Caribbean - Central America Weather

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
505 AM AST Wed Dec 4 2024

.SYNOPSIS...

A frontal boundary extending across the western Atlantic and a
pre-frontal trough (to our west-northwest) will create favorable
conditions for showers and isolated thunderstorms through
tomorrow, especially in the afternoon and evenings. Expect a
mixture of sunshine/clear skies and clouds under an easterly wind
flow. Occasional showers will arrive each day, especially across
PR/USVI's windward sections. East to northeasterly winds will
return from Thursday onward, resulting in a cooling trend from
this weekend into next week. The frequency of these occasional
pockets of moisture will increase by next week as a TUTT-low
amplifies near the Northeast Caribbean, promoting unstable weather
conditions.

&&

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

Like previous nights, pockets of moisture and passing showers
prevailed across the Caribbean and Atlantic waters, with some
reaching the islands of Saint Thomas and Saint John. Meanwhile, over
Puerto Rico, Vieques, Culebra, and Saint Croix, mainly fair or calm
weather conditions dominated. Coastal and urban temperatures
remained in the mid to upper 70s, while mountain areas experienced
temperatures in the 60s to low 70s. This slight decrease in
temperatures across the islands was associated with the clear skies
that prevailed overnight. Winds were relatively variable and light,
with weather stations across the islands reporting wind speeds of
around 5 to 10 mph.

A pre-frontal trough is expected to move relatively close to the
region from the west allowing the afternoon convection to be
slightly stronger than previous days. The latest guidance suggest
moisture content extending from the surface to the mid levels,
favoring the development of afternoon showers and isolated
thunderstorms this afternoon. Today, there is limited to elevated
flooding risk across over western Puerto Rico and the Mona Passage.

The mid-to-upper-level high-pressure system continues to
build, stretching from the Northeast to the Central Atlantic, while
the trough remains well to the north of the forecast area. The
latest guidance indicates that this trough will stay far north,
allowing the high-pressure system to dominate the region. The
predominant high pressure, combined with the warmer-than-normal 500
mb temperatures, will promote stable weather conditions aloft from
Thursday onwards. These weather features will limit the potential
for significant rainfall and thunderstorm development (limiting
vertical growth). The islands will remain under the influence of
shallow moisture driven by the easterly winds. However, the
moisture content is expected to remain near or above normal
climatological levels for this year, with patches of moisture
streaming across the forecast area from time to time, particularly
on Thursday. Each afternoon, expect the sea breeze convergence
and orographically driven convection to still trigger some
isolated thunderstorms, especially when diurnal heating is at its
peak. As mentioned in previous discussions, although atmospheric
conditions are not favorable for extensive precipitation or
significant thunderstorm development, isolated convective activity
remains possible.

A multilevel high-pressure system building over the Caribbean will
dominate the weather on Friday, allowing the weather conditions to
dry out. Nonetheless, precipitable water values should remain in the
50th percentile or near normal climatological levels for this time
of year.

.LONG TERM...Saturday through Wednesday

A mid-high pressure system over the Caribbean will create a
relatively stable weather pattern during the weekend. This
pattern will dry out the mid-levels of the atmosphere and promote
subsidence, which will confine available moisture to around or
below 850 MB. As the mid-level high pressure moves into the
western Caribbean, a TUTT low is expected to develop from the
northeast and reach the US Caribbean by late Monday, extending
into mid-next week. A jet stream will also approach the region as
early as Monday morning. As the TUTT-low remains near the Lesser
Antilles, it will induce a surface low that may move closer to the
islands by the second part of the following workweek.

This TUTT low will affect the islands from the northeast, causing
wind perturbations that will be carried across Puerto Rico and
the U.S. Virgin Islands by the trade winds, mainly from Monday to
Wednesday. Once again, global models show discrepancies in the
intensity and position of the TUTT low, ultimately influencing the
weather patterns that develop across the local islands. As a
result, there is significant uncertainty regarding the amount of
precipitation we might experience in the long-term forecast.

Moisture over the islands will be influenced by a cold front
moving across the western Atlantic during the weekend, remnants
of an old boundary, and a high-pressure system over the North
Atlantic. These frontal boundaries could approach the islands by
Tuesday. Still, easterly winds will bring plenty of low-level
moisture to the northeast Caribbean, leading to a typical tropical
winter rain pattern and cooling local temperatures.

Expect a mix of sunshine/clear skies and clouds daily, with
moisture primarily in the mornings and evenings. Orographic
effects, diurnal heating, and sea breezes will drive afternoon
convection in western Puerto Rico. Rain frequency and intensity
will likely increase next week as the upper-level ridge weakens
and trade wind disturbances arrive.

The return of the trade winds may cause a cooling trend in
temperatures, although this is still connected to sea surface
temperatures, which are currently one to two degrees Celsius above
normal for this time of year.

&&

.AVIATION...
(06Z TAFs)

Today, all TAF sites should experience VFR conditions. However,
frequent quick passing SHRA/-SHRA will move across the local flying
area, resulting in brief MVFR conditions, especially at TJSJ / TISX
/ TIST / TJPS throughout the day. After 04/17-23z, TSRA could
develop across TJBQ, impacting the terminal with brief MVFR
conditions. Winds should remain from the ESE at 10 to 15 kt with
higher gusts and sea breeze variations. Late today (around 23Z),
winds will gradually shift from the ENE.

&&

.MARINE...

A surface high pressure over the central Atlantic and a frontal
system extending across the western Atlantic will promote a moderate
to locally fresh east to east-southerly wind flow through at least
Wednesday. A prefrontal trough will promote additional showers and
thunderstorms across the surrounding waters today and tomorrow. Winds
will then return from the northeast as the frontal boundary lingers
north of the northeastern Caribbean from Thursday onward. Confused
seas due to locally induced seas and an easterly swell are expected
around Thursday. A northerly to northwesterly swell could move across
the Atlantic Offshore waters by the weekend.

&&

.BEACH FORECAST...

Beachgoers, life-threatening rip currents will develop along the
Atlantic Coastline of PR, the northern US Virgin Islands, and the
eastern half of St Croix, where the risk of rip current is
moderate. Another north-to-northwesterly swell will move closer to
the regional waters by Sunday, so stay tuned for the evolution of
the surf zone beach forecast.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
446 AM AST Thu Dec 5 2024

.SYNOPSIS...

A very seasonal weather pattern is expected for most of the period,
with limited flooding risk at most. Pleasant temperatures will
return as winds shift more northeasterly over the next few days.
Hazardous marine conditions are anticipated across the offshore
Atlantic waters today.

&&

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

Skies were partly cloudy to variably cloudy overnight with a mix of
low and high level clouds moving in and out of the region. The light
to moderate easterly winds continued to steer fragments of trade
wind moisture across the region bring periods of light to moderate
showers across the local waters and parts of the north and east
coastal areas of the islands. Estimated rainfall accumulation were
less than a tenth of an inch in most areas. Overnight low
temperatures were in the mid to upper 70s along the coastal areas
and near the mid 60s to low 70s in higher elevations and valleys.
The wind was calm to light and variable. For the rest of the morning
hours and throughout the day, expect a mix of sunshine and occasional
clouds. Locally and diurnally induced afternoon shower development
will possible over parts of the central interior and west sections
of Puerto Rico with fewer showers expected mainly downwind of the
USVI steered by moderate east to northeast winds. Local sea breeze
variations and occasionally higher gusts can be expected along the
coastal areas.

A building mid-to upper-level ridge over the northeastern Caribbean
will promote warmer than normal 500 mb temperatures and drier air
aloft through the period. However, a weak upper-level trough sliding
eastwards across the western Atlantic Friday into Saturday may
slightly erode the upper ridge and help promote a brief enhancement
of an easterly perturbation. This in turn may lead to an increase in
the chance for more passing showers especially during the overnight
and early morning hours over the coastal waters and across the USVI
and eastern PR. Isolated thunderstorm developing cannot be ruled out
over the regional waters during that time. Otherwise, relative fair
to near seasonal weather conditions are expected in most areas
during the rest of the day with near normal temperatures forecast to
prevail each day. Periods of isolated to scattered showers can
however be expected each afternoon but should be focused mainly over
portions of the interior and west section of Puerto Rico and mainly
downwind of the USVI.

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

The long-term forecast will begin with a deep layer of air featuring
an east-northeast wind flow at low levels, which will shift further
northeast by the end of the week. This will bring pleasant weather
conditions, with 925 mb temperatures gradually decreasing to near
the climatological normal for this time of year. A mid- to upper-
level ridge will persist during the early part of the forecast
period, although a surge of low-level moisture will lead to
increased shallow convection across the area.

Similar weather conditions can be expected for the first half of
next week, depending on moisture availability. Under an east-
northeast wind flow, a cool advective pattern will promote showery
weather across windward coastal areas during the late and morning
hours. Sea breeze convergence and local effects may enhance
convective activity across the interior and southwestern portions of
Puerto Rico, with a few isolated thunderstorms possible. Any
flooding resulting from these showers should be minor.

Global models suggest a deepening polar trough and an induced
surface low developing east of the Caribbean basin by mid-week next
week. However, discrepancies remain between the GFS and ECMWF
models, with the ECMWF positioning the induced surface low slightly
farther west than the GFS, suggesting the potential for
deteriorating conditions under this scenario.

A blended solution of the two models has been adopted for the latter
part of the week. Nevertheless, the latest Global Tropics Hazards
Outlook from the Climate Prediction Center (CPC) indicates that
the area of above-normal rainfall is expected to remain east of
the northern Leeward Islands. We will continue to monitor the
forecast closely, as any shifts in the positioning of the trough
could significantly alter the anticipated impacts.


&&

.AVIATION...
(06Z TAFS)

Prevailing VFR at all terminals thru fcst prd. Quick passing trade
wind SHRA will however continue to affect the regional waters and
mainly the north and east coastal areas of PR and USVI til 05/13Z.
SCT OCNL BKN lyrs nr FL025...FL050...FL080 enroute between islands.
Brief Mtn top obscr ovr E PR due to -SHRA/FEW low clds. SFC wnds
will be calm to lgt/vrb bcmg fm E-NE 12-15 kts with ocnly hir gusts
and sea breeze variations aft 05/14Z. L/LVl winds fm E-NE BLO FL120.
No sig operational wx impact attm.

&&

.MARINE...

A surface high pressure over the central Atlantic and a frontal
system extending across the western Atlantic will continue to promote
a moderate to locally fresh easterly wind flow today. This pattern
will also briefly promote hazardous seas across the offshore
Atlantic waters through this evening. Winds will then return from
the east-northeast as the frontal boundary lingers north of the
northeastern Caribbean from Friday onward. A northerly to
northwesterly swell could move across the offshore Atlantic waters by
the weekend.

&&

.BEACH FORECAST...
A small northerly swell continues to invade the local waters.
This, along with the winds, is promoting a moderate rip current.
The risk will increase to high by late Sunday or Monday as a
potential larger swell arrives.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
430 AM AST Fri Dec 6 2024

.SYNOPSIS...

Pleasant temperatures will persist throughout the period.
Alternating periods of moisture and drier air will dominate over the
next few days. Expect mostly showery weather conditions across
eastern portions of Puerto Rico and the smaller islands during the
morning hours. Additionally, a northerly swell may lead to hazardous
beach conditions by late this weekend.

&&

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

A mid-to upper-level ridge will continue to build over the
northeastern Caribbean today into Saturday to promote stable
conditions aloft. This ridge will however erode by late Saturday and
Sunday as a weak upper-level short wave trough is forecast to shift
eastwards across the western Atlantic promoting marginal instability
aloft. Meanwhile a stalled frontal boundary/shear line northwest of
the region will sink further southwards towards the area by Sunday
in response to a surface high pressure building across the southwest
Atlantic. This expected pattern along with an induced low level
trough across the area will promote a more northeasterly wind flow
and better low level moisture convergence across the region.
Consequently this will result in more showery weather pattern with
increased probability for passing shower activity especially during
the overnight and morning hours. Mostly isolated to scattered
afternoon shower development is expected thereafter across portions
of the islands each day.

For the remainder of this morning, the passing trade wind showers
will continue to affect the coastal waters and local passages steered
by the moderate easterly trades. Intervals of passing clouds and
showers will affect parts of the north and east sections of Puerto
Rico, as well as portions of the U.S. Virgin islands. Shower
activity will then diminish by late morning, with afternoon showers
to be then focused and limited to portions of the west and southwest
sections of Puerto Rico and mainly downwind of the U.S. Virgin
Islands.

