Caribbean - Central America Weather

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
342 AM AST Wed Jan 24 2024


.SYNOPSIS...

The remnants of a frontal boundary will continue to sink
southward today increasing cloudiness and shower activity across
the local islands. Rainfall accumulations are not expected to be
significant, however, reduced visibility and slippery roads may be
present throughout the day, particularly across northern and
eastern portions of the islands. Breezy to windy conditions will
also impact the region for most of the week. Hazardous marine and
coastal conditions will persist for the rest of the workweek.

&&

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

An analysis of overnight radar and satellite imagery indicated that
most of the region mainly remained rain- and cloud-free, except for
windward areas of eastern and northern Puerto Rico and the US Virgin
Islands, where the remnants of an old frontal boundary began to
bring pockets of low-level clouds and passing showers after
midnight. Overnight temperatures from official reporting sites
ranged from around 62 degrees in higher elevations to about 76
degrees across eastern Puerto Rico and the local islands. Winds were
generally light from the east to east-northeast across windward
areas but calm and variable elsewhere.

Dominant synoptic features during the short-term forecast period
include a persistent mid-level ridge and associated strong trade
wind cap inversion, a building surface high pressure over the
Central Atlantic causing the tightening of the local pressure
gradient, and thus, generating breezy to windy conditions, and the
remnants of an old frontal boundary approaching the local islands
from the north-northeast.

Despite hostile conditions for deep convective development, the
remnant's arrival will cause a considerable rise in moisture levels
to as high as 1.5-1.6 inches, exceeding two standard deviations from
typical seasonal values and supporting an increased chance for
shower activity today into Thursday. While the focus of activity
will likely favor the eastern half of Puerto Rico and the local
islands, other areas may also experience some shower activity.
However, the likelihood of flooding impacts is limited, primarily
attributed to the rapid movement of showers. Rainfall amounts will
likely remain around half to three-quarters of an inch with the most
frequent activity, possibly generating ponding of water on roadways
and poorly drained.

Another dry air mass is forecasted to move over the region by
Thursday evening, with precipitable water values briefly dropping
two standard deviations below typical seasonal values (below 0.9
inches). Consequently, stable weather conditions are anticipated
until the flow generated by the high pressure across the Atlantic
brings intermitted patches of relatively dry and shallow moisture,
leading to variable weather conditions, with no significant flooding
risk expected.

The general forecast features seasonal to below-seasonal
temperatures at 925 bar and consistently higher-than-normal wind
speeds throughout the period. Except for Thursday evening, partly to
variably skies and showery conditions should persist. Daytime high
temperatures will likely stay in the mid 80s, accompanied by east to
east-northeast winds at 15-25 mph with higher gusts.

&&

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

Over the weekend, the surface high pressure will continue to develop
and move into the central Atlantic, resulting in easterly winds
and occasional trade wind showers across the islands. These
showers will be associated with patches of moisture from an old
frontal band pushed across Puerto Rico and the U.S. Virgin Islands
by the easterly winds. The latest model guidance suggests
precipitable water values in the 50th percentile or around normal
climatological values during the weekend. As we head into the
workweek, the mid-to-upper-level ridge will weaken and move
westward, allowing a weak mid-to-upper-level trough to move closer
to the region. This troughing will enhance the vertical
development of rainfall activity across the islands. Additionally,
an upper-level jet maxima of around 60 knots is expected to move
over the forecast area on Monday.

At this time, models suggest an additional increase in moisture with
precipitable water values staying above normal climatological
content from Tuesday into Wednesday. Therefore, we forecast the
best chance for rainfall activity, along with some unstable
weather conditions across Puerto Rico and the U.S. Virgin Islands,
by the end of the long-term period.

&&

.AVIATION...

(06Z TAFS)
VFR conditions will prevail at all terminals, with an
increased chance of SCT-BKN near FL025-050 and SCT SHRA along a
frontal boundary just north of PR and the northern USVI. VCSH/-RA
may lead to brief MVFR conditions but with minimal impact on
operations. E to ENE wind at 5-15 knots, increasing to 16-22 knots
with gusts up to 25-30 knots between 24/13-23Z. Wind speeds will
fall back to 5-15 knots after 43/23Z, but gusty near SHRA.

&&

.MARINE...

A broad surface high pressure ridge building in the western Atlantic
will continue to promote deteriorating seas due to increasing
easterly winds in combination with a northerly swell. A weak frontal
boundary is forecast to sink southwards across the regional waters
by today as the surface high pressure prevails across the western
Atlantic. Therefore, the moderate to fresh easterly winds will
continue through the end of the workweek, thus prolonging hazardous
marine conditions.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
350 AM AST Thu Jan 25 2024

.SYNOPSIS...

The remnants of an old frontal boundary will continue to cross
the forecast area as it sinks southwards, maintaining cloudy skies
and showery weather conditions through this afternoon. The
weather pattern should remain relatively dry and stable despite a
patchy weather scenario expected from Friday into early next week.
The remnants of another frontal boundary aligned with a deep-
layer trough could promote increased shower activity by midweek
next week. Hazardous marine and life-threatening rip current
conditions will continue into the weekend.


&&

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

Showers from a cold front moved across the eastern and northern
municipalities of Puerto Rico, and over the U.S. Virgin Islands at
times. There was no heavy accumulation, though. It was breezy too,
with the airports across the islands showing winds at 15 mph, with
gusts around 25-30 mph. Skies were mostly cloudy.

The main story for this period is the strong winds across the
region. A surface high pressure over the western Atlantic maintain
the gradient tight, with wind speeds around 20 to 25 mph out of the
northeast. The gradient is expected to relax just a little by the
end of the week, with a low level steering flow of 20 knots on
Friday and around 16 knots on Saturday. At the mid and upper levels,
high pressure also dominates, with very dry air above 700 mb. The
trade wind cap will also be strong, so lingering showers will be on
the light or moderate side.

For today, recent satellite-derived precipitable water indicates
that the main moisture field of the cold front that crosses the area
on Wednesday is now over the Caribbean waters. Some moisture and
clouds remain over the local islands, and showers will persist this
morning, leaving wet roads in some areas. By the afternoon hours,
precipitable water values will fall below the climatological mean
for this time of year, so shower activity will decrease by then. For
the rest of the period, generally tranquil conditions (in terms of
rain) are expected, but brief, small and shallow patches of moisture
may make their way into the islands at times.

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

In the extended forecast period, the persistent mid-level ridge
over the Caribbean in recent days is expected to shift south-
southwestward, moving away from the region. This shift will be
influenced by a deep-layer polar trough advancing westward across
the western Atlantic, extending southward into the northern
Caribbean. As a result of this transition, the trade wind cap
inversion will weaken, creating conditions that will likely become
marginally conducive for deep convective development, with
moisture exceeding the 700 mbar layers.

At the surface, a frontal boundary moving off the east coast of
the United States will steer a high-pressure system into the
central Atlantic. Consequently, easterly winds on Sunday will veer
progressively from the southeast and weaken on Monday. As the
frontal boundary and its associated pre-frontal front approach the
northeastern Caribbean, winds will become variable from Tuesday
onward, with a slight southerly component on Tuesday and a
northeasterly component on Wednesday and Thursday.

Regarding moisture and showers, the transition from a patchy and
variable weather scenario from Sunday to early Tuesday,
characterized by intermittent patches of relatively dry and
shallow moisture, is expected to evolve into a wetter pattern
starting Tuesday. This shift is associated with the remnants of
the frontal boundary moving over the local islands, leading to a
significant increase in precipitable water and, consequently, a
heightened likelihood of shower activity.

Currently, model-estimated precipitable water values indicate
normal to slightly below normal seasonal moisture levels ranging
between 1.1 and 1.4 inches early in the period. However, these
values are projected to rise to one standard deviation, reaching
around 1.6 inches on Wednesday, and nearly two standard
deviations, reaching approximately 1.8 inches on Thursday. The
anticipated increase in shower activity raises concerns about
potential flooding impacts, particularly in windward areas of
Puerto Rico and the local islands.

Temperatures will also respond to wind and moisture variations.
The warmest days are expected to occur following days with
southerly winds, specifically on Monday and Tuesday, whereas
cooler temperatures are anticipated on Wednesday and Thursday.


&&

.AVIATION...

(06Z TAFS) Windy conditions will persist through the forecast
period, out of the ENE at 22-25 kts, with 25-25 kts gusts. SHRA
will continue across the area, with periods of low ceilings for
the USVI and TJSJ terminals. SHRA should taper off from 15-18Z.


&&

.MARINE...

A broad surface high pressure ridge in the western Atlantic will
continue to promote fresh to locally strong easterly winds. These
winds and a northerly swell will maintain deteriorating seas of up
to 10 feet across most local waters, prolonging the hazardous
marine conditions for small craft into the weekend. A weak frontal
boundary will continue to sink southwards across the regional
waters today, generating isolated to scattered shower activity.


&&

.BEACH FORECAST...

Life-threatening rip current conditions will continue for most
local beaches for the rest of the week. For more information,
please refer to the latest Coastal Hazard Message (CFWSJU) and
Surf Zone Forecast (SRFSJU).

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
406 AM AST Fri Jan 26 2024

.SYNOPSIS...The weather pattern should remain relatively dry and
stable despite a patchy weather scenario prevailing into early
next week. The remnants of another frontal boundary aligned with a
deep-layer trough could promote increased shower activity by
midweek next week. Hazardous marine and life-threatening rip
current conditions will continue through the weekend.


&&

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

Satellite imagery shows fragmented patches of clouds moving from the
northeast into the islands. A few very light showers moved over
eastern Puerto Rico, but accumulations were very light. Skies were
clear elsewhere.

Satellite-derived precipitable water imagery indicate that a very
dry air mass has moved over the northeastern Caribbean, putting an
end to the shower activity that was observed over the past two days.
The forecast has not change too much since last time, with ridge
dominating at the mid and upper levels. At the surface, high
pressure centered well north of the region maintains the gradient
tight today, with wind speeds around 20 knots at surface. As a cold
front exits the eastern coast of the United States this weekend, the
surface high pressure will migrates toward the central and eastern
Atlantic. This will cause the gradient to weaken, and wind speeds
will fall to around 16 knots on Saturday and 12 knots on Sunday.

