Caribbean - Central America Weather

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
516 AM AST Wed Dec 22 2021

.SYNOPSIS...
A mid to upper ridge will continue to build across the region
through Thursday. An easterly perturbation and associated moisture
now crossing the area will be lifted north northwest, as the local
winds become southeasterly while diminishing through Friday. A drier
airmass will spread across the region today, thus limiting shower
activity in and around the islands. A cold front will continue to
stall across the west Atlantic, while a surface trough is forecast
to set up over the forecast area by Friday. This will favor an increase
in instability aloft, as the upper level ridge erodes in response to
an amplifying polar trough over the west Atlantic, as well as increase
moisture convergence from then on into the upcoming weekend.

&&

.SHORT TERM...Today through Friday...
A low to mid-levels high pressure over the central Atlantic will
maintain a southeasterly flow over the islands. Total Precipitable
Water from GOES-16 has another pocket of drier air, with values at
0.8 to 1.0 inches moving into the eastern Caribbean. Therefore, a
mainly fair weather pattern is expected to prevail early on
Wednesday. However, another patch of moisture will quickly follows.
Most of the shower activity associated with this feature should stay
to the northeast of the Virgin Islands, although some showers may
brush the U.S. Virgin Islands in the afternoon. Additionally, there
is the potential for afternoon convection over northwestern Puerto
Rico, leaving ponding of water on roadways and low-lying areas.

In the meantime, a cold front near the Bahamas will act to pull
moisture from the lower latitudes into the eastern and central
Caribbean. So far, the global models are bringing this plume of
moisture around the Mona Passage, with an increase in shower
activity for late Wednesday into Thursday. Under a southeasterly
flow, some showers may reach the southern coast of Puerto Rico and
the U.S. Virgin Islands from time to time. By Friday, with the front
stalling north of the islands, the wind flow will become light and
variable, then gradually acquiring a more northeasterly component.
With the available moisture provided by the proximity of the front,
advective showers will affect the northeastern sections of Puerto
Rico, as well as the U.S. Virgin Islands through the day, and the
usual convection in the afternoon for the interior and western
Puerto Rico.

.LONG TERM...Saturday through Thursday...
A weakly induced surface trough is forecast to develop across the
region, as the aforementioned cold front stalls and weakens across
the west Atlantic and north of the region. An upper level ridge will
gradually erode in response to an amplifying polar trough over the
west and southwest Atlantic as it moves eastwards. This is still
expected to increase instability aloft along with low level moisture
convergence over the region. Recent forecast guidance still suggest
layered precipitable water values to increase to near 2.0 inches
on Friday and into the weekend.

Latest model guidance remain in agreement and maintain the stalled
frontal boundary/shearline north of the islands but with moisture
gradually sinking just north of the islands by Christmas`s Eve
and on Christmas Day. This scenario suggests a continued trend for
a wetter pattern with increasing instability aloft and moisture
convergence through at least Saturday, as the prevailing winds
become more northeasterly and increase. Therefore there is moderate
potential for enhanced shower development as the cool advective
pattern increases over the islands as well as the possibility of
isolated thunderstorms over the local Atlantic waters or near the
north and east coastal areas. This scenario will increase the
potential for minor urban and small stream flooding and or ponding
of water on roads in isolated areas.

A gradual improvement in the weather pattern is forecast by Sunday
and through the early part of the following week, as a drier and
stable airmass will spread across the region. Winds will gradually
increase while becoming more northerly as a strong surface high
pressure ridge spreads across the west Atlantic. Expect a return
of a seasonal weather pattern through at least midweek with a cool
advective pattern expected to continue. This will promote periods
of late evening and early morning showers along the north and east
coastal areas, followed by limited afternoon convection mainly over
parts of the interior and southwest sections of Puerto Rico. Lesser
activity forecast in and around the U.S. Virgin islands. By Wednesday
and Thursday the is a bit more uncertainty as the pattern is forecast
to change again with approach of another remnant frontal boundary as
the high pressure ridge builds north of the region and moisture returns
from the northeast carried by the prevailing winds.

&&

.AVIATION...
Mainly VFR conditions expected to prevail across the terminals
through the forecast period. VCSH are expected for TJBQ after 18Z,
which could briefly cause reduction in VIS and low ceilings. Winds
will be out of the ESE at 10 to 16 kts with stronger gusts and sea
breezes variations.

&&

.MARINE...Choppy seas up to 6 feet expected mainly over the offshore
Atlantic waters and portions of the local passages until Thursday,
with southeasterly winds up to 15 knots. There is a high risk of
rip currents for the Cramer park beach in St Croix and some of the
northern beaches of St Thomas through this afternoon and also for
some of the San Juan and Vicinity and north central to northeast
beaches later this evening through Thursday. There is a moderate
risk across most of the remaining beaches.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 75 85 73 / 20 40 40 30
STT 84 76 83 74 / 30 60 40 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
508 AM AST Thu Dec 23 2021

.SYNOPSIS...

Increasing shower activity is expected across the region, as
moisture is pulled across the islands. These more active
conditions will persist into the weekend. Drying is expected early
next week, though another influx of moisture looks likely for late
Monday into Tuesday.

&&

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

At the surface, high pressure both in the east central Atlantic
and moving offshore from North Carolina will form a ridge just
north of the local area. A weak frontal boundary will abide north
of the high pressures and continue moving into the Atlantic, while
a pre-frontal trough moves into Puerto Rico on Friday with
additional moisture brought up from the south and then turned
eastward back into Puerto Rico, and to a lesser extent, the U.S.
Virgin Islands. This will cause flow at lower levels, currently
from the south to reverse this afternoon and evening and become
northerly by early Friday morning. Finally, Friday night and
Saturday the flow will become nearly east and increase to 15 to 20
knots.

Ridging at mid and upper levels will move east allowing a vigorous
polar trough to approach the area. Its associated jet is expected to
remain north of the area as SW flow turns more westerly on Saturday.

Precipitable water will peak at around 24/13Z at over 2 inches and
should remain above normal for the season through Saturday evening.
Winds will be gentle to moderate, so showers will not linger too
long in any one place and orographic effects will be mild to
moderate. Nevertheless showers are expected along the windward
coasts and slopes increasing today through Friday, but are not
expected to produce flooding at this time. The GFS also shows some
afternoon showers in western Puerto Rico.

.LONG TERM...Sunday through Friday...

Patchy moisture will be affecting the region on Sunday. Precipitable
waters values are likely to be varying between values that are below
normal, and values that are on the low end of normal. This moisture
will be generally contained within the lower levels, and will help
to sustain some shower activity over the area. Aloft, a ridge is
forecast to be over the area in the mid- to upper-levels, which will
provide stability for the region, inhibiting shower activity.
Convection is possible in the afternoon, but is unlikely to become
significant.

Late Monday into Tuesday, a weak disturbance will approach. This
will bring increased moisture to the area; however, it is likely to
only have significant impacts over eastern portions of the CWA. At
the same time, an upper-level trough is forecast to make its way
through the region from the west. A slight increase in instability
is possible, which could also support the development of showers
over the region. An increase in shower activity is likely for Monday
evening into late in the day on Tuesday, especially for eastern
islands and eastern Puerto Rico, as well as over the eastern and
southern local waters.

A frontal boundary is forecast to approach the region Tuesday night,
passing over the islands from north to south on Wednesday. More
active weather is expected for Wednesday because of this. Even so,
ridging aloft will promote stability, thereby inhibiting somewhat
the shower development.

Northeasterly flow in dry air is anticipated behind the frontal
passage. Because of this, relatively calm weather is anticipated,
likely with cooler-than-average temperatures. Some passing showers
are still likely, and afternoon convection does remain possible,
though.

It is worth noting that model guidance has tended to be a bit on the
aggressive side with suggesting the potential for frontal passage in
the long-term period, before backing off to an extent as time
progresses. This is contributing to some uncertainty with this
forecast. On the whole, though, forecast confidence is not much
lower than typical.

&&

.AVIATION...

Mainly VFR conditions expected to prevail across the terminals
through the forecast period. VCSH are expected for TJBQ after 23/18Z
which could briefly cause MVFR CIGs. Also aft 23/18Z SHRA in wrn PR
will generate mtn obscurations. Land breezes less than 10 knots
will become ESE at 10 to 16 kts with stronger gusts and sea breeze
variations. Max winds WSW 50-60 kts btwn FL390-440.

&&

.MARINE...

Seas of 6 feet or less are expected across the local waters today,
supported by winds out of the east to southeast at up to 15 knots.
Model guidance is over-estimating slightly the wave heights, based
on buoy observations. Buoy 41043 has seas of up to 5.9 feet, while
41044 has seas of up to 7.5 feet. Because of this overestimation,
forecast is slightly under guidance.

Winds are forecast to weaken tonight into tomorrow, and seas will
gradually subside somewhat.

There remains a high risk of rip currents for beaches of San Juan
and vicinity, north central and northeastern Puerto Rico, Culebra,
and St. Thomas for today.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 74 85 74 / 30 20 60 60
STT 85 76 84 75 / 30 20 20 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
452 AM AST Fri Dec 24 2021

.SYNOPSIS...

Above average moisture is expected over the region today into
tomorrow, supporting increased shower activity. Scattered to
numerous showers are expected for portions of the region, and
thunderstorms are possible this afternoon into evening. A trend
towards generally drier, fairer weather is expected by early next
week, likely lasting through the week.