For the rest of the period and through the weekend, expect
increasing moisture convergence due to the interaction of an
easterly perturbation and the moisture remnants from the
aforementioned frontal boundary. This in turn will lead to an
increase potential for shower and possibly isolated thunderstorm
development by Saturday afternoon and also with similar conditions
on Sunday. So far based on model guidance, an overall showery
weather pattern will persist with a mix of sunshine and passing
clouds and showers. Widespread flooding impacts are however not
anticipated, but there may be periods of moderate to locally heavy
showers that could cause minor ponding of water on roads and brief
hazardous driving conditions at times. Near seasonal overnight and
daytime temperatures are expected during the period.

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

The long-term forecast continues to indicate a predominantly
seasonal weather pattern across the region, with the prevailing
low-level wind flow gradually shifting from east-northeast to a
more northeasterly direction as the week progresses. This pattern
will sustain pleasant conditions overall, with temperatures near
climatological normals. A cool advective pattern is expected to
dominate, favoring showers along windward coastal areas during the
late night and morning hours. Sea breeze convergence and
orographically driven convection may enhance afternoon showers and
thunderstorm activity across the interior and southwestern
portions of Puerto Rico. However, any flooding impacts are
expected to remain limited.

Regarding the previously mentioned polar trough and induced surface
low, global models persist in keeping the primary axis of this
feature to the east of the forecast area. However, subtle westward
shifts in some solutions, particularly from the ECMWF, suggest the
potential for closer proximity to the region. While dynamics aloft,
including decreasing 500 mb temperatures, 250 mb height fields, and
1000-500 mb thickness values, appear marginally favorable for
enhanced convective activity, our position relative to the trough,
likely on its convergent side where subsidence dominates, should
limit widespread development.

As a result, any convective activity during this period is expected
to remain localized. Forecast confidence remains low, as this
scenario is still several days out and model solutions continue to
adjust. However, there is a consistent signal across models that
these features will remain primarily east of the forecast area
throughout the week, with the potential for closer proximity
approaching the following weekend.


&&

.AVIATION...
(06Z TAFS)

VFR at all terminals thru fcst prd. At least til 06/14Z, passing
trade wind SHRA will continue to affect the regional waters enroute
between the local islands with VCSH likely at TJSJ and USVI
terminals. SCT OCNL BKN lyrs nr FL024...FL040...FL080 enroute
between islands. Brief Mtn top obscr ovr E PR due to -SHRA/FEW low
clds. SFC wnds will be calm to lgt/vrb bcmg fm ENE 12-15 kts with
ocnly hir gusts and sea breeze variations aft 06/14Z. L/LVl winds
generally fm E 15-20 kts BLO FL120...bcmg fm W and incr w/ht ABV
FL250.

&&

.MARINE...

A surface high pressure over the central Atlantic and a frontal system
extending across the western Atlantic will continue to promote a moderate
to locally fresh easterly wind flow. This pattern will also briefly
promote choppy seas across the Atlantic waters today. Winds will
then turn from the northeast by the end of the weekend as another
surface high exits the eastern coast of the United States and a
frontal boundary lingers northwest of the islands. A northerly to
northwesterly swell could move across the offshore Atlantic waters by
the weekend.


&&

.BEACH FORECAST...
The risk of rip current will remain moderate through the upcoming
weekend. However, a northerly swell may lead to hazardous beach
conditions by late this weekend.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
451 AM AST Sat Dec 7 2024

.SYNOPSIS...

Clear skies with minimal shower activity are expected again today as
another dry slot moves across the islands. Pleasant temperatures
will persist throughout the period.

&&

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

Periods of light to moderate passing showers will continue to affect
the regional waters and local passages as well as portions of the
north and east coastal sections of the islands through at least the
early morning hours. Rainfall accumulations however are expected to
be generally less than a tenth of an inch with the heaviest shower
activity. For the rest of the day, a mix of sunshine and passing low
level clouds is again expected with another round of isolated to
scattered afternoon showers possible mainly over parts of the
central, southwest and east interior sections of Puerto Rico and
possibly just downwind of the USVI.

Intervals of quick passing shallow moisture will continue to cross
the region from time to time during the period but no significant
rainfall accumulations are anticipated. Recent model guidance as
well as satellite derived precipitable water products all suggest
precipitable water values to range between 1.00 and 1.60 inches.
Only brief shower development will be likely in some areas the rest
of today as the mid to upper leve ridge should hold in place.
However the upper level ridge is expected to erode later this
afternoon through Sunday, as an upper trough will shift eastwards
just north of the islands and linger while becoming amplified east
of the region by Monday afternoon. This in turn will slightly
destabilize condition aloft favoring better chance for shower
development over the coastal waters and in and around the islands
Sunday through Monday. The moderate easterly trade winds will be
maintained today into Sunday but will gradually become more east
northeast later Sunday and Monday as another surface ridge will
build across the southwest Atlantic. This overall pattern should
maintain weak troughiness across the region resulting in some low
level moisture convergence due to the interaction of a weak easterly
perturbation and remnants from a frontal boundary sagging just north
of the region Sunday and Monday.

All in all, no significant weather impacts are forecast for the
period except for periods of passing overnight and early morning
showers, followed by limited localized afternoon shower activity
across and downwind of the islands each day. These showers are
expected to be fast moving and of short duration and consequently no
significant flooding impacts are so far anticipated.

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

Forecast confidence is increasing as model guidance continues to
remain consistent across model cycles for the long-term forecast
period. The polar trough and induced surface low are expected to
deepen east of the Leeward Islands. The proximity of this strong
trough will likely enhance local dynamics at upper levels, turning
conditions slightly more favorable for convective activity.
Indicators such as 250 mb height fields, 100-500 mb thicknesses,
and 500 mb temperatures are forecast to drop to near-normal
levels, occasionally reaching the bottom 25th percentile during
the week.

However, the northeastern Caribbean remains positioned under the
area of greatest subsidence associated with the trough. As mentioned
in earlier discussions, this subsidence could inhibit widespread
convective activity. Another limiting factor is moisture content,
which is expected to remain below 1.7 inches. Furthermore, model
guidance suggests that moisture levels will plummet by the end of
the week, potentially falling below 1.0 inches. This value is well
below the 10th percentile of the climatological normal for this
time of year.

As a result, mostly showery weather is expected across windward
coastal areas during the night and morning hours as a cool advective
pattern develops under a northeasterly wind flow. This will likely
be followed by some convective activity in the afternoons, primarily
over the interior and southwestern portions of Puerto Rico. However,
limited shower activity is anticipated between Thursday and Friday,
which are forecast to be the driest days of the long-term period. By
the weekend, a change in this weather pattern is possible as a surge
of moisture, combined with the axis of the surface-induced trough,
approaches the local islands from the northeast.

This northeasterly wind pattern will also bring very pleasant
temperatures across the area, with 925 mb temperatures expected to
drop to nearly two standard deviations below the climatological
normal.


&&

.AVIATION...
(06Z TAFS)

VFR at all terminals durg prd. however passing SHRA Will continue to
affect the regional waters en route btw the local islands til at
least 07/14Z. Mtn top obscr psbl ovr E PR due to passing low clds
and -SHRA. SFC wnd calm to lgt/vrb bcmg E-ENE with sea breeze
variations aft 07/14Z. L/LVL wnds generally fm NE 15-20 kts BLO
FL120...bcmg W-NW and incr w/ht ABV FL250. Aftn SHRA again psbl
mainly ovr ctrl and btw E PR and USVI fm 07/18-22Z but, btw no sig
wx impact fcst attm.

&&

.MARINE...

A surface high pressure exiting the eastern coast of the United
States will continue to promote mostly moderate east northeasterly
wind flow today. On Sunday, the pressure gradient will intensify in
the area promoting moderate to fresh winds. This pattern will result
in choppy seas across the Atlantic and Caribbean waters through
early next week. A northerly to northwesterly swell could move across
the offshore Atlantic waters by Sunday into Monday.

&&

.BEACH FORECAST...

The risk of rip currents will remain moderate today and tonight. By
Sunday, a weak northerly to northwesterly swell is expected to
impact northern and northwestern exposed beaches, potentially
leading to hazardous beach conditions in localized areas.

[cycloneye]

Discussion
National Weather Service San Juan PR
441 AM AST Sun Dec 8 2024

.SYNOPSIS...
A weak surface trough and pulses of low level moisture east of the
Leeward Islands will continue to move across the local area today
through Monday. This will bring occasional periods of passing clouds
and showers over the coastal waters and local islands steered by
the moderate east northeast winds. A small northerly swell will move
across the Atlantic waters and passages today. Overall pleasant temperatures
and a mix of sunshine and clouds will persist throughout the period
with an even drier trend by the middle of the upcoming week.

&&

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

GOES-16 Total Precipitable Water (TPW) satellite imagery detected a
patch of moisture early in the night, associated with a weak surface
trough, with values ranging from 1.6 to 1.7 inches moving over the
forecast area. This contributed to intermittent showery weather
throughout the night across the northeastern and northern coastal
areas of Puerto Rico, Culebra, and the northern USVI. However,
rainfall accumulations were minimal. Minimum temperatures ranged
from the mid to upper 80s across coastal areas of Puerto Rico and
the USVI, and from the mid to upper 60s across the mountains and
valleys of Puerto Rico.

Variable weather conditions will persist today as another surface
trough, currently over the Leeward Islands, moves into the region.
This trough carries higher moisture levels, with Total Precipitable
Water (TPW) values approaching 2.0 inches. It is expected to reach
the U.S. Virgin Islands during the morning hours and Puerto Rico by
18Z. The combination of this moisture with sea breeze convergence
and orographic effects may lead to the development of showers and
thunderstorms, particularly across interior and western Puerto Rico,
posing a limited to elevated flooding risk. Additionally, streamers
forming downwind of El Yunque could impact the San Juan metropolitan
area as east-southeast steering winds develop with the trough's
passage. This weather pattern will persist through early Monday with
showers developing mostly over the regional waters and moving over
eastern coastal areas at times.

The synoptic pattern for the rest of the short-term forecast appears
quite complex across the northeastern Caribbean. A deepening polar
trough east of the region is expected to enhance upper-level
dynamics, particularly over the northeastern quadrant, including the
regional waters. By Monday, the area may find itself at the entrance
of a strengthening jet, with winds potentially reaching 75 knots at
the 250 mb level. This setup could promote an upper-level divergence
and diffluence pattern, resulting in good ventilation aloft.
Additionally, cold air advection at the 500 mb level is expected to
lower temperatures to between -7C and -8C by late Monday into
Tuesday, leading to steeper lapse rates. As a result, Monday could
be the most active day, depending on how close the trough settles
over the area. The steering wind flow will remain from the
northeast, likely resulting in convective activity clustering across
the interior and southwestern portions of Puerto Rico during the
afternoon hours, with most activity shifting to the northeastern
sections of Puerto Rico and the smaller islands during the late-
night hours.

Tuesday may be the least active day, as a gradual decrease in
moisture levels is anticipated through the end of the short-term
forecast period. Precipitable water values are expected to drop to
around 1.17 inches by late Tuesday night. Furthermore, with the
trough remaining primarily to the east, the region is likely to be
positioned under its subsidence side, which could suppress convective
development.

.LONG TERM...Wednesday through Sunday...
By Wednesday recent model guidance remains persistent for the long
term suggesting the amplified TUTT LOW will linger just east of the
northern Leeward Islands while deepening along with an associated
induced surface low. This surface low is forecast to eventually lift
northwards while producing a broad trough of low pressure which will
spread across the northeast Caribbean and local region, as the TUTT
also lifts northwards into the Central Atlantic. All models suggest
that the proximity of this deepening and developing trough will
likely enhance local dynamics in the upper levels, resulting in more
favorable conditions for enhanced localized convective activity
across the area by the end of the period. In addition, recent
indicators such as 250 mb height fields, 100-500 mb thickness
values, along with the 500 mb temperatures all suggest a continued
drop to near-normal levels, reaching the bottom 25th percentile with
precipitable water values diminishing from 1.60 to 0.95 by early
Friday. Thereafter and into the weekend moisture content rebounds
and values increase once again to near of slightly above normal 1.60
to 1.90 inches as the broad surface trough spreads across the region
from the east.

During the early part of the period, moisture erosion and stable
condition aloft is expected as we should remain on the subsident
side of the aforementioned trough. This in turn should help to
inhibit/limit widespread convective activity across the region.
However by the weekend as the trough spreads across the area,
moisture will increase once again and thus support better potential
of early morning and afternoon convection. However widespread
convection and significant weather impacts are still not
anticipated at this time with the wettest period so far being
Saturday and Sunday due to the instability aloft and increasing
moisture content.