As the frontal system approaches, the winds will begin to shift more
from the south on Sunday. This may bring additional patches of
moisture into the region, with an increase in the chance of showers
this day. Temperatures will gradually increase too, with lows and
highs again above the climatological value for late January.

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

The long-term weather outlook remains essentially unchanged, with
minor adjustments in the timing of moist and dry intervals. A
mid-level ridge will continue to move south-southwestward and away
from the region, influenced by a short-wave trough advancing
westward across the western Atlantic and extending southward into
the northern Caribbean. As a result, the trade wind cap inversion
will weaken, creating conditions that will likely become
marginally conducive for deep convective development, with
moisture exceeding the 700 mbar layers.

At the surface, a frontal boundary moving over the western
Atlantic will approach the northeastern Caribbean while steering
a high-pressure system into the central Atlantic, weakening the
local pressure gradient. Consequently, southeasterly winds on
Monday will gradually weaken and become variable between Monday
night and Tuesday. As the frontal boundary and its associated pre-
frontal front linger across the region, winds will become
northeasterly on Wednesday, veering from the east on Thursday and
southeast on Friday.

Regarding moisture and showers, the transition from a patchy and
variable weather scenario, characterized by intermittent patches
of relatively dry and shallow moisture, is expected to evolve into
a wetter pattern starting Tuesday. This shift is associated with
the remnants of the frontal boundary moving over the local
islands, leading to a significant increase in precipitable water
and, consequently, a heightened likelihood of shower activity. By
Friday, patches of drier air will move in, causing precipitable
water values to drop again to typical seasonal thresholds.

Model-estimated precipitable water values indicate normal to
slightly below normal seasonal moisture levels ranging between
1.1 and 1.4 inches on Monday. However, these values are projected
to rise to one standard deviation, reaching around 1.5 inches on
Tuesday, and remain nearly two standard deviations, around 1.8
inches, from Tuesday evening into Thursday evening. The
anticipated increase in shower activity raises concerns about
potential flooding impacts, particularly in windward areas of
Puerto Rico and the local islands.

Temperatures will also respond to wind and cloud cover variations,
with warmer-than-normal temperatures likely throughout the
period. The coolest periods are expected to occur following days
with northerly winds, specifically on Wednesday.


&&

.AVIATION...
(06Z TAFS)

Mainly VFR conditions are expected to prevail through the forecast
period. It will be breezy though, with winds at FL050 out of the E
at 18-22 kts and stronger gusts, mainly from 12Z to 21Z. SHRA will
be very limited, with no impacts to operations expected.


&&

.MARINE...

A surface high-pressure building north of the islands across the
Atlantic Ocean will promote moderate to fresh easterlies through
next week. The combination of choppy seas and a northerly swell
will promote hazardous marine conditions through this weekend.


&&

.BEACH FORECAST...

Life-threatening rip current conditions will continue for most
north- and east-facing beaches through Saturday afternoon. For
more information, please refer to the latest Coastal Hazard
Message (CFWSJU) and Surf Zone Forecast (SRFSJU).


&&

.FIRE WEATHER...

Today, a dry air mass with moisture content below normal will
likely result in humidity levels ranging from the lower 40s to mid
50s. Coupled with breezy conditions at approximately 15-20 mph and
occasional stronger gusts, the absence of anticipated wetting
rains, ongoing abnormally dry to moderate drought conditions,
notably dry soils, and available fuels, the prevailing weather
conditions are expected to heighten the risk of wildfires
spreading. As a result, a Fire Danger Statement (RFDSJU) has been
issued for all Puerto Rico, with the highest risk across southern
coastal areas.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
339 AM AST Sat Jan 27 2024


.SYNOPSIS...
Fragmented group of clouds will continue to make their way into
the local islands, but no heavy or long lasting rains are
anticipated in the next couple of days. Winds will gradually die
down by early this week. At the same time, temperatures will
become warmer. Another cold front is expected to approach by
midweek. Marine conditions will gradually improve today, but
another swell will arrive by the middle of the workweek.


&&

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

Recent satellite imagery and doppler weather radar showed fragments
of low level clouds and passing showers moving in and out of the
region steered by the moderate to strong low level wind flow. Most
of the showers were light to moderate, of short duration and so far
have left little or no accumulations. Brief gusty winds accompanied
the passing showers from time to time. Overnight low temperatures
were in the low to mid 70s along the coastal areas and in the upper
50s to low 60s in higher elevation and valles. Surface winds were
calm to light and variable inland and less than 10 mph long the
coastal areas.

Deep layered high pressure ridging across the west and central
Atlantic will maintain moderate easterly winds today with a fairly
strong 2-5 degree cap inversion through the weekend and into early
next week. That said, fragments of trade wind moisture from old
frontal boundaries will make its way across the region, bringing
periods of shallow low level clouds and passing showers to the
islands and coastal waters, especially during the evening and early
morning hours. This will be followed by overall fair weather skies
with showers limited to isolated areas across the interior and west
sections of Puerto Rico steered by the dominant easterly trades.
Elsewhere and around the U.S. Virgin Islands, except for passing
early morning showers , any shower activity if any will be mostly
downwind of the islands and over the coastal waters as mostly fair
weather skies will prevail. No significant weather impacts are so
far forecast for the period as overall dry and stable airmass are
expected to persist. Winds are however forecast to become light and
more southeasterly by late Sunday into Monday resulting in warmer
unseasonal temperatures once again.

As previously mentioned the local pressure gradient will relax
resulting in light southeasterly winds by Late Sunday into Monday as
the surface high pressure will shift farther northwards into the
northeast Atlantic and a cold front enters and crosses the west
Atlantic. As a result local temperatures will gradually increase
with lows and highs again forecast to be above the climatological
value for late January.

&&

.LONG TERM...Tuesday through Saturday

A deep-layered trough moving over the western Atlantic will cause
the trade winds to collapse by the middle of the week, with very
low speed values anticipated. This low pressure will also escorts
a cold front that will be located northwest of Puerto Rico by
Tuesday. The front will be meandering north of the region through
much of the workweek, with the moisture field reaching the islands
at times. With the light wind flow, some convection should develop
along the Cordillera Central, drifting toward the northern
municipalities of Puerto Rico. So far, none of the global models
are showing significant moisture amounts, or even good dynamics at
the upper levels, so these showers should leave modest rainfall
accumulations.

As the deep layered trough moves toward the central Atlantic, high
pressure will build just northwest of the islands, and winds will
recover a little bit. However, this will not last long, as another
trough/low pressure system is expected to exit the eastern coast
of the United States by late Thursday. Winds will slow down again,
and some showers may reach the islands by then. Once again, no
significant amounts are anticipated.

&&

.AVIATION...
(06Z TAFS)

VFR conds durg prd. SCT ocnl BKN lyrs nr FL025.. Wdly SCT
.FL050 ovr regional waters and en route btw islands with wdly SCT
SHRA/-SHRA. Brief MVFR and Mtn Top obscr w/passing clds and SHRA ovr
E interior sections of PR. L/Lvl wnd fm E 15-20 kts BLo FL100, then
backing and bcmg fm N-NW ABV. SFC wnd E-SE 5-10 kts bcmg fm ENE at
12-18 kts and ocnl hir gusts aft 27/14Z. Brief wind gust may also
accompany passing showers.

&&

.MARINE...
A surface high-pressure north of the islands across the Atlantic
Ocean will promote moderate to fresh easterlies through tomorrow.
The combination of choppy seas and a northerly swell will promote
hazardous marine conditions through tonight. A surface low and its
cold front exiting the Eastern Seaboard around Sunday will generate a
northwesterly swell forecast to arrive by mid next week.

&&

.FIRE WEATHER...
No wetting rains are on sight for the southern plains of Puerto
Rico. Additionally, winds remain enhanced, out of the east at
around 15 to 20 mph, with stronger gusts. These conditions would
favor the spread of fires along these areas. For these reasons,
the risk for fire weather will be elevated today.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
330 AM AST Sun Jan 28 2024

.SYNOPSIS...
Shallow patches of moisture are expected to move in at times
across the northeastern Caribbean, but no significant rains are
expected. Winds are slowing down and will become light and
variable by Tuesday. A weakening cold front will approach by the
latter part of the week, although no significant rain impact is
anticipated.

&&

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

The deep layered ridge spread across the west and central Atlantic
will hold across the region today, but is later forecast to
gradually erode in response to an upper trough crossing the
Atlantic. In the meantime, overall dry and stable conditions aloft
will be maintained through Monday. The local trade winds will
however continue to diminish today through Monday, as the surface
high pressure will lift farther north into the northeast Atlantic
causing the winds to become light from the southeast. By Tuesday,
the low level winds are to become light and variable but with a
southerly component, as a weakening cold front and associated band
of frontal moisture is forecast to sink southwards and sag just
northwest of the region.

Until then, shallow patches of trade wind moisture will continue to
cross the regional waters and brush parts of the north and east
coastal areas of the islands time to time mainly during the early
morning hours. Mostly fair weather and limited to no shower activity
is forecast for today. Slightly breezy conditions may continue along
the coastal areas as local sea breezes kick in. Elsewhere and around
the U.S. Virgin Islands, other than the slight chance of a few
passing morning showers, overall sunny skies and pleasant weather
conditions will prevail today through Monday.

No significant weather impacts are so far forecast for the period as
an overall continued dry and stable weather pattern will remain in
place. Local winds are still forecast to diminish and become light
and southeasterly by Monday, then even lighter and more southerly on
Tuesday. This will result in warmer than normal temperatures Monday
and Tuesday. So far, the overall pattern and model guidance
continued to suggest no significant moisture transport across the
region with only marginal upper level dynamics and instability aloft
expected Monday into Tuesday, as the broad upper trough crosses the
Atlantic just north of the region. That said , the best day for
daytime shower development during the period far looks like Tuesday
due to the light southeasterly winds and low level level convergence
induced by a weak prefrontal trough expected to set up in advance of
the frontal boundary which as mentioned is to settle just northwest
of the islands over the offshore Atlantic waters.