Hazardous coastal conditions continue, with a high risk of rip
currents for many beaches through the weekend.

&&

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

The TPW product shows a very wet plume of moisture advancing
northeast through the Mona Channel and invading Puerto Rico. At the
same time considerably drier air remains over the U.S. Virgin
Islands. At the surface high pressure both in the east central
Atlantic and moving offshore from South Carolina will create a ridge
of high pressure just north of the local area today. A weak frontal
boundary will abide north of the high pressures and continue moving
into the central Atlantic supported by an advancing upper level
trough, while a pre-frontal trough moves into Puerto Rico today from
the northwest with additional moisture brought up from the south
through the Mona Channel. This pressure pattern of high pressure and
front/shearline will cause flow at lower levels over the forecast
area to be in a col with light and variable winds. It then becomes
northerly as the shear line, from the front north of the high, moves
through the area tonight. Again, on Saturday the flow at lower
levels will become nearly east and increase to 15 to 20 knots. A
weak trough can also be seen moving into the Leeward Islands early
Sunday morning. There will be some moisture behind it as well.
However the GFS shows precipitable water values reaching a peak of
around 2 inches today (24/18Z) and then steadily falling through
Sunday night. By 26/18Z precipitable water values in the area should
be below 1.5 inches.

Ridging at mid and upper levels will move east allowing a vigorous
polar trough to approach the area. Its associated jet is expected to
remain north of the area as SW flow turns more westerly on Saturday.
The trough will move rapidly east, pulling its associated jet with
it. On Sunday, the trailing jet will sink over Puerto Rico and the
U.S. Virgin Islands with up to 50 knots winds from the west at 250
mb.

As mentioned before, precipitable water will now peak at around
24/18Z at around 2 inches (a delay of about 5 hours from the
forecast 24 hours ago) and should remain above normal for the season
through Saturday afternoon. Moderate rain had accompanied the
moisture plume in the Mona Channel and moisture from the south will
also enhance the showers today with a possibility of localized urban
and small stream flooding, which due to the col will be relatively
slow moving until later this afternoon or tonight. The GFS also
shows some afternoon showers in western Puerto Rico. This showery
trend will continue through the short-term period.

.LONG TERM...Monday through Saturday...

On Monday, a disturbance is expected to be over southeastern
portions of the CWA, mostly over the waters. This system will bring
enhanced moisture to the affected areas, likely including portions
of the eastern islands, especially St. Croix, Monday into Tuesday.
Elsewhere in the region, relatively dry conditions are likely, with
some patchy moisture that could help to sustain shower activity in a
typical pattern. The low levels of moisture will combine with
stability due to ridging at the mid- and upper-levels to lead to
decreased shower activity, however.

Monday night through Tuesday, frontal boundaries are expected to
approach, and likely push over the area from north to south. This
will increase moisture over the area. A small increase in
instability is possible, but with the ridge remaining in place
aloft, stability will continue to dominate, and showers will be
somewhat inhibited.

Behind the these remnants of frontal boundaries is dry air. Some
patchy moisture Wednesday into Thursday could keep moisture levels
just in the normal range, though on the low end. Friday into
Saturday, however, look to be drier than normal. Even so, a few
showers are possible from time to time, largely as passing showers
developing over the waters and making their way onshore. Stability
continues aloft through at least Friday.

Weakening and erosion from the southeast of the ridge aloft is
possible on Saturday. Instability is likely to increase slightly
because of this. Even so, dry air will persist for around 700 hPa
and above, much as it will have through the rest of the week. A weak
disturbance, which looks to be the remnants of an old frontal
boundary, could bring another increase in moisture to the region
during the day on Saturday. This will be the best chance for an
active weather day through the long term period.

Forecast confidence is moderate. Dry conditions are quite likely.
However, there is still some uncertainty with respect to the frontal
boundaries, and whether or not they will make it to the region,
Monday into Tuesday. Even if they do, though, it looks like they
will be relatively weak, with only a modest increase in moisture
associated, when they get here.

&&

.AVIATION...

Areas of rain will drift east into NWrn PR bringing MVFR conds
mainly for CIGs. Isold TSRA cont ovr the Mona Channel. SHRA expected
to increase ovr interior PR aft 24/14Z with mtn obscurations and
MVFR/IFR conds. VFR conds expected to prevail over USVI. Sfc winds
VRB less than 7 knots with sea breeze influences after 24/14Z. LLVL
winds to bcm NE 5-10 kt aft 25/00Z. Max winds WSW-WNW 45-60 kt btwn
FL330-470.

&&

.MARINE...

Seas of 5 feet or less are expected across the local waters today.
Winds will be generally out of the east-southeast at 5 to 10 knots,
becoming more east-northeasterly tonight into tomorrow, with speeds
of up to 10 to 15 knots for tomorrow.

Even with the improved marine conditions, hazardous coastal
conditions continue to be a concern. There is a high risk of rip
currents for beaches along the north coast of Puerto Rico, from
north central to northeast, including beaches of San Juan and
vicinity. Beaches of Culebra and eastern St. Croix will also have a
high risk of rip currents today. The high risk will spread to
beaches of northwestern Puerto Rico tonight.

These hazardous coastal conditions will likely persist through most
of the weekend, into at least Sunday.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 85 74 83 73 / 60 60 60 40
STT 83 74 84 73 / 20 40 40 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
459 AM AST Sun Dec 26 2021

.SYNOPSIS...Mid and upper levels will dry rapidly today and
tomorrow leaving only a shallow moist layer centered around 5000
feet. Weak frontal boundaries will disturb this layer sufficiently
to bring generally light passing showers to the north and east
coasts and mountains Wednesday through Friday, but somewhat drier
conditions are expected for the following weekend.

&&

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

Moisture has decreased across the region, though there remains
sufficient moisture over portions of the region to sustain passing
shower activity. Moisture levels will continue to decrease overall
through the day today, contributing to lessened shower activity
compared to yesterday. Additionally, a ridge has built in over the
region from the west at the mid and upper-levels, increasing
stability. However, this ridge is expected to weaken somewhat
later today, under the influence of a mid-level trough to the
north/northeast of the region. This could inhibit somewhat the
decrease in shower activity, but still, generally fair weather is
likely for most of the islands today, with isolated to locally
scattered showers possible.

The drying trend continues tomorrow. As the ridge gradually re-
asserts itself, stability will also increase. As such, what moisture
is available will largely be constrained to below 850 hPa by the end
of the day tomorrow. With the wind flow more northerly, there is
additional support for drier, cooler conditions. Precipitable water
values over the area are forecast to be below normal, around 0.9 to
1.2 inches over the islands. As such, generally fair weather is
expected for tomorrow. That being said, some shower activity is
still possible from time to time, especially over the local waters,
with increased moisture expected to affect the northwestern and
southeastern corners of the CWA.

On Tuesday, the remnants of an old frontal boundary are forecast to
make their way into the region from the north. Fragments of moisture
will affect the area, and the dry air will gradually erode. Moisture
levels are likely to remain unimpressive, though near-normal values
are possible, even if on the low end of normal, near 1.25 inches.
Aloft, stability will persist, under the continuing influence of the
mid- to upper-level ridge. As such, fair weather is expected across
most of the region for Tuesday, as well, though a few showers cannot
be ruled out, in a typical pattern. Another frontal boundary is
forecast to approach the region from the north during the overnight
on Tuesday night, which could lead to an increase in shower activity
then, particularly over the local Atlantic waters and the
northern/northeastern coast of Puerto Rico.

And so, on the whole, generally fair weather is expected through at
least Tuesday. However, a few showers are possible from time to
time, with decreasing potential with over time. These showers would
be in the form of passing showers affecting windward portions of the
islands and potential afternoon convection in western/southwestern
and interior Puerto Rico. Forecast confidence is high today and
tomorrow, but decreases on Tuesday, due to some lingering
uncertainty with respect to the frontal boundaries.

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

With high pressure at the surface and at 700 hPa producing
northeast to east northeast flow, a weak frontal boundary will
move across the region Wednesday with slightly cooler air behind
it. By this time mid and upper level layers are almost completely
dry, but the 850 hPa layer maintains around 90 percent relative
humidity through the entire period. At this time the NBM keeps a
chance of showers over northeast Puerto Rico for much of the
period while the GFS lowers POPs into the teens or less for every
period except Monday morning. Low level flow will become stronger
on Wednesday and this is often an excellent driver for quick-
passing, shallow showers that will leave as much as a tenth of an
inch over the windward mountains and coasts during any given
24-hour period, therefore have kept the NBM POPs and augmented
POPs over the Atlantic waters in response to the better moisture
since the NBM had little or no chance of rain over our northern
waters for much of the long-term period. Only stray showers are
expected over the U.S. Virgin Islands at this time.

&&

.AVIATION...Generally VFR conditions are expected across all terminals for the
next 24 hours. Passing showers will move onshore from time to time,
with VCSH at TJSJ/TIST this morning; no operational impacts are
expected at terminals, however. Winds will pick up after sunrise,
generally out of the east-northeast, with speeds of 10 to 15 knots
and sea breeze variations. Winds will diminish after sunset,
becoming light again tonight. Maximum winds W 50-60 kts btwn
FL340-475.

