for
any updates to the forecast.

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

A broad surface high pressure will hold over the north central
Atlantic through the workweek, shifting slightly southward during
the weekend. Patches of moisture associated to a lingering
surface trough over the central Atlantic are expected to move
close or just north of the region early in the forecast cycle
under northeasterly steering winds. Later in the week into the
weekend, an upper-level trough and associated surface front are
expected to exit the U.S. East Coast and move over the western
Atlantic, gradually shifting the broad surface high pressure
southwards and merging the weak surface trough with the front
under southeasterly winds. In response, moisture content should
pool across the northeastern Caribbean. However, at this moment
the global model guidance suggest near-normal precipitable water
values across the islands. Therefore, fair weather conditions
should prevail during the first part of the long term period,
followed by a gradual increase in shower activity from Thursday
onwards.


&&

.AVIATION...

(06Z TAFS)

Mainly VFR conditions will prevail across during the next 24 hours.
VCSH are possible across TJSJ during the morning hours as showers
embedded in the northeast trades move near the area. Activity, if
any, should remain very limited. Breezy ENE winds are expected at
around 14-22 kts with gusts at 20-30 kts.


&&

.MARINE...

Fresh to locally strong northeasterly winds will continue through
the weekend as a broad surface high pressure will move northeastward
across the western Atlantic during the next several days and spread
into the north central Atlantic. Confused seas are anticipated
through early next week due to the increasing northeast winds and
the arrival of a northerly swell.


&&

.BEACH FORECAST...

Strong onshore winds are causing seas to build around 6 and 7
feet across the nearshore coastal waters of northern Puerto Rico.
Therefore, life-threatening rip currents will continue across the
north and east facing beaches of Puerto Rico and Culebra today,
and will continue through early next week as a northerly swell
slowly fills across the Atlantic waters later this weekend. A
High Rip Current Risk (CFWSJU) is in effect through at least
Monday.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
502 AM AST Sun Mar 3 2024

.SYNOPSIS...

Breezy conditions will persist today under ENE winds due to broad
a broad surface high pressure. over the north central Atlantic.
Patches of low-level moisture embedded in the trades will reach
the islands from time to time and enhance shower development.
Southeasterly winds will return by mid-week onwards, as well as
warmer temperatures. A mid-to upper-level trough will pass close
to the area late in the week. Hazardous seas and life-threatening
rip currents will persist for the next several days.


&&

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

Partly cloudy skies prevailed through the overnight hours across the
forecast region. Light showers moved over the northern half of
Puerto Rico and the interior through the early morning hours.
Doppler radar rainfall estimates are showing limited values, around
0.01–0.02 inches of rainfall. Light showers are moving fast with the
breezy northeast winds. Current surface observations are showing
winds around 10–12 mph with gusts up to 20 mph, especially across
the northern coastal areas of Puerto Rico and the U.S. Virgin
Islands. Overnight temperatures ranged from the mid-70s near coastal
areas to the 60s over the mountains.

Broad surface high pressure, previously located over the western
Atlantic, will continue to dominate and move over the north-central
Atlantic today. Under this pattern, breezy northeasterly winds will
prevail through early next week. On tab for today, partly cloudy
skies should prevail across all the islands. Based on the latest
model guidance, PWAT values are expected to increase from below-
normal to near-normal values today and oscillate between them for
the next several days. Patches of moisture associated with a surface
trough located over the central Atlantic Waters will be coming from
the east thanks to the wind flow pattern. That cluster of cloudiness
and moisture will increase the potential for shower activity
development across the forecast area. affecting windward sectors
during the night and mornings, and helping promote convective
activity over the SW quadrant of PR during the afternoon. Given that
stable conditions and drier air are holding in the mid-levels, no
significant rainfall accumulations are expected. Additionally,
showers should move quickly due to the breezy winds. At this time,
models are showing mainly half an inch or less across the interior,
SW quadrant, and USVI, and up to 1 inch or less for eastern PR. We
are anticipating similar weather conditions in the short term. We
will continue to closely monitor the model guidance for any updates
to the forecast.

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

Patches of moisture associated with a lingering surface trough
over the central Atlantic are expected to move close or north of
the region early in the forecast cycle under northeasterly
steering winds. This will promote shower activity across the
windward areas of the islands. Later in the workweek into the
weekend, an upper-level trough and associated surface front are
expected to exit the U.S. East Coast and move over the western
Atlantic. A broad surface high pressure over the north-central
Atlantic will shift southwards by the end of the week, causing the
winds to shift from the southeast. A warming trend is expected by
midweek. Meanwhile, the frontal system will absorb the weak
surface trough well north of the region.

By Thursday, the 500 MB temperatures could drop around -10 degrees
Celsius as the mid-to upper-level trough passes close to the area.
In addition, the moisture content will increase to around or just
above normal levels(1.45-1.60 inches) through Saturday as the
trade wind cap relaxes under the lighter southeasterly winds.
However, the 500 mb temperatures will warm to around -4C by
Saturday as a mid-level ridge builds over the central Caribbean.
In general, shower activity will increase from Thursday through
Saturday across Puerto Rico and the U.S. Virgin Islands. For
Sunday, northeasterly winds will return as a weak surface high
pressure moves north of the area, and overall fair weather
conditions should prevail as the mid-level ridge promotes drier
air and stable conditions aloft.


&&

.AVIATION...

(06Z TAFS)

VFR conditions are expected through the period across TAF sites. NE
SFC winds btw 10 to 15 kts with stronger gusts at 20-30 kts are
expected to continue today. Other than VCSH and possible brief
periods of SHRA, no significant operational wx impacts are
anticipated at this time.


&&

.MARINE...

A surface high pressure system is generating moderate to locally
fresh northeasterly winds across the region. Consequently, hazardous
seas will continue across all exposed waters and local passages.
The combination of the wind-driven seas and pulses of a northeasterly
swell will maintain hazardous seas up to 8 feet across exposed
Atlantic waters and passages until at least mid-week. Small Craft
Advisories are in effect, please refer to the latest Marine
Weather Message (MWWSJU) for more information.


&&

.BEACH FORECAST...

There is a high risk of rip currents across the north and eastern
beaches of Puerto Rico, Culebra, and St. Croix. Life-threatening
rip currents will continue for the next several days due to the
combination of short-period waves and the arrival of a northeasterly
swell. For more information please refer to the latest Coastal
Hazards Message (CFWSJU) and Surf Zone Forecast (SRFSJU) for more
information.


&&

.FIRE WEATHER...

Winds speeds greater than 15 mph with stronger gusts are expected
at times across the southern coastal plains of PR today. The KBDI
remains above critical levels in Guanica and limited shower
activity should continue through the early afternoon hours across
southwestern Puerto Rico. Therefore, a Fire Danger Statement
(RFDSJU) is in effect for the southern coastal plains.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
503 AM AST Mon Mar 4 2024

.SYNOPSIS...

For today, a band of low-level moisture is expected to exit the
area later this morning with showers possibly still lingering over
portions of the northern half of PR. A drier air mass is then
expected to filter across the area later in the afternoon and
evening hours, limiting shower development to SW PR. Fair weather
conditions should then last through Tuesday morning, becoming more
variable after. Unstable weather conditions are forecast for the
second half of the workweek, resulting in more frequent showers.
Hazardous Marine and Coastal Conditions will persist through
midweek due to increasing winds and a northeasterly swell.

&&

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

Variably cloudy skies prevailed through the overnight hours across
the islands. Passing showers under northeasterly winds moved over
the northern half of Puerto Rico through the early morning hours.
The Doppler radar estimated between 0.40-0.75 inches of rain between
Rio Grande and Quebradillas. Minimum temperatures were from the low
60s across the higher elevations to the low and mid 70s across the
lower elevations. Wind gusts were up to 26 mph in St. Thomas, and up
to 22 mph in Carolina.

Patches of moisture associated with a lingering surface trough over
the central Atlantic are expected to move close or north of the
region through the short-term period under northeasterly steering
winds. This will promote shower activity mainly across the windward
areas of the islands during the night and early morning hours,
followed by afternoon convection over portions of the SW quadrant of
Puerto Rico. For the rest of today, a band of low-level moisture is
expected to exit the area later this morning, and showers could
still linger over portions of the northern half of PR. Later during
the day and evening hours, a drier air mass is expected to filter
across the area, limiting shower development to SW PR, where half to
an inch of rain is possible. Fair weather conditions should last
through Tuesday morning. By late Tuesday and Wednesday, showers
could increase across the region as an upper-level trough with a jet
max around 70-75 kts moves over the northeastern Caribbean. The
afternoon convection is expected to shift slightly northwards across
western PR as winds gradually turn more from the east on Tuesday and
southeasterly by Wednesday.

&&

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

A broad surface high pressure over the north-central Atlantic will
sink southwards as an upper trough and surface low exit the Eastern
Seaboard, promoting southeasterly winds across the islands. Current
model guidance indicates a more humid air mass, steered into the
region by these southeasterly winds, on Thursday. Available moisture
will be limited to below 700 mb, with drier air aloft, the exception
being Thursday due to a mid- to upper-level trough moving close to
the islands. Available moisture on Thursday could reach the mid- to
upper- levels with 500mb temperatures also possibly dropping to
around -10C, before gradually warming and reaching -4C on Saturday.
Above normal precipitable water (PWAT) values, up to around 1.70
inches, are forecast to persist through Saturday evening as winds
become more easterly due to another surface high moving into the
western Atlantic. This will all promote increased rain chances
Thursday through Saturday across the region. A drying trend is then
forecast on Sunday as winds become more northeasterly due to the
surface high moving north of the area, with only patches of above
normal PWAT reaching the islands. Drying continues on Monday as
easterlies return. Overall fair weather conditions should prevail to
end the period as a mid-level ridge builds over the area, increasing
stability aloft.

&&

.AVIATION...
(06Z TAFS)
Issued at 450 AM AST Mon Mar 4 2024

Mainly VFR conditions are expected to prevail across all terminals
during the next 24 hours. However, passing showers may occasionally
bring -RA to -SHRA with SCT-BKN Cigs btw FL015-030 thru 04/12z at
TJBQ and TJSJ. Winds will continue from the ENE btw 11-16 kts with
gusts at 20-25 kts thru 04/22Z.

&&

.MARINE...

Fresh to locally strong northeasterly winds accompanied by
scattered showers will continue as a broad surface high pressure
moves northeastward across the western Atlantic during the next
several days and spreads into the north central Atlantic. Confused
seas are anticipated through midweek due to the increasing
northeast winds and the arrival of a northerly swell. The
combination of wind-driven waves and pulses of northeasterly swell
will sustain hazardous sea conditions of up to 8 feet across
exposed Atlantic waters and passages. Several small craft
advisories are currently in effect; for more information, consult
the latest Coastal Waters Forecast (CWFSJU & CWFSPN) and Marine
Weather Message (MWWSJU). Marine conditions are forecast to
improve by Thursday.

&&

.BEACH FORECAST...

A high risk of rip currents is in effect for the northern
coastline of Puerto Rico, from Rincon to Fajardo, and Culebra. A
High Risk of Rip Currents is also in effect for the northern
coastline of the northern USVI and the easternmost beaches of St.
Croix. Dangerous coastal conditions will persist until mid-week
as the northeasterly swell affects the north coastal areas. For
additional information, please refer to the latest Coastal Hazards
Message (CFWSJU) and Surf Zone Forecast (SRFSJU).

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
522 AM AST Tue Mar 5 2024

.SYNOPSIS...

Instability and moisture will increase across the local region
from later this afternoon and linger through late Thursday night/early
Friday morning, promoting increased shower activity and possible
isolated thunderstorms. Each afternoon convective activity is
forecast to develop from central to western PR. Under ENE winds
today, convective activity should mainly affect the SW quadrant
of PR. A surface trough approaching from the east will promote a
shift in the local winds from the east-southeast from Wednesday
onward and increase the available moisture locally. Afternoon
convective activity should then focus mainly on the NW quadrant of
PR during those days. A noticeable drying trend is forecast
Sunday onwards. Hazardous Marine and Coastal Conditions will
persist through tomorrow due to increasing winds and a
northeasterly swell.