Consequently, expect mostly showery weather at times mainly across
the windward coastal areas during the overnight night and morning
hours under a cool advective pattern steered by light to moderate
northeasterly winds. This will be followed limited convective
activity in the afternoons, primarily over the interior and
southwestern portions of Puerto Rico through at least Friday.
Thursday through Friday are forecast to be the driest days of the
period. By the weekend, a change in this weather pattern remains
possible as as low level moisture and instability increases due to
the proximity of the surface-induced trough approaching the islands
from the northeast and a polar trough sweeping across the west
Atlantic. This will result in the best potential for shower and
isolated thunderstorm development across the islands and coastal
waters during the period.

As mentioned in previous discussion, this seasonal northeasterly
wind pattern will also bring very pleasant temperatures across the
area, with 925 mb temperatures expected to drop to nearly two
standard deviations below the climatological normal for the period.

&&

.AVIATION...
06Z TAFS)

Mostly VFR conds expected through the 06Z TAF cycle. However, a sfc
trough crossing the region may promote vicinity SHRA/TSRA aft 08/17z
across all TAF sites. PROB30 groups were added to TJSJ/TIST as some
of this activity may briefly promote MVFR.IFR conds. Winds incrg aft
08/12Z to bcm E 10-16kt wind sea breeze influences

&&

.MARINE...
A surface high pressure exiting the eastern seaboard of the United
States will continue to promote mostly moderate east northeasterly
wind flow across the regional waters. The pressure gradient will tighten
across the area into the beginning of the workweek promoting moderate
to fresh winds. This pattern will result in choppy seas across the Atlantic
and Caribbean waters through early next week. A northerly to northwesterly
swell will spread across the offshore Atlantic waters today into Monday.

&&

.BEACH FORECAST...
A small northerly to northwesterly swell is expected to impact the
northern and northwestern exposed beaches of the islands, potentially
leading to hazardous beach conditions in localized areas. However,
the risk of rip currents will remain moderate for most coastal
areas of the islands.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
444 AM AST Mon Dec 9 2024

.SYNOPSIS...
Moderate east northeast winds will prevail today into Tuesday then
increasing while becoming more north northeast by Wednesday and the
rest of the workweek, as an induced surface trough develops east and
northeast of the area and surface high pressure builds north of the
region. Breezy conditions and pleasant temperatures and a mix of sunshine
and clouds will persist with an even drier trend by the middle of the
week. Choppy seas due to moderate to locally fresh winds are forecast
across the Atlantic and Caribbean waters through most of the week
with a small north to northwesterly swell forecast to spread across
the offshore Atlantic waters today through Tuesday.

&&

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

Earlier in the night, as the axis of the surface trough was
positioned over the Mona Passage, Doppler radar detected strong
showers along the northern coastal waters of Puerto Rico and parts
of the Caribbean waters. Some of these showers moved across
southeastern Puerto Rico, with radar-estimated rainfall reaching up
to 0.70 inches in coastal areas of Maunabo. Currently, the trough
axis has continued moving westward and is now over eastern
Hispaniola, with shower activity diminishing for the most part.
However, some showers persist over the regional waters and are
expected to move across eastern portions of Puerto Rico and the
smaller islands through the morning hours. Minimum temperatures once
again ranged from the mid to upper 70s across coastal areas of
Puerto Rico and the USVI, and from the mid to upper 60s across
higher elevations and valleys of Puerto Rico.

The synoptic pattern for the remainder of the short-term forecast
period remains unchanged. Current GOES-16 infrared satellite data
indicates that the most active portion of the polar trough,
associated with the area of greatest divergence at upper levels, is
well northeast of the forecast area. Model guidance suggests that,
although a strong 250 mb jet will develop near the region, the
forecast area will remain under its subsidence side, with the
greatest divergence and diffluence pattern confined to areas farther
northeast as the TUTT deepens. This setup will limit widespread
convective activity across the region. Consequently, rainfall
coverage expected for the next few days has been slightly reduced.

However, surface-induced perturbations east of the Leeward Islands,
associated with the upper-level pattern, will occasionally stream
across the area. This will maintain moisture levels between the 50th
and 75th percentiles, which are near climatological normals for most
of the short-term period, with slightly lower values expected by
late Tuesday night. Under a northeasterly steering wind flow,
showery weather will affect windward sections of the islands during
the night and morning hours.

Additionally, certain low- to mid-level parameters will support
convection if sufficient lifting occurs. These include cold air
advection at mid-levels, which contributes to lower 1000-500 mb
thicknesses and steeper lapse rates between the 700-500 mb levels.
As a result, the combination of sufficient low-level moisture, sea
breeze convergence, and marginal instability could lead to
orographically driven convection each afternoon, particularly today.
Expect a limited to localized elevated flooding risk each afternoon,
mainly across interior and southwestern sections of Puerto Rico.

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

Latest model guidance remains persistent and continued to suggest
the amplified TUTT will linger just east of the northern Leeward
Islands while deepening through Friday along with a broad induced
surface trough which will slowly shift westwards across the area by
the weekend. This trough and possibly a weak surface low is forecast
to eventually lift northwards while spreading across the northeast
Caribbean and local region, as the TUTT lifts northwards into the
Central Atlantic. Models continue to suggest that the proximity of
this deepening and developing trough will aid in increasing
instability in the upper levels, resulting in more favorable
conditions for enhanced localized convective activity across the
area by the end of the period. Precipitable water values are still
expected to diminish and range between 1.60 to 0.95 through early
Friday. Thereafter and into the weekend moisture content rebounds
and values increase once again to near of slightly above normal 1.60
to 1.90 inches, as the broad surface trough spreads across the
region from the east.

During the early part of the period, moisture erosion and stable
condition aloft are expected as all guidance suggest we should
remain on the subsident side of the aforementioned upper trough.
This in turn should help to limit widespread convective activity
across the region. However by the weekend the pattern changes as the
trough spreads across the area, moisture will increase once again
and thus support much better potential for early morning and
afternoon convection. Widespread convection and significant weather
impacts are still not anticipated at this time but some localized
flooding will be possible, with the wettest period so far being
Saturday through Sunday due to the instability aloft and increasing
moisture content.

Mostly showery and an advective weather pattern can be expected at
times but mainly across the windward coastal areas during the
overnight night and early morning hours steered by moderate
northeasterly winds. This will be followed by limited convective
activity in the afternoons, primarily over the interior and
southwestern portions of Puerto Rico through at least Friday.
Thursday through Friday are forecast to be the driest days of the
period. As mentioned, a shift in this weather pattern remains
possible by the weekend and through the early part of the following
week, as low level moisture and instability increases due to the
developing of the surface-induced trough approaching the islands
from the northeast and a polar trough sweeping across the west
Atlantic. This will result in the best potential for showers and
isolated thunderstorm development across the islands and coastal
waters during the latter part of the period.

Seasonal northerly wind pattern will also bring very pleasant
temperatures across the area through the early part of the period,
with winds forecast to becoming more easterly by the end as now
suggested by model guidance. Occasional breezy conditions with an
occasional advective pattern of passing overnight and early morning
shower will be likely at times along the north and east coastal
areas but widespread and impactful rainfall accumulations are not
still not anticipated at this time.

&&

.AVIATION...
(06Z TAFS)

Mainly VFR conditions are expected to prevail across all terminals
during the next 24 hours. However, brief mtn top obscr ovr E PR til
09/12Z. Also, SHRA with possible iso TSRA may develop in and around
TJPS btw 18z-22z. Sct mdt ocnly strong SHRA may move across the FA
with some reaching the windward side of the islands aft 09/22z. SFC
wnd light and variable to calm bcmg ENE 10-16 kts with some sea
breeze influences and ocnl hir gusts aft 09/14Z.

&&

.MARINE...
A surface high pressure spreading across the southwestern Atlantic,
will continue to promote a moderate east northeasterly wind flow across
the regional waters. The pressure gradient will tighten across the area
over the next few days promoting moderate to fresh winds. This pattern
will result in choppy seas across the Atlantic and Caribbean waters.
A small northerly to northwesterly swell will spread across the offshore
Atlantic waters today through Tuesday.

&&

.BEACH FORECAST...
A small north to northwesterly swell will impact the northern and
northwestern exposed beaches of the islands, potentially leading
to hazardous beach conditions in localized areas today through
Tuesday. However, the risk of rip currents will remain moderate
for most coastal areas of the islands. Increasing trade winds will
maintain choppy seas and hazardous beach conditions especially
along the north and east facing beaches by Wednesday.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
518 AM AST Tue Dec 10 2024

.SYNOPSIS...

Moderate east-northeasterly winds will bring scattered showers to
northern and eastern areas, with drier air reducing rainfall by
midweek. Over the weekend, a cutoff low and surface trough will
maintain unsettled conditions with scattered showers. Warmer
temperatures with a southeasterly wind shift is forecast once
again by Sunday into the upcoming workweek. Small craft operators
should exercise caution across the offshore Atlantic waters.
There is a high risk of rip currents in effect for the northern
exposed beaches of Puerto Rico.


&&

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

Since midnight, satellite derived precipitable water (PWAT) values
over Puerto Rico were around 1.44 to 1.66 inches, at normal values
for this time of the year, with the higher values over north and
east Puerto Rico. PWAT values of around 1.66 inches were also
observed over the USVI, Vieques and Culebra. With a shearline north
of the islands, an advective pattern has prevailed with showers,
some locally heavy, under ENE steering winds, mainly across northern
and eastern Puerto Rico, Vieques, Culebra and the USVI. By 4 AM, the
highest radar estimated amounts were over Vega Baja east until
Catano, with localized amounts of 0.6 to 0.8 inches. Reported lows
were in the low to mid 60s at higher elevations of Puerto Rico and
in the mid 70s to upper 70s over lower elevations of the islands.

Current model guidance has PWAT values at 1.5 to 1.7 inches through
tonight, with drier air at around 1.4 inches filtering in late
tonight through late Wednesday afternoon. Model guidance indicates
even drier (and cooler) air filtering in Wednesday night through
Thursday and into the long term period with values around an inch.
In the mid to upper levels, a low pressure is positioning itself
east of our local area centered at around 20N, 55W at the mid
levels, where it should remain through most of the period. To our
west, however, a high pressure will be over Cuba, gradually drifting
west by Thursday. This will promote northerly flow over the region
along with a strong jet near the region. A surface high pressure
will remain over the central and western Atlantic through the
period. This will maintain a generally up to breezy ENE steering
flow will throughout the period, becoming more NNE late Thursday,
when a surface induced trough approaches the region as we head into
the long term period. Highs will be in the the mid 80s to upper 80s,
with some areas like southern PR reaching around 90 while lows reach
the low to mid 60s (with some areas possibly reaching the upper 50s)
at higher elevations of Puerto Rico and in the mid 70s to upper 70s
at lower elevations of the islands. Showers will continue to be
steered by ENE winds today (especially during the morning hours) and
tonight, affecting northern and eastern regions, and leaving ponding
of water over roads and poorly drained areas. Urban and small stream
flooding is possible. Sea breeze convergence and local effects,
along with some instability, can produced convective showers over
WSW Puerto Rico during the afternoon hours. This pattern will
continue each day but with available moisture gradually decreasing.

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

A cutoff low aloft will influence local weather conditions by
inducing a surface trough just east of the region. This setup will
result in northeasterly winds dominating from Friday through
Saturday afternoon, supporting low-level convergence and scattered
showers, mainly across windward areas of Puerto Rico and the U.S.
Virgin Islands. Despite the instability associated with the
cutoff low, moisture levels are expected to remain near moderate
to normal values, limiting the intensity and coverage of rainfall
through Saturday afternoon.

By late Saturday into Sunday, an increase in relative humidity
reaching up to the 500 mb level will enhance the potential for
showers across the region. As the surface trough moves westward
and winds shift to a southeast flow, moisture convergence, and
instability will deepen. This will likely result in more
widespread shower activity, particularly across southern and
interior sections of Puerto Rico during the afternoon hours. The
combination of the deepening moisture profile and favorable upper-
level dynamics could support isolated moderate to heavy rainfall,
particularly on Sunday, as the atmosphere becomes more conducive
to organized convection.

On Monday, strong horizontal winds at the 250 mb level, oriented
from west to east, will dominate the upper atmosphere over Puerto
Rico as a jet moves over the region will provide ventilation for
convective development. These upper-level dynamics, combined with
diurnal heating and local effects, will support rising motion and
scattered afternoon showers with isolated thunderstorms,
especially across interior and northwestern Puerto Rico. By
Tuesday, the global model guidance suggests the potential
development of a surface low just north of the region. This
feature would result in a shift in the prevailing wind flow to a
south-southeasterly direction. The change in wind flow is expected
to bring warmer temperatures, particularly to northern and
western areas of Puerto Rico, as downslope warming effects enhance
daytime heating. High cloud coverage associated with the upper-
level jet may inhibit the heating in some areas.