&&

.MARINE...Winds and seas will remain gentle to moderate across the
area until Tuesday night. By Wednesday small craft advisories will
be necessary in the Atlantic waters and the Caribbean passages,
with unprotected Caribbean waters following. A high rip current
risk is expected to return to Puerto Rico`s north central coast
Monday night and spread around all of the islands with few
exceptions by Friday night.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 85 75 84 75 / 30 30 30 40
STT 86 75 85 74 / 20 20 20 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
333 AM AST Mon Dec 27 2021

.SYNOPSIS...Ridging aloft will maintain mainly fair and stable
weather condtions through early next week. Trade wind showers
will continue to favor the local waters into northern and eastern
sections, while afternoon convection, if any, will cluster across
the interior and southwestern areas of the local islands. By
midweek, increasing winds and a northerly swell will cause choppy
to hazardous marine conditions.


&&

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

Ridging at all levels over the southwestern Atlantic into the
northeastern Caribbean is expected to prevail through the short term
period. This will promote plenty of drier mid-to-upper level air,
and overall stable conditions aloft. Precipitable water content
during the next few days is forecast to remain below normal for the
season, with values ranging between 0.90-1.40 inches. Having said
that, the relative humidity trapped below 850 mb is expected to
remain near 90%, and two small peaks in low-level moisture are
expected by Tuesday evening, and by noon on Wednesday. This is
associated with the remnants of an old frontal boundary across the
western Atlantic being pushed across the region by stronger
northeast steering winds.

Therefore, mostly fair weather conditions are expected to prevail
across the islands in general, with the occasional passing shower
moving over windward areas of the islands during the night and early
morning hours, followed by shallow afternoon convection over the
southwestern quadrant of Puerto Rico each day. On Wednesday, a weak
frontal boundary is expected to move from the Atlantic waters and
across the islands as trade winds increase in response to a building
surface high pressure north of Hispaniola. This will result in a
noticeable increase in low-level clouds and shower activity.
Seasonable temperatures will prevail through the short term period
across all the islands.

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

The reasoning behind the long-term forecast analysis has not changed
much, suggesting mainly fair and stable weather conditions across
the region. At mid-to upper-levels, ridging will maintain a
generally strong trade wind cap through early next week. At the
surface, a building high pressure will maintain breezy to windy
conditions out of the east-northeast through the weekend.
Thereafter, winds are forecast to diminish while gradually
turning more from the east as the high pressure moves away into
the north central Atlantic and the local pressure gradient
relaxes.

Mid-to-upper levels are expected to have a cooling trend with 500 mb
temperatures gradually decreasing, dropping to -9 celsius by
Saturday. However, low moisture availability at mid to upper
levels will suppress thunderstorm development despite steeper mid-
level lapse rates across the area. Although the overall weather
pattern expected will only support limited shower activity, there
is a chance that cool advection along with patches of slightly
higher moisture content will enhance showers moving from the
waters into northern and eastern sections of the local islands.
This will be more likely for the latter part of the forecast
period. At the moment, model-estimated precipitable water is
anticipated to reach 1.25 inches at most by Monday. This will
result in very isolated shower activity, mainly over northeastern
coastal areas during night and morning hours with occasional
scattered showers across southwestern Puerto Rico in the
afternoon.


&&

.AVIATION...Mainly VFR conditions are expected to prevail across all
terminals during the next 24 hours. Low-level winds will continue
from the east-northeast at 7-12 kt.


&&

.MARINE...Seas of 5 feet or below will prevail through Tuesday
night, but increasing winds and a small northeasterly swell will
cause choppy to hazardous seas by Wednesday. Small Craft
Advisories may be required.

There is a high risk of rip currents for beaches of eastern St
Croix. A moderate risk continues for most of the remaining beaches
in Puerto Rico and the U.S. Virgin Islands.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 84 74 85 74 / 20 40 10 50
STT 80 78 80 78 / 20 20 10 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
358 AM AST Tue Dec 28 2021

.SYNOPSIS...Fair weather will continue across the islands for most
of the week through the weekend. Winds will increase starting
tonight, and seas will become choppy to hazardous.

&&

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

A low-to-mid level ridge over Florida will move over the
southwestern Atlantic, and it will remain as the main weather
feature through the short term period. This will continue to promote
stable conditions aloft and dry air across the local area. Northeast
trades are expected to prevail during the next several days, and as
the ridge tightens the pressure gradient on Wednesday, winds will
increase from 10-15 kt today to 15-20 kt through the second part of
the workweek. Embedded in this northeasterly steering wind flow, the
remnants of an old frontal boundary will move over the local
Atlantic waters on Wednesday. This should cause an increase in low-
level clouds and showers along the northern and central sections of
Puerto Rico. However, only minor rainfall amounts are forecast due
to the influence of the mid-level ridge. For today, fair weather
conditions will continue across the islands, with little to no
rainfall activity. On Thursday, trade wind showers should increase
during the overnight/early morning hours and minor rainfall amounts
could be observed over land areas across the USVI and east/northeast
sections of PR.

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

Model guidance now suggests a slightly wetter pattern for the latter
part of the long-term forecast period than previous model cycles.
However, mainly fair and stable weather conditions are still
expected to prevail across the region, especially for Friday through
the weekend. At mid-to-upper levels, ridging will maintain a
generally strong trade wind cap and unfavorable conditions for
shower development. Precipitable water values will remain close to
one inch or below maintaining moisture content well below normal for
this time of year through at least Sunday. Under these weather
conditions, shower activity, if any, will be very isolated with
minimal to trace rainfall accumulations. A patch of moisture, mainly
confined to the lower levels, will reach the forecast area by late
Monday. This slightly higher moisture content in combination with a
slight weakening of the trade wind cap and diurnal local effects may
promote somewhat higher chance for showers. Highest impact can be
expected for portions of eastern Puerto Rico and the U.S. Virgin
Islands during Monday night and Tuesday morning and later moving to
western Puerto Rico by the afternoon.

At the surface, a building high pressure will maintain moderate to
fresh winds at 15-20 mph for Friday through early next week. Then,
winds are forecast to diminish at 5-15 mph while gradually turning
from the east southeast as the high pressure moves away into north
central Atlantic, weakening the local pressure gradient. Under this
flow, expect warmer temperatures by Tuesday.


&&

.AVIATION...Mainly VFR conditions are expected to prevail across all
terminals during the next 24 hours. Low-level winds will continue
from the east-northeast at 8-15 kt.


&&

.MARINE...Light to moderate winds will prevail today across the
regional waters with seas 5 feet or less. Increasing winds and a
small northerly swell starting tonight should result in choppy to
hazardous seas. For the beaches today, the rip current risk is
high for the northern coast of Puerto Rico, Culebra, and St.
Thomas.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 84 72 84 74 / 10 30 30 30
STT 80 78 80 78 / 10 30 20 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
446 AM AST Wed Dec 29 2021

.SYNOPSIS...Mainly fair and stable weather conditions will
continue to prevail across the local islands for the next few
days, with light and brief showers possible. Increasing winds
will result in choppy seas through at least this upcoming
weekend. Showery conditions are possible the upcoming work
week.

&&

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

A mid-level ridge and a broad surface high pressure north of the
area will promote moderate to fresh northeasterly trades through the
short term period. Embedded in this wind flow, the remnants of a
cold front are forecast to move across the local waters and over
portions of the islands later this afternoon. This will bring a
small surge in low-level moisture, and some cloudiness with passing
showers in general through the evening hours. However, under the
influence of the mid-level ridge, stable conditions and drier air
aloft should limit the vertical development of the showers, and only
minor rainfall amounts are anticipated.

During the rest of the workweek, overall fair weather conditions are
expected to prevail across all the islands as the ridge remains as
the dominant weather feature. Nevertheless, northeast trades moving
over warmer waters should promote a cool advective pattern, with
shallow development of showers across the local waters moving at
times over portions of the USVI and northeastern PR. Normal to below-
normal temperatures are expected to prevail through the short term
period.

.LONG TERM...Saturday through Thursday...

A mid to upper level ridge will hold across much of the Caribbean
basin through at least Sunday. However, this feature is expected to
erode early next week as a TUTT develops across the central Atlantic
into the eastern Caribbean. Although the aformentioned TUTT is
expected to weaken by mid week, trofiness is expected to develop
once again north of the area by the end of the forecast cycle. At
lower levels, a fresh to moderate northeasterly wind flow will
continue to prevail. Model guidance suggests available moisture
remaining below normal values through at least mid week. Better
moisture advection could be expected by the end of the week as
trofiness develops north of the area.

As a result...continue to expected mainly fair and stable weather
conditions with partly cloudy skies. Showers, if any, will favor
coastal areas of northern and eastern Puerto Rico as well as the
US Virgin Islands during the evening-early morning hours, followed
by limited afternoon shower development over southwestern Puerto
Rico. Seasonable temperatures to continue with maximum ranging
from the mid 80s across coastal areas to the low 70s across the
higher elevations.

&&

.AVIATION...Mainly VFR conditions are expected to prevail across all
terminals during the next 24 hours. However, -SHRA and SCT/BKN cigs
btw FL030-FL060 are possible fm 29/17z-23z across the USVI/PR
terminals. Sfc winds will continue from the northeast at 10-15 kt
with gusts in the low 20s aft 14z.

&&

.MARINE...Increasing trade winds up to 20 knots and a small northeasterly
swell will result in choppy seas today and lasting through at least
this upcoming weekend. Small craft should exercise caution.
Dangerous rip currents expected due to breaking waves greater than
8 feet.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 83 74 84 74 / 40 40 30 30
STT 84 74 84 74 / 20 20 20 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
405 AM AST Thu Dec 30 2021

.SYNOPSIS...High risk of rip currents will continue through the
weekend across most of the northern and eastern beaches of the
islands. Fair weather conditions are expected to prevail during
the next several days under the influence of a mid-level ridge.
Breezy conditions are expected to continue today.


