Caribbean - Central America Weather

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
335 AM AST Sat Sep 24 2022

.SYNOPSIS...
Peripheral moisture from Tropical Storm Ian will continue to
affect the region early today. Drier air will gradually filter in
later in the day. Conditions will be more favorable for shower and
thunderstorms development Monday onward.

&&

.SHORT TERM...Today through MONDAY...
Mid to upper level ridge will linger across the region through
early sunday , then erode and be Replaced late Sunday through
Monday, as a TUTT low will approach from the east and settle north
of puerto rico by Monday. Peripheral trailing moisture from
Tropical Storm IAN now located well south of Hispaniola over the
central Caribbean, will continue to affect the region during the
rest of the early morning hours, bringing showers and isolated
thunderstorms mainly over the Caribbean waters and the Mona
passage. Expect a gradually drier weather pattern during the late
morning and early afternoon as a slot of drier and more stable air
mass will filter in across the region during the afternoon into
Sunday. However, as winds increase and become more east northeast
during today, expect local and diurnally induced afternoon
convection to develop mainly over parts of the interior and west
to southwest sections of Puerto Rico. Afternoon showers around the
USVI will be mainly downwind and on the west-end of the islands
but no significant rains are anticipated. Some of the afternoon
showers and thunderstorms over Puerto Rico may lead to ponding
water on roads and in poor drainage areas and minor urban and
small stream flooding in isolated areas, at least until sunset.
Drier conditions expected for Sunday, however the proximity of the
upper TUTT will favor some enhanced afternoon convection mainly
over parts of the central interior and west sections of Puerto
Rico. Again urban and small stream flooding in isolated areas will
be possible as well as minor ponding of water on roads and in
poor drainage areas, especially as soil remains loose and
saturated in many area due to recent rains. On Monday expect
increasing low level moisture and instability aloft as the tutt
low is to linger overhead and an induced trough is forecast to
cross the region. This will favor better chance for increased
early morning trade wind showers and possible isolated
thunderstorms over the coastal waters, followed by afternoon
convection over the interior and west to northwest sections of
Puerto Rico as well as around the San Juan metro. Urban And small
stream flooding again be possible with the afternoon convection
especially over the west interior.

&&

..Long term...Tuesday through Sunday...
On Tuesday, the upper level low continues to move southward, while a
broader mid to upper level low approaches from the northeast. These
series of lows will maintain instability aloft, with cooler
temperatures at the mid levels. At the surface, induced surface
perturbations carried by the trade winds will move infrequently
across the islands, increasing low level moisture. As is usual with
this kind of pattern, passing showers will move across eastern
Puerto Rico and the United States Virgin Islands throughout the day,
followed by active afternoon across the interior and western Puerto
Rico. For the upcoming weekend, the GFS has a surface low developing
across the Caribbean Sea. This feature could further increase the
columnar moisture across the islands. Additionally, with the upper
level low just east of the islands, wet conditions could prevail for
these days, increasing the risk for flooding.

&&

.AVIATION...VFR conditions at all terminals durg prd. However,
SHRA/Isold TSRA will cont ovr the Caribbean waters and Mona passage
with some shra ovr Ern PR. This may cause brief MVFR conds en route
btw islands and VCSH at TJSJ/TJPS til 24/14Z. Elsewhere mstly SCT
lyrs nr FL025...FL050. Btw 24/18z-24/22z, SHRA/Isold TSRA may
develop VCTY TJBQ, which may cause MVFR/brief IFR conds. L/LVL
wnds fm E-NE 10-15 KTS blo FL150. SFC wnds lgt/vrb to calm.

&&

.MARINE...
Seas will continue to gradually diminish across the Mona Passage
as Tropical Storm Ian continues to move away from the region.
Then, a surface high pressure over the central Atlantic will
maintain the trade winds out of the east at 10 to 15 knots. Seas
up to 5 feet will prevail for the next several days. For the
beaches, the risk of rip currents will be moderate.


&&

.SJU WATCHES/WARNINGS/ADVISORIES...

PR...None.
VI...None.

$$

SHORT TERM...RAM
LONG TERM....ERG

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
328 AM AST Sun Sep 25 2022

.SYNOPSIS...
Instability will gradually increase this week, with a higher
chance of shower and thunderstorm formation each afternoon. Urban
and small stream flooding will remain a concern each day,
especially along the interior and western municipalities of Puerto
Rico.

&&

.SHORT TERM...Today through Tuesday... A gradually eroding mid to
upper level ridge aloft will be replaced by a TUTT low which will
relocate just north of the region today, then further strengthen and
linger across the northeastern Caribbean through Tuesday. This will
favor increasing instability aloft on Monday and Tuesday. A surface
high pressure ridge will build and spread westwards across the
western and southwest Atlantic during the period, to maintain a
moderate east southeast wind flow across the area. A broad weakly
induced surface trough is forecast to cross the region later tonight
through Tuesday, bringing a slight increase in tropical moisture and
low level convergence.

For today although an overall drier pattern is expected, a few
passing showers will continue to affect the coastal waters the
rest of the early morning. This will be followed by a seasonal
weather pattern with isolated to scattered shower development
mainly over parts of the interior and west sections Puerto Rico.
Ponding of water on roads and minor, urban an small stream
flooding will remain possible with the heaviest rains in west PR.
Elsewhere mostly fair weather skies is forecast with only few
shower expected to develop in and around the U.S. Virgin islands
and adjacent islands. However, most of the showers if any should
be mainly on the west-end or just downwind of the islands.

For Monday and Tuesday, the instability aloft caused by the
repositioning of the TUTT, along with increasing moisture
convergence created by the surface trough, will all favor a better
chance for increasing frequency of passing morning showers, followed
by some enhanced afternoon convection in and around the islands
especially over parts of the interior and west sections of Puerto
Rico including the San Juan Metro, where urban and small stream
flooding will again be likely as well as ponding of water on roads
in poor drainage area with the heaviest rains.

&&

.LONG TERM...Wednesday through Monday...
Another upper level low will detach from a wide Tropical Upper
Tropospheric Trough localed over the central Atlantic, and then the
low will approach to the northeastern Caribbean on Wednesday. At the
surface, patches of moisture induced by the upper level system will
continued to be dragged by the trade winds, increasing low level
moisture. As a result, with the upper level support and the low
level moisture, active afternoon are expected across the area, with
advective showers moving across eastern Puerto Rico and the United
States Virgin Islands during the day, and afternoon convection
developing across the interior and western Puerto Rico. The islands
will be under the influence of the upper level trough through
Friday. Then, on Saturday, a mid level ridge tries to build in north
of the region. At the same time, moisture will be pulled out from
the ITCZ (Intertropical Convergence Zone) across the northeastern
Caribbean. With this deep-layered moisture, the wetter pattern
will be stretching into the upcoming weekend, with an elevated
risk of flooding, water surges along rivers and mudslides in areas
of steep terrain.


&&

.AVIATION...VFR conds at all terminals durg prd. VCSH possible
TJSJ/TIST/TISX with -SHRA psbl til 25/14Z and brief Mtn top obscr
ovr Ern PR. Mstly SCT lyrs nr FL025...FL050. SFC wnds light and vrbl
to calm bcmg fm E 10-15 kts with some sea breeze variations
developing along with ocnly hir gusts. VCTS psbl just S of TJBQ in
the vcnty of TJMZ aft 25/17Z due to isold TSRA across west interior
sections of PR.