&&

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

Calm weather conditions prevailed overnight, with fragmented clouds
arriving under the east-northeast wind flow. Those fragments
produced isolated to scattered passing showers across the local
waters and windward sections in the U.S. Virgin Islands and Puerto
Rico. The overnight minimum temperatures dropped into the low 70s
and upper 60s along the coastal sections and even cooler in
mountains and valleys, with values ranging between the mid-50s and
low 60s degrees Fahrenheit.

Fair weather conditions will prevail early this morning but with the
arrival of fragments of clouds and rain showers pushed by the trade
winds. Although isolated areas along the windward sections may see
periods of moderate to locally heavy rains, we are not anticipating
significant rainfall accumulation beyond the typical ponding of
water due to poor drainage.

A mid to upper-level trough and its associated jet maxima will
increase instability across the local region from later this
afternoon and linger through late Thursday night or early Friday
morning. As a result, isolated thunderstorms were introduced to the
forecast grids, especially during the afternoon hours, during which
local effects and sea breezes may enhance the chance for
thunderstorm formation, and between late Thursday afternoon and
early Friday morning.

A surface trough approaching from the east will promote a shift in
the local winds from the east-southeast from Wednesday onward and
increase the available moisture locally. The upper-level feature may
promote favorable weather conditions for the development of
scattered showers and isolated thunderstorms from the afternoon into
the evening hours each day (Wednesday and Thursday). Regardless of
the increasing instability and moisture, neither GFS nor ECMWF show
a strong signal for widespread flooding across the region. However,
we can anticipate periods of locally heavy rain producing ponding of
water in roads and poorly drained areas or even urban and small
stream flooding.

&&

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

Current model guidance indicates normal to above normal precipitable
water (PWAT) values on Friday, under southeasterly winds. A broad
high pressure over the central Atlantic will continue to sink
southeastward to start the period as an upper trough and surface low
exit the Eastern Seaboard, promoting these southeasterly winds.
Friday is forecast to be the wettest day in the period as PWAT
values gradually erode on Saturday under easterly winds, but still
remain in normal to locally above normal values. The highest rain
chances will be Friday and Saturday. Due to a mid- to upper- level
trough affecting the area to end the workweek, available moisture on
early Friday could reach the mid- to upper- levels with 500mb
temperatures also possibly dropping to around -10C, before gradually
warming and reaching -6C on Saturday. A more pronounced drying trend
is then forecast for Sunday through Tuesday with below normal PWAT
values with the addition of patches with up to normal PWAT values.
Available moisture will be mostly limited to below 800 mb Sunday
through Tuesday, with drier air aloft. Winds should be more east-
northeasterly on Sunday with easterlies returning on Monday. Overall
fair weather conditions, along with seasonal weather patterns of
morning/overnight showers along windward sectors and afternoon
seabreeze convergence over western PR, should prevail to end the
period as a mid-level ridge builds over the area by next week,
increasing stability aloft.

&&

.AVIATION...
(06Z TAFS)
Issued at 522 AM AST Tue Mar 5 2024

VFR conditions will prevail today under an ENE wind flow across the
local flying area in PR/USVI. Fragments of clouds may arrive,
producing occasional quick passing SHRA. TSRA may develop late this
afternoon due to an approaching upper-level trough with a jet
stream, mainly across the interior and SW-PR between 05/18-22z.
Winds will increase between 10-15 kt with higher gusts and sea
breezes after 05/13z and become calm to light and Variable after
05/23z.

&&

.MARINE...

A broad surface high spread over the western to central Atlantic and
a short wave trough to our northeast will promote moderate east-
northeasterly winds, with higher gusts, across the local waters. The
surface high will continue to move over the central Atlantic before
sinking southeastward by the second half of the week. Confused seas
are anticipated through midweek due to the presence of a northerly
swell and slightly diminishing easterly winds. We cannot rule out
isolated thunderstorms moving over the waters southwest of Puerto
Rico this afternoon. A mid- to upper- trough will increase shower and
possible thunderstorm activity across the waters by the second half
of the workweek. Several small craft advisories are currently in
effect; for more information, consult the latest Coastal Waters
Forecast (CWFSJU & CWFSPN) and Marine Weather Message (MWWSJU).
Seas should improve by Thursday, reaching up to 5 feet with winds
from the east-southeast at 15 knots.

&&


.BEACH FORECAST...

A high risk of rip currents is in effect for the northern
coastline of Puerto Rico, from Rincon to Fajardo, and Culebra, as
well as easternmost beaches of St. Croix. Dangerous coastal
conditions will persist until through tomorrow as the
northeasterly swell affects the north coastal areas. For
additional information, please refer to the latest Coastal Hazards
Message (CFWSJU) and Surf Zone Forecast (SRFSJU).

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
458 AM AST Wed Mar 6 2024

.SYNOPSIS...

Under east to east-southeast wind flow morning showers will
affect windward sectors today. With the arrival of a surface
trough and afternoon sea breeze convergence, areas of PR's NW
quadrant will receive convective activity. An increase in
instability and moisture is forecasted Thursday and Friday,
increasing the potential for shower activity and resulting in a
limited threat of flooding for Puerto Rico, especially on Thursday
afternoon. Under the ESE wind flow, the islands may observe near
to above- normal highs each afternoon through the rest of the
workweek, which, combined with high humidities, could make the
apparent temperatures warmer than usual. A drying trend is
forecast for the first half of next week.

Hazardous seas across the offshore Atlantic waters will last
through this afternoon. Small Craft, however, should continue to
exercise caution over the nearshore northern waters and Anegada
Passage through tonight, and through tomorrow night for the
offshore Atlantic waters. High rip current risk will persist until
through this afternoon for Culebra and St. Croix and through
tonight for northern Puerto Rico.

&&

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

We observed another calm night in the U.S. Virgin Islands and
Puerto Rico, with the overnight minimum temperatures dropping into
the low 70s and upper 60s along the coastal sections and even
lower in mountains and valleys, with values ranging between the
mid-50s and low 60s degrees Fahrenheit. The GOES-East detected a
perturbation approaching from the east that produced variably
cloudy skies across the eastern half of Puerto Rico and the Virgin
Islands late yesterday night, becoming mostly clear to partly
cloudy in today's early morning.

Once again, we anticipate fair weather conditions this morning.
Still, with the arrival of the surface trough, there is a chance for
cloudy skies and showery weather to increase by the afternoon,
ranging between 50 and 60% chance to receive around half an inch
with isolated higher amounts (especially across PR's northwest
quadrant) that may result in ponding or water in poorly drained
areas or even in isolated urban flooding. Today's afternoon
convection will be mainly due to local effects and sea breeze
variations. However, a jet stream associated with an approaching
upper-level trough could enhance the convection, so we include
isolated thunderstorms in the grids.

The upper-level jet will increase even more on Thursday, lingering
through Friday, combined with increased available moisture. Winds
will prevail from the east-southeast in response to the surface
trough Thursday through Friday. As a result, we may observe better
shower activity with isolated thunderstorms on Thursday afternoon,
extending into the late night or even early Friday morning. Despite
the increasing instability and moisture, model guidance does not
indicate a strong signal for widespread flooding across the region.
However, we can anticipate periods of locally heavy rain producing
ponding of water in roads and poorly drained areas or even urban and
minor stream flooding, especially on Thursday afternoon.

Under the east-southeast wind flow, the islands may observe near to
above-normal maximum temperatures each afternoon, which, combined
with the high humidity, could make the apparent temperatures warmer
than usual.

&&

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

No major changes to the long term forecast. Current model guidance
indicates generally normal to slightly above normal precipitable
water (PWAT) values on Saturday, as east to east-northeast winds
prevail and an upper trough moves away from the region. The highest
rain chances for most of the period will be on Saturday. Moisture
will then erode on Sunday to start the next week as a surface high
moves north of the region. A drying trend is then forecast for
Sunday through most of Wednesday with below normal PWAT values with
only patches with up to normal columnar moisture reaching the
region. As surface highs and frontal lows move from the eastern
seaboard into the Atlantic, winds throughout the period are forecast
to be east-northeasterly to easterly on Sunday, mainly easterly on
Monday, and east-northeasterly on Tuesday and Wednesday, somewhat
increasing on Wednesday. Both the GFS and ECMWF indicate that any
available moisture will be mostly limited to below 800 mb Sunday
through Wednesday morning, with drier air aloft. Overall fair
weather conditions, along with seasonal weather patterns of
morning/overnight showers along windward sectors and shallow
afternoon seabreeze convergence over western PR, should prevail for
the first half of next week as a mid-level ridge builds over the
area, increasing stability aloft. Temperatures should be near
normal, somewhat cooler when under ENE flow. Current model guidance
indicates a more pronounced moisture patch reaching the islands by
Wednesday afternoon, but uncertainty remains high.

&&

.AVIATION...
(06Z TAFS)
Issued at 458 AM AST Wed Mar 6 2024

VFR conditions will prevail today under an E-ESE wind flow across
the local flying area in PR/USVI. Fragments of clouds may arrive,
producing occasional quick passing SHRA/+SHRA, which, if it
affects terminals, may briefly reduce visibilities. TSRA may
develop this afternoon, especially near JBQ between 06/18-23z.
Winds will increase between 10-15 kt with higher gusts and sea
breezes after 06/13z and become calm to light/vrb after 06/23z.

&&

.MARINE...

A broad surface high spread over the central Atlantic and a short
wave trough to our east will promote moderate east- southeasterly
winds, with higher gusts, across the local waters. The surface
high will continue to move over the central Atlantic before
sinking southeastward during the next few days. Hazardous seas
across the offshore Atlantic waters will last through this
afternoon. Small Craft, however, should continue to exercise
caution over the nearshore northern waters and Anegada Passage
through tonight, and through tomorrow night for the offshore
Atlantic waters. We cannot rule out isolated thunderstorms moving
over the waters northwest of Puerto Rico this afternoon. Shower
and possible thunderstorm activity will increase across the waters
for the second half of the workweek. For more information,
consult the latest Coastal Waters Forecast (CWFSJU & CWFSPN) and
Marine Weather Message (MWWSJU).

&&

.BEACH FORECAST...

A high risk of rip currents is in effect for the northern
coastline of Puerto Rico, from Rincon to Fajardo, and Culebra, as
well as easternmost beaches of St. Croix. Dangerous coastal
conditions will persist until through this afternoon for Culebra
and St. Croix and through tonight for Puerto Rico, becoming
moderate after. For additional information, please refer to the
latest Coastal Hazards Message (CFWSJU) and Surf Zone Forecast
(SRFSJU).

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
503 AM AST Thu Mar 7 2024

.SYNOPSIS...
Issued at 457 AM AST Thu Mar 7 2024

The risk of rip currents is high along the Atlantic coast of
Puerto Rico today and moderate in the U.S. Virgin Islands. A wet
and unstable weather pattern will prevail today into tomorrow.
Winds will prevail from the east-southeast; thus, showers will
affect St Croix and PR's southern, southeast, and southwest coast,
spreading into the interior, north, and northwest areas during
the afternoon and evening hours. Thunderstorms will also develop
around this afternoon and during the evening. The unstable weather
may continue on Friday. Conditions will slowly improve during the
weekend into next week; however, showery weather may also affect
the region on Saturday and by the middle of next week. Above-
normal temperatures are possible on Friday, especially during the
afternoon.


&&

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

Shower activity steered by ESE winds gradually increased over the
waters, mainly affecting southeastern municipalities of Puerto Rico,
as a patch of more humid air approached the area from the south.
Current satellite derived precipitable (PWAT) values indicate that
moist patch having up to 1.70 inches. As low level ESE winds
continue today, this moist air will cross the region today,
maintaining above normal PWAT values today and tonight. Normal to
above normal PWAT values are forecast to continue during the period,
gradually eroding late Saturday. Instability will also increase
today, as an upper-level trough moves into the region from our west.
500mb temperatures are forecast to be below normal, at -9 to -10C,
today and tonight, before gradually increasing through the rest of
the period after Friday morning, when the subsidence side of the
upper-level trough moves over the region. Available moisture will
reach the mid levels, today before being limited to below 700 mb for
the rest of the period. An upper level jet will also persist over
the area today, gradually moving out of the area through Friday.