&&

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

A mid-level ridge will hold over the region for the next several
days. This will continue to promote a trade wind cap, drier air and
stable conditions aloft. Latest GOES-16 water vapor satellite
imagery still shows strong subsidence aloft associated to the mid-
level ridge hindering widespread shower activity across the area.
Infrared imagery and Doppler Radar detected some cloudiness and
scattered showers over the Caribbean waters associated with the
remnants of a cold front. Meanwhile, precipitable water values
continue to drop over land areas as a surface high pressure north of
Puerto Rico pushes dry air across the region as it maintains a
moderate to fresh northeasterly wind flow. Model guidance suggests
this pattern will persist through the short term period with the
remnants of the cold front moving further south and precipitable
water values plummeting to 0.8 inches by Saturday. Therefore,
expect mainly clear to partly cloudy skies and fair weather
conditions through Saturday. Brisk winds could increase somewhat
moisture convergence along windward coastal areas with models
suggesting highest 850-700 mb humidity by early Friday. Showers, if
any, are more likely by late tonight through Friday morning over
northern and eastern portions of the islands. However, minimal to
trace amounts of rainfall accumulations can be expected with this
activity.

.LONG TERM...Sunday through Friday...

The upper level ridge is forecast to gradually weaken, but still
hold over the region through the long term period. Meanwhile, a
TUTT-low is forecast to develop just east of the Leeward Islands
by Monday from an upper level trough over the central Atlantic.
This is expected to induced weak perturbations in the trade winds
on Monday and Wednesday, and increase low-level clouds and
scattered showers across the local area. Otherwise, fair weather
conditions are expected to prevail in general with only brief
passing showers moving at times across portions of the USVI and
east/northeast sections of PR during the night/early morning
hours. During the afternoons, limited shower development is
expected over land areas, if any.


&&

.AVIATION...Mainly VFR conds are expected to prevail across all
terminals during the next 24 hours. Winds primarily out of the ENE
will increase after 14Z to around 15KT and gusting to 25KT, and
turning more from the ESE later this morning for TJPS.


&&

.MARINE...Choppy seas up to 6 feet and east to northeast winds up
to 20 knots are expected to continue across the regional waters
today. A northeasterly swell will continue to filter across the
Atlantic waters, and promote a high risk of rip currents for most
of the northern and eastern exposed beaches of all the islands.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 84 73 84 72 / 30 30 30 20
STT 84 71 84 71 / 20 30 30 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
349 AM AST Fri Dec 31 2021

.SYNOPSIS...Life-threatening rip currents along the northwest to
northeast coasts of all the islands will continue to be the main
hazard through next week. Fair weather conditions are expected to
prevail during the next several days under the influence of a mid-
level ridge. An increase in moisture content is expected by
midweek.


&&

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

No major changes to the short term forecast as a surface high
pressure north of Puerto Rico and U.S. Virgin Islands and a mid-
level ridge continues to dominate the area promoting a trade wind
inversion cap. With a tight pressure gradient, a moderate to fresh
east northeast wind flow with gusty conditions will prevail through
the weekend. Precipitable water content has remained close to 1.0
inches with GOES-16 satellite imagery showing a field of clouds
being advected from the northeast across the area. Some isolated
very quick showers have been detected across windward coastal areas
during the overnight hours. This pattern will persist through the
morning hours with minimal rainfall accumulations. Afterwards,
precipitable water is expected to further drop, reaching values as
low as 0.7 inches by early Sunday. Under this weather pattern,
expect dry and fair weather conditions to continue across the local
islands. By early afternoon on Sunday, the leading edge of a
slightly moister airmass will approach the northeast regional
Atlantic waters. As the airmass gets advected, precipitable water is
forecast to gradually increase, bringing back values close to 1.0
inches through late Sunday night over land areas. Moisture content
will still remain below normal levels, however, increasing
cloudiness and some quick showers can be expected over western
portions of Puerto Rico in the afternoon and later over eastern and
northern coastal areas of the local islands after evening hours.

.LONG TERM...Monday through Saturday...

At least through midweek, the ridge pattern west and north of the
region is forecast to gradually weaken under pressure from a
polar trough lifting across the western Atlantic. In response, the
trade wind cap is forecast to relax somewhat and allow moisture
content to increase on Wednesday and Thursday. Latest guidance
suggest precipitable water content from around 1.00 inch on
Monday, increasing to near 1.75 inches on Wednesday, and slowly
eroding through Friday as another low to mid-level ridge builds
over the northeastern Caribbean and western Atlantic. Meanwhile, a
TUTT low is forecast to develop east of the Leeward Islands on
Monday and move further east across the tropical Atlantic during
the week. Long range guidance suggests that a TUTT induced low-
level trough is forecast to move across the local area on
Saturday. In general, fair weather conditions should continue to
prevail across the islands through the long term period, with a
noticeable increase in shower activity on Wednesday.


&&

.AVIATION...Mainly VFR conditions are expected to prevail across
all terminals during the next 24 hours. Trade wind SHRA are
expected to move across the USVI and windward coastal areas in PR
through 31/14Z, resulting mainly in VCSH across TJSJ/TJBQ/TISX.
Winds below 10 kts from the ENE through 31/14Z, increasing to
between 12-18 kts with sea breeze variations and gusty conditions
afterwards.


&&

.MARINE...At least through next week, choppy seas up to 6 feet
and east to northeast winds up to 20 knots are expected to prevail
across the regional waters. The highest seas are expected across
the Atlantic waters due to a northeasterly swell, and across the
offshore Caribbean waters due to wind driven seas. A high risk of
rip currents will continue through next week for most of the
northern and eastern exposed beaches of all the islands.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 84 75 82 72 / 20 20 20 20
STT 84 75 84 71 / 20 20 20 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
454 AM AST Sat Jan 1 2022

.SYNOPSIS...Fair weather conditions are expected to prevail for
the next several days. Few passing showers are expected for the
windward sections of the islands. High rip currents risk continue
in effect along the northwest to northeast coasts of all the
islands.

&&

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

A mid-level high pressure will promote dry air and subsidence aloft
and a strong trade wind inversion. A dry air mass with below-normal
moisture with precipitable water ranging from 0.90 or less will
continue through Monday. Therefore, a stable weather pattern with
pleasant temperatures will prevail over the short term. Puerto Rico
and the U.S. Virgin Islands will observe a mix of clouds and
sunshine each day, with a few passing showers making their way
across the windward sections at times. The combination of sea breeze
variations and topography could result in a few showers across the
interior and western areas of Puerto Rico during the afternoon.

.LONG TERM...Tuesday through Sunday...

A present mid-level ridge pattern west and north of the region is
forecasted to weaken by early next week. Moisture content is
expected to increase with the arrival of the remnants of a surface
front propagating through the area. This will enhance the
potential for showers over portions of eastern, northern, and
southwestern Puerto Rico from time to time. East to northeasterly
trade winds are forecast to persist over the local area and
active weather will be seen by Wednesday through Thursday.

The latest GFS model guidance continues forecasting patches of
moisture pulled from the Atlantic waters. Those patches will
place over the islands, enhancing unstable conditions aloft and
shower formation. This pattern will linger through the end of the
long period. A pre-frontal band is expected to arrive before
Sunday, bringing more instability before a cold front reaches the
local area.

&&

.AVIATION...VFR conditions will persist across the local flying area, with a few
VCSH from time to time. Surface winds will continue from the NE
around 10 kt, increasing at 15 to 20 kt with gusty winds up to 30 kt
and sea breeze variations after 01/13z and onward.

&&

.MARINE...Choppy seas up to 6 feet and east to northeast winds up
to 20 knots are expected to prevail across the regional waters.
The highest seas are expected across the Atlantic waters due to a
northeasterly swell, and across the offshore Caribbean waters due
to wind driven seas. A high risk of rip currents will continue
through next week for most of the northern and eastern exposed
beaches of all the islands.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 84 71 83 73 / 20 20 20 30
STT 83 70 84 72 / 10 20 20 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
412 AM AST Sun Jan 2 2022

.SYNOPSIS...Fair weather conditions are expected to prevail
through at least Monday, when moisture content will filter into
the area. Seas will remain choppy today. High rip currents risk
continues in effect along the northwest to northeast coasts of
all the islands for the next several days.

&&

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

Today, a mid-level high pressure will hold over the islands,
promoting dry air and subsidence and a strong trade wind inversion.
Also, the below-normal moisture content will continue with total
precipitable water ranging around 0.90 inches. Therefore, a similar
pattern with stable weather and pleasant temperatures will return
over the islands today. Puerto Rico and the U.S. Virgin Islands will
observe a mix of clouds and sunshine each day, with a few passing
showers making their way across the windward sections at times. The
combination of sea breeze variations and topography could result in
a few showers across the interior and western areas of Puerto Rico
during the afternoon.

The mid-level ridge will weaken tomorrow into Tuesday, weakening the
trade wind inversion and allowing better mixing. The remnants of an
old frontal boundary will sink southward, pushed by the trade winds,
which will increase the frequency and intensity of showers Monday
and Tuesday. Although showery weather should be possible, no
significant rainfall event is anticipated.

.LONG TERM...Wednesday through Monday...