&&

.MARINE...
No changes were made to the marine forecast. Seas will remain at
five feet or less with winds out of the east at 10 to 15 knots.
There is a moderate rip current risk for the local beaches.


&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...None.
VI...None.

&&

$$

SHORT TERM...RAM
LONG TERM....ERG

[cycloneye]

Area Forecast Discussion National Weather Service San Juan PR 507 AM
AST Mon Sep 26 2022

.SYNOPSIS...A seasonal pattern will continue across the region
through Tuesday with occasional periods of passing low clouds and
trade wind showers enhanced by the presence of a Tropical upper
tropospheric trough (Tutt) low, as they move westward across the
forecast area.
Surface high pressure spread across the north central Atlantic and a
broad equatorial trough over the central and eastern Caribbean, will
maintain an east southeast wind flow. The meandering TUTT low will
become amplified and extend southwards across the region then into
the eastern Caribbean by the end of the week. This will maintain
unstable conditions aloft to support daily convection. Increasing
tropical moisture convergence and unstable conditions aloft is
forecast through most of the week due to the moist southeasterly
wind flow and the strengthening of the TUTT low as it crosses the
region.

&&

.SHORT TERM...Today through Wednesday...
The short term period will be dominated by a series of upper level
TUTT lows approaching from the northeast, increasing instability
aloft. The first, weaker low, will be positioned over the islands
today, while a stronger low will arrive by Wednesday and become
amplified across the region. At the surface, patches of moisture
induced from this lows will be carried by the trade winds at times.
Additionally, moisture from the ITCZ (Intertropical Convergence
Zone) will be lifted across the northeastern Caribbean late tonight
and tomorrow. In general, the pattern will favor advective showers
advancing across eastern Puerto Rico and the United States Virgin
Islands at times. Then, in the afternoons, local effects will
trigger showers and thunderstorms along the interior and western
Puerto Rico.
The activity should be strong enough to create minor flooding, and
water surges along rivers and small streams. Thunderstorm activity
could result in frequent lightning and gusty winds, so people are
advised to seek shelter if they hear thunder. Although everyday is
expected to have active afternoons, dynamics at all levels look
better on Wednesday, so convective activity could be stronger this
day.

&&

.LONG TERM...Thursday through Tuesday...
The Tutt low is still forecast to strengthen and become detached
from the amplifying upper trough which will linger over the region
and extend into the eastern Caribbean during beginning of the period.
At the surface, tropical moisture will gradually increase under a
moist southeasterly wind flow which will continue across the area,
as a broad induced surface trough lifts northwards. This pooling of
moisture and low level convergence along with the unstable
conditions aloft and good daytime heating, will support daily
convection and good chance for afternoon showers and isolated
thunderstorms each day, with advective showers moving across eastern
Puerto Rico and the U.S. Virgin Islands each morning. This will be
followed by afternoon enhanced convection mainly across the interior
and western Puerto Rico. This pattern and influence of the TUTT will
continue through Friday and into the weekend. By Saturday, a mid to
upper level ridge is forecast to build across the region and
gradually stabilize the upper levels. However by then a dominant
moist and humid southerly flow is forecast to continue as good ITCZ
(Intertropical Convergence Zone) moisture will be pulled up across
northeastern Caribbean. With this deep- layered moisture, a much
wetter pattern is expected especially Saturday into early Sunday.
Therefore active weather conditions are forecast for the upcoming
weekend with layered precipitable water values to exceed 2.00
inches. That said expect a very wet pattern with elevated risk of
flooding expected to continue especially over Puerto Rico, where
soil conditions remain saturated in many areas.
By Monday and Tuesday a gradual drying trend is expected as low
level moisture advection will erode, in response high pressure ridge
building aloft and winds becoming more easterly once again as the
surface high pressure builds north of the region. Hot and humid
conditions will also lead to slightly above normal daytime high
temperatures and relative humidities.

&&

.AVIATION...
VFR conditions expected to prevail across the forecast period. SHRA
will be moving across USVI and TJSJ terminals, but without significant
operational impacts. VCTS are expected after 17Z for TJBQ, with periods
of reduced VIS and low ceilings. Mountain obscuration is expected
for the Cordillera Central between 17 and 22Z as well. Winds will
be out of the NE at around 15 knots with strong gusts and sea breeze
variations.

&&

.MARINE...
Mariners can expect seas up to 5 feet across the offshore waters and
local passages and 4 feet or less across rest of the coastal areas.
Winds will be from the east increasing to up to 20 knots during the
afternoon hours, creating choppy conditions where small craft operators
should exercise caution. Afternoon convection may result in isolated
thunderstorms mainly over the coastal waters of western Puerto Rico
and downwind from the Virgin Islands.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...None.
VI...None.
&&

$$

SHORT TERM...ERG
LONG TERM....RAM
AVIATION...ERG

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
448 AM AST Wed Sep 28 2022

.SYNOPSIS...
An elongated Tropical Upper Tropospheric Trough (TUTT)and a
series of low pressure centers will continue to move over the region
during the next few days enhancing passing morning showers and afternoon
convective development. Seas will gradually improve across the regional
waters but a slight wind chop expected to continue. An overall moist
and unstable weather pattern is forecast for most of the period as moisture
from the ITCZ (Intertropical Convergence Zone) will be lifted northwards
over the northeastern Caribbean. The greatest local impacts will be
the risk of isolated thunderstorms with excessive rainfall mainly across
central to western Puerto Rico during afternoon hours and a moderate
risk of rip currents for the northern and some eastern coastlines of
Puerto Rico and the USVI.Maximum heat indices between 102-105 degrees
will be possible across the north central and northwest municipalities.

&&

.SHORT TERM...Today through Friday...
A broad surface high pressure over the central Atlantic is maintaining
east-northeast moderate trade winds. Satellite imagery shows patches
of moisture being advected into sections of eastern Puerto Rico and
the United States Virgin Islands, with light to moderate accumulation
registered. This pattern will prevail early in the morning hours,
so drivers may find wet roads in their way to work or school. The
big picture remains unchanged from previous discussions. A Tropical
Upper Tropospheric Trough will approach from the northeast, increasing
instability aloft today through Friday. At the lower levels, induced
patches of moisture are being dragged by the trade winds through
the area. During the afternoon hours, when the instability provided
by the trough combines with the available moisture and local effects,
showers and thunderstorms are expected to develop along the interior
and western Puerto Rico, and also downwind from El Yunque into the
San Juan metro area. Showers could be heavy at times, with flooding,
river rises and mudslides possible. The thunderstorms could be strong
as well, with periods of frequent lightning and gusty winds.

By Thursday and Friday, while the TUTT lingers, moisture will
increase as the Intertropical Convergence Zone (ITCZ) lifts into the
northeastern Caribbean Sea. The steering flow will relax as well,
coming out of the southeast on Thursday and out of the south on
Friday at around 8 knots. Again, the environment favors active
afternoon along the Cordillera Central, and the northern and western
half of Puerto Rico. The south sections of Puerto Rico, as well as
the U.S. Virgin Islands will also experience a wetter pattern, as
showers and thunderstorms develop over the Caribbean Sea and move
inland. The users are advised to pay attention at the evolution of
the forecast and any further updates issued by this Weather Forecast
Office.