Available moisture and instability will promote showers and isolated
thunderstorms development today, steered by low level winds ESE
winds. During the morning hours, advective shower activity will
continue to reach windward sectors of the islands, isolated
thunderstorms cannot be ruled out. Under the east-southeast wind
flow, above normal high temperatures can be observed across sectors
of the islands, with isolated areas with warmer than usual apparent
temperatures. This heating will in turn help convective activity
today. During the afternoon hours, this diurnal heating, sea breeze
convergence and local effects will promote better shower and
isolated thunderstorm activity mainly over the interior to NW
quadrant of the island and from El Yunque to the metro area. Shower
and isolated thunderstorm activity should gradually move over the
northern waters and extend into late tonight as the moisture patch
starts moving away from the islands. We can anticipate periods of
locally heavy rain this afternoon producing ponding of water over
roadways and poorly drained areas with the addition of urban, road
and small stream flooding. Each afternoon, convection is forecast
over the NW on Friday and over the W on Saturday, as winds become
more easterly to east-northeasterly to start the weekend.

&&

.LONG TERM...SUNDAY THROUGH THURSDAY...

The ridge pattern aloft will turn into a zonal flow from Sunday
through the middle of next week. Meanwhile, mid-level high
pressure will hold over the Northeast Caribbean through at least
Wednesday. A surface high pressure forecast to build north of the
Northeast Caribbean will keep a frontal boundary north of us,
while the tropical moisture will slowly erode Sunday through
Tuesday. As the high pressure migrates from the NE Caribbean to
the eastern Atlantic, the region will be under the typical
advective pattern with the arrival of occasional fragmented
moisture during the first part of next week.

The moisture field from the remnants of a cold front will pool
across the NE Caribbean late Tuesday night into mid-week as
another surface high pressure migrates eastward from the Western
Atlantic near the PR and the USVI region. Although the mid- and
upper-level dynamic will not be the most favorable for organized
convection, if model guidance is correct, we may see showery
weather around the middle of next week due to above-normal
moisture content pooling over the islands.
&&

.AVIATION...
(06Z TAFS)
Issued at 457 AM AST Thu Mar 7 2024

Mainly VFR conditions will prevail under an ESE wind flow. Brief
MVFR conditions are possible during the morning hours as
SHRA/+SHRA move over TJPS and possibly TIST/TISX, briefly reducing
visibilities. During the late morning to afternoon, TSRA
development can also result in MVFR conditions at TJSJ and TJBQ,
especially TJBQ after 07/17z. ESE winds between 10-15 kt, with
higher gusts and sea breezes as well as locally higher near
SHRA/TSRA activity, after 07/12z and become calm to light and
variable after 07/23z.

&&

.MARINE...
Issued at 457 AM AST Thu Mar 7 2024

A broad surface high pressure spreading across the central Atlantic
will promote moderate east southeasterly winds. The winds, in
combination with weak pulses of a northeasterly swell, will continue
to create rough seas across the Atlantic waters. Therefore, small
craft should exercise caution. Greater instability will increase
thunderstorm activity across the region this afternoon into the
evening hours. Winds will then return from the east to east-
northeast during the weekend into next week as the high pressure
builds over the Western Atlantic.

&&

.BEACH FORECAST...

The east-to-east-southeast winds and a fading northeast swell will
cause a high risk of rip currents along PR's Atlantic Coastline.
We have a moderate risk of rip currents from Rincon to Aguada,
Culebra, St Thomas, St John, and St Croix.

Thunderstorm activity may likely from the west to north coast in
Puerto Rico and downwind from the Virgin Islands during the
afternoon and evening hours.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
424 AM AST Fri Mar 8 2024

.SYNOPSIS...
Issued at 423 AM AST Fri Mar 8 2024

Due to the east-southeast wind flow, we expect above-normal
maximum temperatures in the afternoon, especially across the urban
and coastal areas of north-central Puerto Rico. Winds should
slowly shift from the east to east-northeast from Saturday onward
as the surface high pressure builds to the north-northeast of the
U.S. Virgin Islands. Conditions will gradually improve, but
fragments of moisture and local effects may result in periods of
occasional showers each day. Two northerly swells, one on Monday
and another by mid-week will deteriorate coastal conditions next
week. The trade winds will increase from Thursday onwards,
increasing moisture convergence, especially across windward
sections in PR/USVI.

&&

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

Current satellite derived precipitable water (PWAT) values indicate
an air mass with seasonal values ranging from around 1.3 to 1.45
inches, approaching the region from the southeast. A surface high
pressure over the central Atlantic is promoting ESE winds across the
islands. Steered by these low level ESE winds, the air mass will
continue to approach the region today, followed by one with slightly
above normal PWAT values behind it. As the aforementioned surface
high moves away from the islands and winds back and become more
easterly later this afternoon, tropical moisture to our east will
reach the region, and persist through late Saturday bringing
slightly above normal PWAT.

A brief ENE steering flow Saturday night into early Sunday will
bring drier air over the region to start the next week, with winds
becoming easterly again on Sunday afternoon. Most available
moisture will be below 700mb today, and as a mid-level high
builds across the region by Sunday, most available moisture then
will be below 850mb. As a mid to upper level trough makes its way
across and out of the area today, the islands should be under its
subsidence side for most of the day, bringing more stability to
our area.

During the morning hours, passing shower activity will reach some
windward sectors. Under east-southeast wind flow, above normal
high temperatures can be observed across sectors of the islands,
with areas in north-central PR experiencing warmer than usual
apparent temperatures. 925mb temperatures are forecast to be +2
standard deviations above normal today. During afternoon hours,
diurnal heating, sea breeze convergence and local effects will
promote convective activity mainly over the interior to NW
quadrant of the Puerto Rico. More stable conditions are forecast
on Saturday, and especially Sunday as conditions become drier.

&&

.LONG TERM...MONDAY THROUGH FRIDAY...

A mid-level high pressure will hold over the Northeast Caribbean,
reinforcing the trade wind cap and promoting drier air and
subsidence around Thursday. It may weaken around Thursday
afternoon or Friday. This weakening may lead to a moisture
increment along the air column, surpassing the 850 or 700 mb,
which may provide better conditions for scattered or numerous
showers. Meanwhile, a migratory surface high pressure moving
eastward north of the region will hold a cold front to sink over
the area. This frontal boundary may linger north or near the
northeast Caribbean until it dissipates Wednesday or Thursday. GFS
suggests a trade wind perturbation increasing the available
moisture content on Thursday and Friday, and if the mid-level
ridge weakens, it may promote showery weather conditions those
days.

Although we can expect a mixture of sunshine and clear skies with
passing clouds, the trade winds may advect fragments of moisture
that, interacting with local effects, could result in periods of
moderate to locally heavy rain across portions of the islands each
day, especially across the windward locations.

The robust surface high pressure forecast to build across the
eastern Atlantic will tighten the local pressure gradient,
promoting increased trade winds between Wednesday and Friday.

&&

.AVIATION...
(06Z TAFS)
Issued at 423 AM AST Fri Mar 8 2024

Mainly VFR conditions will prevail across the terminals. SHRA
development could result in brief MVFR conditions at TJBQ, from
08/17z to 08/22z. ESE (bcmg E) winds between 10-15 kt, with higher
gusts and sea breezes, bcmg become calm to light and variable after
08/23z.

&&

.MARINE...
Issued at 423 AM AST Fri Mar 8 2024

A broad surface high pressure across the central Atlantic,
interacting with surface low well to the northeast of the northern
US Virgin Islands, will promote east-southeast winds and moderate
chops through at least this afternoon. Small craft operators
should exercise caution across the Atlantic Waters. Winds will
then return from the east to east-northeast during the weekend
into early next week as surface high pressure builds north of the
region, spreading into the eastern Atlantic. A set of northerly
swells will reach the islands next week, one around Monday and
another around mid-week.

&&

.BEACH FORECAST...
Issued at 423 AM AST Fri Mar 8 2024

The CariCOOS local buoy network observed winds between 10 and 15
knots out from the east-southeast across the nearshore waters of
PR and the USVI, resulting in moderate chops between 3 and 5 feet.
The seas are coming from the northeast in the Atlantic and the
east-southeast to the southeast in the Caribbean. The peak wave
period fluctuates between 10 and 11 seconds in the Atlantic and
around 6 seconds in the Caribbean. These conditions generate a
moderate risk along the north- and east-facing beaches of PR and
the USVI and a low risk in the west- and south-facing beaches.

As two sets of northerly swells arrive on Monday and the middle of
next week, the risk will turn high along the north-facing beaches.
As the trades increase, the conditions will deteriorate for most
beaches from the middle of next week onward.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
513 AM AST Sat Mar 9 2024

.SYNOPSIS...

Variable weather conditions will persist for the rest of the day
as moisture with precipitable water values of 1.5 inches, as GOES
satellite Imagery shows, moves into the region. As a result, the
island can expect showers in the morning hours over the windward
sections and afternoon showers over the interior. Widespread
shower activity is not anticipated due to a mid-level ridge in
place. Conditions will remain more stable from Monday onwards when
drier air moves into the region, which is dominated by a high
surface pressure over the western Atlantic.

&&

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

The US Virgin Islands and Puerto Rico observed calm weather
overnight with clear skies and little to no rain over land. However,
fragments of moisture impulsed by the easterlies brought a few rains
over the windward sections. Clear skies mostly led to fog formation,
especially along the interior near the eastern interior and central
interior municipalities of PR. The nighttime cooling allowed minimum
temperatures to drop into the low 70s along the coastal sections and
the mid-50s in valleys and mountain areas.

A mid-to-upper-level ridge moving eastward over the northeast
Caribbean will promote a stable atmosphere and a dry air mass above
700 MB. The ridge will reinforce over the islands while a mid-level
high pressure builds over the region, confining the available
moisture below 850 MB on Sunday and Monday. Under the weather
pattern mentioned above, a surface easterly disturbance will
increase the low-level moisture today (Saturday), resulting in the
best chance to observe the wettest day between today and Monday.

Under an easterly wind flow, showers will affect mainly the
surrounding waters of the US Virgin Islands, moving inland at times,
and the windward sections of Puerto Rico today during the morning.
Then, by mid-morning, showers will spread into the interior and
western PR, dispersing to the rest of the region by the afternoon
and evening hours. Periods of moderate to locally heavy rain have a
50 to 60 percent chance of producing urban and small stream flooding
across PR's western and western interior between noon and early this
evening.

Showers will spread into the local waters this evening, affecting
the west, north, and southwest coasts of PR. Meanwhile, the Virgin
Islands have a more than 80 percent chance of observing mostly clear
skies.

Although the atmosphere will turn more stable on Sunday and Monday,
the trade winds will push fragments of low-level moisture that may
result in periods of showery weather across the windward sections,
especially overnight and early in the morning. We cannot rule out
the formation of isolated to scattered showers locally induced
during the afternoon over west PR and downwind from the USVI.

&&

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

A building surface high pressure over the Western Atlantic will
be the dominant feature for the long-term forecast. On Tuesday and
Wednesday, the islands will mostly experience an east-northeast
wind pattern and will have a mid- to upper-level ridge in place,
persisting for most of the period. Surface conditions will
slightly change by Wednesday into Thursday as the broad surface
high pressure moves eastward, extending from the western Atlantic
into the Central Atlantic. Consequently, there will be a period on
Wednesday when surface winds become more easterly, suddenly
shifting by Thursday from the south-southeast for a few hours,
backing again by late Thursday night. Under this pattern for the
middle of the period, the islands can expect an increase in
tropical moisture dragged by the east-southeasterly winds into the
region. Residents and visitors could expect an increase in the
frequency of shower activity across the windward section in the
morning hours, and over the interior in the afternoon hours.
Although the increase in moisture will lead to more showers, the
mid to upper- level ridge will limit vertical development across
the region. Therefore, significant rainfall accumulations are not
expected. From Friday onwards, a much drier airmass will filter
across the region limiting the frequency of the showers.

&&

.AVIATION...
(06Z TAFS)
VFR conds will prevail thru most of the fcst period. SHRA/+SHRA will
develop over the mountain areas, spreading near the terminals of
JSJ/JPS/JBQ btwn 09/15-22z, with JBQ being the location with the
highest prob of observing +SHRA, creating MVFR conds. Winds will
prevail from the E, but they will range from calm to light/var thru
09/13z; after that, they will range at 10-15kt with higher gusts and
sea breeze variations; by the evening (aft 09/23z), they will become
calm to light/var one more time, with land breeze fluctuations.