&&

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

A cold front will be centered just north of the region, while a
surface high pressure system will be located over Hispaniola. This
will create light and variable winds over the northeastern
Caribbean. So far, the guidance does not show this feature crossing
the islands, but some moisture will linger around, increasing the
frequency of showers over the waters. The light steering flow will
aid in the development of activity across the Cordillera Central,
but the dynamics aloft are not favorable for the activity to be too
strong.

Simultaneously, a new low pressure system will exit the Eastern
Seaboard. The associated front of this low will merge with the
moisture field from the previous frontal system and should reach the
islands by late Thursday into Friday. Similar conditions are then
expected to prevail through the end of the workweek, with winds on
the light side, and some showers around the local waters, and
developing in the afternoon over the interior of Puerto Rico.

For the weekend, a drier air mass will follow after the passage of
the frontal boundary. The trade winds will stayed collapsed, with a
steering flow around 3 knots on Saturday and 5 knots on Sunday.
Although moisture levels will be lower than normal, dynamics aloft
will be somewhat more favorable, with a jet stream moving over the
region. Again, the greatest chance for showers will be for the
interior of Puerto Rico, with the activity then spreading toward the
coastal areas.

&&

.AVIATION...
(06Z TAFS)

VFR cond at all terminals. SCT lyrs nr FL030...FL050. Isold trade
wind SHRA en route btw islands and over regional waters. Brief VCSH
psbl at TJSJ/TIST/TISX til 28/13Z. Sfc wnd calm to lgt and vrb ,
bcmg fm E-NE 12-15 kts with sea breeze variations and ocnly hir
gusts to around 20 kts aft 28/14z. No sig operational wx impacts
fcst for the period.



&&

.MARINE...
A surface high pressure north of the islands will promote moderate
easterlies through tonight. Choppy seas will prevail through today.
A surface low and its cold front exiting the Eastern Seaboard is
moving eastward across the Western Atlantic and will generate a
northwesterly swell forecast to arrive by mid-week.


.FIRE...
Conditions should be a little drier than yesterday, when a small
patch of moisture moved in. Plenty of sunshine is expected for the
south plains. Additionally, winds are out of the east at around
15 to 20 mph, with stronger gusts. These conditions would favor
the spread of fires. For these reasons, the risk for fire weather
will be elevated today.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
449 AM AST Mon Jan 29 2024

.SYNOPSIS...
Satellite imagery depicted mostly clear skies with only a few patches
of shallow low to mid level clouds noted over the Atlantic waters and
the Anegada passage. The doppler weather radar detected little or no
precipitation overnight. A dry and stable airmass remained anchored
across the region dominated by a high pressure ridge aloft and light
east to southeast winds. The surface high pressure ridge will gradually
lift northwards into the northeast Atlantic as a cold front crosses
the west Atlantic while weakening. Local winds will continue to diminish
and become light and variable by Tuesday as the remnants of the cold
front and a short wave trough aloft approaches the region by midweek.
This will favor better moisture convergence and instability aloft, allowing
better potential for shower activity across the region by midweek. Cool
overnight temperatures can be expected but warmer then normal high temperature
are forecast especially along the north coastal areas for today and
Tuesday.

&&

.SHORT TERM...Today through Wednesday...
Only a few clouds were observed during the nighttime across the
local islands, while some showers streamed over the Atlantic waters
north and northwest of Puerto Rico, and also around the Virgin Islands.
The most recent satellite-derived precipitable water imagery indicates
a dry air mass engulfing the northeast of the Caribbean, while a weak
surface trough over the Leeward Islands will continue to move to the
northeast without reaching the area of responsibility.

A deep-layered trough just offshore of the eastern coast of the
United States, as well as the surface trough east of the islands,
are maintaining weak trade winds, with a forecast steering flow of
nearly 5 knots on Monday, barely 2 knots on Tuesday, and 6-8 knots
on Wednesday. The winds will also be shifting from the south on
today through Tuesday, and temperatures will be above average
these days.

In terms of rain...for Monday, it will be on the dry side, and
conditions should be fair. By Tuesday and Wednesday, however, a
cold front will approach and stall just north of the local islands.
Moisture content will increase, and along with local effects, there
will be a better chance for showers to develop across the Cordillera
Central and then stream toward the coastal areas. With the wind flow
being so light, it will be hard to pinpoint exactly where the showers
will move after they form. Rainfall accumulations should be moderate,
with some ponding of water possible.

&&

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

Moisture remnants from the aforementioned frontal boundary will linger
near of just north of the region, while a surface high pressure system
will spread across the southwest Atlantic. This will create light and
variable winds over the forecast area through most of the period. Recent
model guidance and the overall weather pattern does not suggest
that this frontal boundary will cross the islands, however low level
moisture convergence may increase the chance for showers over the
coastal waters and mainly along the north and east coastal sections
of Puerto Rico and the northern U.S. Virgin Islands on Thursday
and Friday. The light steering flow and pockets of shallow moisture
will also aid in the development of shower development mainly across
the central interior of Puerto Rico. However, the conditions aloft
will not be favorable for significant development.

By the upcoming weekend and into Monday, a much drier air mass is
so far forecast based on the latest model guidance, as the moisture
fragments from the old frontal boundary will erode leaving mostly fair
weather skies. Only shallow patches of low clouds and less frequent
passing showers are forecast to affect the region from time to time
steered by the prevailing winds which are forecast to remain fairly
light resulting in less moisture transport. Additionally,conditions
aloft will only be marginally favorable for convective development
under a westerly wind flow with a jet segment quickly crossing the
area just north of the region. That said, the best chance for any
shower development will be for the interior sections of Puerto
Rico Rico during the afternoon, with the activity later drifting
toward the coastal areas. No significant rainfall accumulations
or weather impacts are so far expected across the islands during
the period.

&&

.AVIATION...
VFR conditions are expected to prevail through the forecast period.
Winds will be on the light side through 14Z, below 6 kts, and
picking up to 7-11 kts after 14Z. Winds will be shifting from the
southeast before 12Z for the USVI and TJSJ terminals, and then
from the south for all terminals after 16-18Z. Variations due to
sea breezes can be expected. SHRA is not expected to impact
operations.

&&

.MARINE...
Surface high pressure ridge across the central and northeast Atlantic
and a weak surface trough near the northern Leeward Islands will promote
gentle to moderate east southeast winds across the local waters and
passages today, then becoming even lighter and more southerly by mid
week. A cold front moving eastward across the west Atlantic will approach
the region by mid- week increasing the chance for showers across the
local waters. A northerly swell generated by the surface low associated
with the cold front will arrive from Wednesday onwards. Overall Seas
between 1 to 4 feet and winds between 5-15 knots will prevail across
the local waters and passages at least until Tuesday.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
422 AM AST Tue Jan 30 2024

.SYNOPSIS...

Above normal high temperatures will persist today particularly along
the north coastal areas of Puerto Rico, under light and variable winds
but with a southerly component most of the day. Expect sunny skies
and fair weather across the region with little or no shower activity
expected in most areas at least until the early afternoon hours. The
remnants of a cold front and a short wave trough aloft is forecast
to approach the region later today through Wednesday, then linger near
or just north of the region through the second half of the workweek.
By then, this pattern should slightly increase instability aloft and
low level moisture convergence, thus favoring better potential for
shower activity. Considering the weak steering wind flow, any afternoon
convection should be focused mainly over the central interior sections
of Puerto Rico each afternoon. Cool and near normal overnight temperatures
can also be expected during the period.

&&

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

Clear skies prevailed overnight with no rainfall across the area as
dry air continues to remain across the northeast portion of the Caribbean.
Fair weather conditions are forecast throughout this morning before
a short wave frontal trough begins passing by during later this afternoon
through Wednesday. This will cause a veering in the wind direction from
mostly southerly to northerly by the evening and associated moisture
with this feature should bring an increase of showers during the
late afternoon hours especially for the central portions of Puerto
Rico, however nothing significant is expected.

With light northerly flow on Wednesday, an increase of passing
showers is forecast for northern sections of Puerto Rico and the
USVI. During this time, across the upper levels a ridge continues
to stretch across the southern Caribbean, which will aid in
preventing any significant rainfall. The development and movement
of an area of low pressure in the western Atlantic Wednesday night
into Thursday will maintain a lighter wind flow throughout these
days, with a return to a southerly direction by Thursday morning,
however veering by the evening back to the north. Temperatures are
expected to be slightly cooler than average with the arrival of
northerly winds over the next few days.

&&

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

Remnant moisture from the lingering frontal boundary will continue
across the region but will gradually erode on Friday into the upcoming
weekend, while a weak surface high pressure ridge will spread eastwards
and anchor across the southwest Atlantic. This will favor light and
variable surface winds over the forecast area through most of the period
but with a more southerly component by Monday and Tuesday. Recent model
guidance suggest that this frontal boundary will not cross the islands,
however low level moisture convergence may increase the chance for
showers over the coastal waters and mainly along the north and east
coastal sections of Puerto Rico and the northern U.S. Virgin Islands
through Friday. The light steering flow and pockets of shallow moisture
will however also aid in the development of showers mainly across the
central interior of Puerto Rico. However, conditions aloft will remain
unfavorable for significant and widespread development.

By the weekend overall drier conditions are so far forecast. Afternoon
shower development cannot be ruled out, as remnant moisture will
linger across the region. In addition, the upper ridge is to erode
as broad polar trough crosses the Atlantic, favoring the passage
of a jet maxima which is to round the base of the upper trough and
cross the region Saturday into Sunday. Occasional patches of low
level moisture are forecast to affect the region from time to time
steered by the prevailing winds which are forecast to remain
fairly light. That said, the best chance for shower development
will be over the interior sections of Puerto Rico during the
afternoon hours especially on Sunday, with the activity later
drifting toward the coastal areas. Thereafter, only shallow moisture
and less frequent passing showers are forecast to affect the islands
steered by the prevailing south to southwest low level wind flow
forecast to remain light resulting in less moisture transport. No
significant of widespread rainfall accumulations or weather impacts
are so far expected across the islands during the period but brief
periods of wetting rains will remain possible the latter part of
the period.

&&

.AVIATION...
(06Z TAFS) VFR conditions are expected to prevail through the forecast
period. Winds will be on the light side through 14Z mostly from the
south/west then shifting to north after 16-18Z. Variations due to
sea breezes can be expected. Showers are likely to increase during
the evening for northern terminals. SHRA is not expected to impact
operations.