&&

.LONG TERM...Saturday through Thursday...
The deepening Tutt low is forecast to become cutoff from the
amplified trough by Saturday, but will linger just west of Puerto
Rico and extend into the eastern Caribbean through early Sunday.
Thereafter it is to fill/weaken and will be replaced by a mid to
upper level ridge which will hold across the area through Wednesday.
Meanwhile another Tutt low will retrograde to just northeast of
the region for the rest of the period, to maintain overall unstable
conditions. Deep layered tropical moisture will continue to be steadily
lifted across the region under a dominant south- southeasterly wind
flow, which will persist through Sunday as a broad induced surface
trough lifts northwards. This pooling of moisture and low level
convergence along with the unstable conditions aloft and good
daytime heating, will favor convective activity each day with high
potential for enhanced shower and isolated thunderstorm development
during the early morning over the coastal waters and mainly across
the interior, northern and western section of Puerto Rico during
the afternoon hours.

This overall synoptic pattern influenced by the proximity of the
TUTT and the broad southerly windflow disrupted by the distant major
hurricane Ian, will continue most of the weekend. A more seasonal
pattern is expected to return by late Sunday, when surface high
pressure is forecast to build north of the area and surface winds
increase and become more easterly. Recent model guidance remains
persistent in suggesting a prevailing moist and humid southerly
flow. With this deep- layered moisture, an overall wet and unstable
pattern can be expected through Sunday with layered precipitable
water values exceeding two inches. Recent model guidance however now
suggest active weather conditions for most of the period with moderate
to high potential for showers and isolated thunderstorm activity each
day, especially over Puerto Rico where daytime heating and local forcing
will be more impactful. That said elevated risk of flooding will continue
for much of the region especially over Puerto Rico, where soil conditions
remain saturated in many areas. For the U.S. Virgin Islands some urban
and small creek/gut flooding may be possible but so far only isolated
areas. By late Wednesday into Thursday, another Tutt induced surface
trough is forecast to cross the region followed by a tropical wave.
Hot and humid conditions will bring slightly above normal daytime high
temperatures and relative humidities through the upcoming weekend.

&&

.AVIATION...
Mainly VFR conditions expected to prevail, but SHRA will move through
the period across USVI and TJSJ terminals. After 17Z, VCTS are expected
for TJBQ, with possible periods of reduced VIS and low ceilings. Mountain
obscuration along the Cordillera Central is also expected, especially
for the western half of Puerto Rico. FL050 winds will be out of the
ENE at around 12-16 knots.

&&

.MARINE...
Seas will be generally up to 5 feet over the offshore Atlantic
waters and local passages and 4 feet or less elsewhere. Winds will
be generally from the east 10 to 15 knots with occasionally higher
gusts. These is a moderate risk of rip currents for the northwest
to northeast facing beaches of Puerto Rico, Vieques and all beaches
of Culebra. Moderate risk for St Croix, Vieques, and some of the
north and eastern beaches of the U.S. Virgin islands.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...None.
VI...None.
&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
509 AM AST Thu Sep 29 2022

.SYNOPSIS...

A strong TUTT and deep-layered moisture will maintain a wet
unstable weather pattern across the local islands through at
least Sunday. A more seasonal pattern is expected to return by
early next week, when surface high pressure is forecast to build
north of the area and surface winds increase and become more
easterly.

&&

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

A Tropical Upper Tropospheric Trough (TUTT) northeast of Puerto Rico
extends across Puerto Rico and into the Caribbean sea and is causing
unstable weather and scattered thunderstorms across the local
waters. The TUTT will move to the Dominican Republic late Friday
night, but areas of divergence aloft will continue to affect the
area. Showers will begin to develop over land during the morning
heating each day. A trough over the southeastern Caribbean at lower
levels will begin to turn winds southeasterly and is loaded with
moisture that will bring the fuel necessary to keep showers and
thunderstorms active over the area through at least Saturday when
the trough passes through the forecast area. Some areas in the
northwest, interior and downstream from El Yunque will have very
heavy rainfall that will produce urban and small stream flooding
each day. Showers and thunderstorms are likely to be active during
most of the period including the overnight hours. With soils still
saturated from recent rains, some mud or debris slides remain
possible in steep terrain.



&&

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

Southerly induced winds due to Hurricane Ian's northward path will
continue to affect the local islands on Sunday. Therefore, deep-
layered moisture advected from the south in combination with lasting
instability aloft will support wet and unstable weather
conditions throughout the day. Increased areal coverage of showers
with isolated thunderstorms can be expected to develop across the
local waters and over portions of the islands on Sunday,
especially during the day with diurnal convection favoring along
interior and northern slopes of Puerto Rico. This activity will
continue on Sunday night and extend to early Monday. Therefore,
the flood threat will remain elevated on Sunday and Sunday night
with a flooding potential across urban, roads and small streams.
Localized flash flooding cannot be ruled out.

According to model guidance, this pattern will gradually diminish
by early next week as winds shift out of the east by late Monday
into Tuesday. Although instability aloft may decrease slightly due
to a building ridge aloft, enough low-level moisture along with
surface heating and local effects will be sufficient for afternoon
convective development. Therefore, expect showers and isolated
thunderstorms across interior and western portions of Puerto Rico
each afternoon along with showers across windward coastal areas
of the local islands during night and morning hours. Flooding
threat for Monday through mid week will be limited with the
potential of ponding of water in roads and poorly drained areas.
Localized urban and small stream flooding can be expected at times.
Both GFS and ECMWF models suggest the arrival of a vigorous
tropical wave by the end of next week. The eventual path and
strength of this tropical wave will determine how significant the
impacts will be and which locations will affect the most.
Therefore, please continue to monitor the latest forecasts as more
details emerge as we get closer to the forecast period.

&&

.AVIATION...
(06Z TAFS)

SHRA with lcl MVFR and mtn obscurations are occurring in
far ern PR and arnd Vieques and Culebra and the USVI. These will
cont thru at least 30/02Z. SHRA will sprd west across PR and TSRA
will dvlp fm 29/15Z to 29/18Z causing areas of MVFR conds and mtn
obscurations that will last thru arnd 29/23Z. Sfc winds E-ESE 6-12
kt with gusts to 25 kt psbl arnd TSRA. Max winds W-NW 25-40 kt btwn
FL240-420.

&&

.MARINE...

Gentle to moderate winds with seas at 5 feet or below will persist
through much of the forecast period. There is a moderate rip current
risk for the beaches along the north coast of Puerto Rico and
Culebra.


&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...None.
VI...None.
&&

$$

SHORT TERM...WS
LONG TERM....CVB
AVIATION...WS

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
507 AM AST Fri Sep 30 2022


.SYNOPSIS...

A Tropical Upper Tropospheric Trough (TUTT) and high moisture
content will continue to promote active weather through the
weekend. Given the expected conditions, elevated flooding threat
will persist each day.

&&

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

A Tropical Upper Tropospheric Trough (TUTT) now over the Mona
Channel and south of the Dominican Republic is having the greatest
influence over the local weather. A southerly jet around the
eastern side of the TUTT is now over Puerto Rico and will cause
considerable divergence over the island today. Although moisture has
been good, satellite imagery and latest model results suggest that
moisture will lessen today as a dry slot associated with the TUTT
moves across Puerto Rico at mid levels. This will limit the amount
of convection to some degree, but may also cause warmer temperatures
along the northern coast of Puerto Rico and more intense
thunderstorms shortly thereafter. Therefore have kept POPs high, but
the heaviest rainfall may be more spotty.