&&

.AVIATION...
(06Z TAFS)

Mainly VFR condtions across the terminals. Scattered moderate to
occasionally strong SHRA will continue to move into the islands
during the morning, mainly affecting TJBQ/TJSJ/TIST/TISX and
posible promoting brief MVFR condtions. SHRA with possible
isolated TSRA may develop in and around TJPS between 18Z to 22Z.
Winds will continue from the ENE at 8 to 16 kts with higher gusts
(especially near SHRA) and sea breeze variations.

&&

.MARINE...

A surface high pressure system spreading across the southwestern
Atlantic will maintain a moderate east-northeasterly wind flow
across the regional waters. Over the next few days, the tightening
pressure gradient will promote moderate to fresh winds across the
area, resulting in choppy seas across the Atlantic and Caribbean
waters. A Small Craft Advisory is in effect for the offshore
Atlantic waters from noon through 6 AM on Wednesday, as
conditions are expected to become hazardous for small vessels.
Additionally, a small northerly to northwesterly swell is forecast
to propagate into the offshore Atlantic waters, further impacting
marine conditions through Tuesday. Mariners and small craft
operators should exercise caution, particularly in exposed waters.

&&

.BEACH FORECAST...
A weak north to northwesterly swell will impact northern and
northwestern beaches of the islands through Tuesday, leading to
potentially hazardous beach conditions in localized areas. While
the swell energy is limited, it may still contribute to rougher
conditions at exposed beaches. The risk of rip currents is
expected to remain high for most of the northern coastal areas,
were a high risk of rip current is in effect across the northern
exposed beaches of Puerto Rico.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
448 AM AST Wed Dec 11 2024

.SYNOPSIS...
A variable weather pattern will prevail at least until late Friday
into Saturday, when an induced surface trough moves into the
region, resulting in showers and thunderstorms across the region.
Daytime temperatures will remain near the normal seasonal
temperatures across the coastal and mountain areas. Hazardous
marine conditions will prevail across the offshore Atlantic
waters, where a small craft advisory still in effect.

&&

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

Light passing showers were observed during the night hours across
the Virgin Islands and the eastern and northern portions of Puerto
Rico. Temperatures dropped to the low and mid 70s in the coastal
areas, and into the mid-60s in the mountains.

The most recent satellite imagery show a trough just to the east-
northeast of the local islands. This system will maintain the winds
from the northeast to north at speeds of 15 to 20 mph, with stronger
gusts through the forecast period. The trough will begin to approach
the local islands through Friday, with a showery weather pattern
anticipated. The areas most affected by the rain will be the north
and eastern municipalities of Puerto Rico, and the Virgin Islands.
In the afternoon, stronger showers may fire up along the
southwestern portions of Puerto Rico. The moisture associated with
the trough is expected to be shallow in nature, confined to the
lowest 850 mb of the atmosphere. Additionally, the winds are
strong, so rainfall accumulations are not expected to be too
significant, and impacts should be limited to wet roads and
ponding of water in roadways. Gusty winds can be anticipated at
times too.

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

An induce surface trough will be the main weather feature for the
first part of the long term. On Saturday, as the trough
approaches, winds will shift from south-southwesterly to
northeasterly and later transition to east-southeasterly after the
trough's passage. During this time, precipitable water (PWAT)
values will range between 1.5 and 1.7 inches, supporting scattered
showers mainly over windward areas of Puerto Rico and the U.S.
Virgin Islands, and as well the local waters. By Sunday into
Monday, the subtropical jet will lift northward into the region,
introducing strong horizontal upper- level winds and enhancing
higher cloud coverage. While PWAT values will remain sufficient
for isolated to scattered showers, the increased presence of high
clouds will likely limit surface heating and reduce the potential
for significant convection. Any showers that do form will be more
isolated and affecting mostly across the interior and southern
areas during the afternoon hours.

On Monday,the strong horizontal winds at 250 mb will promote
upper-level divergence, supporting limited convection across
interior and northwestern Puerto Rico. By Tuesday into Wednesday,
a potential surface low north of the region may shift winds to a
south- southeasterly direction, leading to warmer temperatures for
northern and western areas due to downslope warming effects. High
cloud coverage is expected to persist, further mitigating
widespread shower activity.

&&

.AVIATION...
(06Z TAFS)

SHRA are expected to increase in frequency today. However, mainly
VFR conditions are anticipated, with brief period of reduced VIS and
low ceilings anticipated. SHRA will reach the USVI and TJSJ
terminals through the entire period, and will reach TJPS and TJBQ
from 17-22Z. Winds will be from the ENE at 14-20 kts, with stronger
gusts at times.

&&

.MARINE...
A surface high pressure system spreading across the southwestern
Atlantic will maintain a moderate east-northeasterly wind flow
across the regional waters. Over the next few days, the tightening
pressure gradient will promote moderate to fresh winds across the
area, resulting in choppy seas across the Atlantic and Caribbean
waters. A Small Craft Advisory is in effect for the offshore
Atlantic waters through late tonight, as conditions are expected
to become hazardous for small vessels. Mariners and small craft
operators should exercise caution, particularly in exposed waters.
An induced surface trough by the end of the workweek into the
weekend will enhance thunderstorm activity, resulting in localized
hazardous marine conditions.

.BEACH FORECAST...

There is a moderate risk of rip currents across the northern
exposed coastal beaches of Puerto Rico, Culebra, Vieques, and the
U.S. Virgin Islands. Similar coastal conditions will continue for
the rest of the workweek across all the coastal areas.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
408 AM AST Thu Dec 12 2024

.SYNOPSIS...
A surface trough northeast of the region will maintain moderate to
fresh northeasterly winds through early in the weekend. These
trough will bring passing showers today, with the frequency
gradually increasing through early Sunday. These breezy conditions
will also maintain seas hazardous for the Atlantic waters, with
the risk of rip currents moderate to high for the local beaches.

&&

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

A northeasterly wind flow is influencing the weather across Puerto
Rico today, resulting in an advective pattern with showers
reaching the northeastern sections of the island during the
morning. By the afternoon, localized convection is expected to
lead to showers over the southwestern areas, driven by sea breeze
convergence and daytime heating. Atmospheric conditions remain
slightly stable, which should help limit widespread heavy
rainfall. Overnight, conditions across Puerto Rico and the U.S.
Virgin Islands were generally calm, with isolated showers
affecting the northern sections of Puerto Rico due to the
prevailing northeasterly flow. Overnight temperatures were cooler
across the region, with mid-70s observed in coastal areas, and
much colder conditions recorded in the mountains.

However, a shift in the weather pattern is anticipated from Friday
into Saturday as a surface trough moves into the region from the
east. This system will bring increased moisture, as indicated by
elevated relative humidity between 850-500 mb and lower heights at
250 mb. The axis of the vigorous surface trough is forecast to be
over Puerto Rico by Saturday morning, maintaining a northeasterly
wind flow and resulting in widespread morning showers, particularly
over the northern and eastern sections. As the trough moves
westward, winds will shift to a southeasterly direction, introducing
a warmer and more humid air mass. This will enhance afternoon
convection, favoring showers and isolated thunderstorms over western
and northwestern Puerto Rico for the rest of the period. Residents
should monitor updates, as localized heavy rainfall and urban and
minor flooding is possible, particularly Friday afternoon through
Saturday morning. The southerly wind component will result in more
warmer temperatures across the region once again, specially across
northern coastal areas.

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

Trailing moisture from the surface trough will continue to drag
some showers into the region on Sunday. With the edge of the
trough over the Dominican Republic, the steering flow will shift
from the southeast. Under these winds, showers developing along
the Cordillera Central will move into the north and northwest of
Puerto Rico. Also, the temperatures will go above normal again, so
it will feel warmer than the temperatures being experienced in the
past couple of days.

For the workweek, the forecast becomes uncertain. On one hand the
GFS shows a surface low pressure developing north of the region,
with light and variable winds through the forecast period. The
ECMWF on the other hand show stronger easterly winds and also more
moisture. The forecast at this time is a compromise between the
solutions. It shows the potential for scattered showers reaching
the Virgin Islands, eastern and northern Puerto Rico during the
day, and the usual showers developing in the west and interior
each afternoon. The rain does not appears to be too strong, so the
risk of flooding will be limited at best.

&&

.AVIATION...
(06Z)

VFR conditions will prevail across all the TAF sites. VCSH will
continue for TJSJ and TJBQ and winds from the E-NE at 10 kts
increasing up to 15 kt with gusty winds up to 25 knots between
12/15Z-12/22Z. Afternoon showers will briefly result in lower
ceilings and SHRA across the mountains and near TJPS at around
12/18Z.

&&

.MARINE...
A surface high pressure to the northwest of the islands and a surface
trough to the northeast will promote a moderate to fresh
northeasterly wind flow. These winds will result in hazardous seas
across the Atlantic waters, lasting through the weekend. The surface
trough near the Lesser Antilles, will move westward into the local
islands by the weekend, resulting in showers and thunderstorms
across the local waters.


&&

.BEACH FORECAST...
The risk of rip currents will be moderate today. However,
hazardous seas due to enhanced winds will likely increase the risk
to high from Friday into at least the weekend. The areas most
affected will be the north-facing beaches in Puerto Rico.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
426 AM AST Fri Dec 13 2024

.SYNOPSIS...
North-northeasterly breezy winds will continue to drag showers
across the islands. These showers will lead to wet roads and
ponding of waters at low-lying areas, as well as gusty winds. The
winds are also generating hazardous seas for small crafts along
the offshore Atlantic, with a high rip current risk for the north
facing beaches of Puerto Rico.

&&

.SHORT TERM...Friday through Sunday...

An advective pattern dominated the local islands overnight and into
the early morning hours. Continuous patches of cloudiness and
showers moved into the region from the Atlantic waters, traveling
across the coast and into the island's interior. The rainfall
activity was fast-moving due to wind flow ranging between 10 to 15
mph. Rainfall accumulations were insignificant and primarily
resulted in hazardous driving conditions.

The region remains under the influence of an advective weather
pattern, dominated by a northeastern wind flow associated with a
strong surface trough positioned just northeast of the islands. This
setup has strengthened the pressure gradient, leading to breezy
conditions across Puerto Rico and the U.S. Virgin Islands. These
enhanced winds will carry patches of moisture and cloudiness into
the area, resulting in a showery weather pattern throughout the day.
Expect frequent but brief showers, particularly over windward
sectors, with some showers drifting into interior and leeward areas
due to the prevailing flow. As the surface trough lingers near the
region, its influence will begin to change at the surface, winds are
forecast to weaken, veering more east-southeast, and a surge of
tropical moisture will enter the area. This pattern will
significantly enhance shower activity, particularly in the late
morning and afternoon hours. Showers will be widespread, with
heavier rainfall expected across interior and eastern Puerto Rico
due to the interaction of moisture with local terrain. The U.S.
Virgin Islands can anticipate scattered showers, with some locally
heavy showers. Isolated thunderstorms are also possible. Rainfall
rates may lead to ponding of water in low-lying areas, though
significant flooding is not expected at this stage.

By Sunday, the surface trough will shift away from the region, yet
its trailing effects will leave behind abundant moisture and a new
wind pattern. Winds will shift to a more southeasterly direction,
bringing warmer temperatures and higher humidity levels. This flow
will favor moisture convergence, particularly across the San Juan
Metro Area, and showers will become more concentrated and persistent
in this region. Heavier showers and isolated thunderstorms may lead
to urban flooding and ponding of water on roadways. Coastal areas
and interior regions should also remain vigilant for localized
flooding, especially during periods of peak rainfall.

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

The workweek will start with winds coming out from the east or
southeast. Under this flow, precipitable water values are expected
to remain above normal, with moisture flowing from the Caribbean
Sea into the islands. In general, atmospheric conditions are not
expected to be too favorable for strong convection, but moisture
will climb between 700 to 500 mb. The trade winds will be on the
slow side, at speeds of 5 to 10 knots, and will drag some showers
over the Virgin Islands and eastern Puerto Rico at times,
resulting in wet roads and ponding of water in roadways and low-
lying areas. In the afternoon, shower activity could also develop
in the interior and west. Although isolated urban and small stream
flooding cannot be ruled out, widespread flooding is not
anticipated.