&&

.MARINE...
Surface high pressure ridge across the central and northeast Atlantic
and a weak surface trough across the northeast Caribbean will promote
gentle south to southeast winds across the local waters and passages
overnight, becoming even lighter and more southerly by Wednesday.
A weakening cold front moving eastward towards the western central
Atlantic will approach the regional waters later today and Wednesday,
then linger across the area through the end of the workweek. This
will increase the chance for mostly isolated showers over the Atlantic
waters. A northwest to north swell generated a distant surface low
an associated cold front will arrive and affect the local waters
and portions of the local passages from Wednesday onwards.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
530 AM AST Wed Jan 31 2024

.SYNOPSIS...
Increasing low to mid level moisture from the remnants of a cold
front now quickly approaching the Atlantic waters and local areas
will increase the potential for scattered to locally numerous showers
across portions of the islands today and through at least Thursday.
Rainfall accumulations have so far been between an inch to two inches
overnight. Additional amounts near an inch or so will be possible
in isolated areas mainly along the northern half of Puerto Rico,
adjacent islands and portions of the U.S Virgin Islands later in
the day and overnight. Ponding of water on roadways and poorly
drained areas is possible with minor urban flooding possible in
isolated spots. Low level winds will remain light but will become
more south to southwesterly later in the afternoon and overnight.

&&

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

The passage of a frontal boundary brought numerous to scattered
showers across northern Puerto Rico throughout the night with most
of the northern coastline receiving rainfall. Winds were light and
variable with this shower activity. This pattern of showers
spreading across northern Puerto Rico will continue throughout today
as this frontal boundary passes through the islands. The movement of
a low pressure system moving into the northern central Atlantic will
keep winds light across the area, which will allow showers to linger
at times. Due to slow moving showers, there is a risk of flooding
mainly across northern Puerto Rico which may be seen in the form of
urban and small stream flooding. Ponding of water is likely to occur
across San Juan and other urbanized areas.

This rainfall pattern will continue over the next few days. However,
a veering in the surface winds arriving to a southwesterly
direction on Thursday will occur due to the development of a
frontal cyclone in the western Atlantic. This will cause afternoon
rainfall to congest across northeastern Puerto Rico, which will
be more sensitive to rainfall due to a day of prior rainfall.
Again flooding across areas of poor drainage is possible. Winds
speeds should remain light, allowing showers to linger. By Friday
northerly winds will begin to prevail as the frontal cyclone moves
northeast of the area, which will bring cooler temperatures and a
band of moisture that will further the pattern of showers across
northern Puerto Rico with afternoon activity for the central to
southern hills.

&&

.LONG TERM...Saturday through Wednesday...
Overall drier conditions are so far forecast for the weekend.
However early morning and afternoon shower development cannot be
ruled out, as remnant moisture will linger across the area. The
upper level ridge will continue to erode as a broad polar trough
crosses the Atlantic and eventually become amplified just west of
the region by the latter part of the period. This will favor the
passage of a series of jet segments along with increasing instability
aloft beginning on Saturday and continuing through the weekend. Available
moisture and local effects will therefore enhance afternoon showers.
In the meantime, occasional patches of low level moisture will be gradually
lifted across the region steered by the light prevailing south to southwest
winds. The best chance for shower development will be over the central
interior and north sections of Puerto Rico during the afternoon hours
over the weekend with the activity later drifting toward the north
and east coastal areas. By Monday and for the rest of the period
a wetter pattern appears to unfold based on recent model guidance
which now suggests increasing west to southwest wind flow accompanied
by increasing instability aloft due to the amplifying upper trough
west of the region and the approach of yet another cold frontal
boundary which will bring increasing low level moisture convergence
as well.

&&

.AVIATION...
SHRA expected to increase gradually from the NW as a front moves
across the local area this morning. Mostly VCSH expected across all
terminals, but mainly for TJSJ/TJBQ. Light and variable winds expected
through the day/night, with an easterly component dominated by local
sea breeze variations.

&&

.MARINE...
A surface high pressure across west Atlantic and a weak surface trough
across the northeast Caribbean will promote light northerly winds this
morning, then becoming more southerly later today. A weakening cold
front moving eastward into the west central Atlantic will sag southwards
and linger across the area through the end of the workweek, increasing
the chance for showers mainly over the Atlantic waters and local passages.
Northwest to north swells generated a distant surface low an associated
cold front will arrive and affect the local Atlantic waters and passages
later today eventually leading to hazardous marine conditions for small
craft. As a result precautionary statements and Small craft advisories
will be possible later tonight and more likely Thursday and into the
weekend. Please refer to the latest Coastal Waters Forecast (CWFSJU)
issued by NWS WFO San Juan Puerto Rico.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
517 AM AST Thu Feb 1 2024

.SYNOPSIS...

Frontal boundaries and remnants will promote variable weather
conditions over the area. A general drying trend is expected by
tomorrow and into the weekend, with shallow moisture still
affecting the region. Gradually increasing moisture is forecast
during the next workweek. Deteriorating marine and coastal
conditions are expected tonight and through Saturday with the
arrival of northwest to north swells. Rip Current Statements and
Small Craft Advisories will be in effect.

&&

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

Showers dissipated over land during the night and other showers
tended to form briefly over the Caribbean waters. By the predawn
hours, a few showers moved into Guanica with minor accumulations.
Temperatures over land varied from the lower 60s to the mid 70s with
a few of the higher valleys reaching the 50s. Skies were mostly
cloudy all night.

A surface low pressure and its trough at mid levels aloft have moved
into the western Atlantic around 30 degrees north latitude and will
continue to move east northeast through Friday night. This will
bring in a reinforcing cold front overnight north of the area
tonight. At that time another low pressure will move southeast out
of New York. Although distant, this will keep surface winds
generally lighter than usual and allow the multiple fronts to merge
into a diffuse boundary with patchy moisture in a layer generally
below 12.5 Kft. This boundary will continue to produce some showers
Friday. Moisture will continue through the period, but forcing will
be minimal Friday night. Better showers and forcing will likely be
seen when winds just above the surface become southwesterly
Saturday. At upper levels WNW winds of 60 to 70 knots will continue.
These will gradually become west southwest on Saturday. A warming
trend is expected to begin on Saturday. Although showery weather
will continue, some sun is also expected each day.

&&

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

No major changes to the long term forecast, Sunday appears to be
the driest in the period as only patches of moisture managing to
reach and move across the area, under light wind flow. A
transition into a wetter pattern will is forecast as we enter the
workweek as winds increase and reinforce a sw to southerly
component. Instability increases as an amplifying upper trough
west of the region by Tuesday will continue moving northwestward
across the Atlantic. A frontal boundary will also bring an
increase in low level moisture and convergence. Current model
guidance indicates precipitable water values (PWAT) increasing to
above seasonal values for this time of the year across sectors of
the eastern region as moisture from the frontal boundary affect
the region, particularly on Tuesday evening into Wednesday, with
normal to above normal PWAT values lingering into Thursday. This
will promote increasing rain chances as we move towards midweek.
SSW winds are forecast to decrease Wednesday onwards, taking on a
more westerly component on Thursday.

&&

.AVIATION...
(06Z TAFS)
Issued at 430 AM AST Thu Feb 1 2024

The cold front across the areas will continue to sag slowly south
until 02/02Z, but the axis of best mstr is expected to remain over
Puerto Rico and the U.S. Virgin Islands. VFR conds with isold -SHRA
will cont thru 01/14Z then areas of SHRA and lwr clds will form with
areas of MVFR and mtn obscurations. Sfc winds VRB genly less than 10
kt bcmg westerly 6-10 kt with sea breezes. Max winds WNW 70-80 Kt
btwn FL385-435.

&&

.MARINE...

A surface high pressure across the west Atlantic and a weak surface
trough across the northeast Caribbean will promote light southerly
winds today. A weakening cold front just over the region will
continue to enhance shower activity over the local waters through the
end of the workweek. Northwest to north swells generated a distant
surface low, and an associated cold front will arrive and affect the
local Atlantic waters and passages late tonight through Saturday,
resulting in hazardous marine conditions for small craft
operators.

&&

.BEACH FORECAST...

For today, a moderate risk of rip currents will prevail across the
northern coastline of Puerto Rico, from Rincon to Fajardo, as well
as northern Culebra and north central to western St. Thomas.
However, a northerly swell will result in hazardous coastal
conditions with breaking waves up to 6-7 feet. A High Risk of Rip
currents will be in effect tonight for north-central Puerto Rico,
then spreading tomorrow to the rest of the northern coastline of
Puerto Rico, from Rincon to Fajardo, as well as northern Culebra
and north-central to western St. Thomas through late Saturday
night.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
541 AM AST Fri Feb 2 2024

.SYNOPSIS...

A low over the west central Atlantic moving just north of east
has a front extending towards north of the region. Today, weather
conditions will be under the influence of that boundary. Expect
shallow moisture with shower activity to continue to affect the
region with afternoon convection also possible across central to
southern PR. A general drying trend is expected by tomorrow and
into the weekend, with shallow moisture still affecting the
region. Gradually increasing moisture is forecast during the next
workweek, especially on Tuesday and Wednesday. Deteriorated marine
and coastal conditions through Saturday due to NNW. Rip Current
Statements, High Surf Advisories and Small Craft Advisories are or
will be in effect.

&&

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

Low pressure is now in the west central Atlantic moving just north
of east with multiple troughs and fronts extending into the
Caribbean and behind it. The front appears to have stalled over
Puerto Rico and the northern U.S. Virgin Islands. Areas of central
and eastern Puerto Rico and the local waters--especially north of
Culebra have received over one half inch of rain since midnight in
regenerating light to moderate shower activity over the area, with
most parts of the island receiving one to two tenths of an inch.
Temperatures in the lower elevations have been in the low to mid
70s, while mid and upper elevations have been in the 60s.