Southerly flow is expected to continue across the forecast area and
the trough at lower levels moving north out of the southeast
Caribbean now appears to move east of the area with the best
moisture Friday and Friday night. However a tail develops south and
southwest of the lower level trough that will pull more abundant
moisture into the U.S. Virgin Islands and Puerto Rico Saturday and
Sunday as the TUTT continues to drift west and stretch north.
Expecting better rainfall on Saturday and Sunday, with a renewed
possibility of localized flash flooding and ample urban and small
stream flooding across the area.


&&

.LONG TERM...Monday through Saturday

Monday now looks to be pulling the wet pattern from the weekend with
available moisture content remaining above the climatological
normal across the northeastern Caribbean. However, by this time,
winds would have be shifted more east southeast as the
southwestern edge of a surface high pressure over central Atlantic
dominates the region. Instability aloft will be fairly normal as
a weak ridge at upper levels meanders over the northern Caribbean.
Nevertheless, model guidance suggests an induced surface
perturbation from a retrograding Tropical Upper Tropospheric
Trough (TUTT) northeast of the local area reaching the local
islands on Monday, being dragged by the southeasterly trades. This
perturbation will enhance low-level convergence and enough
forcing to promote shower and thunderstorm activity. Both GFS and
ECMWF Galvez-Davison Index show fairly high values throughout the
day indicating an elevated potential for deep convective activity
across the region. Therefore, expect the weekend trend to continue
on Monday with elevated flooding threat across the local islands,
especially over interior and western/northwestern Puerto Rico in
the afternoon. Showers and isolated thunderstorms are also
possible in and around the San Juan Metropolitan area as
convection develops downwind of El Yunque. Model soundings suggest
slow steering winds which will enhance the residence time of
showers in some locations. Urban and small stream flooding can be
expected with this weather pattern. Flash flood incidences cannot
be ruled out.

Afterwards, model solutions diverge as GFS maintains wetter
conditions through at least Wednesday with ECMWF showing rapid
moisture erosion instead. Even wider discrepancies exist as we go
further into the week. The aforementioned retrograding TUTT will
continue to slowly approach the local area. But as it do so, it
will invigorate a weak tropical wave/ITCZ perturbation. ECMWF has
this perturbation moving faster, but weaker, reaching the area by
Thursday. GFS, on the other hand, develops this perturbation at a
slower pace reaching the northeastern Caribbean by the weekend.
Other deterministic global models are not too eager in developing
this feature either, aligning closer to the ECMWF solution. Even
very few GFS ensemble members have this perturbation developing
into a tropical system. Therefore, models are not very supportive
of this scenario, but high uncertainty still persists regarding
weather conditions for the latter part of the long-term forecast
period. In the mean time, continue to monitor our latest forecasts
and also the National Hurricane Center for any region of
interest across the tropical Atlantic.

&&

.AVIATION...
(06Z TAFS)

Unusual LLVL flow from SSE at around 10 knots today.
SHRA will dvlp by 30/15Z and sprd MVFR/IFR conds and mtn
obscurations across PR. TSRA expected aft 30/1630Z--mainly N of the
Cordillera Central TSRA to last byd 30/02Z ovr the lcl waters. Max
winds S 35-50 kts btwn FL330-440.

&&

.MARINE...

Marine conditions will continue at 4 feet or less in the Caribbean
Sea and passages and between 3 and 5 feet in the Atlantic waters.
However, localized marine conditions can turn hazardous at times
due to thunderstorm development across the local waters.

Beachgoers, there is a moderate rip current risk for the beaches
along the north and northeastern coast of Puerto Rico and Culebra
and St Croix.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
516 AM AST Sat Oct 1 2022


.SYNOPSIS...

Wet unstable weather pattern will persist across the local
islands through at least early next week. Given the expected conditions,
elevated flooding threat will persist each day. Marine conditions
continue fairly tranquil.

&&

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

Tropical Upper Tropospheric Troughs (TUTTs) that are now just south
of Haiti and 1000 miles northeast of Saint John are having the
greatest influence over the local weather. A southerly jet around
the eastern side of the Haiti TUTT is now over the Mona Channel and
will cause pockets of strong divergence over and around western
Puerto Rico. Although moisture has been good precipitable water
values will increase slowly through Sunday afternoon to reach 2.25
inches. This should bring better shower coverage--especially since
mid level moisture has also recovered from yesterday. Rainfall
amounts could be a little heavier and southerly flow should hold
temperatures near or a degree warmer than yesterday's maximum
values.

Southerly flow is expected to continue across the forecast area
until around 01/21Z and then become southeasterly through Monday.
Moisture at 850 mb drops somewhat during the evening around 02/00Z
and shower activity should subside for a short while. Some recovery
is expected overnight tonight and scattered showers over southeast
Puerto Rico and around the U.S. Virgin Islands will return. The GFS
does not see the convergence zone south of Puerto Rico across 15.5
degrees north latitude, but instead favors a convergence band
northeast of the forecast area that leads back to extra tropical
storm Ian, hence there is great uncertainty regarding the timing of
the moisture/rainfall during the period. The previous forecast runs
seemed to have a better handle on this, but the entire period will
have good moisture and general instability that will allow showers
and thunderstorms to continue on and off through the period.


&&

.LONG TERM...Tuesday through Sunday

GFS continues to show a much wetter long-term forecast compared to
the ECMWF. However, both show the proximity of a retrograding
Tropical Upper Tropospheric Trough (TUTT) first located northeast
of the forecast area at the beginning of the week but with
different outcomes as the week advances into the weekend. First,
GFS shows the retrograding TUTT and surface induced trough
interacting with above normal columnar moisture maintaining a
fairly wet and unstable Tuesday into early Wednesday. ECMWF shows
a similar pattern but with a much faster drying set up by mid-
week. Although both models show a similar initial set up, the
timing of moisture erosion will determine the duration of unstable
weather conditions. Nevertheless, you can expect a continuation
of active weather from the weekend on Tuesday with elevated flood
potential, especially over eastern Puerto Rico, Vieques, Culebra
and the U.S. Virgin Islands during morning hours. Later, showers
and isolated thunderstorms will develop over the Cordillera
Central and western/northwestern Puerto Rico in the afternoon, as
surface heating ad local effects enhances convection in these
parts maintaining an elevated flooding threat. By midweek, both
models suggests a drying trend, although the proximity of the TUTT
could aid in afternoon convection but more localized than in
previous days.

By the end of the week, both models show different scenarios,
especially regarding the movement of the retrograding TUTT and also
the eventual evolution of a tropical wave now currently located
close to 40W. ECMWF does not do much with the TUTT maintaining it
northeast of the area with the tropical wave passing mostly south
of the local islands by the weekend. The proximity of the TUTT
could aid in deep convective activity across the area, but nothing
widespread. GFS, on the other hand, shows a very fruitful
interaction between the TUTT and tropical wave. Moreover, the TUTT
crosses the area bringing cold air advection aloft with 500 mb
temperatures dropping between -9 to -8 C by late Friday into the
weekend. This will promote steep lapse rates throughout the latter
part of the forecast period. GFS has backed off on tropical
development for this tropical wave, but passes over Puerto Rico
and U.S. Virgin Islands as a vigorous one. This scenario would
promote widespread heavy rain producing thunderstorms over the
weekend. Given the discrepancies between model guidances, forecast
confidence regarding specific impacts related to the weather
pattern for next weekend continues to be low as trough placement
and moisture availability continues to change between model
cycles. Please continue to monitor our forecast as we follow the
evolution of this event.