Overall a showery weather pattern prevails over the forecasted area.
A mid-level ridge west of the region will move and weaken under
pressure from a trough. The remnants of a frontal boundary will
bring moisture content, and is expected to enhance the potential for
showers over portions of northern and eastern Puerto Rico from time
to time, followed by afternoon convection over the western area.
East to northeasterly trade winds are forecast to persist over the
local area and active weather will be seen by Wednesday through the
next several days.

The latest GFS model guidance continue forecasting patches of
moisture pulled from the Atlantic. Those patches will place over the
islands, enhancing unstable conditions aloft and shower
formation. This pattern will linger through the end of the long
period. A pre- frontal band is expected to arrive before Sunday,
bringing more instability before a cold front reaches the local
area on Monday.

&&

.AVIATION...VFR conditions will persist across the local flying
area, with a few VCSH from time to time. Surface winds will continue
from the NE at 10 kt or less, increasing at 15 to 20 kt with gusty
winds up to 30 kt and sea breeze variations after 02/13z and onward.


&&

.MARINE...Choppy seas up to 6 feet and east to northeast winds up
to 20 knots are expected to prevail across the regional waters. For
the beachgoers, a high risk of rip current is in effect for all
the north coast of Puerto Rico, Culebra, Vieques, St. Thomas and
the eastern tip of St. Croix. For the rest of the local beaches,
the risk will remain moderate.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 83 72 84 74 / 10 30 30 30
STT 83 72 84 73 / 10 20 20 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
442 AM AST Mon Jan 3 2022

.SYNOPSIS...Remnants of an old frontal boundary across the islands
will increase the moisture, clouds and shower activity through
morning hours. Expect a showery weather pattern for the next several
days. Hazardous coastal conditions are expected to prevail across
all the north-exposed beaches across the islands.

&&

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

The trade winds will bring the remnants of an old frontal boundary
across the islands, increasing moisture, clouds, and shower activity
through the morning hours. Therefore, expect clouds and showers
across the local waters and the windward portions of Puerto Rico and
the U.S. Virgin Islands. Although some of these showers will produce
moderate to locally heavy rains, their fast-moving nature will limit
rainfall accumulations. The U.S. Virgin Islands and east PR can
expect a pause in rain activity later this morning into the
afternoon. However, showers will migrate into the interior and
western portions of PR.

A set of surface high pressure across the Atlantic Ocean will
promote an advective pattern pushing patches of moisture, resulting
in showery weather Tuesday and Wednesday. The frequency and
intensity of the shower activity could increase as the mid-level
high pressure weakens in response to a TUTT low near the Lesser
Antilles. Therefore, the moisture content will enhance from Tuesday
to Wednesday.

.LONG TERM...Thursday through Tuesday...

A surface to mid level trough prevailing north of the forecasted area
and over the Atlantic waters is expected to linger across the
islands for several days. This trough will continue to bring bands
of tropical moisture into the forecast area for the beginning of the
long term. This pattern will support the development of showers with
rainfall accumulations over Puerto Rico and the U.S. Virgin Islands.
A shift on the winds from the north-northeast will noticeable, when
the trough merge with a frontal system located in the east coast of
the U.S.. Latest model guidance continues to forecast bands of
moisture associated to a cold front and a trough. Those bands will
place over the islands, enhancing unstable conditions aloft and
shower formation. This pattern will linger through the end of the
long period. The frontal system is expected to arrive over the
weekend into next week, bringing more instability to the local
area.

&&

.AVIATION...VFR conditions will persist across the local flying area. However,
cloudiness will increase and ISOLD to SCT SHRA/-SHRA are expected
across the local flying area. Surface winds will continue from the E-
NE at 10 kt or less, increasing around 15 kt with higher gusts and
sea breeze variations after 03/13z.

&&

.MARINE...Choppy seas up to 6 feet and east to northeast winds up
to 20 knots are expected to prevail across the regional waters.
For the beachgoers, a high risk of rip current is in effect for
all the north coast of Puerto Rico, Culebra, Vieques, St. Thomas
and beaches of the northeastern and eastern St. Croix. For the
rest of the local beaches, the risk will remain moderate.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 83 74 84 74 / 30 20 50 50
STT 84 73 84 73 / 10 10 50 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
429 AM AST Tue Jan 4 2022

.SYNOPSIS...Few passing showers are anticipated through the
morning, followed by afternoon convection across the
interior and western PR. The presence of the surface high
pressure just northeast of the area will continue to result in a
trade wind pattern pushing some fragments of moisture for the rest
of the week. Hazardous coastal conditions are expected to remain
in place for the next several days.

&&

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

The ridge aloft will erode throughout the day, breaking the trade
wind inversion over the region. Meanwhile, the pressure gradient
will lose in response to a weakening surface high pressure
diminishing the winds across the islands. Under this pattern, fewer
passing showers are anticipated through the morning, leaving a mix
of clouds and sunshine across the region. However, sea breeze
variations will aid afternoon convection across the interior and
western PR. At the same time, a surge of moisture will bring another
round of passing showers across the local waters, the U.S. Virgin
Islands, and north and east PR late in the afternoon into the
evening. Periods of moderate to locally heavy showers could produce
ponding of water in roads and low-lying areas, especially late in
the afternoon into the evening.

This evening into Wednesday, an old frontal boundary remnant will
make its way from the east-northeast across the islands, promoting
showery weather. However, the Virgin Islands should observe more
sunshine than rain activity by Wednesday morning. On Thursday, the
Three King Days (El Dia De Reyes), a disturbance in the trades
combined with low-level convergence could result in pesky showers
throughout the day. Although Wednesday and Thursday look rainy, no
significant flooding is forecast at this time.

.LONG TERM...Friday through Wednesday...

Overall a surface to mid level ridge continues dominating the local
weather conditions, and is expected to linger across the islands
until Sunday. Bands of tropical moisture will continue to filter
into the forecast area enhancing the development of showers with
rainfall accumulations over Puerto Rico and the U.S. Virgin Islands.
By Sunday night into Monday, winds are expected to shift from the
north-northeast with the arrival of the remnants of a frontal
system. Latest model global guidances (GFS and ECMWF), forecast
fragments of moisture from the frontal system sinking into the area
and bringing more instability across the islands. By midweek, a high
surface pressure is expected to intensity over the Atlantic. Much
drier air will filter into the local area promoting stable
conditions.

&&

.AVIATION....VFR conditions will prevail across the local flying
area. However, clouds and a few showers will move across terminals
from time to time. SHRA activity and cloudiness will increase
across the region late this afternoon into the evening. Surface
winds will continue from the E-NE at 10 kt or less, increasing
around 15 kt with higher gusts and sea breeze variations after
04/13z.

&&

.MARINE...Choppy seas up to 6 feet and east to northeast winds up
to 15 knots are expected to prevail across the regional waters.
For the beachgoers, a high risk of rip current is in effect for
all the northern coasts of Puerto Rico, Culebra, Vieques, and the
U.S. Virgin Islands. For the rest of the local beaches, the risk
will remain moderate.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 84 73 84 75 / 40 60 50 40
STT 84 72 84 73 / 50 60 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
529 AM AST Wed Jan 5 2022

.SYNOPSIS...

An old frontal boundary will promote a showery weather across the
islands today. The U.S. Virgin Islands can expect a mix of
sunshine and clouds later this morning. In general a wet pattern
will persist the rest of the work-week. Increasing winds and a
northeasterly swell deteriorate marine and coastal conditions
mainly across the Atlantic waters and Caribbean passages.

&&

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

A mid/upper-level ridge will build across the Greater Antilles
through the next few days. However, low-level moisture associated
with the remnants of an old frontal boundary will result in
showery weather across the windward sections of Puerto Rico
(northern and eastern coast) and the U.S. Virgin Islands through
the morning hours. However, the Virgin Islands will observe a lull
in rain activity as a dry slot filter from the east, limiting
showers later this morning. Showers will move inland across the
interior and southwest sections of Puerto Rico by mid-morning into
the afternoon. Periods of moderate to locally heavy rains could
produce water ponding in roads and poorly drained areas.

Rain activity should diminish this evening into early Thursday
morning, before the arrival of another surge of moisture embedded
in the trades by Thursday morning (El Dia de Los Tres Reyes
Magos). This surge of moisture will bring showers, mainly across
the windward sections of Puerto Rico and the typical afternoon
activity across the interior and western portions. At the same
time, the Virgin Islands can expect a mix of clouds and sunshine
until the arrival of a second trade wind perturbation around late
Thursday afternoon/evening. This perturbation will create
favorable weather conditions to observe a wet pattern.

.LONG TERM...Saturday through Thursday...

A mid-level ridge will promote a strong trade wind cap over the
islands through at least early next week. A migrating surface high
pressure moving eastward from the western Atlantic to the central
Atlantic will promote an east to northeast wind flow across the
northeast Caribbean. Under this wind flow, patches of moisture
will move across the islands, promoting the typical tropical
winter pattern.

A frontal boundary is forecast to exit the Eastern Seaboard early
next week, sinking southward near the northeast Caribbean by mid-
week. A polar trough could amplify near the region at upper
levels, increasing instability. This feature could promote an
unstable weather pattern for the second part of the work week.

&&

.AVIATION...

SHRA/-SHRA will affect local terminals of PR/USVI from time to
time. However, VFR conditions will persist across the local flying
area. Surface winds will continue from the E-NE at 10 kt or less,
increasing around 15-20 kt with higher gusts and sea breeze
variations after 04/13z.