Today, weather conditions will be under the influence of this front.
Much drier air is behind the front north of 21 or 22 degrees north,
but models do not show it to be advancing into the area, rather the
front will hold for about 12-24 hours and then come under the
influence of southwesterly flow at lower levels moving out of
Colombia and Venezuela. The first surge of moist air will fill much
of the eastern Caribbean by Saturday, but leave somewhat drier air
over the local area. Then later on Sunday more moisture will ride up
the western side and begin to affect the southeastern corner of the
forecast area. There will be less precipitable water over the area,
and less showers, today through Sunday once the band in place clears
out later today. But as the moisture in the Caribbean begins to
arrive late in the period, more persistent showers will return. We
will have to wait for the long-term period for significant changes
and better rainfall chances.
&&

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

For the next workweek, a transition into a wetter pattern is
forecast, with moisture peaking Tuesday and Wednesday, and then
gradually decreasing Thursday onwards. Monday will have generally
seasonal precipitable water (PWAT) values as patches of low level
moisture and drier air reach the islands. Available moisture should
generally remain below 700mb, and winds will be moderate from the
south, gradually veering to become SSW and increasing. Model
guidance continues to indicate an amplifying upper polar trough
exiting the eastern sea board and ultimately being west of the
region by Tuesday, moving northwestward across the Atlantic, north
of the region, through the rest of the workweek, increasing
instability across the region. A frontal boundary will also bring
an increase in low level moisture and convergence. Surface flow will
be more fresh from the SSW on Tuesday, decreasing and veering to
become westerly by Wednesday evening, NNW to northerly by Thursday
morning and NNE by Friday night, increasing again by that time.
Models continue to suggest a moist plume developing and extending
from South America, over our area (increasing PWAT to above normal
and extending moisture into the upper levels) and into the Central
Atlantic on Tuesday and Wednesday. This will increase the risk of
flooding over the islands. This moisture will gradually move out on
Thursday morning as drier air pushes in from the NW. This drier air
will result in more fair conditions Thursday morning through Friday.

&&

.AVIATION...
(06Z TAFS)
Issued at 446 AM AST Fri Feb 2 2024

The CDFNT will carry areas of SHRA and BKN-OVC skies across PR and
the nrn USVI with MVFR conds nr SHRA and mtn obscurations genly thru
03/00Z. Winds NW-N less than 10 kts excp nr SHRA where 10-15G25kt
may be expected. Lcl sea breeze influences aft 02/15Z. Max winds
WNW 80-90 kt btwn FL365-460.|

&&

.MARINE...

A low pressure system northwest of the region and its associated
frontal boundary north of our region will promote light northerly
surface winds across our region, veering during the day to become
more easterly by tonight. This weakening cold front just over the
region will continue to enhance shower activity over the local waters
through tonight. Northwest to north swells that were generated by
that surface low, and the cold front will continue to affect the
local Atlantic waters and passages through tomorrow, resulting in
hazardous marine conditions for small craft operators.

&&

.BEACH FORECAST...

A High Surf Advisory is in effect for the northern coastline of
Puerto Rico through 6 PM AST due to breaking waves up to 10 feet.
A High Risk of Rip Currents will continue across those areas
through late Saturday night. A High Risk of Rip Currents is also
in effect for the northern coastline of Rincon and Aguada, Culebra
and the northern USVI through late Saturday night.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
523 AM AST Sat Feb 3 2024

.SYNOPSIS...
Issued at 448 AM AST Sat Feb 3 2024

A frontal boundary to our southeast and a post frontal trough to
our north will leave some instability at the lowest levels for
isolated shower development today in the northerly flow. Flow will
become southeasterly by Sunday and significant moisture will be
brought up over the area by mid week. Rainfall could be quite
heavy during that time--especially in southern and eastern Puerto
Rico.


&&

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

A low pressure system is located well to the northeast of the local
islands, north of 30N, with its associated frontal boundary well
south of and moving away from the region. Current Satellite
derived precipitable water (PWAT) values show up to around 1.3
inches across the region, at normal values for this time of the
year. Last night was fair, with the radar not detecting any
precipitation since midnight. Cloudiness gradually decreased
during the overnight hours and minimum temperatures were in the
lower 70s across coastal areas of the islands and in the upper 50s
to low 60s across higher elevations of Puerto Rico. Wind flow with
a southwesterly component at 850 mb will steer patches of low
level moisture across the region, particularly tonight and into
Sunday. Moisture should, however, stay mostly within normal PWAT
values during the period. Current model guidance indicates a peak
in moisture late Sunday night through Monday morning and then on
Monday night and into the long term period. Available moisture
should be mainly below 700 mb. Light low level winds will become
more southerly during the weekend, increasing on Monday. Today and
into the weekend, light shower activity should affect windward
sectors during the day with possible convection over the interior
and sectors of northern PR each afternoon. Rain chances will
increase during the period when the mentioned patches of moisture
move across the area. Highs during the weekend are forecast in the
low to mid 80s across coastal areas of the islands, somewhat
higher on the SW coast of Puerto Rico and over St. Croix. On
Monday, a large polar trough is forecast to move out of the
eastern U.S. seaboard and into the western Atlantic, affecting our
region during the first part of the long term forecast period.

&&

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

Low pressure will develop over the western Atlantic northwest of
the area and east of Florida on Tuesday. This will pull a cold
front deep into the western Caribbean and across Haiti. Above the
surface however, southwest flow will have begun even by Sunday,
allowing time to pick up moisture over Colombia and Venezuela. By
12Z on Tuesday good moisture will already be streaming over the
area. This is expected to bring clouds and showers--first to the
southwest and south coasts and mountains and then to the rest of
Puerto Rico as the front moves into the area. The focus of the
showers will shift eastward during the day and begin to affect the
U.S. Virgin Islands by Tuesday night. Timing and exact locations
then become unclear, with some models suggesting continued rain
over Puerto Rico and others keeping it mostly east of all but
eastern Puerto Rico. As the low pressure with the frontal system
moves northeast into the central Atlantic on Wednesday this will
carry the cold front across the area and also bring cooler but
moist and unstable air across the local forecast area Wednesday
and Thursday. Showers should be only sporadic by Thursday
afternoon. By Friday and Saturday, high pressure builds into the
western Atlantic and the air flow across the area becomes much
drier. This will allow a few shallow showers where flow is
orographically lifted, otherwise a much drier weekend is expected.

At upper levels, a rapidly moving trough will be found just east
of Florida Tuesday morning and across Hispaniola by Wednesday
afternoon. It will have a significant role in fostering a better
environment for the showers expected Tuesday and Wednesday. This
trough will cross the local area on Wednesday night, while still
carrying southwest flow over the area. Flow will turn northwest by
Thursday but a weak trough will still be noted over the central
Caribbean on Saturday. Ridging is indicated Friday and Saturday.

&&

.AVIATION...
(06Z TAFS)

VFR conditions will prevail across the terminals. Light E wind flow
up to around 10 kts will gradually become more southerly during the
period. Passing VCSH affecting the region at times. Possible VCSH
developing in the interior of Puerto Rico around 02/19Z, and movg
into VCTY TJSJ.

&&

.MARINE...
Issued at 448 AM AST Sat Feb 3 2024

Seas have stabilized around 8 feet for now at the outer buoy with
periods of 10-13 seconds and swell continuing from the north. This
should continue to affect the north coastal waters of Puerto Rico
through the day. Seas will subside to 5 feet or less by Sunday. By
the beginning of the week however seas will begin to rise with
increasing south winds over the area such that small craft
advisories are likely by Tuesday.

[cycloneye]

Area Forecast Discussion...CORRECTED
National Weather Service San Juan PR
533 AM AST Sun Feb 4 2024

.SYNOPSIS...
Issued at 440 AM AST Sun Feb 4 2024

Shower activity will increase during the day as low-level flow
becomes more southerly. The increased south to southwest flow will
bring up moisture from Colombia and Venezuela that will form an
atmospheric river over the area and bring period of heavy rain
Tuesday and Wednesday with some thunderstorms. Conditions will
slowly dry from west to east Thursday through Saturday, but
shallow showers will still continue to be seen.

&&

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

Last night was fair with radar estimated accumulations since
midnight staying offshore as shower activity was pushed away by land
breezes. Since midnight the most prominent cloudiness moved over
western Puerto Rico, and is still making its way across the
island. Several official and unofficial stations reported minimum
temperatures in the lower 70s across coastal areas of the islands
and in the lower 60s across higher elevations of Puerto Rico.
Lows in the high 60s were also seen across the Caguas valley.

Two low pressure systems, were located well to the northeast of
the local islands, north of 40N. One of their associated frontal
boundaries was well north and the other, as a shearline, well to
the southeast of the local islands, continuing to move away from
the region. A resulting southwesterly wind component at 850 mb is
steering low level moisture across the region. Current satellite
derived precipitable water (PWAT) indicates moist air masses,
with PWAT values above 1.55 inches, above seasonal values, to our
north and south. The islands find themselves on the high end of
seasonal values to barely above seasonal in the eastern region.
Moisture should generally stay within normal PWAT values through
Monday, with patches of drier and more humid air arriving to the
region. Available moisture should be mainly below 700 mb through
most of Monday. However, current model guidance indicates a dry
air mass on Monday morning, limiting available moisture to below
850 mb. Low level winds will become more southerly and increase today
and Monday, becoming more south southwesterly on Tuesday.

Today, light shower activity should affect windward sectors during
the day with additional convective activity affecting mainly the
interior to sectors of northern PR during the afternoon. Highs
today are forecast in the low to mid 80s across coastal areas of
the islands, somewhat higher on the SW coast of Puerto Rico, and
also the northeast coast and over St. Croix. Light passing
showers should persist tonight into Monday and a drier air mass
could limit shower activity Monday morning through Monday evening,
allowing temperatures to rise even more Monday afternoon in the
Greater San Juan and Bayamon Metropolitan areas.

Monday evening into Tuesday, an amplifying polar trough is
forecast to move out of the eastern U.S. Seaboard and into the
western Atlantic. This feature will continue to approach the
region Tuesday, increasing instability across the region. A
frontal boundary will also bring an increase in low level moisture
and convergence. As south southwest surface flow increases on
Tuesday, a moist plume will develop and extend from South
America, over our area, and into the Central Atlantic on Tuesday.
This plume will elevate PWAT values to more than 2 standard
deviations above seasonal normals, which is above 2 inches, with
moisture extending towards the upper levels. The Galvez-Davidson
Index indicates a risk of isolated to possibly scattered
thunderstorms by at least late Tuesday morning onwards. The risk
of heavy rainfall, thunderstorms and flooding will range from
limited to elevated during this period. Please stay tuned for
future updates. These conditions will continue into the first part
of the long term period.