&&

.MARINE...

A surface high pressure over the central Atlantic will continue
to promote moderate easterly winds across the region. Therefore,
seas will continue up to 5 feet with winds up to 15 knots from the
east across all the local waters. Deteriorating marine conditions
are forecast for the upcoming workweek, with the arrival of
pulses of a northerly swell invading the local waters. Seas are
forecast to build up to 7 feet. Therefore, small craft advisories
could be in effect for that time frame. There is a moderate rip
current risk across all northern coastal areas of Puerto Rico,
Culebra, and St Croix for the next several days. By Monday, the
risk will increase up to high across the northern exposed beaches
of Puerto Rico.

&&

.BEACH FORECAST...

Recent bouy data from the CariCOOS local network winds are from
the east at 10 knot or less and seas up to 5 feet or less. There
is a moderate risk of rip current across the northern coastal
region of Puerto Rico, Culebra and St.Croix. Model guidance
continues to suggest a two sets of northerly swells arriving into
the local waters. The first pulse will be on Monday persisting to
the middle of next week, the risk will turn high along the north-
facing beaches. As the trades increase, the conditions will
deteriorate for most beaches from the middle of next week
onward.Resident should stay tuned for further information about
coastal marine hazards.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
431 AM AST Sun Mar 10 2024

.SYNOPSIS...

Variable weather conditions will persist for the period due to
the presence of a mid-level ridge, which will result in drier air
aloft and warmer temperatures at the 500 mb. Although stable
weather conditions should persist for the rest of the period,
shallow moisture at the surface embedded will enhance isolated
showers in the morning, followed by the afternoon convection
across the interior due to the diurnal and local effects. A
surface low pressure at the western Atlantic will result in a
northerly swell invading the local waters by Monday night,
resulting in building seas and dangerous breaking waves for
midweek.

&&

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

An overnight radar and satellite imagery analysis indicated remnants
of afternoon convective development persisted into the evening. From
midnight through approximately 4 AM AST, light showers extended into
eastern Puerto Rico. In other areas, including the US Virgin
Islands, the prevailing conditions were mainly clear to partly
cloudy skies, with some clearing observed over most of Puerto Rico
after midnight. From 8 PM AST onward, radar-estimated rainfall
totals peaked at around 0.50-0.75 inches near the Corozal-Naranjito-
Barranquitas tri-county line and east of El Yunque. As reported by
official sites, overnight temperatures ranged from 62 degrees in
higher elevations to 75 degrees across lower elevations. Winds were
generally light to calm and variable.

According to the latest model guidance, a drying trend is forecast
throughout the short-term forecast. Precipitable water values are
expected to decrease from around 1.4 inches, within typical seasonal
levels, this morning to about 0.85 inches, falling well below
typical moisture levels by Tuesday evening. In the meantime,
environmental conditions will gradually become less conducive for
shower development due to strengthening a mid-level ridge over the
western-central Caribbean region. This ridge will maintain a strong
trade wind cap inversion and a flow of drier air aloft. At the
surface, high pressure to the north of the area will sustain gentle
to moderate easterly winds until another high pressure system,
moving into the western Atlantic, causes the winds to back from the
northeast on Tuesday.

The forecast suggests that stable and tranquil weather conditions
will likely prevail throughout the period. Nevertheless, some
passing shower activity may occur due to persistent shallow moisture
below the 800 mbar layer, particularly favoring eastern Puerto Rico
and the US Virgin Islands. Furthermore, the potential for afternoon
convection persists for the interior to western sections of Puerto
Rico and downwind of the local islands, influenced by local effects
and diurnal heating. Consequently, shower development is more likely
this afternoon, with decreasing probabilities and areal coverage on
Monday and Tuesday. In this anticipated scenario, warmer-than-normal
temperatures are expected each day, playing a significant role in
the development of afternoon convection, even during the drier
days.

&&

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

The long-term forecast is still on track with just a few time
frame periods. From the beginning of the period, a broad building
surface high pressure over the western Atlantic will promote east-
northeasterly winds across the region. Under this pattern, the
islands will persist under a drier airmass dominating the area. As
a result, the islands will mostly experiment with stable weather
conditions with much fresh temperatures. As the surface high
pressure develops and moves eastward, extending into the central
Atlantic, veering winds will drag patches of shallow moisture over
the region. Recent model guidance now suggests a drier Wednesday
into Thursday with an increase in moisture by early Friday, when
the surface high pressure will be located just north of the region
over the Central Atlantic. Under this pattern, by Friday, the
islands can expect an increase in the frequency of shower activity
across the windward section in the morning hours and over the
interior in the afternoon hours. Although the increase in moisture
will lead to more showers, the mid to upper- level ridge will
limit vertical development across the region. Therefore,
significant rainfall accumulations are not expected. From Saturday
onwards, drier air will move again to the CWA, leading to stable
weather conditions once again.

&&

.AVIATION...
(06Z TAFS)VFR conditions will prevail at all terminals. However,
there is a chance of SCT-BKN between FL020-040 and VCSH through
11/14Z for TJSJ and USVI terminals. Afternoon SHRA could result in
brief MVFR conditions at TJBQ between 10/17-23Z, with limited
impact on operations. Light and variable winds will increase to
10-15 knots, with higher gusts and sea breeze variations, between
10/14-23Z. Wind speeds will become light and variable again after
10/23Z.

&&

.MARINE...

A surface high pressure over the central Atlantic will continue
to promote moderate easterly winds across the region. Seas will
continue up to 5 feet with winds up to 15 knots from the east
across all the local waters for the rest of the weekend into
early next week.. Deteriorating marine conditions are forecast
from Monday night onwards, with the arrival of a northerly swell.
Seas are forecast to build up to 7 feet by midweek. Therefore,
small craft advisories could be in effect for that time frame.
There is a moderate rip current risk across all northern coastal
areas of Puerto Rico, Culebra, and St Croix for the next few days.
However, once the swell arrives, the risk will increase up to
high across the northern exposed beaches of Puerto Rico by Monday
night.

&&

.BEACH FORECAST...

Pulses of a northerly swells generated by a surface low pressure
exiting the eastern seaboard of the United States will promote
hazardous marine and coastal conditions across the region from
Monday night into the rest of the week. The big pulse of energy
from the swell is forecast by Wednesday, when dangerous coastal
conditions will large breaking waves up to 11 feet. As a result,
high risk of rip current is forecast from Monday night into the
rest of the week. Given the expected conditions, high surf
advisory conditions are forecast as well from Wednesday into
Thursday. By the end of workweek, an increase in the pressure
gradient will enhance moderate to locally strong winds, inducing
wind-driven seas.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
500 AM AST Mon Mar 11 2024

.SYNOPSIS...Starting tonight and continuing through the weekend,
the primary hazard risks focus on marine and rip currents driven
by pulses of a northerly swell spreading across the Atlantic
waters. Then, by midweek, the tightening of the local pressure
gradient will cause an increasing non-thunderstorm wind risk.
Thus, breezy to windy conditions are likely. Weather-wise,
conditions should remain fairly stable, influenced by persistent
mid-level ridging. However, increasing moisture content will
likely cause an increase in passing shower activity by the weekend
and early next week. The prevailing east-southeast flow will
support warmer-than-normal temperatures today, followed by more
typical temperatures from Tuesday onward.


&&

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

Very stable weather conditions prevailed during the night. In the
early morning, some clouds and a few showers developed over the
coastal waters near Isabela and Aguadilla, but those showers
remained over the local waters. Overnight temperatures were in the
low to mid-70s across the coastal areas and in the mid to upper 60s
in the mountains.

For the rest of the morning hours, winds will persist from the east
until the high pressure in the center of the Atlantic shifts
eastward, pushed by a broad building of high pressure over the
western Atlantic extending into the Caribbean and shifting the winds
more from the east-northeast. Under this wind pattern, patches of
shallow moisture with PWAT values of 1.1 inches, as suggested by the
GOES Satellite Imagery, will remain in place, increasing the chances
for isolated showers in the morning across eastward areas and for
the interior and southwestern sections in the afternoon. Although
model guidances point to today as the wettest day of the short term,
a mid-level ridge will result in a trade wind cap, eroding the
moisture at the upper levels. Therefore, showers that develop today
will not result in significant rainfall accumulations.

On Tuesday, a much drier airmass will move in, limiting the
possibility of observing significant shower activity in the region.
Even though it will be the driest day, residents of the interior and
the southwestern sections do not rule out some showers resulting
from the daily and local effects as the surface high pressure moves
eastward and extends to the eastern Atlantic, inducing veering
winds, becoming more east-southeasterly. This wind change will
induce warmer temperatures on Wednesday and more tropical moisture
moving into the area, increasing the potential for shower activity
across the northeastern and northwestern sections of Puerto Rico.

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

The latest model guidance suggests a drier weather pattern earlier
in the period, followed by increasing moisture content during the
weekend and early next week. Precipitable water values will likely
range from typical moisture levels around 1.2-1.3 inches on
Thursday to above-typical levels around 1.6-1.7 inches on Saturday
night and again on Monday. Despite this trend, persistent mid-
level ridging across the region will support less conducive
conditions for deep convective development with a strong trade
wind cap inversion and drier air entrainment above the 700 bar
layers. Except for Friday, when east-northeast winds are likely,
the general flow should remain from the east throughout the
period, yielded by a surface high pressure moving eastward across
the western-central Atlantic. As this feature builds north of the
region, breezy conditions are likely between Thursday and
Saturday. Temperatures, however, should remain within typical
seasonal thresholds throughout the period, ranging from lower 60s
across higher elevations to mid 80s across lower elevations.
Locally lower or higher temperatures are likely, mainly in
response to increased or decreased cloudiness and shower activity.


Overall, mainly fair and stable weather conditions with limited
shower activity are expected on Thursday and Friday. With
increasing moisture content, there is a likelihood for increased
shower activity from Saturday onward, reflected in increased
passing showers moving over eastern Puerto Rico and the local
islands. Afternoon shower development, aided by local effects and
diurnal heating, will likely occur daily, even during the driest
days. However, excessive rainfall risks should remain low
throughout the period.


&&

.AVIATION...
(06Z TAFS)

VFR conditions will persist for the entire period across all the
TAF sites. E winds will continue up to 8 knots, veering at 11/18Z,
becoming more from the E-NE up to 15 knots. Afternoon showers
will affect the ceiling across the mountain areas and increase the
VCSH over TJPS for 11/18Z.


&&

.MARINE...

An area of high pressure northeast of the region will promote light
to moderate east winds today as it moves eastward into the central
Atlantic. Winds will then become more northeasterly on Tuesday due to
a surface high pressure in the western Atlantic near the coastline
of Florida. Northerly swells will begin to reach the local waters by
tonight and bring hazardous seas across the Atlantic waters by
Wednesday. Moderate to fresh trades return by midweek.


&&

.BEACH FORECAST...

The rip current hazard remains at moderate risk levels for beaches
across the western-northwestern to the eastern-northeastern
coastline of Puerto Rico, Culebra, and the northern U.S. Virgin
Islands. As northerly swells spread across the region tonight into
Tuesday, the risk will elevate to high, with life-threatening rip
currents likely across most Atlantic-facing beaches.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
500 AM AST Tue Mar 12 2024

.SYNOPSIS...The primary hazard risks focus on marine and rip
currents driven by pulses of a northerly swell spreading across
the Atlantic waters and local passages. Then, by Wednesday, the
tightening of the local pressure gradient will cause an increasing
non-thunderstorm wind risk, with breezy conditions likely across
coastal areas and the local islands. Weather-wise, conditions
should remain reasonably stable, influenced by persistent mid-
level ridging. However, the weakening of the mid-level ridge and
increasing moisture levels will likely cause an increase in shower
activity early next week. Warmer-than-normal temperatures are
still likely today.


&&

.SHORT TERM...Today through Thursday

Fair weather conditions prevailed across the entire CWA during the
night. Satellite imagery showed a few clouds over the coastal
waters, with no rainfall activity detected by the Doppler radar.
Overnight temperatures were colder than yesterday due to the
northeasterly winds, ranging from the low to mid-70s across the
coastal areas and in the low 60s across the mountains.