&&

.AVIATION...
(06Z TAFS)

.AVIATION...LLVL flow from SE at around 10 knots today. Isold SHRA
ovr south central PR will dvlp and bcm SCT by 01/15Z and sprd
MVFR/IFR conds and mtn obscurations across PR. TSRA expected aft
01/1630Z--mainly N of the Cordillera Central. TSRA to last byd
01/22Z ovr the lcl waters. Max winds SSW 35-45 kts btwn FL420-480
and arnd 36 knots btwn FL310-360.

&&

.MARINE...

Marine conditions will continue at 4 feet or less across the local
waters. However, seas can turn hazardous at times as scattered to
locally numerous showers and isolated thunderstorms across the
regional waters will persist through the weekend.

Beachgoers, there is a moderate rip current risk for the beaches
along the north coast of Puerto Rico, Culebra and St Croix.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
521 AM AST Sun Oct 2 2022


.SYNOPSIS...

Unsettled weather conditions will prevail across the islands,
increasing the potential for showers and thunderstorms each day. A
drying trend can be expected by the end of the workweek. Seas
will remain below 5 feet for the next several days.


&&

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

High pressure at upper levels north of Puerto Rico has pushed the
Tropical Upper Tropospheric Trough (TUTT) to the west to the
Windward Passage and greatly squeezed it in a east-west direction.
The TUTT to the northeast, however is following the high and is now
only about 900 miles east northeast of San Juan, Puerto Rico. The
TUTT will continue to travel westward and will be about 600 miles
northeast of Saint Croix by Tuesday night. It will not be close
enough to have very much influence, however. The main influence will
be the mid and upper level high pressure north of the forecast area.
A surface high in the central Atlantic is ridging into the area and
there is also a 700 mb high approaching the area and some moisture
is wrapping around it. The next main feature will be a tropical wave
that will enter the forecast area early Tuesday morning and cross
the area during following 24 hours.

Low level flow is southeast, but will turn briefly easterly early
tonight before returning to southeast Monday afternoon. This will
also coincide with a minor dip below 2 inches of the precipitable
water. Otherwise precipitable water values will remain above 2
inches throughout the period and conditions will remain generally
unstable. Urban and small stream flooding are expected each day,
although the focus will be mostly in western Puerto Rico on Monday.

Due to southerly flow and a little more sunshine today, warmer
temperatures are expected on the northern coast today and a heat
advisory has been issued for heat indices there pushing up to 108 to
111 degrees.


&&

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

On Wednesday, near normal to above normal moisture content will
still be present across the CWA. The proximity of another
retrograding Tropical Upper Tropospheric Trough (TUTT) northeast
of the local islands could interact with moisture availability to
support wet and unstable weather conditions. Activity is not
expected to be widespread, but could promote moderate to heavy
rain in localized areas with the heaviest convection. Vieques,
Culebra and the northern U.S. Virgin Islands could observe strong
showers and thunderstorms developing over the local waters by
being closer to the TUTT, with some moving offshore at times,
mostly during early morning hours. Under an east southeast wind
flow, the northwest quadrant of Puerto Rico would be the most
affected in the afternoon as surface heating and local effects
would enhance low-level convergence in that region. A fairly quick
steering wind flow, as indicated by model soundings, could aid in
streamers developing downwind of the smaller islands and from
central mountainous region such as El Yunque, possibly affecting
the San Juan Metropolitan area. This will result in some regions
experiencing ponding of water in roadways and in poorly drained
areas with the possibility of localized urban and small stream
flooding.

Both GFS and ECMWF are now more aligned in presenting a slightly
drying trend by Thursday and Friday. However, the TUTT will
continue to move closer to the northeastern Caribbean during this
time frame which could enhance bursts of convective activity at
times, especially each afternoon across western portions of Puerto
Rico. Latest ECMWF model solution also trended towards GFS with
the TUTT crossing the local islands through the weekend. This will
enhance cold air advection at mid-levels with weather conditions
aloft becoming more conducive for deep convective development.
Both models show the tropical wave, currently close to 45W,
interacting with the TUTT, but now with a delayed arrival time
into the region. Therefore, high uncertainty still persists for
the latter part of the long-term forecast. Nevertheless, it seems
that a very moist and unstable weather environment across the
forecast area could unfold by next weekend into early next week
elevating the potential for widespread convection and heavy
rainfall.

&&

.AVIATION...
(06Z TAFS)

LLVL flow from SE at arnd 10 knots today, bcmg by 02/22Z
ESE less than 10 kt. Areas of RA across srn PR with TSRA E of TJPS.
Mtn obscurations and MVFR conds. Aft 02/16Z sct SHRA/TSRA to dvlp
across the rest of PR with isold SHRA arnd the USVI. TSRA to last
byd 02/22Z ovr the lcl waters. Max winds SE-SW less than 25 kt BLO
FL540.

&&

.MARINE...Gentle to moderate winds will continue, with seas at 5
feet or less for the next few days. For the beaches, there is a
moderate rip current risk for the northern beaches of Puerto Rico.
Elsewhere, a low rip current risk can be expected.


&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...Heat Advisory from 11 AM this morning to 4 PM AST this afternoon
for PRZ001-005-008.

VI...None.
&&

$$

SHORT TERM...WS
LONG TERM....CVB
PUBLIC...ICP

[cycloneye]

FXCA62 TJSJ 030824
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
424 AM AST Mon Oct 3 2022


.SYNOPSIS...Unsettled weather conditions will continue throughout
the local area with very active afternoons accompanied by heavy
rainfall and thunderstorm. A tropical wave will cross the region
by Tuesday promoting unstable weather conditions. A slight patch
of drier air will arrive to the islands on Thursday, but then
after a wetter weather pattern will return.

&&

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

A TUTT-low will remain northeast of the region while a weak mid-to-
upper-level ridge builds over and west of the area through the short
term period. At the surface, a high pressure over the central
Atlantic will continue to promote light southeasterly trades today,
increasing between 10-15 kt and more easterly on Tuesday and
Wednesday. PWAT content is expected to remain at or above normal
values during the next few days. This available moisture will
combine with daytime heating and the sea breeze convergence,
resulting in shower and thunderstorm development each afternoon.
Today, mainly over central and west/northwest Puerto Rico and as
well over isolated areas of northern PR. In addition, a TUTT-induced
low-level trough is expected to cross the region between Tuesday and
Wednesday. This will further increase moisture content and enhance
early morning convection between the U.S. Virgin Islands and eastern
PR, followed by an increase in areal coverage of afternoon
convection across PR. Urban and small stream flooding can be
expected each day with the thunderstorms.

Maximum temperatures today are forecast to reach the low 90s across
urban areas of northern, western and southwestern PR. The heat index
could reach 108F between Arecibo and Dorado, where a Heat Advisory
is in effect from 1100 AM AST through 300 PM AST.