&&

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

Low pressure will develop over the western Atlantic northwest of
the area and east of Florida on Monday night. This will pull a
cold front deep into the western Caribbean and into the local area
by Wednesday. Above the surface however, southwest flow has
already begun, allowing time to pick up moisture over Colombia
and Venezuela. This stream of moisture already in place over our
area by Tuesday will continue bringing relatively deep moisture
over Puerto Rico and the U.S. Virgin Islands on Wednesday with a
good possibility of thunderstorms enhanced by cooler mid level
temperatures and the approach of a vigorous upper level trough
from the east. The GFS holds this stream across the local area
until Thursday afternoon coincident with the passage of the upper
level trough through the area from the west. Drier air will have
moved into the local area and then showers are expected to be more
limited but still present over the higher terrain and windward
coasts. Showers will taper off slowly through Sunday, but shallow
moisture associated with the cool airmass behind the front will
produce scattered showers-- especially over high terrain and the
north coast of Puerto Rico. This will also apply to the U.S.
Virgin Islands but with much less shower activity.

&&

.AVIATION...
(06Z TAFS)
Issued at 440 AM AST Sun Feb 4 2024

Mainly VFR conditions will prevail across the terminals. Light
southerly wind flow up to around 10 kts is expected. Passing VCSH
affecting the region at times. Possible SHRA developing in the
interior of Puerto Rico around 04/18Z, mainly affecting the
northern VCTY of TJPS and TJSJ as they are steered by SW steering
flow. Locally higher winds near stronger SHRA. Maximum winds W
85-95 knots btwn FL355-455.

&&

.MARINE...
Issued at 440 AM AST Sun Feb 4 2024

Seas will subside on Sunday, but increasing south winds will
bring seas back up on Monday with increasing seas due to southerly
flow through Tuesday. On Wednesday and Thursday swell from the
north will invade the area continuing the hazard. Also the passage
of a cold front and upper level trough will make for hazardous
and inclement weather with poor visibilities Tuesday through
Thursday. Small craft advisories are likely to be reinstated by
Tuesday afternoon.

&&

.BEACH FORECAST... Issued at 440 AM AST Sun Feb 4 2024

Seas will subside through early Monday, and with them the rip
current risks that were high on the northwest coast today.
However another swell event will bring a high risk of rip currents
back to the northern coasts on Wednesday. The risk of lightning
will also increase on Tuesday and Wednesday for most beaches and
rainy weather will preclude chances of a sunny day.

[cycloneye]

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
535 AM AST Mon Feb 5 2024

.SYNOPSIS...

Today, a stable weather pattern is expected, dominated by a south
wind flow, resulting in slightly warmer temperatures than usual.
A more unstable weather pattern is expected from Tuesday through
Thursday, with rain activity across the entire forecast area until
at least Thursday. For more details on the rainfall event, please
refer to the Hydrologic Outlook (ESFSJU). A small northerly swell
and fresh northerly winds will aid buildings seas from Tuesday to
Thursday, resulting in hazardous and choppy seas. Please refer to
the Marine Weather Message (MWWSJU) for more information.

&&

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

A deep layered trough will promote unstable weather conditions and
increase the risk of flooding across Puerto Rico and the U.S. Virgin
Islands on Tuesday and Wednesday. Hazardous seas and life-threatening
rip currents are expected from late Tuesday onwards.

Partly to variably cloudy skies prevailed through the overnight
hours as southerly steering winds pushed the remnant moisture from
an old frontal boundary across the islands. Scattered showers with
periods of moderate to locally heavy rainfall were observed along the
southern and eastern sections of Puerto Rico, as well across portions
of the U.S. Virgin Islands. The doppler radar estimated near 1.50
inches of rain in Naguabo and close to 1 inch in Ponce and St. Croix.
Minimum temperatures were from the mid 60s across the higher elevations
to the mid 70s and low 80s across the lower elevations.

Moderate southerly winds are expected to prevail today. This will
cause normal to above normal temperatures across most lower
elevations of the islands, with heat indices reaching 102-106
degrees Fahrenheit from Arecibo to Bayamon, and isolated areas of
western Puerto Rico. In terms of rainfall, orographic lifting should
favor shower development along the Cordillera Central and the
eastern portions of PR this afternoon. Meanwhile, a deep layered
polar trough with a broad surface low and frontal boundary will
gradually approach the central and northeastern Caribbean through
mid-week. This will promote a deep southerly wind flow and pooling
of tropical moisture from South America into the northeastern
Caribbean and the Atlantic waters from late tonight through at least
Wednesday. Breezy conditions are expected on Tuesday. Therefore, an
unsettled weather pattern is expected to prevail on Tuesday and
Wednesday with shower and thunderstorm development across the local
waters and over portions of the islands. Urban and small stream
flooding, as well as flash flooding and mudslides in areas of steep
terrain are likely with the heaviest rainfall and any prolonged
period of rainfall activity. A Hydrologic Outlook (ESFSJU) was
issued yesterday afternoon, and a Flash Flood Watch may be required
if guidance continues to show an increasing trend in rainfall
accumulations from Tuesday through Wednesday.

&&

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

A transition in the weather pattern is expected for Thursday as
the tropical moisture and instability associated with a deep layer
trough slowly exit from the forecast area. According to the
global guidances (GFS & ECMWF), the highest probability of showers
is anticipated across sectors of the eastern part of the island
and the U.S. Virgin Islands, resulting in additional rainfall.
Although the intensity and duration of showers during the day are
not expected to be very significant, additional rain on already
saturated soils could exacerbate flooding issues in sectors of
eastern Puerto Rico. Therefore, for Thursday, there is a limited
flood threat for the southeastern sections of Puerto Rico.

As the day progresses, all the tropical moisture is expected to
shift east of the island, pushed by a mass of dry air with
precipitable water values below climatological normals.
Additionally, a broad mid-level range will replace the divergent
side of the trough, eroding the available moisture and resulting
in more stable conditions. From Friday onwards, the island will
mostly be dominated by high pressure in the western Atlantic,
resulting in a northwest wind flow by early Friday. From Saturday
into Monday, winds are forecasted to veer as the surface high
pressure moves farther eastward into the Central Atlantic,
becoming northeast by Sunday.

&&

.AVIATION...
(06Z TAFS)
Mainly VFR conditions are expected to prevail across
all terminals through the forecast period. However, SHRA expected
to develop in and around TJPS today, which may cause tempo MVFR
conditions. Surface winds will continue from the south at 10-15
kts with higher gusts across the USVI terminals. SHRA expected to
increase aft 06/06z across the local area.

&&

.MARINE...

A transition weather pattern is expected for Thursday as the
tropical moisture and instability associated with a deep layer
trough slowly exit from the forecast area. According to the global
guidances (GFS & ECMWF), the highest probability of showers is
anticipated across sectors of the eastern part of the island and
the U.S. Virgin Islands, resulting in additional rainfall.
Although the intensity and duration of showers during the day are
not expected to be very significant, additional rain on already
saturated soils could exacerbate flooding issues in sectors of
eastern Puerto Rico. Therefore, for Thursday, there is a limited
flood threat for the southeastern sections of Puerto Rico.

As the day progresses, all the tropical moisture is expected to
shift east of the island, pushed by a mass of dry air with
precipitable water values below climatological normals.
Additionally, a broad mid-level range will replace the divergent
side of the trough, eroding the available moisture and resulting
in more stable conditions. From Friday onwards, the island will
mostly be dominated by high pressure in the western Atlantic,
resulting in a northwest wind flow by early Friday. From Saturday
into Monday, winds are forecasted to veer as the surface high
pressure moves farther eastward into the Central Atlantic,
becoming northeast by Sunday.

[HurricaneFan]

Hi,how will the seas between Anguilla and Saint Martin look Tommorow(Tuesday)?

[cycloneye]

Hi,how will the seas between Anguilla and Saint Martin look Tommorow(Tuesday)?

Fresh to locally strong southerly winds will affect the eastern Caribbean
through midweek. Looking ahead to Thu and Fri, large northerly
swell may impact Atlantic passages in the northeast Caribbean.
Fresh to strong trade winds and building seas are possible over
the south-central Caribbean by late Fri.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
458 AM AST Tue Feb 6 2024

.SYNOPSIS...

A more unsettled and wet pattern is forecasted for today through
Thursday as a deep-layer trough moves over the region, increasing
instability and a plume of tropical moisture. During this weather
event, residents across the southeastern sections of Puerto Rico
can expect rainfall accumulation from 3 to 6 inches, and for the
rest of the island and the U.S. Virgin Islands, from 1 to 4
inches. Consequently, a Flash Flood Watch is in effect from 6 AM
today through Thursday morning. For more detailed information
about the weather, please visit www.weather.gov/sju. Wind-driven
seas and a pulse of northerly swell will result in hazardous
marine conditions across the offshore Atlantic waters and local
passages from today into the upcoming days. Please visit the
Marine Weather Message (MWWSJU) for more detailed information.

&&

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

A deep layered trough will promote unstable weather conditions and
increase the risk of flooding across Puerto Rico and the U.S. Virgin
Islands through Wednesday. A Flash Flood Watch(FFASJU) is in effect for
all of Puerto Rico and the U.S. Virgin Islands. Hazardous seas and life-
threatening rip currents due to increasing winds and a northerly swell
will affect the local waters and most northwest to northeastern coastal
areas of the islands through the rest of the week.

Variably cloudy skies prevailed through the overnight hours as showers
and isolated thunderstorms developed under southerly steering winds
across portions of the interior and eastern Puerto Rico. The doppler
radar estimated near 1 inch of rain in Orocovis and Cayey after
midnight. Minimum temperatures were from the mid 60s across the higher
elevations to the mid 70s and low 80s across the lower elevations. Wind
gusts were between 16-22 mph across coastal areas. Breezy conditions
are expected to prevail across the islands today as low-level wind
speed convergence continues over the region.