The latest model guidance continues to suggest the presence of a mid-
level ridge holding in place over the western Atlantic for the
entire period. This feature will maintain a strong trade wind cap
and dry air aloft, inhibiting vertical development and the longevity
of showers. Despite the stable conditions aloft, surface changes may
increase the chances of shower activity.

Starting today and extending into tomorrow, a broad area of high
pressure extends from the western Atlantic into the Caribbean,
maintaining northeasterly winds across the region. This pattern will
largely favor dry air with some patches of shallow moisture
dominating the forecast area. As the surface high pressure shifts
further into the central Atlantic, easterly to southeasterly winds
will prevail, leading to a more showery pattern over the windward
sections by Wednesday. On Thursday, recent model guidance suggested
more moisture near climatological normals trapped between 850 and
700 MB. However, it will be sufficient to enhance shower activity
coverage across northeastern and northwestern sections, including
the San Juan metro area, due to the southeasterly wind component.

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

The latest model guidance now supports a drier weather pattern
through most of the forecast period, except for Monday evening
into late Tuesday night, when above to well-above typical moisture
values are likely. In this scenario, precipitable water values
will range from typical moisture levels around 1.2-1.3 inches on
Friday to well-above typical levels around 1.8-1.9 inches on early
Tuesday morning. Mid-level ridging will support less conducive conditions
for deep convective development, maintaining a trade wind cap
inversion and drier air entrainment above the 700 bar layers.
Weakening of the mid-level ridge is likely early next week,
allowing the anticipated moisture increase, with moisture spanning
beyond the 700 mbar layer. Except for Friday, when east-northeast
winds are expected, the general flow should remain from the east
throughout the period, yielded by a surface high pressure moving
eastward across the western-central Atlantic. As this feature
builds and meanders north-northeast of the region, breezy
conditions will likely persist through early next week.
Temperatures, however, should remain within typical seasonal
thresholds throughout the period, ranging from lower 60s across
higher elevations to mid 80s across lower elevations. Locally
lower or higher temperatures are likely, mainly in response to
increased or decreased cloudiness and shower activity.

Fair and stable weather conditions with limited shower activity
will prevail by the end of the workweek into the weekend. With
increasing available moisture, there is a likelihood for increased
shower activity on Monday and Tuesday, reflected in increased
passing showers moving over windward areas and more robust
afternoon convective development, mainly across central to western
Puerto Rico. Even during the driest periods, afternoon convective
development is likely, but with less coverage and intensity. So
far, excessive rainfall risks should remain low throughout the
period.


&&

.AVIATION...
(06Z TAFS)

VFR conditions will prevail for the period across all the TAF
sites. Winds will continue VRB at 5 knots or less, increasing at
12/15Z from the E-NE with sea breeze variation across all the sites.
Showers are not anticipated near the TAF sites. Winds will prevail
from the NE, again diminishing at 12/23Z.


&&

.MARINE...

A building surface high pressure across the western Atlantic near
the coastline of Florida will yield moderate easterly winds today,
and moderate to fresh winds from Wednesday onwards. Northerly
swells will begin to reach the local waters today and generate
hazardous seas for small craft across the Atlantic waters by this
evening, followed by the coastal Atlantic waters and local
passages on Wednesday. Small Craft Advisories have been issued for
these areas.

&&

.BEACH FORECAST...

The rip current hazard risk remains high for north-facing beaches
of Puerto Rico, from Aguada and Rincon eastward to Fajardo and
Ceiba, Culebra, and the northern U.S. Virgin Islands. As northerly
swells continue to spread across the region, the risk will elevate
to high for Vieques and Saint Croix beaches. For details, refer to
the Coastal Hazard Message (CFWSJU) and Surf Zone Forecast
(SRFSJU).


&&

.FIRE WEATHER...

Despite notable discrepancies in KBDI readings between Cabo Rojo
and Guanica in southwestern Puerto Rico, Guanica's KBDI readings
indicate favorable soil conditions for the spread of wildfires,
where KBDI values exceed 550. In addition, abnormally dry to
moderate drought conditions persist across these areas. In
contrast, improved drought conditions across the southeast suggest
improved soils and fuel conditions.

Wind speeds are forecast to back from the east-northeast and
likely exceed 15 mph today, attributed to a surface high pressure
building over the western Atlantic. In the meantime, a drier-than-
normal airmass is expected to move across the region, with
humidity values likely falling below 55 percent. Considering
recent soil conditions, this scenario supports an elevated fire
danger risk. For this reason, a Fire Danger Statement has been
issued. The most favorable conditions are likely across the
southwest quadrant of the island between the late morning and
early afternoon.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
444 AM AST Wed Mar 13 2024

.SYNOPSIS...The primary hazard risks focus on marine and rip
currents driven by pulses of a northerly swell spreading across
the Atlantic waters and local passages. Small Craft Advisories,
High Surf Advisories, and a High Rip Current Risk remain in effect
across the area. Starting today, the tightening of the local
pressure gradient will cause an increasing non-thunderstorm wind
risk, with breezy conditions likely across coastal areas and
portions of the local islands. An increase in moisture levels and
weakening of the mid-level ridge will likely cause an increase in
shower activity early next week. Warmer-than-normal temperatures
are still likely today. Current soil conditions and the expected
weather scenario will contribute to an elevated risk of wildfire
spreading, particularly across southwestern Puerto Rico.


&&

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

Stable weather conditions prevailed across all the islands during
the night and early morning hours. Satellite imagery showed a few
clouds over the coastal and exposed waters, with no shower activity
over the coastal areas. Surface winds prevailed in the east-
northeast at eight mph or less. Overnight temperatures across the
coastal areas were in the mid to upper 70s, and the mountains were
much fresher from the low to mid-60s.

Very stable weather conditions will persist for the rest of the day
due to a drier airmass remaining in place. According to the imagery
derived from the GOES satellite, PWAT values are 0.79 inches, which
is well below the climatological normals. As a result, mostly sunny
skies will prevail today, with a few clouds across the northern
sections of the islands. Localized afternoon activity cannot be
ruled out due to the local and daily effects. However, the chances
of rain remain below 20% for the interior and western interior
sections. Daytime temperatures will range from the low to mid 80s
across the coastal areas, and in the mid 70s across the mountains.

From Thursday onwards, model guidance continues to suggest an
increase in tropical moisture reaching the local islands, pushed by
the east-southeasterly winds across the region. This increase in
humidity trapped at 700 MB will turn into a more variable pattern
across the islands, with chances of more frequent passing showers in
the evening and early morning hours. Although an increase in
moisture will enhance good periods of shower activity, a mid to
upper-level ridge will hold a hostile environment for widespread and
long-life shower activity. As a result, shower activity was included
in the forecast for both days, but significant rainfall
accumulations are not anticipated at this moment.

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

The latest model guidance now supports an even drier weather
pattern through most of the period, interrupted by a premature and
shorter wet period. Mid-level ridging will maintain less conducive
conditions for deep convective development, with a robust trade
wind cap inversion and drier air entrainment above the 700 bar
layers. A brief weakening of the mid-level ridge is likely early
next week, allowing an increase in precipitable water as moisture
spans beyond the 700 mbar layer. Regarding moisture variations,
normal to below-normal seasonal moisture levels ranging between
1.0-1.4 inches will be the norm, with wetter-than-normal
conditions likely between late Sunday night and early Tuesday
morning, when above to well-above moisture levels exceeding 1.5
inches are possible.

At lower levels, a high pressure moving across the western into
the central Atlantic will yield easterly winds during the weekend,
gradually veering from the east-southeast to southeast early next
week. As this feature builds and meanders north-northeast of the
region, breezy conditions are also likely early next week. In
response to the expected weather conditions, colder-than-normal
conditions are possible on Friday, followed by more seasonal
temperatures on Sunday and possibly warmer-than-normal conditions
during the first half of next week.

Fair and stable weather conditions with limited to no shower
activity will prevail during the weekend and will likely return on
Tuesday and Wednesday with the entrance of a drier-than-normal
airmass. With increasing available moisture, there is a likelihood
for increased shower activity on Monday, reflected in increased
passing showers moving over windward areas and more robust
afternoon convective development, mainly across northwestern
Puerto Rico. So far, excessive rainfall risks should remain low
throughout the period.


&&

.AVIATION...
(06Z TAFS)

VFR conditions will prevail throughout the period across all
TAF sites. Winds will continue from the NE at 10 knots or less until
13/15Z, increasing up to 15 knots from the E-NE with gusty winds and
sea breeze variation. Shower activity is not anticipated near the
TAF sites; however, afternoon activity across the mountains will
result in lower ceilings across the interior areas. Winds will
diminish at 13/23z, becoming more from the east.


&&

.MARINE...

A building surface high pressure spreading eastward across the
western Atlantic will yield moderate to locally fresh easterly
winds. Northerly swells will continue to arrive and spread across
the local waters today. These swells will create hazardous seas
for small craft across the Atlantic waters and local passages.
Small Craft Advisories remain in effect for these areas due to
seas. For details, refer to the latest Coastal Waters Forecast
(CWFSJU, CWFSPN) and Marine Weather Message (MWWSJU).

&&

.BEACH FORECAST...

A High Surf Advisory remains in effect for the north facing
beaches of Puerto Rico, Culebra, and the northern US Virgin
Islands. Large breaking waves up to 10-12 feet will likely
produce localized beach erosion and dangerous swimming conditions.

Northerly swells continue to spread across the region for the
next several days. The rip current hazard risk remains high for
north-facing beaches of Puerto Rico, from Aguada and Rincon
eastward to Fajardo and Ceiba, Culebra, Vieques, and the U.S.
Virgin Islands through at least Thursday afternoon.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
430 AM AST Thu Mar 14 2024

.SYNOPSIS...

Variable weather conditions will prevail for the next several days
due to low-level moisture and a mid-level ridge. Better moisture
will filter into the region by Friday into Sunday, increasing the
potential for shower development. A northerly swell will continue
to result in extremely dangerous marine and coastal conditions.
Beachgoers are urged to avoid the northern coastal areas of Puerto
Rico, Culebra, Vieques, and the U.S. Virgin Islands. &&

.SHORT TERM...Today trough Saturday...

Fair weather conditions prevailed through the night as dry air
continues to exist across the region. A few light showers carried by
the trade winds passed across the eastern coastlines of Puerto Rico,
leaving traces of rain. Surface winds prevailed in the east-
northeast around 10 mph or less. Overnight temperatures across the
coastal areas were in the mid to upper 70s, and the mountains in the
low to mid-60s.

Stable weather conditions will continue over the next few days as a
mid-level ridge remains present across the eastern Caribbean Basin.
However, an increase of passing showers and afternoon convection
across western Puerto Rico will be seen today as a relatively moist
airmass advects over the islands, replacing the dry air that has
stuck around for a few days. No significant rainfall is expected
though as stable conditions prevail.

On Friday, a surface high pressure begins to reinforce across the
western Atlantic and will cause winds to back slightly to a east-
northeasterly direction with windy speeds. This along with the
lingering moist airmass will maintain passing windward coastal
showers and afternoon convection across southwestern PR. Similar
conditions will continue on Saturday, with winds returning from the
east.

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

The latest model guidance continues to agree on a wet pattern for
the beginning of the long-term period on Sunday into Monday. At
the surface, a building high pressure just east of the region over
the central Atlantic will promote more east-southeasterly winds.
Embedded in those winds, tropical moisture with precipitable water
values in the climatological normals will enhance a more showery
pattern across the region. An interesting pattern will unfold,
with the presence of strong winds aloft and the mid-level ridge in
the 500 MB in place. As the pattern evolves, given the presence
of the mid-level ridge, the forecast calls for a variable day with
the potential to observe heavy localized shower activity across
the interior and northwestern sections of Puerto Rico, with no
significant rainfall accumulations at this moment.