&&

.MARINE...

Winds will continue from the east to east-northeast at 10 to 20
knots across the local waters. The combination of increasing winds
and a northeast swell will result in choppy seas between 4 and 6
feet across most of the local waters. Therefore, Small Craft
Operators should exercise caution. Seas are forecast to increase
at 7 feet across the Atlantic Offshore waters later this evening.
Therefore, a Small Craft Advisory is in effect from late tonight
through Friday morning. Choppy to locally hazardous marine
conditions will persist through much of the forecast period.

Beachgoers...

For Puerto Rico, there is a high risk of rip currents for the
north-facing beaches of Puerto Rico and Vieques and all the
beaches in Culebra.

For the U.S. Virgin Islands, there is a high risk of rip currents
for the north and west-facing beaches of St Thomas and the north-
facing beaches of St John and the north and east-facing beaches
of St Croix.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 84 74 84 74 / 60 50 40 50
STT 84 73 85 73 / 40 50 40 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
510 AM AST Fri Jan 7 2022

.SYNOPSIS...A surface trough moving over the forecast area will
continue to cause cloudiness and shower activity in the morning.
As a result, some ponding of water in roadways and poor drainage
areas is expected. For the late afternoon hours into the evening
hours, a slightly drier airmass will filter into the region and
will result in some cloudy skies with a few showers. For the rest
of the short term period, a variable weather pattern is expected
with patches of moisture filtering into the area. A strong polar
trough is forecast to affect the local area by midweek of the
upcoming week. Choppy marine conditions and hazardous coastal
conditions are expected for the next several days as a long period
northerly swell continues to invade the local waters.

&&

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

Strong surface high pressure across the northeastern Atlantic will
cause easterly winds today across the local area. Another surface
high pressure will enter the western Atlantic on Saturday into
Sunday, tightening the pressure gradient and causing stronger E-NE
winds across the local area. The available moisture will go up and
down through the short term period. A shortwave trough currently
passing through the local area is causing moderate showers across
eastern PR. These showers will continue into the very early morning
hours. The moisture and the shortwave trough will combine with
diurnal heating to cause showers across the northwestern quadrant of
PR this afternoon, but scattered showers will move into eastern PR
as well. The USVI is forecast to observe mainly fair weather today,
but brief isolated showers are forecast this afternoon and evening.
The available moisture will decrease tonight but will increase by
the mid morning hours of Saturday, causing showers to move in from
the east, affecting the USVI first, then the rest of PR during the
day. A decrease in moisture expected late Saturday night, and
increasing again on Sunday. The mid and upper levels are stable with
high pressure, therefore the showers are expected to be relatively
shallow. Also, with the somewhat strong winds, the showers are
expected to move quickly, so that mainly ponding of water would be
the main impact. In terms of temperatures, near normal temperatures
are expected.

.LONG TERM...Monday through Saturday...

A typical winter weather pattern will prevail for the first part
of the long term period forecast. At the surface, on Monday into
Wednesday, a surface high pressure moving eastward through the
Atlantic will maintain a trade wind pattern from the east across
the Atlantic, including the forecast area. Embedded in the trade
winds, patches of moisture with precipitable water values above
normal will filter into the region. This increase in moisture
will enhance the typical passing shower activity. Although the
conditions are expected to remain favorable for showers, the
threat for flooding will remain low as stable conditions prevail
due to a sinking mid level ridge.


Global model guidances( GFS and ECMWF) continue to suggest a
deteriorating pattern for late Wednesday into the weekend across
the region. A deep upper polar trough will amplify over the
region, increasing the instability and the divergence aloft.
Meanwhile, at the surface, the wind pattern is expected to be
affected by a low pressure system well to the north of the
forecast area. In response to the aforementioned feature, the wind
will remain variable and gentle to light. This evolving pattern
with plenty of moisture and unfavorable conditions aloft will
enhance the afternoon shower activity. Isolated thunderstorms
along with the shower activity is possible, as the temperatures
at 500 MB fluctuate between -8 and -10 Celsius. After considering
model uncertainty, the confidence in the forecast for the latter
part of the long term forecast is moderate.

&&

.AVIATION...
VFR conds expected across the local terminals through
the forecast period. SHRA activity early in the morning will affect
TJPS through around 07/11Z, while brief SHRA could affect TJBQ after
07/09Z with CIGS near FL050-060. Winds will be from the east at
around 10KT early, gusty near SHRA. Prevailing easterly winds after
07/13Z at 10-15KT with sea breeze variations.

&&

.MARINE...

A surface high pressure over the northeastern Atlantic will
promote moderate easterly winds between 10 and 15 knots mainly
over the offshore Atlantic and Caribbean waters. This wind flow
in combination with a long-period northerly swell, will result in
choppy to hazardous seas across the Atlantic offshore and
nearshore waters. As a result, there is a Small Craft Advisory in
effect until 2 PM AST this afternoon. Hazardous coastal conditions
will prevail for most of the northern beaches of Puerto Rico and
the U.S. Virgin Islands. As a result, there is a high risk of rip
currents for the north-facing beaches of Puerto Rico and most
beaches of Vieques, Culebra, and all of the U.S. Virgin Islands.
Additionally, breaking waves of 9-11 feet are expected and will
create dangerous swimming and surfing conditions. Therefore, a
High Surface Advisory will be in place for the northwest to the
northeast coast of Puerto Rico and Culebra until 6 PM AST early
the evening. Please refer to the latest Coastal Hazard Message for
more detailed information.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 84 74 84 74 / 30 20 40 40
STT 84 74 85 74 / 30 20 40 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
447 AM AST Sat Jan 8 2022

.SYNOPSIS...Moderate easterly winds expected today, becoming
slightly stronger and more northeasterly on Sunday. Patches of
moisture will be passing through over the next several days.
Scattered showers are forecast across the local area every day
thisweekend into early next week, mainly affecting the USVI and
eastern PR in the morning and night time hours, while western PR
has a better chance of rain in the afternoons. A more significant
increase in moisture and perhaps even thunderstorms could be
possible in the middle to latter part of next week, as a strong
polar trough digs south into the local area.

&&

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

For the rest of the morning hours, according to GOES-16
Precipitable Water imagery, a drier airmass with P-Wat of 0.96
will continue to move across the area, resulting in limited brief
shower activity over the windward sections of the islands. After
that, by the early afternoon hours, a surge of moisture will
filter into the area, this along with diurnal heating will result
in locally induced afternoon showers. The shower activity is
expected to remain shallow, given the presence of the ridge at the
mid levels. For Sunday into Monday, the mid level ridge will
continue to result the dominant feature over the forecast area.
This will promote a strong trade wind cap over the area and stable
conditions aloft. Meanwhile, at the surface, a building high
pressure exiting the east coast of the United States and moving
eastward into the western Atlantic will increase the moisture over
the local area, and at the same time, it will tighten the
pressure gradient. This will increase the frequency though of the
shower activity, but the showers will be brief during the morning
and evening hours. Scattered showers expected in the afternoon
hours each day. The wind pattern will affect the flood threat
potential, remaining low due to the fast moving showers. Daytime
temperatures will range between the mid 70s and upper 80s across
all the local islands.

.LONG TERM...Tuesday into Sunday...

Near normal moisture and easterly winds are expected on Tuesday
and early Wednesday, causing scattered showers. However, starting
late Wednesday into Thursday, the local wind pattern may start to
shift, turning southerly and southwesterly by Friday. Winds are
expected to gradually weaken during this time as well. This is due
to a surface high pressure that develops to the northwest of the
local area then move northeast. By Saturday, a strong surface low
will be to the north northeast of the local area, east of Bermuda,
causing a COL over the local area and therefore light winds. With
respect to rainfall, the increase in moisture during this period,
combined with mid and upper level troughs that are expected on
Wednesday into Thursday, may cause an increase in shower activity
and even some thunderstorms. This is because the 500mb
temperatures are forecast to be near -9 to -10C, which is much
colder than the climatological averages. By late Saturday into
Sunday, a weak surface high pressure could move into the
southwestern Atlantic, causing a frontal boundary that extends to
the east of the local islands, keeping the local islands in the
drier side with ENE winds.

&&

.AVIATION...VFR conds will prevail for all the TAF sites during the
period. At 08/14Z a surge of moisture will result in some VCSH
across TIST, TISX and TJSJ, more shower activity could result in
SHRA at TJPS around 08/18Z. Winds will remain from E-NE 10-15 kt
with some sea breeze influences and gusty wins up to 22 knots.
Winds expected to decrease to 12 knot or less after 08/22Z.


&&

.MARINE...Choppy to hazardous seas expected this weekend into
early next week. Small craft advisory is in effect until Monday
night for the offshore Atlantic waters due to seas up to 7 feet.
However, many of the rest of the local waters will have seas up to
6 feet and small craft operators are urged to exercise caution.
High risk of rip currents remain in effect today for the northwest
to northeast beaches of PR, all of the beaches in Culebra,
northern Vieques, north and western St Thomas, northwestern St
John, and eastern St Croix. There is a moderate risk of rip
currents elsewhere.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 83 74 82 73 / 40 40 40 10
STT 83 73 84 73 / 40 30 30 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
501 AM AST Sun Jan 9 2022

.SYNOPSIS...Surface high pressure across the northeastern Atlantic
and another passing through the central Atlantic today will cause
breezy conditions across the local islands through late tonight.
Patches of moisture will move through for the next few days,
causing brief isolated to scattered showers across the local
islands from time to time. A shift in winds, an increase in
moisture and a mid to upper level troughs will cause a change in
the weather pattern from late Wednesday onward, increasing the
chances of rain and perhaps even a few thunderstorms over the
local area.