A deep layered polar trough and associated surface low will continue to
amplify over the southwestern Atlantic during the next few days. This
will promote a deep southerly wind flow and pooling of tropical
moisture from South America into the northeastern Caribbean and the
Atlantic waters through at least late Wednesday night. Therefore, an
unsettled weather pattern is expected with numerous showers and
thunderstorm development across the local area. The wettest period is
expected from this morning over southern PR, stretching eastward into
the Virgin Islands later today, with a second round of flooding rains
on Wednesday. The highest accumulations should be for the south,
interior, and eastern PR, as well as the U.S. Virgin Islands. The most
likely scenario calls for 3 to 6 inches of rainfall for
southern/eastern PR and 2-4 for the USVI. Isolated higher amounts are
possible through the event. The main impacts are flash flooding and
mudslides, but thunderstorms with strong gusty winds are expected as
well.

By Thursday, a strong surface high pressure over Southeastern USA, and
the surface low now over the north central Atlantic will promote a long
northerly wind fetch across the western Atlantic into the northeastern
Caribbean. This will cause the local winds to turn from the north-
northwest and push the plume of moisture further east and away of the
local area. The precipitable water content is expected to decrease
below normal levels by early Thursday afternoon. However, the upper-
level trough axis is expected to cross the local area earlier in the
day and the 500 mb temperatures are forecast to drop to around -10C.
Therefore, the threat for additional shower and isolated thunderstorm
development could last into Thursday morning.


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

A drier and more stable trend is forecasted for the beginning of
the long term. Model guidance indicates a more stable pattern at
the upper levels as the divergent side of the polar trough moves
eastward out of the forecast area, leaving subsidence over the
islands and being replaced by ridging. A similar trend is expected
at the mid-levels, with the GFS suggesting a broad building mid-
level ridge extending from the western Atlantic into the
Caribbean. The presence of the mid-level ridge will begin on
Friday afternoon and persist for the rest of the period as it
stretches into the central Atlantic.

The last part of the long-term global model guidance shows some
discrepancies between the two solutions, one stable and drier and
another stable but with more moisture. According to the GFS, from
Friday onwards and for the rest of the forecast period, the
islands are expected to be mostly dominated by a building surface
high-pressure system extending from the western Atlantic into the
Central Atlantic, resulting in northerly winds for Friday and
veering winds for the rest of the forecast period. Conversely, the
ECMWF solution shows a similar trend with a surface high-pressure
system located over the western Atlantic, but from Sunday into
Monday, the guide suggests a decent increase in humidity at 850 MB
and a weak short-wave trough over the area. As we are still far
away in the forecast, the forecast for the last part of the long
term reflects a combination of both solutions, resulting in a
variable weather pattern, given the presence of the mid-level
ridge causing a strong trade wind cap inversion and drier air
aloft.

&&

.AVIATION...
(06Z TAFS)

SCT SHRA/Isold TSRA will develop over PR today, and
across portions of the southern and eastern waters of the islands,
affecting the USVI terminals at times through the forecast
period. Tempo MVFR to brief IFR conditions are possible across all
local terminals. Mtn top obscd and BKN/OVC layers through FL100
expected. Low level winds will continue from the south-southwest
between 15 to 25 kt with higher gusts near SHRA/TSRA.

&&

.MARINE...

The interaction of a deep-layer trough and the broad Atlantic
ridge extending into the eastern Caribbean will result in
southerly fresh to locally strong winds. This wind-driven sea will
create hazardous marine conditions for the Atlantic offshore
waters. By midweek, the arrival of a northerly swell will
aggravate the situation, resulting in building seas and large
breaking waves. The local waters will experience squally marine
weather from today through Thursday, resulting in localized
hazardous marine conditions.

For beachgoers, there is a moderate rip current risk across all
the northern coastal areas of Puerto Rico and the local islands.
An increase in breaking waves is forecast from late tomorrow into
the rest of the workweek.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
500 AM AST Wed Feb 7 2024

...New SYNOPSIS, AVIATION, MARINE...

.SYNOPSIS...
Issued at 452 AM AST Wed Feb 7 2024

A unsettled and wet pattern is forecasted through Thursday as a
deep-layer trough moves over the region, increasing instability as
it interacts with a plume of tropical moisture. Consequently, a
Flash Flood Watch is in effect through Thursday morning. Wind-
driven seas and a pulse of northerly swell will result in
hazardous marine conditions across the offshore Atlantic waters
and local passages through early next week.

&&

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

...A Flash Flood Watch remains in effect for all of Puerto Rico and
the U.S. Virgin Islands through early Thursday morning....

Variably cloudy skies prevailed through the overnight hours as
showers and isolated thunderstorms developed along bands between
eastern PR and the USVI. The Doppler radar estimated between 1 and 2
inches of rain in Naguabo, Ceiba and St. Croix. Total rainfall
amounts during the past 24 hours ranged from 3-5 inches, with the
highest accumulations across the eastern interior of PR. Minimum
temperatures were from the mid 60s across the higher elevations to
the mid and upper 70s across the lower elevations. Gusty winds up to
35 mph were observed at St. Croix just after midnight. Breezy
conditions are expected to continue today as low-level wind speed
convergence continues over the region.

A strong polar trough and associated surface low will continue to
amplify over the western Atlantic today and move into the north
central Atlantic by Friday. The wet and unstable weather pattern
will continue today as a pooling of tropical moisture continues
across the region under a deep southerly wind flow. Additional
rainfall amounts between 1-3 inches and locally higher are expected
today. This rainfall over already saturated soils will keep a high
potential for flash flooding and mudslides in areas of steep
terrain. Therefore, a Flash Flood Watch remains in effect for all
the islands. Strong gusty winds are expected with the thunderstorms.

By Thursday and Friday, a strong surface high pressure over
Southeastern USA and the surface low, well north/northeast of the
region will promote a long northerly wind fetch across the western
Atlantic into the northeastern Caribbean with a front moving across
the local area. This will cause the local winds to turn from the
north-northwest and push the plume of higher moisture content
further east and away of the local area. Drier air is expected to
gradually filter over the region, especially by Friday. The latest
global model guidance suggest a slower evolution of the anticipated
drying trend for Thursday, with moisture levels remaining relative
high(PWAT around 1.50-1.75 inches) through at least Thursday
afternoon, and dropping to 0.75-1.00 inches by Friday morning. Also,
the slower solution has the trough axis crossing the islands by the
peak of afternoon convection with colder than normal 500 mb
temperatures. Therefore, the latest forecast was adjusted to show an
increasing trend once again in shower and thunderstorm coverage
across the local area through at least Thursday evening.

&&

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

A drier and more stable pattern is expected to persist this
weekend across Puerto Rico and the U.S. Virgin Islands as models
suggest that a broad high pressure will dominate over the central
Atlantic until early next week. A similar pattern is expected at
the mid to upper levels, with models suggesting a broad building
mid-level ridge extending from the western Atlantic into the
Caribbean. This configuration will support mainly light northeast
to east winds across the forecast area until Sunday. In addition,
the precipitable water content is expected to be mainly below
normal, but some patches of near-normal values over the Caribbean
can result in morning passing isolated showers. Shower activity
development, if any, seems to be limited to eastern Puerto Rico,
as well as the U.S. Virgin Islands.

By early next week, the broad high pressure in the Atlantic will
be pushed farther east in the Atlantic by a cold front that is
forecast to push southeast from the Eastern U.S. into the western
Atlantic, resulting in a more southeasterly flow and warmer
temperatures across the forecast area. With this setup, global
models are suggesting an increase in precipitable water over the
region and a weak surface trough. As a result, by Tuesday the
islands can expect the return of a more variable to wetter pattern
with isolated to scattered showers gradually developing throughout
the day. Drier air should be coming back by Wednesday, limiting
the shower activity. As we are still far away from the forecast,
we will continue to monitor closely for any changes.

&&

.AVIATION...
(06Z TAFS)
Issued at 452 AM AST Wed Feb 7 2024

SCT SHRA/Isold TSRA will develop once again across PR and the USVI.
Tempo MVFR to brief IFR conditions are possible across all local
terminals through the forecast period. Mtn top obscd and BKN/OVC
layers through FL100 expected. Low level winds will continue from
the south-southwest between 15 to 25 kt with higher gusts near
SHRA/TSRA.

&&

.MARINE...
Issued at 452 AM AST Wed Feb 7 2024

A broad surface low pressure will continue to build over the
western Atlantic and move into the north central Atlantic by
Thursday. The interaction of this low with the broad Atlantic
ridge extending into the eastern Caribbean, will result in fresh
to locally strong winds, hazardous seas and squally weather across
the regional waters and passages through at least early Thursday
morning. South to southwesterly winds will prevail through
today, becoming northerly Thursday onwards as a broad surface
high pressure builds over the western Atlantic during the second
part of the week. Pulses of a northerly swell will spread across
the local waters from later today through the weekend.

For beachgoers, starting today there will be a high rip current
risk across all the northern, western, and eastern coastal areas
of Puerto Rico including Culebra and a moderate risk elsewhere. An
increase in breaking waves is forecast tomorrow into the rest of
the workweek, strengthening even more over the weekend.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
503 AM AST Thu Feb 8 2024

.SYNOPSIS...

Today, expect some shower activity to continue over the area as
the deep-layer trough moves away from the region. A gradually
drying trend from west to east is expected to start tonight into
the weekend resulting in more stable weather conditions. However,
shallow moisture may result in light isolated shower activity.
Northerly swells arriving over the next several days will further
deteriorate marine and coastal conditions for the Atlantic waters
and local passages through early next week.

&&

.SHORT TERM...Today through Saturday

Cloudy skies remained across all the CWA during the night and
early morning hours due to the influence of the deep layer trough
affecting the region. As a result, light to moderate rains were
observed across all of Puerto Rico, with minimal rainfall
accumulation during the day. The cloudiness also affected
temperatures, leaving colder temperatures across all the CWA, with
the upper 60s to the lower 70s across all the coastal areas and
the upper 50s to the lower 60s across the mountains.