&&

.AVIATION...
(06Z)

A showery pattern is forecast for all the day with
presence of VCSH and SHRA across all the TAF sites. Winds will
continue from the E-NE at 12 knots with gusty winds up to 25 knots
and even higher near the showers. A SFR trough will move near the
region by Saturday, resulting in weaker and variable winds.

&&

.MARINE...
A surface high pressure to the northwest of the islands and a
surface trough to the northeast will promote a moderate to fresh
northeasterly wind flow. These winds will result in hazardous seas
across the Atlantic waters, lasting through at least the weekend.
The surface trough near the Lesser Antilles, will move westward into
the local islands by late Friday and Saturday, resulting in showers
and thunderstorms across the local waters. Winds will shift from the
south-southeast on Saturday.

&&

.BEACH FORECAST...
Enhanced winds will continue for the next several days,
triggering a high rip current risk for the north-facing beaches in
Puerto Rico. The high risk will last at least into early next
week. Elsewhere, a moderate rip current risk is anticipated.

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
445 AM AST Sat Dec 14 2024

.SYNOPSIS...

Today, winds will shift from the south to southeast gradually
diminishing through the weekend. Additional isolated to scattered
showers are expected to reach the islands at times today,
particularlyacross southern and eastern Puerto Rico. Hazardous
seas for small crafts along the offshore and nearshore Atlantic,
with a high rip current risk for the north facing beaches of
Puerto Rico continue at least through early next week. Another
northeasterly swell is anticipated by midweek.

&&

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

Shower activity was limited across the islands during the night, but
some managed to reach the local islands. Stronger showers were
observed in the local waters between Culebra and Fajardo. In the
recent satellite imagery, the main circulation of the trough is
evident about 150 to 200 miles north of Puerto Rico. Although the
area of better moisture should remain over the waters, additional
showers are expected to reach the islands at times. The winds will
shift from the south early this morning, so the focus of the rain
activity will be switched to southern Puerto Rico and the Virgin
Islands. The steering flow is a lot weaker this morning too, with
speeds of 4-8 kts, but with gusts around 12 knots.

For the rest of the period, and as the surface trough moves into the
Dominican Republic, a deep-layered southeasterly wind flow will get
established. Plenty of moisture will flow into the islands too, with
precipitable water values above the climatological value. With these
winds, temperature are expected to be a little bit above normal
again, while the potential for showers will persist. The areas more
affected, as usual, are the eastern and southeastern portions of
Puerto Rico, and the Virgin Islands. Widespread flooding is not
anticipated, but some isolated urban floods cannot be ruled out.

&&

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

Based on the latest meteorological models, a surface high pressure
will dominate the central Atlantic during the beginning of the
long-term period. We will experience east to southeast winds
across our forecast area, with moisture levels fluctuating between
normal and above-normal values for this time of the year as tropical
moisture and disturbances in the trade winds persist over the
region. In general, atmospheric conditions are not expected to be
highly favorable for strong convection, but moisture will increase
between 700 and 500 mb, especially from Thursday through Saturday.
Overall, expect morning showers across the U.S. Virgin Islands
and eastern Puerto Rico at times. Shower activity may also develop
and concentrate across the interior and western sectors of Puerto
Rico each afternoon, resulting in wet roads and ponding of water
in roadways and low-lying areas. While major flooding is not
expected at the moment, isolated urban and small stream flooding
cannot be ruled out of the forecast.

&&

.AVIATION...
(06Z TAFs)

SHRA will move across the local terminals today as a trough moves
north of the islands. Winds are from the S at the USVI terminals,
and S winds are expected along all terminals by 12-14Z, at speeds of
5-8 kts. SHRA in the terminals will result in brief periods of
reduced VIS and low ceilings.

&&

.MARINE...

An area of low pressure and surface trough located north of the
region are moving west-southwestward, resulting in isolated to
scattered showers and over the local waters through the weekend.
Additionally, hazardous marine conditions for small craft are
expected to continue across the coastal and offshore Atlantic waters
through at least late tonight and late Sunday, respectively, due to a
northeasterly swell. Winds are expected to shift from the south-
southeast today and remain from that direction over the next few
days. Another northeasterly swell is anticipated to spread across the
local Atlantic waters by midweek, with hazardous seas returning.

&&

.BEACH FORECAST...

Beachgoers, a high rip current risk across the north-facing
beaches of Puerto Rico is expected to continue today and at least
through early next week. Elsewhere, a low to moderate rip current
risk is anticipated. Around mid week, high risk of rip currents is
expected to return along the northern beaches of the islands due
to an approaching northeasterly swell. For more details, please
refer to the Surf Zone Forecast for Puerto Rico and the U.S.
Virgin Islands (SRFSJU).

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
508 AM AST Sun Dec 15 2024

.SYNOPSIS...

Isolated showers are expected early today across southern and
eastern portions of the islands, followed by afternoon showers
over northwest Puerto Rico. South to southeast winds will help
to warm up temperatures during the day. Hazardous seas for small
crafts along the offshore Atlantic waters, with a high rip current
risk for the north-facing beaches of Puerto Rico in effect through
at least Monday afternoon. Another northeasterly swell is anticipated
by midweek.

&&

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

The night was mainly tranquil, but passing showers moved at times
across southern and southeastern Puerto Rico. Rainfall accumulations
were mostly light. Temperatures were on the cool side, with lows in
the low and mid 70s, and in the mid-60s in the mountains.

At the surface, there is a trough just north of Haiti, with most of
the moisture moving away from the islands. There is also a high
pressure centered just east of the Carolinas, and these systems are
bringing south-southeast winds into the islands. Under this flow,
temperatures are expected to warm up during the day, being a couple
degrees warmer than normal for mid-December. There is still enough
moisture for some showers to emerge over the Caribbean Sea, reaching
portions of southern Puerto Rico and the Virgin Islands. In the
afternoon, additional activity is anticipated for the northwestern
corner of Puerto Rico. The showers in the northwest could be
stronger, with the potential for ponding of water on roadways and
low-lying areas.

The winds will keep coming from the south on Monday, and even
lighter, transporting additional moisture from the Caribbean Sea.
Precipitable water values are expected to be steady, just above
normal. Then, for Tuesday, as another trough develops just northeast
of the islands, the winds will gradually shift from the northeast.
Each afternoon, showers are expected to develop. On Monday, the
rainfall activity should be focused on the northwest or north-
central, while the interior and southwest are favored on Tuesday.
Minor urban flooding will be possible these days, especially on
Monday.

&&

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

Based on the latest meteorological models, high pressure will
dominate the central Atlantic at the beginning of the long-term
period. We will experience winds with an easterly component.
Moisture levels will fluctuate around normal values on Wednesday
but are expected to increase above normal by Thursday, resulting
in the best chance for showers. In general, atmospheric conditions
are not expected to be highly favorable for strong convection, but
moisture will increase between 700 and 500 mb, especially from
Thursday through Saturday. Under this pattern, morning showers
across the U.S. Virgin Islands and eastern Puerto Rico are likely,
followed by afternoon shower activity across the interior and
western sectors of Puerto Rico each afternoon, resulting in wet
roads and ponding of water in roadways and low-lying areas. While
major flooding is not expected at the moment, isolated urban and
small stream flooding are possible, with limited excessive
rainfall risk persisting throughout the forecast period. For more
details, visit the Experimental Graphical Hazard Weather Outlook
at https://www.weather.gov/erh/ghwo?wfo=sju.

&&

.AVIATION...
(06Z TAFs)

Mainly VFR conditions are expected to prevail through the forecast
period. SE winds from the SFC to 10000 ft at 6 to 13 kts, but
veering from the S at 3000 to 8000 ft after 18z. Isolated SHRA are
expected, mainly for TJPS, with stronger activity after 17Z for
TJBQ. Brief periods of reduced VIS and low ceilings can be
anticipated, especially for TJBQ.

&&

.MARINE...

Moderate to locally fresh easterly to southeasterly winds will
continue today, becoming lighter tonight into Monday. Hazardous
marine conditions for small craft are expected to continue across
the offshore Atlantic waters through at least noon Monday due to a
northeasterly swell. Small craft should exercise caution across
the coastal Atlantic waters. Another northeasterly swell is
anticipated to spread across the local Atlantic waters by late
Tuesday into Wednesday, with hazardous marine conditions quickly
returning.

&&

.BEACH FORECAST...

Beachgoers, a weak northwesterly swell continues spreading across
the local waters, for that reason the high rip current risk across
the north-facing beaches of Puerto Rico was extended through
Monday afternoon. Elsewhere, a low to moderate rip current risk
is expected to prevail. Late Tuesday into Wednesday, a high risk
of rip currents is expected to return along the northern beaches
of the islands due to another northeasterly swell. For more
details, please refer to the Surf Zone Forecast for Puerto Rico
and the U.S. Virgin Islands (SRFSJU).

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
518 AM AST Mon Dec 16 2024

.SYNOPSIS...

The main threat will remain the northeasterly swells, which are
creating life-threatening rip currents for beachgoers and
hazardous conditions for small craft over the coming days. With
increasing moisture levels and favorable conditions, the
potential for heavier rainfall will rise, with isolated
thunderstorms possible by midweek. This could result in ponding
and minor flooding in urban and poorly drained areas. Stronger
northeast winds will bring breezy to windy conditions by midweek,
gradually easing to lighter, variable winds by the weekend.


&&

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

The night was mainly quiet over land, with passing showers mainly
affecting the local waters. Temperatures were on the cool side, with
lows in the low and mid-70s, and in the mid-60s in the mountains.
Light winds prevailed.

The short period is expected to be characterized by variable weather
conditions, with a combination of sunshine and intermittent rain
each day. Based on the latest model guidance, precipitable water
values will increase from today onward. They will range from 1.6 to
1.8 inches, peaking around 2 inches on Wednesday. These values are
considered above normal for this time of year. The southeast winds
will weaken and shift to the east-northeast today due to the
proximity of a weak surface trough. This feature will bring showers
to eastern Puerto Rico this morning and U.S. Virgin Islands, with
scattered showers and isolated thunderstorms possible across the
interior and west during the afternoon hours. Due to the light
winds, there may be slightly more accumulation compared to the past
few days, resulting in a limited risk of ponding on roads and in
poorly drained areas, with potential minor flooding in urban and
small stream areas.

From Tuesday to Wednesday, high pressure will continue to establish
over the central Atlantic, maintaining northeast winds as it pushes
a frontal boundary and keeps moisture flowing into our area, keeping
precipitable water values above normal. Additionally, the pressure
gradient will tighten, resulting in stronger winds across the area.
The eastern sectors of Puerto Rico and the local islands have the
highest probability of seeing rain showers in the early morning
hours of Wednesday, followed by showers focused in the interior and
southwest of Puerto Rico. For more details, visit the Experimental
Graphical Hazard Weather Outlook at weather.gov/erh/ghwo?wfo=sju.

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

Model guidance suggests a predominantly seasonal weather pattern,
with periods of notable increases in moisture levels. Precipitable
water values are expected to peak at 2.0 inches by Thursday and
2.1 inches by Sunday, which is well above average for this time
of year. These elevated moisture levels, combined with favorable
conditions aloft, suggest the potential for isolated
thunderstorms, particularly on Thursday. Hazards to monitor
include excessive rainfall, non-thunderstorm winds, and lightning,
which could lead to localized flooding and other localized
impacts.

A surface high pressure system over the North Atlantic will
maintain breezy to windy conditions early in the period,
transitioning to lighter and more variable winds by the weekend
with the proximity of a frontal boundary. Temperatures are
expected to cool slightly, with more seasonal conditions by the
end of the week, as indicated by 925 mb temperatures in the model
guidance.


&&

.AVIATION...
(06Z TAFS)

Mainly VFR conditions are expected to prevail most of the forecast
period. Winds should remain lighter today, 10 kts or less with an
easterly component. Brief periods of reduced VIS and low ceilings
can be anticipated due to VCSH or SHRA this morning across the USVI
TAF sites. MVFR conds with mtn obscurations may be expected after
16Z in PR sites.


&&

.MARINE...

Light to moderate easterly to southeasterly winds will persist
today, transitioning to fresh to locally strong winds starting
Tuesday due to strengthening surface high pressure over the North
Atlantic. Northeasterly swells will continue to create hazardous
marine conditions for small craft in the offshore Atlantic waters
today. Another northeasterly swell is expected to reach the local
Atlantic waters by late Tuesday into Wednesday, further
contributing to rough and hazardous sea conditions.


&&

.BEACH FORECAST...