&&

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

A Tropical Upper Tropospheric Trough (TUTT) located northeast of the
local islands will continue to interact with the available
moisture to support and enhance unstable weather conditions
across the local area. By Thursday, the latest models guidance
(GFS and ECMWF) shows a slightly drying weather pattern.
Nonetheless, the TUTT will continue to move towards the
northeastern Caribbean during this time. Expect active afternoons
with the potential for thunderstorms and heavy rain. With the
expected activity and saturated soils from the previous rains, the
threat for thunderstorms, urban and small stream flooding, even
mudslides will continue until the early next week. Precipitable
Water Content (PWAT) values will range between 1.70 to 2.10 inches
which indicate a moisture pattern that will continue across the
area, just ahead of a tropical wave on Monday. For Tuesday
onwards, the models are showing and interaction with the TUTT and
the tropical wave, the is a high uncertainty to determine the
impacts associated with these events but unstable weather
conditions will persist for the second half of the long-term.

&&

.AVIATION...Mainly VFR conditions are expected to prevail across all
terminals through the forecast period. However, SHRA/TSRA is
expected to develop btw 03/18-21z over the interior and
west/northwest PR, which may cause tempo MVFR conds at TJBQ. VCTS is
possible at TJPS during this period. East to southeast winds will
continue at 8-12 kt, with sea breeze variations aft 03/14z.

&&

.MARINE...Mariners can expect gentle to moderate winds and seas
at 4 feet or below that will persist through at least today.
Showers and isolated thunderstorms are expected to develop every
afternoon this could result in gusty winds and locally
deteriorated conditions.


&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...Heat Advisory from 11 AM this morning to 3 PM AST this afternoon
for PRZ005.

VI...None.
&&

$$

DSR/GRS

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
448 AM AST Tue Oct 4 2022


.SYNOPSIS...Unsettled weather conditions are expected for the next
several days. Expect passing showers along the coastal waters and
eastern portions of Puerto Rico and the U.S. Virgin Islands. Then
in the afternoon hours, convection will occur with heavy showers
and thunderstorms across the central interior and portions of
western Puerto Rico. Heat indices could reach the mid 100s for
today.

&&

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

The combination of the available low-level moisture with daytime
heating and the sea breeze convergence, will result in afternoon
shower and thunderstorm development today across the interior and
west/southwest quadrant of Puerto Rico. Urban and small stream
flooding is expected with the heaviest showers. Across the U.S.
Virgin Islands and eastern PR, isolated to scattered shower activity
is expected. For tonight into Wednesday, a TUTT induced surface
trough is expected to move across the local area from the east. This
will increase shower activity across the USVI and eastern PR through
Wednesday morning, and enhance afternoon convection across the
interior and northwestern PR. Winds are expected to turn more
southeasterly and a weak Saharan Air Layer is then expected to move
over the region later in the day, lingering through Thursday.
Therefore, expect hazy skies and a decrease in shower activity from
late Wednesday through Thursday. Maximum temperatures are forecast
to range from the upper 80s to low 90s across the lower elevations,
with heat indices reaching the mid 100s each day. Trade winds will
increase between 15-20 kt by Thursday.

&&

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

A high pressure ridge is expected to dominate the weather
conditions for at least the first half of the period. A very
seasonal weather pattern is expected between Friday and Saturday,
with scattered showers during the morning hours across the eastern
portions of Puerto Rico and the U.S. Virgin Islands, followed by
afternoon convection across the Central Cordillera and the western
portions of Puerto Rico. Although, convection could be enhanced
by lifting moisture from the Intertropical Convergence Zone (ITCZ)
and local effects. From Sunday onwards, a wetter pattern will
persist. However, the model guidances (GFS, ECMWF) are showing and
interaction with the TUTT and a tropical wave, there is a high
uncertainty to determine the impacts associated with these events
but unstable weather conditions will persist for the second half
of the long-term. Expect active afternoons with the potential for
thunderstorms and heavy rain. With the expected activity and
saturated soils from the previous rains, the threat for
thunderstorms, urban and small stream flooding, even mudslides
will continue.

&&

.AVIATION...Mainly VFR conditions are expected to
prevail across all terminals through the forecast period. However,
SHRA/TSRA is expected to develop btw 04/17-22z over the interior and
west/southwest PR. This should cause mainly VCTS or VCSH at
TJPS/TJBQ. East winds expected at 9-12 kt, with sea breeze
variations aft 04/14z.

&&

.MARINE...Mariners can expect light to moderate winds between 5 to
15 knots and seas at 4 feet or below that will persist through at
least Wednesday. Showers and isolated thunderstorms are expected
to develop each afternoon. This activity could result in gusty
winds and deteriorated seas conditions.



&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...None.
VI...None.
&&

$$

DSR/GRS

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
425 AM AST Wed Oct 5 2022


.SYNOPSIS...A surface trough is forecasted to move across the
local area today. Expect passing showers along the coastal waters and
eastern portions of Puerto Rico and the U.S. Virgin Islands,
followed by the afternoon convection along the western portions of
Puerto Rico. Saharan dust will filter into the region today but it
will only last until Thursday. Heat indices could reach the mid
100s each day.

&&

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

A surface trough will move across the local area from the east
today. Winds are expected to turn more southeasterly with the trough
passage. This will increase shower activity across the USVI and
eastern PR through the morning hours, and enhance afternoon shower
and thunderstorm activity across the interior and northwestern PR.
Isolated thunderstorm activity is also possible across San Juan and
vicinity. Urban and small stream flooding is expected with the
heaviest showers.

A weak Saharan Air Layer is expected to filter over the region
through Thursday. Therefore, expect hazy skies and a decrease in
shower activity across the islands. On Friday, an upper-level low
northeast of the region will approach the islands and increase
instability to favor shower development across the islands.

Maximum temperatures are forecast to range from the upper 80s to low
90s across the lower elevations, with heat indices reaching the mid
100s each day. East to northeast trades will return and increase
between 15-20 kt on Thursday and Friday.

&&

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

Invest 91L now located east of the Windward Islands is expected to
continue its motion towards the western Caribbean. Associated
moisture from the northern periphery area could enhance an active
first half of the long-term period. Precipitable Water Content
(PWAT) values are expected to range between 1.60 to 2.15 inches
which indicate a moist environment that will conduce to heavy
rainfall and thunderstorms across portions of the islands. The US
Virgin Islands can expect morning showers across the area and
scattered showers during the afternoons. Meanwhile for Puerto
Rico, expect and increase in shower activity during the morning
hours, followed by active afternoon convection with heavy
rainfall, isolated thunderstorms and frequent lightning.
Therefore, with the expected activity and saturated soils the
threat for urban and small stream flooding, and mudslides will
continue. As the system moves towards the west, a tropical wave is
forecasted to reach the islands by early next week until the end
of the period.

&&

.AVIATION...Mainly VFR conditions are expected to prevail across all
terminals through the forecast period. However, SHRA/TSRA is
expected to develop btw 05/17-22z over northwest PR. This may cause
tempo MVFR conds at TJBQ. VCTS possible at TJSJ during the same
period. Winds E-ESE at 10-15 kt, with sea breeze variations aft
05/14z. HZ due to Saharan dust expected later today, but vsby should
remain P6SM.