By Tuesday, as the surface high pressure interacts with a frontal
boundary merging just over the Hispanola, veering winds will
emphasize more southeasterly winds. Under this pattern, slightly
drier airmass will filter in with PWAT values of 1.0 inches. Given
the proximity of the pre-frontal trough, a decrease in the
pressure gradient is forecasted, and winds will turn more lights
on the surface by Wednesday. Additionally, much warmer
temperatures are forecast for mid-week due to the southeasterly
winds and water content near normal across the islands. The
surface high pressure pushing the frontal boundary will migrate to
the central Atlantic. The island will observe backing winds by the
end of the period and an increase in moisture from the previous
old frontal boundary. As a result, an increase in the frequency of
the showers is forecasted once again by Thursday. &&

.AVIATION...
(06Z TAFS)
VFR conditions will prevail throughout the period across all TAF
sites. Winds will continue from the E at 10 knots or less until
14/15Z, increasing up to 15 knots from the E-NE with gusty winds
and sea breeze variation. Shower activity is not anticipated near
the TAF sites besides the possibility of VCSH near JBQ after
14/16z.

&&

.MARINE...

Northerly swells will continue to arrive and spread across the
local waters, resulting in hazardous seas. Additionally, a
building surface high pressure spreading eastward across the
western Atlantic will yield moderate to locally fresh easterly
winds. These swells and moderate winds will create hazardous seas
for small craft across the Atlantic waters and local passages.
Small craft advisories remain in effect for at least the rest of
the workweek for these areas due to seas. For details, refer to
the latest Coastal Waters Forecast (CWFSJU, CWFSPN) and Marine
Weather Message (MWWSJU).

&&

.BEACH FORECAST...

A long period northerly swell continues to result in large
breaking waves across the northern local waters. Therefore, a
High Surf Advisory remains is in effect for the north facing
beaches of Puerto Rico, Culebra, and the northern U.S. Virgin
Islands through at least Friday morning. Large breaking waves up
to 10-13 feet will likely produce localized beach erosion and
dangerous swimming conditions.

Northerly swells will continue to spread across the region for
the next several days. There is a High Risk of Rip Currents for
north- facing beaches of Puerto Rico, from Aguada and Rincon
eastward to Fajardo and Ceiba, Culebra, Vieques, and the U.S.
Virgin Islands through at least Friday afternoon. For details,
refer to the Coastal Hazard Message (CFWSJU) and Surf Zone
Forecast (SRFSJU).

Life-threatening rip currents are expected. Rough surf may also
knock you down. Minor beach erosion may occur due to high surf.
Rip currents that can sweep even the best swimmers away from shore
into deeper water where it becomes difficult to return to safety.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
426 AM AST Fri Mar 15 2024

SYNOPSIS...

Low level moisture convergence will increase the potential for
shower development and breezy conditions will be present through
the weekend. A mid-period northerly swell and moderate to fresh
winds will continue to promote hazardous seas through the end of
the workweek, for the northern waters, the northwestern waters of
Puerto Rico and the Mona Passage. A High Rip Current Risk is in
effect across the northern coastline of Puerto Rico, Culebra and
the northern USVI.

&&

.SHORT TERM...Today through Sunday

Mid to upper level high pressure ridge extending from the central
Caribbean into the southwest Atlantic will maintain west to
northwest winds and stable conditions across the region through the
weekend. Building surface high pressure across the west and central
Atlantic, will maintain moderate to strong easterly winds today into
Saturday, becoming more southeasterly by Sunday as the high pressure
centers itself across the central Atlantic. This in turn will bring
a return of occasional moisture fragments from old frontal
boundaries across the region carried by the dominant easterly
trades.

For the rest of the morning hours, the building high pressure north
of the region and the moderate easterlies will aid in creating low
level moisture convergence across the area resulting in the passage
of occasional bands of moisture with embedded showers across
portions of the north and east sections of Puerto Rico and the U.S.
Virgin Islands. Periods of moderate to locally heavy rains and brief
gusty winds can be expected. Some to these rains will lead to minor
ponding of water on roads. For the rest of the day and afternoon
hours, a break in cloud cover and shower activity is expected,
however available moisture along with local effects and daytime
heating will be sufficient to aid in the development of additional
showers. The activity should then be focused along the central and
west to southwest sections of Puerto Rico and on the west end and
downwind of the U.S. Virgin Islands, steered by the moderate to
strong east to northeast winds. Widespread flooding is not
anticipated, but areas of locally heavy rains may lead to ponding of
water on roads and in poor drainage areas during the rest of the
day. Breezy conditions can be expected due to the tightening of the
local pressure gradient. This will also aid in quickly steering any
developing showers in the form of streamers across portions of the
islands, thus limiting significant and widespread accumulations.

For Saturday and through the weekend a mix of sunshine and variably
cloudy skies can be expected with periods of passing showers
forecast during the overnight and early morning hours, followed by
isolated to scattered shower actvty mainly over the central interior
and west sections of Puerto Rico and mainly downwind of the U.S.
Virgin Islands. Some showers may also develop over the east interior
of Puerto Rico and stream across the San Juan metro during the
afternoon hours, but any activity should be short lived. By Sunday
as previously mentioned , winds are expected to become more
southeasterly. This in turn will bring a surge of trade wind
moisture to the region thus favoring better potential for early
morning and afternoon showers in and around the islands. In
addition a gradual warming trend is forecast with daytime
temperatures expected to be above normal from Sunday into early next
week as the low level winds become more southeasterly.

&&

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

The latest model guidance displays moist tropical air lifting
across the region on Monday as a surface high pressure just east
of the region over the central Atlantic will promote more east-
southeasterly winds. The presence of strong upper-level winds
and a mid-level ridge will provide a variable day of weather with
the potential to observe heavy localized shower activity across
the northwestern sections of Puerto Rico and frequent passing
showers across eastern PR.

On Tuesday, the distance of the surface high pressure in the
central Atlantic and a frontal boundary just over the Hispanola
will cause a veering winds to a southeasterly direction. A slightly
drier airmass will prevail during this time with PWAT values of
1.0 inches. Given the proximity of the pre- frontal trough, a
decrease in the pressure gradient is forecasted, and winds will
lighten across the surface level by Wednesday. Additionally, much
warmer temperatures are forecast for mid-week due to the
southeasterly winds and water content near normal across the
islands. By the end of the week, the island will observe backing
winds and possible a significant increase in moisture from the
previous old frontal boundary. As a result, an increase in the
frequency passing showers and afternoon convection is forecasted
for Friday.


&&


&&

.AVIATION...
(06Z TAFS)

VFR conds at all terminals durg prd but with VCSH at
TJSJ/TJBQ/TISX/TIST til 15/13Z. Mtn top obscr ovr E PR due to low
clds and passing -SHRA/SHRA. L/LVL wnds fm E-NW 15-20 kts BLO FL120
then backing while incr w/ht ABV. SFC wnd mainly fm ENE 5-10 kts but
OCNLY hir with wind gusts accompanying passing SHRA. SCT ocnl BKN
lyrs nr FL025...FL050...FL080 with ISOLD-SCT SHRA en route btw
islands and ovr Nrn PR til 15/14Z.


&&

.MARINE...

A building surface high pressure spreading eastward across the
western Atlantic will yield moderate to locally fresh easterly winds
through the weekend and early next week. These winds will promote
choppy marine conditions where small craft should exercise caution.
Northerly swells will promote hazardous seas through Friday, for the
northern waters, the northwestern waters of Puerto Rico and the Mona
Passage. Small craft advisories remain in effect for these areas.
For details, refer to the latest Coastal Waters Forecast (CWFSJU,
CWFSPN) and Marine Weather Message (MWWSJU).

&&

.BEACH FORECAST...

Mid-period northerly swells and breezy winds will continue to
promote a High Rip Current Risk across the northern coastline of
Puerto Rico, Culebra and the USVI. For details, refer to the
Coastal Hazard Message (CFWSJU) and Surf Zone Forecast (SRFSJU).

Rip currents are powerful channels of water flowing quickly away
from shore, which occur most often at low spots or breaks in the
sandbar and in the vicinity of structures such as groins, jetties
and piers. Heed the advice of lifeguards, beach patrol flags and
signs. If you become caught in a rip current, yell for help.
Remain calm, do not exhaust yourself and stay afloat while waiting
for help. If you have to swim out of a rip current, swim parallel
to shore and back toward the beach when possible. Do not attempt
to swim directly against a rip current as you will tire quickly.
If you do not know how to swim, we advise you to stay out of the
ocean.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
414 AM AST Sat Mar 16 2024

.SYNOPSIS...
.Mid to upper level high pressure ridge extending from the west
central Caribbean into the southwest Atlantic will maintain west
to northwest winds and stable conditions aloft through the weekend.
Building surface high pressure spreading eastward into the central
Atlantic, will maintain moderate to strong easterly winds today,
becoming more southeasterly by Sunday as the high pressure centers
itself across the central and eastern Atlantic. This in turn will
bring a return of occasional moisture fragments from old frontal
boundaries across the region carried by the dominant easterly trades.
A northerly swells will continue to fade across the regional waters,
resulting in a gradual improvement in marine and coastal conditions
during the rest of the weekend into early next week.

&&

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

Scattered showers continued throughout the night over the local
waters, bringing rainfall to coastal regions including San Juan to
Rio Grande and Ponce to Maunabo. There was no significant rainfall
accumulations but enough rain to keep roads wet.

A moist airmass advecting across the region driven by breezy trade
winds will continue to bring passing showers across coastal regions
of northern, eastern, and southern Puerto Rico through this morning.
The main feature influencing this pattern is a robust surface high
pressure that is spread across the northern Atlantic Basin between
30N and 20N. As it moves further into the central Caribbean by this
afternoon, surface to winds will begin to veer to a east-
southeasterly flow bringing a potential for afternoon convection
across northwestern Puerto Rico. Rainfall up to around an inch can
be anticipated across sections that receive the best showers.
Flooding threats remain limited to none, however with heavy showers
ponding of water could occur.

Tonight some drier air is expected to move through before the next
bunch of moisture reaches the area by Sunday, however with the
ongoing breezy conditions passing showers will continue to effect
windward sections through the night. Throughout Sunday and Monday an
advective pattern of passing showers followed by afternoon convection
across northwestern PR will bring beneficial rains across the
islands, especially after last week's dry spell. No significant
weather is expected as a ridge in the mid-levels is helping
stabilize conditions by limiting vertical development to near the
surface which is keeping most the showers shallow and quick.

&&

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

On Tuesday, a broad surface high pressure is forecast to move into
the central Atlantic, as a cold front and associated frontal
boundary will extend from the west Atlantic southwards across
Hispaniola. This will promote veering low level southeasterly
winds across the region. A slightly drier airmass will prevail
through Wednesday with the layered precipitable water content
values (PWAT) forecast to reach around 1.0 inch. By then and
through Wednesday, given the proximity of the pre- frontal trough
and a weak pressure gradient,the local surface winds will become
light and variable across the region. In addition to the drier
conditions, much warmer temperatures are forecast due to the
southeasterly winds and with the water content forecast to be near
normal across the islands. Shower activity will be limited to the
east interior during the overnight and early morning hours followed
by limited afternoon convection over central and west sections of
PR.

By Thursday and or the rest of the period, the pattern changes, as
winds become more east northeast then northeasterly with increasing
moisture convergence across the region due to return moisture from
the previous frontal boundary. As a result, an increase in the frequency
of passing clouds and showers and afternoon shower development is
forecast for Friday and Saturday with better potential for wetting
rains and chance for excessive rains which may lead to ponding of
water on roads or minor urban flooding in isolated areas.

Additionally, due to the prevailing southeasterly winds, expect
warmer and above normal daytime high temperatures at least for
Tuesday and Wednesday, with near normal temperatures forecast for
the rest of the period due to increasing cloud cover and winds
becoming more east to northeast.

&&

.AVIATION...
(06Z TAFS)

Mostly VFR conditions across all terminals, but brief periods of low
ceilings and reduced VIS are possible due to scattered SHRA and
cloudiness crossing the region. Winds will strengthen after 14z out
of the ESE at 15-18 kts, with stronger gusts. VCSH will continue
through the afternoon, especially for TJSJ and TJBQ.

&&

.MARINE...
A broad surface high pressure north of the islands will spread into
the central and eastern Atlantic, promoting moderate to locally fresh
easterly winds through the rest of the weekend and into early next
week. The winds will promote choppy marine conditions across the
local waters and passages where small craft should exercise caution.
A fading northerly swell will continue to affect the local Atlantic
waters and passages through the morning and early afternoon hours.