Northeasterly swells will continue to create life-threatening rip
current conditions along Puerto Rico's northern and northeastern-
facing beaches. As another northeasterly swell arrives, these
hazardous conditions are expected to persist through midweek. If
conditions warrant, additional or extended Rip Current Statements
and possibly High Surf Advisories may be issued as rough seas and
the swell action continues. For more details, please consult the
Surf Zone Forecast (SRFSJU).

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
514 AM AST Tue Dec 17 2024

.KEY MESSAGES...

- Small craft operators should be alert for hazardous seas from
northeasterly swells and increasing winds.
- Beachgoers should watch for life-threatening rip currents,
especially along northern Puerto Rico, Culebra, and the US
Virgin Islands.
- Breezy to locally windy conditions will likely limit outdoor
activities and operations.
- Flooding risks are expected to increase by Wednesday into
Thursday and early next week.

.SYNOPSIS...

Over the next few days, hazard risks will be focused around
marine and surf zone impacts from northeasterly swells and
increasing winds, which will also bring breezy to locally windy
conditions to coastal areas. As moisture levels rise and
conditions become more favorable, the potential for showers with
isolated thunderstorms and possible flooding impacts will increase
by midweek and early next week. Stay informed on the latest
updates for flooding, rip currents, and other hazards through our
social media channels and the Experimental Graphical Hazard
Weather Outlook: https://www.weather.gov/erh/ghwo?wfo=sju.


&&

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

Clear to partly cloudy skies prevailed overnight, with mostly calm
conditions across the forecast area, except for some showers over
local waters that managed to move inland along the northern,
eastern, and southeastern coasts of Puerto Rico. Radar estimates
indicated rainfall amounts of up to 0.75 inches between Ceiba and
Naguabo, with maximum values of 0.20 to 0.40 inches reported
elsewhere. Temperature-wise, lows ranged from the low to mid-70s in
coastal areas and the mid-60s in the mountains. East to northeast
winds prevailed at 10 knots or less.

The short-term period is expected to feature variable weather
conditions, with a mix of sunshine and intermittent rain each day.
At upper levels, the subequatorial jet will move north of the area,
bringing the best divergence early today. According to the latest
model guidance, high pressure across the northern Atlantic will
begin to move east and strengthen. As a result, wind flow around the
local area will become breezy to windy, shifting to the east-
northeast today. This will allow the remnants of an old front to
move from the northeast into our region tonight through Wednesday
morning, maintaining moisture flow into our area. Precipitable water
values will continue to rise today, remaining above normal for this
time of year, around 1.7 to 1.8 inches, and peaking at around 2
inches on Wednesday. The aforementioned features will bring showers
to eastern Puerto Rico this morning and to the U.S. Virgin Islands,
with scattered showers across the interior and southwest during the
afternoon. Isolated thunderstorms are also possible, as 500mb
temperatures are forecast to be around -8°C. A limited flood risk
remains in place today, highlighting the eastern half of Puerto Rico
and a portion of the southwest. Ponding of water on roads and poorly
drained areas is possible, as well as urban and small stream
flooding. For more details, visit the Experimental Graphical Hazard
Weather Outlook at https://www.weather.gov/erh/ghwo?wfo=sju.

By Thursday, winds will gradually shift to a more easterly direction
and decrease in speed as high pressure weakens. However, sufficient
moisture and good ventilation aloft will continue to bring periods
of rain during the morning, primarily focused on the eastern half of
Puerto Rico and the U.S. Virgin Islands, with a shift to the
northwest during the afternoon.

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

Model guidance indicates the development of a weak mid-level
ridge over the northeastern Caribbean early in the period, which
will shift eastward as a strong polar trough deepens to the north-
northwest starting Sunday. At the same time, moisture levels will
increase steadily, surpassing typical thresholds (above 1.7
inches) by Friday and reaching well above normal (above 2.1
inches) by Monday.

As the surface high pressure moves east into the North Central
Atlantic, the local pressure gradient will relax, causing trade
winds to weaken on Friday. Winds will diminish further over the
weekend as a weak pressure area develops to the north. By Monday,
winds will become more northeasterly as another high-pressure
system moves off the eastern United States into the western
Atlantic region.

This developing pattern will heighten the chances of scattered
showers and isolated thunderstorms beginning Sunday and continuing
early next week, with potential risks including excessive
rainfall, gusty winds, and lightning. Aside from localized limited
non-thunderstorm wind hazards persisting on Friday, no
significant hazards are anticipated on Friday or Saturday.

Temperatures will likely warm slightly over the weekend, followed
by cooler, more seasonal conditions likely by early next week, in
line with wind and rainfall pattern trends.

Les vamos a dar información sobre como va a estar el tiempo para nochebuena y el dia de navidad en Puerto Rico con más detalles, ya que el margen de error se achica y los modelos son más precisos en 7 dias o menos. Los principales modelos GFS y Europeo tienen un sistema frontal que va a traer lluvias para ambos dias

&&

.AVIATION...
(06Z TAFs)

Mainly VFR conditions are expected to prevail for the next hours. E
to ENE winds today becoming more breezy aft 14Z. Brief periods of
reduced VIS and low ceilings anticipated due to VCSH or SHRA this
morning across the USVI TAF sites and TJSJ. MVFR conds with mtn
obscurations may be expected after 17-18Z. VCSH likely aft 17-18Z in
the rest of the TAF sites. Around 18/03-06Z remnants of a frontal
boundary can result in SHRA or TSRA where PROP30s were added in
TJSJ, TISX, TIST.


&&

.MARINE...

Fresh to locally strong easterly winds will develop today as
surface high pressure strengthens over the North Atlantic.
Northeasterly swells will maintain hazardous conditions for small
craft in the Atlantic waters throughout the day, expanding into
the local Caribbean passages by this evening. Pulses of
northeasterly swell will likely reach the local Atlantic waters
late tonight into Wednesday, further contributing to rough and
hazardous sea conditions.


&&

.BEACH FORECAST...

New in this forecast: The High Rip Current Risk is now in effect
for Culebra and Saint Croix starting today and for the northern US
Virgin Islands starting this evening.

Rough and hazardous seas, driven by northeasterly swells and fresh
to locally strong winds, will create life-threatening rip current
conditions for beachgoers along Puerto Rico's northern beaches,
Culebra, and Saint Croix today. As additional pulses of
northeasterly swells move through the region, these dangerous
conditions persist through at least Thursday and may spread to
other surf zone areas. High Surf Advisories may be issued if
conditions deteriorate as rough seas and swell action continue.
For further details, please consult the Surf Zone Forecast
(SRFSJU).

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
440 AM AST Wed Dec 18 2024

.KEY MESSAGES FOR TODAY...

- Small craft operators must stay alert for hazardous seas from
northeasterly swells and increasing winds.
- Beachgoers should avoid risky waters, particularly along
northern Puerto Rico, Culebra, and the U.S. Virgin Islands,
where rip currents will be especially dangerous.
- Flooding is possible, with localized impacts due to heavy
rain.
- Isolated thunderstorms may trigger lightning and gusty winds
today, creating hazardous conditions.
- Breezy to windy conditions will continue to affect coastal
areas and local islands, disrupting outdoor activities and
operations.


&&

.SYNOPSIS...

Over the next few days, the primary hazards will be focused on
life-threatening rip currents and hazardous marine conditions for
small craft, driven by northeasterly swells and strengthening
winds. These winds will bring breezy to locally windy conditions
to land areas. Elevated moisture levels and favorable conditions
will continue to support the risk of heavy rainfall and potential
flooding, with isolated thunderstorms also possible. As we move
into the weekend, wet and unstable conditions will return. This
unsettled weather is expected to last into early next week, with
Christmas Eve and Christmas Day likely to be especially rainy.
Stay informed on the latest updates for flooding, rip currents,
and other hazards through our social media channels and the
Experimental Graphical Hazard Weather Outlook:
https://www.weather.gov/erh/ghwo?wfo=sju.


&&

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

Overnight radar and satellite analysis showed rainy weather
conditions, with persistent showers and isolated thunderstorms
affecting northeastern Puerto Rico and less frequent showers
affecting other sections of eastern Puerto Rico and the local
islands. Surface observations recorded rainfall totals up to
three-quarters of an inch over the San Juan metropolitan area. At
the same time, radar estimates showed around two inches of rain
over portions of northern Carolina. Temperatures ranged from the
mid-60s in higher elevations to around 78 degrees across eastern
Puerto Rico and the U.S. Virgin Islands. Winds were generally
easterly at 10-15 knots along coastal areas and light and variable
further inland, with stronger gusts near showers.

A strengthening surface high pressure over the western Atlantic
tightens the local pressure gradient, resulting in breezy to
locally windy east-northeast winds of 15-25 knots across the
region. These winds will steer moisture associated with the
remnants of an old frontal boundary, with precipitable water
(PWAT) values peaking at 2.1 inches this morning. This setup will
sustain scattered to numerous showers across eastern Puerto Rico,
Vieques, Culebra, and the U.S. Virgin Islands, with periods of
moderate to heavy rainfall likely. Some showers will progress or
develop inland, affecting interior and southern Puerto Rico
throughout the day. Enhanced instability from the subequatorial
jet, positioned just north-northeast of the area, will support
isolated thunderstorms, particularly during peak moisture. While
the primary hazards include localized excessive rainfall, minor
flooding, and gusty winds, non-thunderstorm winds are also a
concern.

Breezy east-northeast winds will persist on Thursday as the high-
pressure system remains over the western Atlantic, with PWAT
values dipping to 1.8 inches early in the morning before
rebounding to 1.9 inches later in the day. Showers will remain
frequent, especially over eastern and northern areas, and isolated
thunderstorms may develop with support from lingering marginal
instability from the subequatorial jet. Thursday is expected to
have the highest rainfall impacts of the short-term period due to
sustained moisture convergence, with elevated risks for localized
flooding over eastern Puerto Rico. By Friday, the high will shift
eastward into the central Atlantic, weakening the pressure
gradient and reducing wind speeds to 10-15 knots while veering
from the east, while a weak ridge pattern develops aloft. A col
developing northwest of the region will result in a less organized
wind pattern. However, scattered showers will persist across
windward areas during the morning, with limited activity over
interior/western Puerto Rico in the afternoon. Although marginal
instability will persist, impacts will likely be less widespread
than Thursday.

Temperatures will gradually cool over the next few days, returning
to more seasonal levels in alignment with the prevailing wind and
rainfall patterns. For updates on excessive rainfall, winds, and
any other hazard risk in the coming days, please visit the
Experimental Graphical Hazard Weather Outlook at
https://www.weather.gov/erh/ghwo?wfo=sju.

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

The interaction of a surface low moving from the Western to
Northwestern Atlantic and a surface low developing across the
Central Atlantic will relax the local pressure gradient, weakening
the trade winds from Saturday through at least Monday. A frontal
boundary that model guidance shows moving eastward across the
western Atlantic will stall off to the northwest of the region,
which will induce a pre-frontal trough and pool of abundant
moisture over the Northeast Caribbean. Meanwhile, a polar trough
moving eastward from the Western to Central Atlantic at the upper
levels will weaken the ridge pattern aloft, promoting deep
moisture across the region. Under this weather pattern, we can
anticipate moderate to locally heavy rain each day, especially
across the windward locations early in the morning and overnight.

Global models indicate a moderate chance of observing a wet and
unstable weather pattern as additional moisture pools over the
region as the Nor'easter moves near Nova Scotia and Newfoundland
from Saturday to Monday. There is a slight to moderate chance of
thunderstorms developing during this period. The remnants of the
frontal boundary will then linger north of the region, increasing
the chance to observe a wet Christmas Eve and Christmas Day.


&&

.AVIATION...
(06Z TAFS)

SHRA/TSRA will likely bring brief periods of MVFR conditions
across most terminals over the next 24 hours, potentially
impacting operations. This will affect TJSJ and USVI terminals
throughout the entire period, while TJPS and TJBQ will see these
impacts mainly between 18/14-22Z. Winds will remain from the east
at 10-15 knots, with occasional higher gusts near SHRA/TSRA
activity.


&&

.MARINE...

A surface high pressure strengthening over the North Atlantic will
maintain fresh to locally strong easterly winds for the rest of
the workweek. Pulses of northeasterly swell will reach the local
Atlantic waters, extending the hazardous conditions for small
craft in the Atlantic waters and local Caribbean passages through
at least Friday. Showers and isolated thunderstorms will also
contribute to worsening marine conditions.

&&

.BEACH FORECAST...