Today, we anticipate a rather unusual and complex weather pattern.
Moisture associated with the front is expected to gradually move
out of the forecast area at the surface, replaced by a much drier
air mass (PWAT of 1.1 inches according to the GOES Satellite-
derived imagery) already present over the Hispaniola. On the other
hand, enough instability will be present due to the divergence
side of the strong polar trough reflected at the mid-levels
located just north of the region. Despite the lack of moisture at
the low levels, intense pulses of localized showers are possible
due to the instability present. According to the Gálvez-Davison
Index (GDI), there is potential for a few isolated thunderstorms
over the southeastern sections of the island due to the north-
northwesterly winds. The saturation soil situation increases the
risk of urban and small stream flooding and mudslides in steep
terrains.

From Friday onwards, an improvement in weather conditions is
forecasted as a broad surface high-pressure system exits the
eastern seaboard of the United States and extends over the western
Atlantic, pushing farther east the surface low pressure
responsible for the previous wet pattern. As the surface high
pressure extends over the central Atlantic, veering winds from the
north are forecasted, pushing drier air masses across the region.
According to the model guidance, precipitable water values will
drop two standard deviations from the normal climatological values
from Friday to Saturday. Additionally, a mid to upper level ridge
will be established across the western Atlantic, extending into
the Caribbean and inducing stable weather conditions with warmer
temperatures at 500 MB and drier air aloft. As a result, residents
and visitors can expect mostly stable weather conditions with the
possibility of passing showers, especially over the northerly
sections of Puerto Rico and the local northern waters. In the
afternoon, the local and diurnal effects might increase the
potential for showers, but no widespread shower activity is
forecast each day. Regarding daytime temperatures, much fresh
temperatures are expected, given the northern component in winds
and the lack of cloudiness in the evening hours.

&&

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

By Sunday, the broad high pressure and mid-level ridge will
continue to dominate over the central Atlantic resulting in a
drier and more stable pattern to persist across Puerto Rico and
the U.S. Virgin Islands. This configuration will support mainly
light northeast to east winds across the forecast area.
Additionally, the precipitable water content is expected to be
well below normal, however shallow moisture with some patches of
near-normal precipitable values over the Caribeean can result in
morning passing showers, especially across eastern PR and the U.S.
Virging Islands. No significant rainfall accumulations are
expected.

By early next week, the broad high pressure in the Atlantic will
be pushed farther east in the Atlantic by a cold front that is
forecast to push southeast from the Eastern U.S. into the western
Atlantic, resulting in a light southeasterly flow and warmer
temperatures will develop across the forecast area, mainly in
coastal and urban areas. As this weather pattern unfolds, forecast
models continue to show a slight increase in precipitable water
content as the afformentioned high pressure wind flow will help to
push some tropical moisture with the passage of a weak surface
trough across the northeastern Caribbean. As a result, around
Tuesday afternoon into Wednesday we can expect the return of a
more variable weather pattern with isolated to scattered showers
gradually developing throughout the day. Drier air should be
coming back by Wednesday night into Thursday. As we are still far
away from the forecast, we will continue to monitor closely for
any changes.


.AVIATION...
(06Z TAFS) SHRA will persist across PR and the USVI for at least
08/18Z. Tempo MVFR to brief IFR conditions is possible across all
local terminals through the forecast period. Conditions will
slightly improve by this evening. Winds will rmn from the S-SW at
15 knots during the day, chgg from the N-NW at 09/00Z.

&&

.MARINE...
broad surface high pressure building over the western Atlantic
will result in moderate to fresh northwesterly winds today, then
becoming more northerly tonight. Winds will continue to gradually
veer over the next few days until becoming easterly during the
weekend. Pulses of northerly swells will spread across the local
waters into the weekend, creating hazardous marine and coastal
conditions for the Atlantic waters and local passages through
early next week. Therefore, Small Craft Advisories are in effect
due to seas building between 7 and 10 feet during the next few
days. Please refer to the latest Marine Weather Message (MWWSJU)
for more information.


.BEACH FORECAST...
Pulses of long period swells will cause large breaking wave action
across west, north, and eastern beaches of Puerto Rico, Culebra,
and the northern U.S. Virgin Islands through at least early next
week. Therefore, there is High Rip Current Risk in effect (CFWSJU)
due to life-threatening rip currents. High surf advisory
conditions (minor beach erosion, stronger rip currents, and
dangerous swimming conditions) due to large breaking waves
(greater than 10 ft) are possible later in the weekend into early
next week, as a larger swell with longer wave periods impacts the
northern coastlines of all the islands.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
532 AM AST Fri Feb 9 2024

.SYNOPSIS...
Issued at 522 AM AST Fri Feb 9 2024

Stable weather conditions will persist during the next several
days as a broad high pressure dominates across the Atlantic and a
drier airmass is establishing over Puerto Rico and the U.S. Virgin
Islands. Isolated shower activity cannot be ruled out of the
forecast due to shallow moisture and light winds, mainly during
the morning hours over the eastern PR. A warming trend is
anticipated from Tuesday onwards as winds will shift from the
southeast and moisture will increase from the south. Northerly
swells arriving over the next several days will further
deteriorate marine and coastal conditions for the Atlantic waters
and local passages through early next week.


&&

.SHORT TERM...Today through Sunday

Variable weather conditions prevailed during the night hours, with
isolated to moderate showers affecting northern and interior
sections of Puerto Rico as well as the local waters. Shower activity
was frequent. However, rainfall accumulations remained minimal;
according to the Radar Doppler estimates, the highest occurred
across Manati and Naguabo, with almost 3/4 of an inch. Overnight
temperatures ranged from the low to mid-70s along the coastal areas
and in the low to mid-60s across the mountain sections.

Today, a variable weather pattern is expected as a pocket of
cloudiness and shallow moisture stream across the northern coastal
areas. The shower activity will be shallow, and no significant
rainfall accumulations anticipated for the rest of the morning,
but ponding of water in low-lying areas and urban sections cannot
be ruled out. As the day progresses, a much drier airmass with
Precipitable water around 0.80 inches (GOES Satellite-derived
Imagery) will move into the region, leading to a more stable
weather pattern with some clouds and localized showers in the
afternoon across the interior and southern areas due to the wind
direction.

By Saturday into Sunday, a broad mid- to upper-level ridge across
the western Atlantic extending into the Caribbean will be the
dominant feature, resulting in a strong trade wind cap with warmer
temperatures at 500 MB and drier air aloft. A similar pattern will
be reflected at the surface, with the influence of a broad surface
high-pressure extending from the Western Atlantic into the central
Atlantic. This surface feature will induce a variation in wind
direction, persisting from the northeast early on Saturday and
veering on Sunday, becoming more easterly. According to the model
guidance, precipitable water values will drop two standard
deviations from the normal climatological values on Saturday and
slightly increase on Sunday. Given the expected weather, the islands
can expect shower activity resulting from local and diurnal effects
and available moisture. Although showers are expected, widespread
shower activity is not anticipated.

&&

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

Weather models agree that a broad surface high pressure centered
over the Atlantic will continue to dominate weather conditions in
our region for the beginning of this work week. At the mid-levels,
a similar pattern is expected, with models suggesting a broad
mid-level ridge extending from the western Atlantic to the
Caribbean. As a result, winds will remain relatively light from
the northeast promoting temperatures to remain near normal to
slightly below normal on Monday across Puerto Rico and the U.S.
Virgin Islands. It is forecast that the precipitable water content
in the atmosphere will remain around 1 inch, which is below
normal, however, some isolated shower activity cannot be ruled out
from the forecast due to shallow humidity and light winds, mainly
during the morning hours over eastern PR, but under this pattern
the rain should be very limited.

At the same time, a low pressure along with its associated cold
front will be moving over the Southeastern U.S. towards the
western Atlantic which will weaken and push the high pressure over
the Atlantic towards the east. That pattern will change our wind
flow from the southeast. Therefore, from Tuesday onwards we are
anticipating a warming trend in temperatures and an increase in
tropical humidity across the forecast area. Expect temperatures to
be around 3 to 5 degrees above normal for this time of the year
and PWAT values could be ranging closer to normal; ~1.5 inches. As
a result, around Tuesday afternoon into Wednesday, we can expect
the return of a more variable weather pattern with isolated to
scattered showers gradually developing throughout the day.

By the latter part of the week, the weakening cold front will be
located well north of our region, and patches of drier air will
settle over our region. It will continue to be warmer-than-normal,
and diurnal/local effects will promote a pattern of passing rain
showers across eastern Puerto Rico and the U.S. Virgin Islands,
followed by afternoon convection primarily across the interior to
the western section of Puerto Rico with the easterly wind flow. We
will continue to monitor closely for any changes.


&&

.AVIATION...
(12Z TAFS)
Issued at 522 AM AST Fri Feb 9 2024

VFR conditions will prevail across all the TAF sites as a much
drier airmass moves into the region, limiting cloudiness and
showers. But until 09/15Z, VCSH to -RA will persist across TJSJ
and TJPS. Winds will continue from the N, increasing to 15 knots
at 09/15Z, with gusty winds and sea breeze variations. Winds will
turn more from the N-NE at 10/03Z.


&&

.MARINE...
Issued at 522 AM AST Fri Feb 9 2024

Moderate to fresh northerly wind flow will be present across the
local waters as a broad surface high pressure dominates across the
western Atlantic. Winds continue to gradually veer over the next
few days until becoming easterly by the weekend. Pulses of
northerly swells will spread across the local waters into the
weekend, creating hazardous marine and coastal conditions for the
Atlantic waters and local passages through early next week.
Therefore, Small Craft Advisories will remain in effect due to
seas building between 7 and 10 feet during the next few days.
Please refer to the latest Marine Weather Message (MWWSJU) for
additional details.


&&

.BEACH FORECAST...
Issued at 522 AM AST Fri Feb 9 2024

Pulses of long period swells will cause large breaking wave action
across west, north, and eastern beaches of Puerto Rico, Culebra,
and the northern U.S. Virgin Islands through at least early next
week. Therefore, a High Rip Current Risk and a High Surf Advisory
are in effect due to dangerous large breaking waves and life-
threatening rip currents. Please refer to the latest Coastal
Hazard Message and Surf Zone Forecast (SRFSJU) for detailed
information (CFWSJU). A larger northerly swell with longer wave
periods is expected on Sunday and Monday.