&&

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

A variable weather pattern is expected through the short term
period. At the surface, a building high pressure located over the
northwestern Atlantic exiting the east coast of the Unites States
will continue to result in a more northeasterly wind flow over the
area. Embedded in this trade wind pattern, expect a mixture of
dry air and patches of shallow moisture with precipitable water
values of 1.4 inches or less filtering into the CWA from time to
time during the short term period. Meanwhile, at the mid levels,
stable conditions will prevail with the presence of a ridge
creating converge and a trade wind cap. This will disfavor the
intensity and coverage of the shower activity today into Monday.
For today, as the surface high pressure moves into the central
Atlantic, winds will increase, this will affect the movement
pattern of the showers. Therefore, expect brief passing showers
for the morning hours and for the afternoon hours a little more of
convection over southwest Puerto Rico with minimal rainfall
accumulations. On Monday, according to model guidance (GFS and
ECMWF) an increase in moisture is expected as a surge of moisture
filters into the area and result in mainly morning activity over
the northeastern and north sections of Puerto Rico. On Tuesday,
the mid level ridge is expected to remain in place, but the
influence of a south sinking trough might push the ridge more to
the south of the forecast area, affecting the stable pattern. At
the same time, a brief pocket of drier air will filter into the
area, limiting the shower activity once again. Daytime
temperatures are forecast to remain in the mid to upper 80s
across the south coastal sections and between the mid 70s and the
mid 80s for the rest of the area.

.LONG TERM...Wednesday through Monday...

Easterly winds are expected on Wednesday but weakening as the day
progresses, with increasing moisture moving in. This will cause
scattered showers across the local islands with isolated
thunderstorms as a mid and upper level trough moves in. Starting
late Wednesday into Thursday, the local wind pattern is still
forecast to start to shift and weaken, turning southerly and
southwesterly by Friday. This is due to a surface low pressure
developing to the north northwest of the local area as it moves
northeast. By Saturday, a strong surface low will be to the north
northeast of Bermuda, and a weak high pressure entering the
southwestern Atlantic, causing a COL over the local area and
therefore light winds. With respect to rainfall, the increase in
moisture during this period, combined with mid and upper level
troughs that are expected on Wednesday into Thursday, may cause an
increase in shower activity and even some thunderstorms. This is
because the 500mb temperatures are forecast to be between -8 and -10C
from late Wednesday all the way into Saturday, which is much
colder than the climatological averages. By late Saturday into
Sunday, a weak surface high pressure could move into the
southwestern Atlantic, causing a frontal boundary that extends to
the east of the local islands, keeping the local islands in the
drier side with ENE winds. Therefore, better weather is expected
for next weekend if the models were to verify.


&&

.AVIATION...FR conds will prevail for all the TAF sites. Some VCSH
will continue to affect TIST, TNCM, TKPK and TISX until 09/14Z.
surface winds will continue from the NE at 10-12 kt or less until,
increasing between 15-20 kt with higher gusts and sea breeze
variations after 09/13z. For 10/03Z and increase in VCSH are
expected over TJSJ and this could affect the ceiling and visibility
conditions.


&&

.MARINE...Northeasterly winds between 15 and 20 knots with seas
between 4 and 7 feet are expected due to the combination of a
northeasterly swell and wind waves. Therefore, small craft
operators should exercise caution across many of the local
waters. However, there is a small craft advisory in effect for the
offshore Atlantic waters currently in effect, and another advisory
will go into effect at 8 AM this morning for the Anegada Passage
and the offshore Caribbean waters. These advisories will be in
effect until Monday night for the Atlantic waters and until late
tonight for the Anegada Passage and the offshore Caribbean waters.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 82 74 82 73 / 40 50 40 20
STT 84 72 83 70 / 30 50 40 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
432 AM AST Mon Jan 10 2022

.SYNOPSIS...With evening-early morning trade wind showers and
limited afternoon convective development, a seasonal weather
pattern will prevail through Wednesday. After that, a mid-to-upper
level trough, enhanced low-level moisture convergence, and mid-
level cooler temperatures will lead to a wetter and more unstable
weather pattern for the second half of the week into the upcoming
weekend. Moderate to locally fresh trade winds and a small
northerly swell will maintain choppy to hazardous seas today.


&&

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

A mid to upper level high pressure ridge will hold across the region
through Tuesday but will slightly erode on Wednesday as a short wave
trough crosses just north of the area. A strong surface high
pressure propagating eastward over the western Atlantic will help
maintain a moderate east northeast wind flow across the region this
morning. The local winds are however forecast to gradually diminish
later this afternoon and through Tuesday as the local pressure
gradient loosens in response to the high shifting farther into the
north central Atlantic, as a cold front stalls well north of the
region.

In the meantime, moisture fragments from an old frontal boundary
will cross the area, bringing periods of quick passing clouds and
showers over the regional waters and parts of the coastal areas
mainly during the rest of the morning hours. During the afternoon,
cloudiness and shower activity should be less and will be focused
mainly over the interior and southwest sections of Puerto Rico.
Elsewhere, afternoon shower activity will be mainly downwind of the
adjacent islands including the USVI. No significant shower activity
or rainfall accumulations are so far anticipated during the
afternoon hours. Similar and more of the seasonal weather conditions
are expected on Tuesday.

By Wednesday however the pattern changes somewhat, as the local
winds diminish while becoming more easterly, and the aforementioned
cold front and associated shear line and weakly induced surface
trough approaches the region. This along with the weakness in the
upper level ridge, will increase instability aloft as well as low
level moisture convergence. As a result, there will be a better
chance for an increase in morning shower activity as well as the
chance for isolated afternoon thunderstorms. At this time,
widespread shower development and thunderstorm activity is not
anticipated, as most of the activity should be of short duration.
However, some locally heavy rains at times may increase the chance
for ponding of water on roads, as well as minor urban flooding in
isolated areas.

.LONG TERM...Thursday through Tuesday...

Model guidance suggests a generally weak and variable wind flow at
the surface, shifting clockwise through the long-term forecast
period. On Thursday, a developing surface low-pressure system to
the north-northwest will promote east to southeast winds. This
feature will continue to move eastward across the western
Atlantic, and winds will shift from the south to the southwest on
Friday. In the wake of the developing low, a weak surface high
pressure will begin to move into the western Atlantic by Saturday,
causing a col over the local area, with light and variable winds
of 5-10 mph through Sunday. After that, a generally easterly wind
flow will return, with winds increasing to 10-15 mph Monday into
Tuesday. Regardless of the changing surface winds, a predominantly
south to southwest steering flow will dominate the 850 to 700
mbar layer.

While mid-level ridging will hold northeast of the local islands
through most of the period, a mid-to-upper level trough will
weaken the trade wind cap inversion, allowing for deeper moisture
and slightly cooler 500 mbar temperatures as low as -10 degrees
Celcius due to cold air advection at least through Sunday.
Combined with increased moisture, with model-estimated
precipitable water rising to 1.7 inches by Friday afternoon due to
low-level moisture convergence, expect an increase in shower
activity and the potential for isolated thunderstorm development.
The bulk of the shower activity will favor southern coastal areas
through the evening-early morning hours, while afternoon
convective development will cluster mainly along northern sections
of the local islands. The remnants of an old frontal boundary will
stall north of the area by Sunday into early next week, but so
far, it does not represent a potential rainfall producer. As the
mid-level ridging moves back into the northeastern Caribbean and
the trade wind cap inversion strengthens, improved weather
conditions will return by Monday and Tuesday. A southerly
component in the general wind flow could result in above-seasonal
temperatures between Thursday and Saturday.


&&

.AVIATION...VFR conditions will persist at all terminals durg
prd. SCT ocnl BKN lyrs nr FL025...FL050..FL080 with wdly SCT
-SHRA/SHRA en route btw islands and ovr regional waters. Brief Mtn
top obscr ovr E PR due to low clds/-SHRA til 10/13Z. Sfc wnds fm
the ENE at 10 kt or less but gusty w/ passing SHRA, increasing to
around 15 kts with higher gusts and sea breeze variations after
10/14z.


&&

.MARINE...Moderate to locally fresh winds and a small northerly
swell will maintain choppy to hazardous seas today. As a result,
a Small Craft Advisory remains in effect for the offshore Atlantic
waters through this evening. Conditions will gradually improve
through midweek, but small craft operators should continue to exercise
caution.

There is a high risk of rip currents for beaches across the north
coast of Puerto Rico and Culebra, the southeast coast of Puerto
Rico, the east coast of Vieques, the northwest coast of St Thomas,
and the east and north coast of St Croix.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 83 73 84 73 / 50 50 50 30
STT 84 76 84 76 / 40 50 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
415 AM AST Tue Jan 11 2022

.SYNOPSIS...A patchy weather pattern will prevail through
Wednesday, with intermittent patches of moist and relatively dry
air streaming across the area. After that, enhanced low-level
moisture convergence and somewhat favorable conditions aloft will
lead to a wetter and more unstable weather pattern through the
weekend into early next week. Thus, expect an increase in showers
and possible thunderstorm development, mainly in the afternoon.
Elevated to briefly critical fire danger threat conditions are
possible each day.