&&

.BEACH FORECAST...

Coastal conditions continue to gradually improve across the local
region, however a fading northerly swells and breezy conditions
will continue to promote a moderate Rip Current Risk along almost
all beaches except for the protected waters of southern Puerto
Rico. This includes Culebra,Vieques and the U.S. Virgin Islands
as well. The rip current risk is expected to remain moderate
through the rest of the weekend. For details, refer to the
Coastal Hazard Message (CFWSJU) and Surf Zone Forecast (SRFSJU).

Rip currents are powerful channels of water flowing quickly away
from shore, which occur most often at low spots or breaks in the
sandbar and in the vicinity of structures such as groins, jetties
and piers. Heed the advice of lifeguards, beach patrol flags and
signs. If you become caught in a rip current, yell for help.
Remain calm, do not exhaust yourself and stay afloat while waiting
for help. If you have to swim out of a rip current, swim parallel
to shore and back toward the beach when possible. Do not attempt
to swim directly against a rip current as you will tire quickly.
If you do not know how to swim, we advise you to stay out of the
ocean.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
420 AM AST Sun Mar 17 2024

.SYNOPSIS... A surface high pressure moving towards the central and
eastern Atlantic will promote light to moderate southeasterly winds
through at least Tuesday. Passing low level cloud fragments and few
embedded showers will continue to move over the coastal waters, with
some reaching the east coastal areas during the early morning hours.
A drier airmass will gradually filter in across the region with a
more stable weather pattern anticipated during the rest of the day.
Marine and coastal conditions will continue to improve across the
region. However, a moderate rip current risk will continue along
most of the local beaches.

&&

.SHORT TERM...Today through Tuesday...
The arrival of a dry airmass brought clear skies across the region
since the evening hours, lasting through the early morning. Passing
showers have been very scarce, with traces of rain across eastern
sections. Wind speeds have calmed through the night and a land
breeze was able to develop, hinting at a fair weather morning across
most areas.

The prevailing feature remains to be a surface ridge stretching
across the central Atlantic that continues to steer east-
southeasterly surface winds today and as it migrates further east
into the Atlantic basin, surface/lower level winds will continue to
veer arriving at a southeasterly to south-southeasterly direction by
Tuesday. Across the mid-levels ridging will prevail over the
Caribbean helping to maintain variable weather conditions.

This morning is forecast to be quite dry however by the afternoon
hours patches of moist air will arrival among the trades, increasing
the rate of passing showers for eastern Puerto Rico and fueling the
chance for development over northwestern PR. Ponding of water is
possible with consistent shower activity over eastern Puerto Rico,
especially overnight. By Monday moist air continues to linger over
the northern half of the region, allowing a similar pattern to
prevail. As winds continue to veer with the surface ridge moving
further eastward through the Atlantic, drier air is forecast to
arrive on Monday evening which will provide a calm night with very
little to no rainfall.

Fair weather is forecast for Tuesday until the afternoon when south-
southeasterly surface flow will bring a chance for some afternoon
passing showers. Overall an advective pattern is expected and it is
worth noting that temperatures along northern areas may experience
warmer values, even heat indices in the 100s at times mainly across
northern coastal sections of PR.

&&

.LONG TERM...Wednesday through Sunday...
The broad surface high pressure ridge is forecast to lift farther
northwards into the central and northeast Atlantic, as a cold
front and associated frontal boundary will extend from the west
Atlantic southwards across Hispaniola by Wednesday. This will
maintain light southeasterly winds which will become even lighter
but more northeasterly by Thursday, as another high pressure ridge
will build and spread across the southwest Atlantic. A fairly dry
airmass will persist at least through Wednesday with the layered
precipitable water content (PWAT)forecast to range between 1.0-
1.25 inches. Due to the light southeasterly winds, expected mostly
fair weather skies but still warmer than normal daytime high
temperatures. Thereafter local temperatures will be closer to
normal as the local wind become more northeasterly during the rest
of the period. Shower activity will be limited to the east
interior during the overnight and early morning hours followed by
limited afternoon convection over central and west sections of PR.

By Thursday, the overall pattern is forecast to change, as winds
become more northeasterly with increasing moisture convergence
across the region due to remnant moisture from the previous frontal
boundary and that associated with a another cold frontal boundary
from the west Atlantic. As a result, an increase in the frequency of
low level clouds and shower development is forecast at least into
early Saturday with better potential for wetting rains and chance
for excessive rains. This activity may lead to ponding of water on
roads or minor urban flooding in isolated areas. Light easterly
winds return by Sunday with lesser moisture transport and therefore
less chance for shower development in and around the islands.
However brief early morning and afternoon showers will be possible
but should be focused mainly over parts of the east interior and
central and west Puerto Rico respectively.

&&

.AVIATION...
((06Z TAFS)

Mostly VFR conditions expected to prevail. Winds will increase after
14z along with an increase of VCSH by the evening hours into the
night. Afternoon showers possible for TJBQ. Winds will slow down,
below 10 knots after 22Z and will begin to veer to SE on Monday.
&&

.MARINE...

A broad surface high pressure north of the islands will spread into
the central and eastern Atlantic, promoting moderate to locally fresh
easterly winds through the rest of the weekend and into early next
week. The winds will promote choppy marine conditions across the
local waters and passages where small craft should exercise
caution.

&&

.BEACH FORECAST...

Coastal conditions will continue to improve across the local
region today through the early part of the upcoming week.
However, breezy conditions will continue to promote a moderate rip
current risk along almost all beaches of Puerto Rico, Culebra,
Vieques, and the U.S. Virgin Islands. The protected waters of west
and southern Puerto Rico will remain under a low risk. The rip
current risk is expected to remain moderate through the rest of
the weekend and throughout the next workweek.

Rip currents are powerful channels of water flowing quickly away
from shore, which occur most often at low spots or breaks in the
sandbar and in the vicinity of structures such as groins, jetties
and piers. Heed the advice of lifeguards, beach patrol flags and
signs. If you become caught in a rip current, yell for help.
Remain calm, do not exhaust yourself and stay afloat while waiting
for help. If you have to swim out of a rip current, swim parallel
to shore and back toward the beach when possible. Do not attempt
to swim directly against a rip current as you will tire quickly.
If you do not know how to swim, we advise you to stay out of the
ocean.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
434 AM AST Mon Mar 18 2024

.SYNOPSIS...

A surface high pressure moving from central to eastern Atlantic
will continue to promote breezy conditions across the region. A
dry and stable pattern is expected to dominate the local weather
with limited precipitation. However, passing showers across the
windward sections and afternoon convection over northwestern PR
remains possible. An increase of rainfall is expected for
Wednesday onward. Marine and coastal conditions will continue to
improve this week. A moderate rip current risk will remain along
most of the northern beaches of the islands.

&&

.SHORT TERM...Today through Wednesday
Partly cloudy to mostly clear skies prevailed across the region
during the overnight hours with few passing showers noted moving
over the regional waters and passages. Few showers brushed the
windward side of some of the islands from time to time steered by
the prevailing low level southeast winds. However, there were no
significant accumulations so far. Minimum low temperatures were in
the low 70s along the coastal areas and in the upper 50s to low 60s
in higher elevations and valleys with some areas of patchy fog noted
in the interior sections of Puerto Rico. Winds were light between 5
to 10 mph.

A surface high pressure now centered across the northeast Atlantic
and extending southwest into the central Atlantic to just northeast
of the region will aid in maintaining a light to moderate
southeasterly wind flow today, then becoming light and variable by
Tuesday as the local pressure gradient relaxes. For the rest of the
morning a patch of low level moisture in the easterlies will cross
the region and bring periods of mostly light showers to the coastal
waters and windward side of some of the islands. This will be
followed by isolated to scattered afternoon convection mainly over
the central and northwestern sections of Puerto Rico. Mostly fair
weather skies and warm conditions can be expected elsewhere and in
and around the U.S. Virgin Islands during the afternoon. Later in
the afternoon and evening, another slot of dry air will filter in
from the east and thus limit shower activity once again across the
area.

For Tuesday, as previously mentioned, as the surface high lifts
farther northward into the central and northeast Atlantic, local
winds will continue to veer and become even lighter but mainly from
the south southeast. This will result in overall drier and fair
weather conditions, however expect warmer than normal temperature to
continue especially along the northern portions of Puerto Rico and
the island of St Croix at least into Wednesday, with maximum heat
indices possibly reaching the 100s. Main impacts for this day should
be mainly the warmer temperatures with mostly localized isolated to
scattered showers of short duration possible during the afternoon
hours.

On Wednesday as gradual change in the weather pattern is forecast as
a cold front and associated frontal boundary will move into the
southwest Atlantic and approach the region from the west. This will
induce a weak surface trough across the region and slowly increase
low level moisture convergence due to the combination of remnant
moisture from old frontal boundaries and that of the approaching
frontal boundary. In addition the upper level ridging is to erode,
as a short wave trough is forecast to cross the region by then.
Consequently, expect a better chance for more passing morning
showers with increasing probability for afternoon convection across
the east interior and central and west sections of Puerto Rico and
on the west end of the U.S. Virgin Islands where only isolated shower
will be possible. Some of the afternoon shower activity may lead to
ponding of water on roads and in poor drainage areas due to moderate
to locally heavy rains over western Puerto Rico.

&&

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

A weak frontal boundary moving southeastward in the western Atlantic
will begin to pass through the region on Thursday, causing a backing
of the surface winds to more of a northeasterly direction and a
noticeable increase of moisture content moving over the islands
by Friday morning. This shifting of the winds and increase of
precipitable water will bring a wetter pattern with scattered
showers across eastern Puerto Rico and the USVI during the morning
hours followed by afternoon convection across western Puerto
Rico.

On Friday, a surface low begins to develop in the Gulf of Mexico,
migrating into the western Atlantic as it moves along the eastern
coastline of the US meanwhile displaying nor'easter characteristics.
Eastward of this system a strong surface ridge will direct a moist
easterly flow locally through Saturday which will continue the
pattern of an abundance of passing showers with afternoon
convection, with the heaviest rainfall over western Puerto Rico
during the afternoon.

By Sunday the potential nor'easter would of moved into the upper
western Atlantic and a Rossby wave trough develops to the
southwest, positioning north of the region by Monday morning. The
presence of this will cause a veering in the surface winds to a
southeasterly direction on Sunday, becoming southerly and variable
Monday onward. During this time precipitable water values spike
as this long wave pattern brings a moist airmass and unstable
conditions over the eastern Caribbean. This may bring a
significant increase of rainfall across the islands for multiple
areas, however model guidance is subject to change so stay tuned.


&&


.AVIATION...

(06Z TAFS)

VFR conds at all terminals durg prd with VCSH AT TJSJ/TISX/TIST til
18/14Z. Mtn Top Obscr ovr E PR due to low clds and -SHRA. L/LVL wnds
fm SE 15-20 KTS BLO FL150 veering w/height ABV. SFC wnd mainly fm
ESE 5-10 KTS but brief wnd gusts psbl with passing SHRA. Wnds bcmg
fm SE 12-15 kts aft 18/14Z. SCT lyrs nr FL025...FL050. Isold SHRA
ovr regional waters en route btw islands til 18/14Z.


&&

.MARINE...

A broad surface high pressure moving into the central and eastern
Atlantic will continue to promote moderate to locally fresh trade
winds through early in the workweek, resulting in choppy seas. Winds
will slow down by Tuesday and Wednesday, resulting in subsiding seas
and calm conditions across the local waters.


&&

.BEACH FORECAST...

Breezy conditions will continue to promote a moderate rip current
risk along the beaches from northwest to northeastern Puerto
Rico, Culebra, and the northern U.S. Virgin Islands. The
protected waters of west and southern Puerto Rico, Vieques and St.
Croix will remain under a low risk. The rip current risk is
expected to remain moderate throughout this upcoming workweek.

Rip currents are powerful channels of water flowing quickly away
from shore, which occur most often at low spots or breaks in the
sandbar and in the vicinity of structures such as groins, jetties
and piers. Heed the advice of lifeguards, beach patrol flags and
signs. If you become caught in a rip current, yell for help.
Remain calm, do not exhaust yourself and stay afloat while waiting
for help. If you have to swim out of a rip current, swim parallel
to shore and back toward the beach when possible. Do not attempt
to swim directly against a rip current as you will tire quickly.
If you do not know how to swim, we advise you to stay out of the
ocean.