Rough and hazardous seas, driven by northeasterly swells and fresh
to locally strong winds, will create life-threatening rip current
conditions for beachgoers along the U.S. Virgin Islands and Puerto
Rico's northern and northeastern-facing beaches. As additional
pulses of northeasterly swells move through the region, these
dangerous conditions persist through at least late Thursday and
may spread to other surf zone areas. For more details, please
consult the Coastal Hazard Message (CWFSJU) and the Surf Zone
Forecast (SRFSJU).

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
434 AM AST Thu Dec 19 2024

.SYNOPSIS...

Today, the citizens and visitors of Puerto Rico and the U.S.
Virgin Islands should experience frequent showers. Marginal
instability and above- normal moisture levels will likely produce
periods of moderate to heavy rainfall, sustaining a limited to
elevated flooding risk through the weekend.

&&

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

Overnight radar and satellite analysis showed rainy conditions, with
persistent showers affecting eastern Puerto Rico and less frequent
over the the local islands. Surface observations recorded rainfall
totals up to around a quarter of an inch in eastern Puerto Rico,
similar to radar estimates. Temperatures ranged from the mid-60s in
higher elevations to around 77 degrees across eastern Puerto Rico
and the U.S. Virgin Islands. Winds were generally easterly at 5-10
mph along coastal areas and light and variable further inland, with
stronger gusts near showers moving inland from the waters.

As the strengthening high-pressure system over the western Atlantic
shifts eastward into the North Central Atlantic, winds will veer
from the east, but breezy to locally windy conditions will prevail.
Meanwhile, PWAT values will remain steady around 1.9 inches, well
above seasonal thresholds. Frequent showers, especially over eastern
areas, will produce periods of moderate to heavy rainfall through
tonight, with elevated risks for localized flooding, mainly in
eastern Puerto Rico. Lingering marginal instability from the
subequatorial jet may also support isolated thunderstorms.

The high-pressure system will move farther east into the Central
Atlantic, weakening the pressure gradient and reducing wind speeds
while maintaining an easterly flow. Weak mid-level ridging will
briefly develop over the region, likely limiting the overall extent
of rainfall compared to Thursday. Expect scattered showers mainly
across windward areas during the morning, with limited activity over
interior and western Puerto Rico in the afternoon. Moisture levels
will remain stable but slightly less conducive to widespread impacts.

Shower activity will likely increase as a low-level trough develops
along a stalled frontal boundary to the north, influenced by a
Nor’easter far north near Nova Scotia. While uncertainties remain
about its impact, the stalled boundary is anticipated to generate a
pre-frontal trough, drawing abundant moisture into the Northeast
Caribbean. An associated area of weak pressure will also disrupt the
wind flow, causing winds to weaken further and veer to the east-
southeast. This pattern, supported by the Galvez-Davison Index, will
likely enhance scattered showers and isolated thunderstorms, mainly
over Caribbean waters, with only limited flooding impacts expected
across land areas.

Temperatures will remain closer to seasonal levels over the next few
days, with slightly warmer conditions on Saturday in alignment with
the prevailing wind and rainfall patterns. For updates on excessive
rainfall, winds, and any other hazard risk in the coming days,
please visit the Experimental Graphical Hazard Weather Outlook at
https://www.weather.gov/erh/ghwo?wfo=sju.

&&

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

The end of the weekend into the beginning of the workweek leans
towards a wet weather pattern across Puerto Rico and the U.S.
Virgin Islands. Trade winds are expected to weaken due to surface
low pressures interacting in the Atlantic, decreasing local
pressure gradient. Model guidance suggests Precipitable Water
(PWAT) values above climatological normals through Monday, as on
Tuesday precipitable water values begin to decrease gradually. At
this time, Sunday and Monday are the only days of the long term
period with a higher chance for thunderstorm development as
weather conditions will be favorable. Additionally, 500 mb
temperatures and the Galvez- Davison Index suggest a chance for
isolated thunderstorms in the afternoon. This in combination of
diurnal heating and local effects will promote isolated to
scattered showers mainly in windward sections during the morning
hours with additional convective activity in the afternoon for the
western sections of Puerto Rico. The northeasterly windflow will
return by Monday, as the surface low pressure in the Center
Atlantic dissipates and abroad high pressure lingers over the
southeastern coast of CONUS.

A more seasonal weather pattern and fresher temperatures are
expected for both Christmas Eve and Christmas Day. However, we
encourage people to stay updated for any changes in the long term
forecast. Moisture content will increase once again on Thursday,
elevating the chance of showers across windward sections in the
morning and northwestern Puerto Rico in the afternoon.

&&

.AVIATION...
(06Z TAFS)

SHRA will likely bring brief periods of MVFR conditions
across most terminals over the next 24 hours, potentially impacting
operations. This will affect TJSJ and USVI terminals throughout the
entire period, while TJPS and TJBQ will see these impacts mainly
between 19/16-20Z. Winds will remain from the east at 5-10 knots,
increasing to 10-15 knots after 19/14Z, with occasional higher gusts
near SHRA activity.

&&

.MARINE...

A strengthening high-pressure system over the western Atlantic
will continue to shifts eastward into the North Central Atlantic
maintain fresh to locally strong easterly winds today. Pulses of
northeasterly swell will reach the local Atlantic waters,
extending the hazardous conditions for small craft in the Atlantic
waters and local Caribbean passages through at least Friday.
Showers and isolated thunderstorms will also contribute to
worsening marine conditions.

&&

.BEACH FORECAST...

Breezy conditions resulting in choppy seas and energy from pulses
of a northeasterly swell will result in hazardous breaking waves
across northern, eastern, and southeastern Puerto Rico and the
U.S. Virgin Islands where a high risk of rip current statement is
in effect until Friday. The risk of rip current will remain
moderate for the southwestern coastal areas of Puerto Rico.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
439 AM AST Fri Dec 20 2024

.SYNOPSIS...

Marginal instability and above-normal moisture levels persist,
likely producing periods of moderate to heavy rainfall and
sustaining a limited to elevated flooding risk through the weekend.
Southeasterly wind flow will contribute to above-normal temperatures
during this period. Hazardous marine and coastal conditions remain,
with Rip Current Statements and Small Craft Advisories still in
effect.

&&

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

The area of best convection remained to our west overnight with a
few thunderstorms over the Caribbean waters with tops as high as 39
kft. Showers dampened the southeast quadrant of Puerto Rico and a
few spots on the eastern slopes of El Yunque. Amounts since midnight
were generally less than three tenths of an inch there. Temperatures
continue to run a few degrees above normal with overnight lows in
of 70 to 80 degrees in the lower elevations and the 60s in the mid
and upper elevations.

High pressure at the surface dominates the Atlantic ocean of the
northern hemisphere, except for a developing low pressure moving up
the east coast of the United States and a strong low pressure in the
central Atlantic. Low pressure is seen along the northern coasts of
Venezuela and Colombia generating moderate to locally fresh east
southeast winds over the forecast area. This flow is expected to
continue for the duration of the short term period, although
somewhat weakened overnight and tomorrow. A frontal boundary moving
southeast through the Bahama Islands today and a shortwave at upper
levels moving northeast will generate a northeastward-moving low
pressure in the lower levels north of the Mona channel later this
afternoon and evening that will pull moist air out of the eastern
Caribbean, even though drier air is seen to hold just northeast of
the Leeward Islands. Therefore precipitable water values will be the
lowest around 20/14Z this morning, and rise above the levels seen
last night by Saturday evening. This will allow showers and the
possibility of a thunderstorm over land during the day and over
water by night. Winds at the surface will diminish on Friday night
and Saturday, but will increase Sunday and Monday. Some urban and
small stream flooding could occur then during this quieter period,
but generally these showers will be well behaved and beneficial.

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

A wetter pattern will persist on Monday as remnants of a front and
some troughing aloft linger. Marginal instability will dominate
throughout the week, with shower activity largely dependent on low-
level moisture availability and the steering wind flow pattern. On
Monday, precipitable water content is expected to fluctuate between
1.8 and 2.0 inches, gradually decreasing to less than an inch by
late Friday night. This marks a significant shift, with moisture
levels dropping from values exceeding the 90th percentile on Monday
to well below the 10th percentile of the climatological normal by
the end of the workweek.

The wind pattern will shift from east-northeast on Monday to north-
northeast by the end of the week, driven by a complex surface
pressure pattern developing across the northern Atlantic, which will
influence wind flow over the northeastern Caribbean. As a result,
Monday is expected to be the wettest day, with a cool advective
pattern promoting morning showers primarily over east-northeast
coastal areas, while afternoon convection clusters across the
interior and western/southwestern regions of Puerto Rico. Dynamical
effects from the front and a shortwave trough aloft could enhance
thunderstorm activity in the area. The GFS Galvez-Davison Index
highlights the potential for thunderstorm development or scattered
shallow convection, indicating a limited to elevated flooding threat
in these regions.

As moisture content diminishes and winds gradually shift more from
the northeast, the frequency of showers is expected to decrease
throughout the week, transitioning to a more seasonal weather
pattern with limited shower activity by the start of the weekend.
The northeasterly steering wind flow will also bring pleasant
temperatures across the region, with Friday projected to have the
coolest temperatures of the long-term outlook. Notably, the National
Blend of Models (NBM) indicates a 65% or higher probability of
temperatures dropping below 60F in Puerto Rico's higher elevations,
particularly across the central mountainous areas.


&&

.AVIATION...
(06Z TAFS)

Mainly VFR conditions are expected to prevail across all terminals
during the next 24 hours. However, SHRA/isold TSRA are expected to
dvlp aft 20/16Z across wrn and interior PR that will generate some
mtn obscurations and MVFR conds in the heaviest rains. LLVL flow is
ESE at 6-10 kt except lighter ovr PR with land breezes. Maximum
winds are W 60-70 kts btwn FL385-440.

&&

.MARINE...

Rough seas continue as a strong pressure gradient prevails between a
high pressure in central Atlantic and low pressure in southern
Caribbean, supporting fresh to locally strong easterly winds today.
Additionally, pulses of a weak northeasterly swell will persist,
extending the hazardous conditions for small craft in the Atlantic
waters and local passages through at least late tonight. Showers and
isolated thunderstorms will also contribute to worsening marine
conditions.

&&

.BEACH FORECAST...

The northern nearshore buoy continues to report rough seas of 8
feet, creating very hazardous coastal conditions. In contrast, the
Rincon buoy shows diminishing seas, a trend expected to persist
throughout the day. As a result, the rip current statements for the
beaches of Rincon and nearby areas have been canceled. However, the
statements remain in effect for the northern coast of Puerto Rico,
Culebra, and the U.S. Virgin Islands for the remainder of the day.
For more information, please refer to the SRFSJU and CFWSJU text
products.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
517 AM AST Sat Dec 21 2024

.SYNOPSIS...

An approaching front from the western Atlantic and a low pressure
over the southern Caribbean will promote increasing moisture,
light to moderate southeasterly winds, and warmer than normal
temperatures through the weekend. A building high pressure behind
the front will promote moderate to locally fresh east to
northeast winds early next week. Choppy seas and life-threatening
rip currents continue today.


&&

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

The area of best convection was southwest of us overnight with more
thunderstorms throwing off a shield of high cirrus tops over us
which at times pushed through the tropopause. Thunderstorms over the
Caribbean waters south of the Dominican Republic were showing
satellite tops of less than minus 70 degrees C. Showers over the
Caribbean south of Puerto Rico did affect southeast Puerto Rico as
far west as Guanica. Parts of Salinas received as much as 2.4 inches
of rain and an urban and small stream flood advisory was issued a
little before 11 PM AST. Showers this morning were generally south
of Juncos and San Lorenzo. Also, the heavy tops of the thunderstorms
were producing light rain that moved over western Puerto Rico with a
few hundredths of an inch and over the Mona channel with 4-5 tenths
of an inch. Temperatures continue to run a few degrees above normal
with overnight lows in the range of 70 to 80 degrees in the lower
elevations and the 60s in the mid and upper elevations.

Low pressure is seen along the northern coasts of Venezuela and
Colombia while a lobe of high pressure spilled into the western
Atlantic between the two lows that have developed there: one off the
coast of Maine and one spinning north of 40 north and just a little
west of 40 west. This has caused winds to relax over the local area
while still holding a generally southeast direction. A frontal
boundary moving southeast through Hispaniola today and a shortwave
at upper levels over South Carolina moving east northeast will
generate a northeastward-moving low pressure in the lower levels
north of Puerto Rico today that will pull moist air out of the
eastern Caribbean, even though drier air is seen to hold just
northeast of the Leeward Islands. This will hold and even increase
precipitable water values to 2.1 inches this afternoon and 2.25
inches Sunday evening. With 500 mb temperatures dipping near to or
below minus 7.5 degrees C, this will keep the possibilities of
thunderstorms in the forecast at least through Monday-some off
shore, but some also over Puerto Rico. Southeast surface flow will
keep showers moving onshore over southeast Puerto Rico with only
very limited activity over the U.S. Virgin Islands. Some showers on
the north coast are also expected from streamers off of Saint Croix
and Vieques moving toward the north coast.