&&

.MARINE...Moderate to locally fresh trades are expected to
prevail during the next several days. A broad area of low pressure
located east of the Windward Islands is expected to move well
south of the area over the Caribbean Sea. Mariners can expect seas
around 7 feet across the Caribbean waters and the Mona Passage
through Thursday. A small northerly swell is expected to reach the
Atlantic waters tonight. Therefore, small craft should exercise
caution at the mentioned waters.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...None.
VI...None.
&&

$$

DSR/GRS

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
450 AM AST Thu Oct 6 2022


.SYNOPSIS...Hazy skies are expected today as a weak Saharan Air
Layer (SAL) moves across the area. For today, expect an active
afternoon with showers and isolated thunderstorms aross western
PR, and streamers downwind of the islands and over eastern PR. A
northerly swell will promote high risk of rip currents for some
north-facing beaches of Puerto Rico through late tonight.

&&

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

A weak Saharan Air Layer (SAL) is expected to continue over the
region today. Hazy skies and limited shower activity is expected
across the islands. However, diurnally induced afternoon showers are
possible over western PR and from streamers downwind of the islands
and over eastern PR. On Friday and Saturday, an upper-level low
northeast of the Leeward Islands is expected to sink southwards into
the Anegada Passage. This will increase instability and as the SAL
diminish across the area, shower and thunderstorm activity will
increase once again in diurnal activity as previous days. Urban and
small stream flooding is expected, mainly across the interior and
western PR. Breezy conditions are expected across coastal areas of
northern and southwestern PR due to the sea breeze. Maximum
temperatures are forecast to range from the upper 80s to low 90s
across the lower elevations each day, and the heat index could reach
up to 106F across the northern and western municipalities of PR.

&&

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

Associated moisture from the Invest 91L is expected to move out of
the local area on Sunday, as this system moves westwards towards
Central America. Nonetheless, a very seasonal weather scenario is
forecasted for most of the long-term period. By early Monday, winds
are expected to shift from a more southeasterly flow, which means
the local afternoon convection is likely to be centered over the
northeastern and western portions of Puerto Rico. A tropical wave
is also expected to reach the local islands at the beginning of
the week. This will conduce to heavy rainfall and thunderstorms
across portions of the islands. The US Virgin Islands can expect
morning showers across the area and scattered showers during the
afternoons. In the meantime for Puerto Rico, expect and increase
in shower activity during the morning hours, followed by active
afternoon convection with heavy rainfall, isolated thunderstorms
and frequent lightning. By Wednesday onwards, tropical moisture
will be lifted from the Caribbean Sea and will persist until the
end of the workweek. Therefore, expect a wetter pattern everyday
across the local islands. Heat index values will remain above 100
degrees each day, mostly over urban and coastal areas across
north-central Puerto Rico. It looks like October!

&&

.AVIATION...Mainly VFR conditions are expected to prevail across all
terminals through the forecast period. East winds increasing at 14-
18 kt, with sea breeze variations aft 06/14z. HZ due to Saharan dust
expected but vsby should remain P6SM.

&&

.MARINE...Invest 91L well southeast of the local islands is
expected to promote choppy and hazardous marine conditions for
the offshore Caribbean waters and Mona Passage through late
tonight. Seas around 7 feet will continue across the Caribbean
waters and the Mona Passage until tonight. Therefore, a Small
Craft Advisory is in effect for these waters. A a small northerly
swell will continue to affect the Atlantic waters through Friday,
but expected seas to remain at 6 feet or less.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...High Rip Current Risk through late tonight for PRZ001-002-005-
008.

High Rip Current Risk through late tonight for PRZ012.

VI...None.
&&

$$

DSR/GRS

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
456 AM AST Fri Oct 7 2022


.SYNOPSIS...An induced trough will increase moisture content
gradually each day. Unstable conditions will persist across the
region and favor better convective development across the islands
each day. Marine conditions will improve this weekend and seas
at 5 feet or less will be observed across most of the local
waters.

&&

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

An upper-level low northeast of the Leeward Islands is expected to
move over the Anegada Passage and the northeastern Caribbean Sea
during the short term period. At the surface, an induced trough by
the low will increase moisture content gradually each day. This
scenario will promote unstable conditions across the region and
favor better convective development across the islands each day.
However, due to increasing trades, minor to moderate rainfall
accumulations are expected across the USVI and eastern sections of
PR, where streamers are expected to develop in the diurnal cycle and
trade wind showers will move at times during the overnight/early
morning hours. Meanwhile, across the interior and western PR, better
organized convection is expected and thunderstorm activity could
lead to urban and small stream flooding each afternoon. Seasonal
temperatures are expected across the islands through the weekend.

&&

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

A surface high pressure located in the central Atlantic is expected
to dominate for the first half of the long-term period. Nonetheless,
in our local area, a seasonal weather scenario is forecasted for all
the islands. By Monday, a tropical wave located east of the Leeward
Islands is expected to bring showers and isolated thunderstorms.
Winds are expected to shift from a more southeasterly flow, local
afternoon convection is likely to be centered over the northwestern
and western portions of Puerto Rico. The US Virgin Islands can
expect morning showers across the area and scattered showers during
the afternoons. This tropical wave will bring additional moisture
content from the Caribbean that is forecasted to persist until
Wednesday. From Thursday through Saturday, winds will persist
with a east-southeast flow and shower activity will be observed
across the northwestern, western and northern portions of Puerto
Rico. Although, a slightly drier air mass will filter in to the
region limiting the activity to the mentioned portions. A frontal
boundary will move out of the eastern coast of the United States
and associated moisture could reach the local area by the
beginning of the following week. Heat index values will remain
above 100 degrees each day, mostly over urban and coastal areas
across north-central Puerto Rico.

&&

.AVIATION...Mainly VFR conditions are expected to prevail across all
terminals through the forecast period. However, +SHRA/TSRA is
expected to develop over western PR, which may cause tempo MVFR
conds at TJPS. VCSH expected across the rest of the area terminals.
East winds increasing at 12-16 kt, with higher gusts and sea breeze
variations aft 07/14z.


&&

.MARINE...Moderate to locally fresh trades are expected to prevail during the
next several days. Tropical Depression Thirteen will continue to
move across the Caribbean Sea during the next couple of days. Seas
have subside overnight and seas up to 6 feet or less will prevail
across the Caribbean waters and the Mona Passage until today.
Mariners should exercise caution across the regional waters.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...None.
VI...None.
&&

$$

DSR/GRS

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
513 AM AST Sat Oct 8 2022

.SYNOPSIS...A trough will linger over the region through early
next week promoting unstable conditions for the next several days
and afternoon convection mainly over the interior and western half
of Puerto Rico, which could result in urban and small stream
flooding. Maximum temperatures in coastal and urban areas will
continue to peak in the upper 80s and low 90s with heat index values
above 100 degrees. Seas should remain at up to 5 feet today, with
occasional seas up to 6 feet over the Atlantic waters and the Mona
Passage, and continue to improve throughout the weekend. A moderate
risk of rip currents is expected for the northern, northeastern and
northwestern coastal waters of Puerto Rico and Culebra, along with
some beaches of the USVI.