[cycloneye]

Area Forecast Discussion...CORRECTED
National Weather Service San Juan PR
427 AM AST Tue Mar 19 2024


.SYNOPSIS...
Issued at 406 AM AST Tue Mar 19 2024

Today, predominantly clear skies and hot conditions are expected
across the islands. Remnants from a previous frontal boundary will
promote an advective weather pattern late tomorrow and Thursday,
potentially bringing some showers to the area. Furthermore, a
deep-layered trough and its associated frontal boundary could lead
to an uptick in shower and thunderstorm activity early next week
extending into midweek.

&&

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

Overall Mostly clear skies prevailed overnight across the region
with only a few brief showers noted over the offshore regional
waters but none reaching the islands at this time. Minimum low
temperatures were in the low to mid 70s along the coastal areas and
in the low to mid 60s in higher elevations and valleys.Winds were
calm to light and variable.

A surface high pressure anchored across the northeast Atlantic and
extending southwest into the northeast Caribbean and a cold front
and associated frontal boundary crossing the west Atlantic will aid
in maintaining a very light south southeasterly wind flow today
through Wednesday. For the rest of the morning an overall dry and
stable airmass will prevail with little or no shower activity
expected. Weak ridging aloft will remain in place into Wednesday but
will slightly erode by late Wednesday through Thursday as a short
wave trough is forecast to cross the west and central Atlantic.

For today Mostly fair weather skies and hot conditions are forecast
across the islands. Limited to no shower activity is expected as an
overall dry airmass will remain in place at least until early
Wednesday. Therefore expect warmer than normal temperatures to
continue especially along the northern portions of Puerto Rico and
the island of St Croix, with maximum heat indices again reaching the
100s. Main impacts for today and Wednesday should be mainly the
warmer temperatures with mostly localized and brief isolated to
scattered showers if any possible during the afternoon hours.

By late Wednesday and through Thursday, a gradual change in the
weather pattern is forecast as a weakening cold front and associated
frontal boundary will move into the southwest Atlantic and approach
the region from the west. This will induce a weak surface trough
across the region and slowly increase low level moisture convergence
due to the combination of remnant moisture from old frontal
boundaries and that of the approaching frontal boundary. In addition
as mentioned the upper level ridging is to erode, as the short wave
trough crosses the region. Consequently, expect a better chance for
more advective moisture with passing morning showers and increased
probability for afternoon convection across the east interior,
central and west sections of Puerto Rico. Activity for the remaining
islands including the U.S. Virgin Islands should be limited to
mostly isolated showers and focused mainly on the west-end and
downwind of the islands over the coastal waters. On Thursday, some
localized afternoon shower activity may lead to ponding of water on
roads and in poor drainage areas due to moderate to locally heavy
rains over western Puerto Rico.

&&

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

A seasonally typical weather pattern, characterized by patches of
moisture streaming through the area from time to time, will
persist at least through early in the weekend. A weak ridge will
be present at the mid and upper levels, inhibiting significant
shower development, particularly during the afternoons. However, a
deep-layered trough and associated frontal boundary are expected
to slowly approach the region from the northwest. From Sunday
through Tuesday, there will be moisture convergence over the area
as the trough deepens, drawing tropical moisture into the region.
On Monday, with the approach of the deep-layered trough, a 70-80
knot jet is expected to affect the area at around 200 hPa, lasting
into midweek, potentially providing increased ventilation and
supporting additional convective potential.

Discrepancies arise as the latest GFS model now indicates the deep-
layered trough and frontal boundary pushing toward, if not over, the
islands by late Tuesday. Previous model cycles had these features
stalling north of the CWA. In contrast, ECMWF suggests a weaker
solution remaining north/northeast of the islands.

Surface and low-level winds will begin the forecast period generally
from the east to east-northeast, gradually becoming more
southeasterly, and then tending toward southerly by Monday.
Depending on whether or not the frontal boundary actually crosses
the area, winds may shift again, likely becoming more northerly. As
winds shift, wind speeds are expected to decrease, potentially
enhancing rainfall accumulations due to slow-moving storms over the
area.

Showers are expected to follow a typical pattern for the first part
of the forecast period. Friday is anticipated to be very seasonal,
with Saturday being one of the driest days during this period. An
increase in shower activity is likely from late Sunday through
Tuesday due to moisture convergence, the approaching deep-layered
trough, and the influence of the upper-level jet.

Forecast confidence is normal to below normal. Uncertainties
continue to be largely based on the moisture plume- both the timing
and strength of the deep-layered trough and associated frontal
boundary. The likelihood of frontal passage remains uncertain, and
its impact on regional conditions is expected to be felt for much of
the first half of next week.


&&

.AVIATION...
(06Z TAFS)
Issued at 406 AM AST Tue Mar 19 2024

VFR conds at all terminals durg prd. L/LVL wnds fm SE 10-15 KTS BLO
FL080 backing w/height bcmg lgt/vrb up to FL150, then W-NW ABV w/max
wnd btw 60-70 kts btw FL350-FL400. SFC wnd calm to lgt/vrb, bcmg fm
SE 5-15 with sea breeze variations aft 19/14Z. SCT lyrs nr FL025...
FL050.SKC abv. Isold SHRA en route btw islands durg prd. No sig
operational wx impacts attm.

&&

.MARINE...
Issued at 406 AM AST Tue Mar 19 2024

Winds are expected to diminish today as the surface high-pressure
moves eastward over the central Atlantic. This will result in
subsiding seas and calm conditions across the local waters. Winds
will once again increase by the end of the workweek into the weekend
as a strong low-pressure system develops over the western Atlantic.
This will promote moderate to fresh trade winds, resulting in choppy
seas.

&&

.BEACH FORECAST...
Issued at 406 AM AST Tue Mar 19 2024

While winds are expected to subside today, breezy conditions will
persist, contributing to a moderate rip current risk along the
northern beaches of Puerto Rico, Culebra, and the U.S. Virgin
Islands. However, the protected waters of west and southern Puerto
Rico and Vieques will experience a low risk. This moderate rip
current risk is anticipated to continue through tonight, with the
likelihood of rip currents diminishing to low tomorrow across all
local beaches.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
438 AM AST Wed Mar 20 2024


.SYNOPSIS...
Issued at 435 AM AST Wed Mar 20 2024

Today and tomorrow, a pre-frontal trough will lead to an uptick in
shower activity across the area. Slow steering winds will contribute
to increased rainfall accumulations. As a result, a limited to
elevated flooding threat can be expected, particularly over interior
Puerto Rico. Looking ahead, a strong low-pressure system and
associated frontal boundary are forecast to impact the local islands
by early next week. However, uncertainty persists regarding the
timing, location, and eventual rainfall amounts associated with
these features.

&&

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

Clear skies prevailed across Puerto Rico under a very light wind
flow. The current satellite-derived precipitable water imagery show
a dry air mass engulfing the local islands, with a moisture
gradient over the local Atlantic waters. This moisture is associated
to a cold front now over the Bahamas and Cuba, and a prefrontal
trough near eastern Hispaniola. As the day progresses, the moisture
field will approach the area, with precipitable water values
climbing to near normal values for this time of year. The low
pressure associated with the cold front will maintain the gradient
loose, hence winds will remain on the light side. In fact, the low
level steering flow is expected to be around 2 to 8 knots today.
Since skies are clear, enough sunshine is expected to warm up the
surface, with local effects kicking in, resulting in shower activity
developing over the Cordillera Central in Puerto Rico. Due to the
light winds, these showers are not expected to move much, but should
drift mostly toward the south and west. Some minor flooding cannot
be ruled out.

As the workweek ends, a ridge building over the western Atlantic
will cause the winds to shift from the northeast, and strengthen
some. On Thursday, the low level steering flow will be from the
northeast at around 8-10 knots, increasing to nearly 15 knots by
Friday. This ridge will push more moisture from the front into the
local islands. A shortwave trough is also expected to cross the
region on Thursday, so conditions aloft will allow for better
dynamics for shower generation. Regardless, on both days, showers
are expected to develop over the interior, moving toward the south
and west of Puerto Rico. The chances of rain are better on Thursday,
as some patches of drier air are expected to move over the area on
Friday, limiting the coverage of the rainfall activity.

In terms of temperatures, 925 mb values are still above normal for
today, although not as high as yesterday. Still some urban areas
along northern Puerto Rico could experience values above 102 degrees
Fahrenheit. Heat indices should be at 90-95F over the Virgin
Islands. Temperatures should cool down a little for Thursday and
Friday, but with highs still reaching the mid and upper 80s.

&&

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

Moisture availability from the remnants of a frontal boundary will
continue to stream across the region this weekend. Moisture levels
will be near to above climatological normals. The pressure gradient
will tighten as a strong low-pressure system exits the Eastern
Seaboard and pushes against a surface high pressure over the
northern Atlantic. This will promote breezy wind conditions from the
east-southeast. Shower activity will be mostly shallow during this
period, moving quickly due to fast-steering winds. This could
somewhat inhibit rainfall accumulations across the islands.
Nevertheless, ponding of water on roadways and in poor drainage
areas is possible.

Model guidance continues to suggest a frontal boundary approaching
the region from the northwest by late Sunday into early next week.
This front is associated with the aforementioned strong low-pressure
system. Although models have been consistent in the development of
these features, timing, and position continue to differ, not only
between models but also between each model cycle. The 20/00z GFS
model shows the upper-level features a little bit east and north of
the local islands compared to previous runs. However, the surface
low meanders over Puerto Rico and the U.S. Virgin Islands. The
20/00Z ECMWF now places these features a bit closer than before,
with both models indicating the low closest to the islands by
Wednesday. The limiting factor will be moisture availability. Models
suggest a frontal passage (FROPA) by late Tuesday. After the frontal
passage, moisture levels are expected to plummet from approximately
1.60 inches to less than 1.0 inches.

As such, uncertainty persists regarding when the frontal boundary
will be nearest, whether it will pass over the islands, and the
amount of moisture it will bring into the area. This uncertainty
arises from both the front itself and potential moisture convergence
over the area ahead/southeast of the front as it interacts with the
deep-layered low-pressure system.

In summary, stability is expected to decrease from late this weekend
into midweek of next week as the deep-layered trough and associated
frontal boundary approach from the northwest. Moisture convergence
over the region is likely to occur early next week, with the most
probable timing being late Monday into Tuesday. By Tuesday, the
frontal boundary is forecast to be near or over the islands, further
enhancing shower and thunderstorm activity. However, the full
impacts of this frontal boundary remain unclear. Shifting and slow
steering winds will influence the location of the strongest shower
activity, with the extent of wind shifts largely depending on
whether or not a frontal passage occurs. At most, a limited to
elevated flooding threat can be expected, with urban and small
stream flooding likely, and isolated flash flooding in some areas.
Landslides in the most vulnerable places cannot be ruled out.


&&

.AVIATION...
(06Z TAFS)
Issued at 435 AM AST Wed Mar 20 2024

Mainly VFR conditions expected to prevail. SHRA are expected to
develop after 17Z across the Cordillera Central, spreading toward
the south and west. This activity could reach TJPS from 17-22z,
with reduced VIS and low ceilings possible. Winds are on the light
side, out of the ENE at 10 knots or less.

&&

.MARINE...
Issued at 435 AM AST Wed Mar 20 2024

Light east to southeast winds will continue today as the surface
high pressure builds over the eastern Atlantic and a cold front
approaches the northeast Caribbean from the western Atlantic. The
cold front will induce a pre-frontal trough off to the northwest of
PR today. The frontal boundary will linger north of the region
through the second part of the work week, while the moderate to
locally fresh trade winds will push fragments of moisture over the
local waters. Another surface high pressure will build over the
western Atlantic, increasing the winds and seas during the weekend.

&&

.BEACH FORECAST...
Issued at 435 AM AST Wed Mar 20 2024

Today, winds will be calmer, resulting in a low rip current risk
across all beaches of the local islands. However, winds are expected
to increase by the end of the workweek, raising the rip current risk
to moderate once again, mostly across the northern exposed beaches
of the islands.