&&

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

A mid to upper level ridge will hold across the region today but
will continue to erode through Wednesday as a short wave trough
crosses the west Atlantic just north of the region. A surface high
pressure will lift farther northward into the north central
Atlantic, as a cold front and associated band of moisture crosses
the west Atlantic and stalls north of the region by Wednesday while
weakening and becoming sheared. This in turn will promote a light
east northeast wind flow today, then become more easterly by
Wednesday and Thursday as an induced surface trough sets up across
the area.

The light east northeast low level wind flow will continue to
transport occasional patches of low level moisture from an old
frontal boundary across the area. Periods of passing clouds and
showers will affect the regional waters and the north and east
coastal areas during the rest of the early morning hours. Afternoon
cloud and shower development should be focused mainly over the
central interior and west sections of Puerto Rico, with mostly fair
weather skies expected elsewhere including around the USVI. No
significant shower activity or rainfall accumulations are
anticipated during the afternoon hours.

By Wednesday and Thursday the weather pattern changes, as the local
winds become more easterly and continue to diminish. A weak surface
trough is forecast to develop over the area and the aforementioned
frontal boundary and moisture associated with a shear line will
linger just north of the region. This along with the eroding upper
level ridge, will increase instability aloft as well as low level
moisture convergence. As a result, this will favor an increase in
morning shower activity along the east coastal areas followed by a
better chance for scattered showers and isolated afternoon
thunderstorms mainly over parts of the central interior and west to
northwest sections of Puerto Rico, as the steering winds become more
east southeasterly by Thursday. Recent model guidance still does no
suggest widespread shower development and thunderstorm activity, as
most of the activity should be of short duration. However, some of
the locally heavy rains with the stronger afternoon convection may
increase the chance for ponding of water on roads, as well as minor
urban flooding in isolated areas.

.LONG TERM...Friday through Wednesday...

The most recent model guidance now suggests a delay in the peak of
the col, caused by the interaction between a developing low
moving eastward across the western Atlantic and north of the local
islands with a weak surface high pressure moving over the western
Atlantic. Thus, expect variable and the lightest winds of 10 mph
of below by Friday into Saturday. By Sunday, a surface high
extending into the northeastern Caribbean will promote moderate
east to southeast winds of 10 to 15 mph through early next week,
increasing up to 20 mph by midweek next week. Regardless of the
changing surface winds, a predominantly south to southwest
steering flow will dominate the 850 to 700 mbar layer.

Enhanced low-level moisture convergence and somewhat favorable
conditions aloft, with 500 mbar temperatures as low as -10
degrees Celsius, will maintain a generally moist and more unstable
environment through the weekend. This scenario could support
isolated thunderstorm development, mainly with the afternoon
activity. Although mid-level ridging will gradually extend
westward into the northeastern Caribbean, promoting unfavorable
conditions aloft, low-level moisture convergence will maintain
near- to above-normal seasonal moisture levels through early next
week, ranging between 1.3 and 1.6 inches. The bulk of the
expected shower activity will favor mainly southern and eastern
sections through the evening-early morning hours, followed by
afternoon convective development across the interior into northern
and western areas of the local islands. The expected weak
steering flow will lead to slow-moving showers and possible
isolated thunderstorms for Friday and Saturday, increasing the
urban and small stream flooding potential. As winds increase and
trade wind cap strengthens, the potential for deep convective
development and thus flooding will decrease, but prolonged periods
of moderate to locally heavy rains could lead to localized
flooding, mainly with the afternoon activity. A southerly
component in the general wind flow will result in above-seasonal
temperatures.


&&

.AVIATION...VFR conds all terminals durg prd. SCT- BKN lyrs nr
FL025...FL050... with mstly SCT SHRA en route btw islands and ovr
regional waters. Brief Mtn top obscr ovr E PR due to passing low
clds/-SHRA til 11/13Z. Sfc wnds lgt/vrb to calm ,incr to 10-15 kts
aft 11/14Z. No sig operational wx impacts attm.


&&

.MARINE...Light to moderate east to northeast trade winds will
prevail through midweek, becoming light and variable by Thursday
into the upcoming weekend. The resulting wind-seas will maintain
choppy marine conditions, mainly across the Atlantic waters
through at least Wednesday. Brief isolated to scattered showers
will affect the local waters at times.

There is a high risk of rip currents for beaches across the north
coast of Puerto Rico and Culebra. A moderate risk remains in place
for most of the remaining local beaches.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 83 72 83 72 / 40 50 40 40
STT 83 72 82 72 / 20 20 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
427 AM AST Wed Jan 12 2022

.SYNOPSIS...A patchy weather pattern will prevail, with
intermittent patches of shallow moisture and relatively drier air
streaming across the area. Somewhat favorable upper-level
conditions during peak higher moisture and/or daytime heating
periods will enhance shower and possible thunderstorm activity.
Thus, increasing the potential for ponding of water to localized
urban and small stream flooding. A southerly component in the
general wind flow will result in above-normal seasonal
temperatures by the end of the workweek into early next week.


&&

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

The mid- to upper-level ridge will continue to erode as a short wave
trough crosses the west Atlantic just north of the area. This will
create an unstable divergent pattern aloft today through Thursday.
This increased instability along with cooler 500 millibar
temperatures will aid in enhancing the advective morning showers
over the regional waters and also during the afternoon hours in
isolated areas.

A stalled cold frontal boundary will continue to cross into the west
central Atlantic and gradually weaken, as a high pressure ridge will
build across the west and southwest Atlantic. This pattern will
induce a weak surface trough across the northeast Caribbean and
consequently induce a light northeasterly wind flow. This in turn
will continue to transport occasional patches of shallow moisture
across the region from time to time during the next several days.
However, the local steering winds are forecast to become more east-
southeast later today, then south-southeasterly by Thursday into
Friday.

The available pockets of moisture along with local effects and the
instability aloft, will aid in afternoon shower development mainly
over the central and west to northwest sections of Puerto Rico.
There is also a chance isolated thunderstorms later in the afternoon
and therefore areas of locally heavy rains may cause minor ponding
of water on roads and in poor drainage areas today.

Increased potential of early morning and afternoon shower activity
is expected on Thursday into Friday, resulting in scattered to
numerous showers over the region. There is also increased potential
for thunderstorm activity due to the proximity of the upper trough,
with isolated thunderstorms possible each afternoon. With winds more
east-southeasterly, expect the most likely affected areas to be the
north central to northwest and interior sections of Puerto Rico,
with a chance of minor Urban and small stream flooding in isolated
areas. Some brief afternoon showers will also be possible in and
around the U.S. Virgin islands, but significant accumulations and
flooding is so far not anticipated over the islands. By Friday, with
the low level steering flow forecast to become more south-southeast,
isolated to scattered showers will be likely in and around parts of
the San Juan metro areas as well, However widespread rainfall
accumulations and significant flood impacts are still not
anticipated at this time.

.LONG TERM...Saturday through Thursday...

The most recent model guidance suggests a generally east to
southeast wind flow dominating the long-term forecast period,
supported by a surface high pressure extending into the
northeastern Caribbean. A slightly drier pattern is also
suggested, with low-level moisture convergence driving patches of
moisture across the area and model-estimated precipitable water
vapor ranging between 1.2 and 1.4 inches through late Monday
night. After that, a set of easterly disturbances will increase
the available moisture, with precipitable water values peaking
around 1.5 inches by Monday night and gradually increasing to 1.6
inches by Wednesday into Thursday.

The bulk of the resulting shower activity should remain over the
local waters, but evening-early morning showers will over southern
and eastern sections of the local islands at times. Afternoon
convective development should be limited. However, somewhat
favorable conditions aloft, with 500 mbar temperatures between -7
and -10 degrees Celcius, during peak daytime heating and/or
higher moisture periods could result in enhanced showers and
possible isolated thunderstorm activity across portions of the
interior into western and northern sections of the local islands.
Thus, an increase in the potential of ponding of waters to
localized urban and small stream flooding is likely, especially
with the afternoon activity during the weekend and Wednesday
onwards. A southerly component in the general wind flow could
result in above-seasonal temperatures early next week.


&&

.AVIATION...VFR conds at all terminals with SCT ocnl BKN lyrs nr
FL025...FL050...and wdly sct SHRA ovr regional waters and en route
btw the local islands til 12/14Z. Mtn top obscr psbl ovr E PR til
12/14Z due to low clds and -SHRA. SHRA expected ovr wrn PR and VCTY
TJMZ/TJBQ/TJSJ fm 12/16Z-22Z. Sfc winds calm to lgt/vrb bcmg fm E-NE
10-15 kts with some hir gusts and sea breeze variations aft 12/14Z.
Low/lvl wnds fm NE BLO FL200...then backing and bcmg fm WSW and incr
w/ht. Max wnds of 60-70 kts btwn FL330-450.


&&

.MARINE...Light to moderate east to northeast trade winds will
prevail today, becoming light and more southerly to southeasterly
on Thursday and Friday. Seas will remain at 5 feet or below
through the workweek, but a small northerly swell will cause
choppy seas up to 6 feet during the upcoming weekend. Brief
isolated to scattered showers will affect the local waters at
times.

There is a high risk of rip currents for beaches across the north
coast of Puerto Rico, while a moderate risk remains in place for
most of the remaining local beaches.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 83 72 84 74 / 30 40 30 30
STT 85 74 85 75 / 30 50 50 40

&&