.LONG TERM...Tuesday trough Saturday...

From Tuesday through Saturday, Puerto Rico and the U.S. Virgin
Islands will experience a progression from wet to significantly
drier weather conditions. On Tuesday, a high-pressure system in the
mid-levels will maintain overall stable weather conditions with
drier intrusion at the upper levels and a trade wind cap inversion.
Although instability will be absent, at the surface, a northeasterly
wind flow induced by a perturbation in the central Atlantic will
bring continuous patches of tropical moisture along the CWA. This
setup will result in scattered to numerous showers across the
islands, particularly during the morning in windward areas and in
the interior and southwestern regions of Puerto Rico during the
afternoon.

By Wednesday, the tropical moisture will move out of the region,
making way for a slightly drier air mass with precipitable water
values decreasing to 1.5 inches or less. The islands will see
reduced shower activity under the influence of continued high
pressure aloft. Winds will remain light and variable from the
northeast due to a loosening pressure gradient, and weather
conditions will generally trend toward fair and stable. Thursday
will bring more of the same, as the drier air mass persists and mid-
level stability suppresses significant convective development. Any
showers will be brief and isolated, favoring coastal areas in the
early morning and interior locations during the afternoon. Winds
will continue to be light and variable, with overall calm weather
across the islands.

By Friday and Saturday, a broad surface high-pressure system
building over the central Atlantic will change the surface pattern,
pushing a much drier air mass into the region. This will further
suppress any significant shower activity, leaving the islands with
predominantly clear skies and slightly cooler temperatures,
particularly during the night and early morning. This drying trend
will mark the end of an active start to the week, providing more
tranquil weather for the weekend.


&&

.AVIATION...

(06Z TAFS)

Mainly VFR conditions are expected to prevail across all terminals
during the next 24 hours. However, SHRA/TSRA over southern PR may
cause brief tempo MVFR especially over the Cordillera Central
through 22/06Z and over ern PR from 21/15-20Z. The 21/00Z TJSJ
sounding indicated ESE winds of 10-15 knots up through FL050, but
winds above this had a westerly component. Maximum winds WSW-W 45-55
kt btwn FL420-460.


&&

.MARINE...

Choppy seas continue across the offshore Atlantic waters, and a
Small Craft Advisory (MWWSJU) is in effect though late this
afternoon for these waters. A weak surface high pressure over the
central Atlantic and an approaching front from the western
Atlantic will promote light to moderate east to southeast winds
through the rest of the weekend. Showers and isolated
thunderstorms will also contribute to worsening marine conditions
during the weekend. Moderate to fresh east to northeast winds
return early next week due to a building surface high over the
western Atlantic.


&&

.BEACH FORECAST...

Life-threatening rip currents will continue today across the
beaches from Aguadilla to Fajardo along the northern coast of
Puerto Rico, Culebra, and St. Croix. There is a High Rip Current
Risk (CFWSJU) in effect through this afternoon for these areas. A
moderate risk is expected on Sunday for most east and north facing
beaches of the islands.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
543 AM AST Sun Dec 22 2024

.SYNOPSIS...

A frontal boundary extending from the Caribbean into the Atlantic
north to northwest of the Northeast Caribbean and a pre-frontal
trough will promote unstable weather conditions through Christmas
Eve. Showers and thunderstorms will increase by this afternoon
into the evening. The front will linger near the Northeast
Caribbean through the middle of the week, promoting above-normal
surface moisture. Conditions will slowly transition to a stable
atmosphere with moisture content near to below normal for the
second part of the week, with the return of the winter tropical
temperatures. Beachgoers should be aware of the possibility of
observing rip currents along the exposed north-facing and east-
facing beaches in the Atlantic Ocean.

&&

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

A cold front with showers and thunderstorms was draped across the
Mona Channel and the northwest corner of our forecast area. A feed
of good moisture with showers and thunderstorms over the western
portion of our Caribbean waters was coming in to the boundary from
the southeast. The showers along the frontal band have faded in the
west but are still active over the outer Atlantic waters north of
Dorado. Rain and showers have spread over most of Puerto Rico from
the south and clouds over the island are overcast 080-100 hundred
feet. Temperatures have been running about 2 degrees above normal
and the low so far this morning at San Juan was 79 degrees.

Low pressure is seen along the northern coasts of Venezuela and
Colombia while a lobe of high pressure is wrapping around a low
pressure spinning north of 40 north and just a little west of 40
west. This is spilling into the eastern Caribbean Sea. Another low
northeast of Maine is pulling a frontal boundary eastward, but
currently it has gone nearly stationary and is maintaining some
thunderstorms previously mentioned in our offshore Atlantic waters.
Therefore winds are still relaxed over the local area and still
holding a generally southeast direction. High pressure will move
southeast into the western Atlantic overnight tonight and send
another cold front boundary south toward the area. Although it will
approach the area it is not expected to pass through the area in the
short-term time frame. However it will bring cooler air and hold
good moisture over the area such that showers and clouds will
continue during the period. Dry air is expected to break through
under force from another high pressure to form northeast of the area
and changes will commence on Wednesday.

.LONG TERM...Christmas Day through Sunday...

The frontal boundary will remain north of the islands as a
surface high-pressure system builds from the Western to Central
Atlantic on Christmas Day and Thursday. At the same time, a mid-
level high-pressure area will create a trade wind cap aloft,
limiting the vertical development of rain showers. However, trade
wind disturbances will consistently affect the Puerto Rico and
U.S. Virgin Islands region, leading to numerous scattered showers
on Christmas, particularly in the windward areas. Additionally,
the typical tropical winter temperatures will return from
Christmas Day onward, shifting from the northeast to north-
northeasterly winds by the weekend.

Moisture will continue to decrease from Friday into the weekend,
resulting in a mix of sunshine, clear skies, and clouds, leading
to generally pleasant weather conditions. Although we can expect
periods without rain, occasional showers may still pass through
the windward sections of Puerto Rico and the U.S. Virgin Islands.
This advective pattern will remain in place until next Sunday when
another frontal boundary could approach the region in the
following week.

&&

.AVIATION...
(06Z TAFS)

Mainly VFR conditions are expected to prevail across across all
terminals except those on the south coast of PR where lower ceilings
and VSBYs as low as 4-5 miles may be experienced through at least
22/14Z. The 22/00Z TJSJ sounding indicated ESE winds of 10-15 knots
up through FL050, but winds above this had a westerly component. The
22/00Z TJSJ sounding indicated ESE winds less than 10 kt blo FL080,
bcmg light SW 5-15 kt up thru FL180 and WSW to FL540. Maximum winds
WSW 53-63 kts Btwn FL420-470.

&&

.CLIMATE...

The presence of the cold front and the pre-frontal trough bringing a
converging mass of air over the area kept temperatures warm
overnight. A record warmest minimum occured in San Juan yesterday
with 79 degrees. The high in Saint Croix also tied the record
warmest with 88 degrees. Although slightly cooler temperatures are
expected today due to the heavier overcast. The record warm low
for the day in San Juan is 77 degrees and may be broken. The
record high in Saint Croix for today may also be broken again.

&&

.MARINE...

A cold front extending from the Caribbean and the Windward Passage
into the Atlantic and a prefrontal trough near the Mona Passage will
maintain an unstable weather pattern with light to moderate east
southeast winds today. Therefore, expect showers and scattered
thunderstorms across the regional waters. The frontal boundary will
linger north of the islands through the middle of the week. Moderate
to fresh east to northeast winds return early next week due to a
building surface high over the western Atlantic.

&&

.BEACH FORECAST...

Easterly winds at 5 to 15 knots and sea conditions across the
Atlantic Ocean are experiencing wave heights ranging from 3 to 5
feet, coming from the northeast with a wave period of
approximately 9 seconds. This situation creates a moderate risk of
rip currents along the north and east-facing beaches of Puerto
Rico and the U.S. Virgin Islands. In contrast, the risk of rip
currents is low for beaches oriented to the west and south.

The CariCOOS Ponce buoy indicates a significant wave height of 3
feet with 6 seconds, originating from the southeast. Meanwhile,
the St. John buoy has reported a significant wave height of 3 feet
from the east-southeast, with 9 seconds.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
524 AM AST Mon Dec 23 2024

.SYNOPSIS...

The remnants of a frontal boundary will continue to promote
showers and isolated thunderstorms across the region today.
A drier air mass with Saharan Air Layer will arrive on Tuesday,
leading to hazy conditions A more stable and seasonal weather
pattern is expected later this week with cooler temperatures
across the islands. Beachgoers should be aware of the possibility
of observing life- threatening rip currents along the exposed
beaches of Puerto Rico and the US Virgin Islands.

&&

.SHORT TERM...Today through Christmas Day...

A cold front with showers and thunderstorms was draped across the
northeast corner of the forecast area with little movement. A feed
of good moisture with showers and thunderstorms over the western
portion of our Caribbean waters was coming in to the boundary from
the southeast. The showers along the frontal band are still active
over the outer Atlantic waters, but the U.S. Virgin Islands are
feeling the proximity of the drier air to the east. Rain and showers
drew close to the north shores of Puerto Rico owing to a shift in
the winds to the east northeast, but only a few showers with minimal
accumulations made it on to the southeast coast. Minimum
temperatures remain above normal tonight as well and more records
may fall. Low temperatures ranged from the mid 60s to around 80
degrees.

Low pressure is seen along the northern coasts of Colombia. High
pressure over the northeast Atlantic has become much stronger but is
just able to make it into the northeastern Caribbean Sea due to the
frontal system holding its own northeast of Puerto Rico. Because the
front is so close to the area, winds continue to be fairly relaxed
over the area and flow has been less than 10 knots at most stations
overnight with land breezes dominating. Winds are expected to become
stronger from the east during the day today and continue through
Wednesday. Since we are still on the warm and moist side of the
front we expect thunderstorms to continue today through Wednesday.
Some rainfall amounts could also become heavy in the west and west
southwest. A second front behind the current one will push the
boundary further south and cut off the drier air that has been
trying to intrude from the east. By Wednesday some cooler air and
will be able to infiltrate the area and some drier air will be able
to mix through allowing the shower and thunderstorm activity to
abate somewhat.


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

Overall stable and relatively drier conditions are anticipated
during the long-term period. A frontal boundary will continue to
linger north of the region as a strong surface high pressure builds
in the western Atlantic. In the mid-levels, stability aloft will
help to suppress any significant convective development across
the islands. Under this pattern and trade wind perturbations, the
development of isolated to scattered showers is possible during
the morning hours across eastern Puerto Rico and the U.S. Virgin
Islands. The interior, western and southwestern Puerto Rico may
observe numerous to scattered showers in the afternoon hours. As
the surface high pressure migrates from the western to central
Atlantic, winds will persist from the northeast to north
northeast. Therefore, tropical winter temperatures will return
into the region and lasting until the weekend. A drying trend with
limited shower activity is expected for early next week,
promoting cooler temperatures, especially over the municipalities
along the Cordillera Central in the early morning hours.

&&

.AVIATION...
(06Z TAFS)

Mainly VFR cond.s are expected to prevail across across all
terminals. However, dvlpg SHRA and TSRA are expected aft 23/16Z in
southwestern and interior PR brief MVFR conds and mtn obscurations
are expected there. Winds will be E 10-15 kt with sea breeze
influences that will boost some winds to 15-20 kts and some hir
gusts. Max winds are WSW 57-67 kts btwn FL390-460.

&&

.MARINE...

East light to moderate winds will prevail today across the region.
Then, a building surface high pressure over the Western Atlantic will
gradually yield moderate to fresh east to northeast winds from
tonight onwards, creating choppy conditions for small craft. In the
meantime, the remnants of an old frontal boundary north of the local
islands, will continue to generate scattered showers and isolated
thunderstorm across the regional waters.

&&

.BEACH FORECAST...

A moderate risk of rip currents will continue along the north and
east-facing beaches of Puerto Rico, Culebra, and Saint Croix
through Tuesday. For the rest of the area, the risk of rip
currents remains low.

&&

.CLIMATE...

Warm water, and being on the warm side of the front has kept low
temperatures up across all three ASOS stations in the area. Both San
Juan and Saint Thomas broke their warm minimum records and Saint
Croix tied it yesterday. It will be closer today as to whether they
can do it again.