&&

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

A TUTT-low will linger over the Archipelago of Puerto Rico and the
U.S. Virgin Islands through early next week, providing instability
and enhancing convective activity. In addition, near to above-normal
moisture content will benefit rainy conditions in the typical (but
more frequent) seasonal weather pattern, consisting of passing
showers across the windward sections, followed by afternoon
convection across the interior and western locations. Sea breeze,
diurnal heating, and local effects will boost thunderstorm activity
each afternoon. Downpours associated with thunderstorm activity may
result in urban and small stream flooding, and we cannot rule out
flash flooding if persistent rain activity and training of showers
materialize.

Today`s afternoon convection will develop to the southwest quadrant
due to the northeast winds and more to the northwest quadrant Sunday
and Monday due to the southeast winds. The leading edge of a
tropical wave will continue to promote a wet/unstable pattern late
Monday into the long-term period.

Maximum temperatures in coastal and urban areas will continue to
peak in the upper 80s and low 90s. Combined with the relative
humidity, this will result in heat index values of 100s degrees
Fahrenheit or more each day during the maximum heating.

&&

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

To start the long term forecast period a weak tropical wave will
bring an increase in moisture and chances of convective activity.
Current model guidance shows tropical moisture with around 2 inches
of precipitable water, at normal values for this time of the year,
moving over our southern local waters and reaching Puerto Rico and
the local islands. This will enhance rain chances and the typical
weather pattern of showers mainly over eastern Puerto Rico and the
local islands during the morning hours and afternoon convection
mainly over interior and western Puerto Rico during the afternoon
hours. Relatively drier conditions will then dominate for most of
the rest of the workweek. Drier mid and upper levels will be present
during that time period. By Wednesday GOES Aerosol Models show a
drier air mass along with a Saharan Air Layer (SAL) reaching the
forecast area, this should promote hazy skies and inhibit rain
chances. This drier pattern should promote a limited variation of
the seasonal weather pattern. Of note in the upper levels, a
Tropical Upper Tropospheric Trough (TUTT) will establish itself to
the east-northeast of our forecast area by Friday and into the
weekend and the start of next week. A generally east-southeasterly
wind flow and heat indices over coastal areas above 100 with higher
values mainly over north-central Puerto Rico. Humidity related to a
frontal boundary that will move out of the east coast of the
continental United States could also start to filter into the local
area at the end of the long term forecast period.

&&

.AVIATION...
VFR conds will persist across the local flying area, with a few
passing SHRA/-SHRA moving over terminals from time to time.
+SHRA/TSRA are forecast to develop across the Cordillera Central/La
Sierra de Luquillo, creating mount obsc and frequent lightning btwn
08/16-22z. This activity may impact JBQ/JSJ, and the VCTY of
JPS/ISX. Winds will continue calm-light/variable, returning from the
E/ENE at 10-15 kt with higher gusts and sea breeze variations.

&&

.MARINE...Moderate to locally fresh easterly winds are expected
to continue to prevail during the next several days. Seas should
remain at up to 5 feet today, with occasional seas up to 6 feet
over the Atlantic waters and the Mona Passage. Enhanced shower
activity is expected across the waters, with the potential for
isolated thunderstorms, especially near western Puerto Rico in the
afternoons. Locally deteriorated conditions are possible near
stronger showers and thunderstorms. A moderate risk of rip
currents is expected for the northern, northeastern and
northwestern coastal waters of Puerto Rico and Culebra, along with
some beaches of the USVI.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...None.
VI...None.
&&

$$

SHORT TERM...CAM
LONG TERM....MRR

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
526 AM AST Sun Oct 9 2022

.SYNOPSIS...

A TUTT-low continues to promote unsettled weather conditions with
widespread showers and scattered thunderstorms affecting the local
waters, eastern Puerto Rico and the USVI during the overnight
hours. This activity should continue into the morning hours.
Today`s afternoon activity, including showers and thunderstorms,
will spread to most of Puerto Rico and can also affect the USVI
from time to time. Active weather will persist until early this
week as a tropical wave moves over the islands, maintaining a wet
and unstable weather pattern. By midweek a Saharan Air layer will
start affecting the region. Maximum temperatures in coastal and
urban areas will continue to peak in the upper 80s and low 90s
with heat index values of 100s degrees. Low to moderate risk of
rip currents will prevail for the local beaches.

&&

.SHORT TERM...Tonight through Tuesday...

GOES-East depicted a TUTT-low aloft and drifting westward. This
upper-level feature promoted unsettled weather conditions overnight,
resulting in widespread showers and scattered thunderstorms across
the local waters, the eastern third of Puerto Rico, and the U.S.
Virgin Islands.

The TUTT-low will linger until it dissipates over the Archipelago of
Puerto Rico and the U.S. Virgin Islands through early next week,
providing instability and enhancing convective activity. Model
guidance suggested near to above-normal moisture content, which will
benefit showery conditions and a high potential for thunderstorm
development affecting the islands in the typical pattern across the
windward sections overnight and the morning, followed by organized
afternoon convection across the interior and western locations. Sea
breeze, diurnal heating, and local effects will boost thunderstorm
activity each afternoon. Under this weather pattern, urban and small
stream flooding is likely. We cannot rule out flash flooding or
mudslides if persistent heavy rain activity and showers` training
develop.

Today`s afternoon convection will spread across most PR, with little
to no rain over the southwest coast. Afternoon showers and
thunderstorms will also affect the Virgin Islands from time to time.
Active weather will persist on Monday and Tuesday as a tropical wave
moves over the islands, maintaining a wet and unstable weather
pattern.

Maximum temperatures in coastal and urban areas will continue to
peak in the upper 80s and low 90s. Combined with the relative
humidity, this will result in heat index values of 100s degrees
Fahrenheit or more each day during the maximum heating.

&&

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

Current model guidance shows tropical moisture with precipitable
water values of around 2 inches, at normal values for this time of
the year, filtering out of the region on Wednesday, making way for a
relatively drier air mass. The seasonal weather pattern continues to
be expected with showers present mainly over eastern Puerto Rico and
the local islands during the morning hours and afternoon convection
mainly over interior and western Puerto Rico during the afternoon
hours. Relatively drier conditions will then dominate for most of
the rest of the workweek as precipitable water values at or slightly
below normal values are expected. The mid levels will continue
drying after Wednesday morning, there is some discrepancy between
the GFS and ECMWF models with regards to how dry the mid to upper
levels will be. Nevertheless, generally drier mid and upper levels
will be present during the second half of the workweek. On
Wednesday, the NASA/GMAO GOES Aerosol Model show a Saharan Air
Layer (SAL) along with the drier air mass reaching the forecast
area, this should promote hazy skies and inhibit rain chances. The
GOES Aerosol Model currently shows this Saharan Air Layer over
our region from Wednesday through the end of the workweek. This
drier pattern should result in a limited variation of the seasonal
weather pattern. By late Friday, an upper level trough will be to
the east-northeast of the forecast area and into the start of
next week. A generally east- southeasterly wind flow and heat
indices over coastal areas above 100 with higher values mainly
over north-central Puerto Rico will affect the region. Humidity
related to a frontal boundary that will move out of the east coast
of the continental United States and should filter into the local
area at the start of next week.


&&

.AVIATION...VFR conditions will persist across the local flying area,
with passing SHRA/+SHRA moving over terminals from time to time.
+SHRA/TSRA will develop over most PR during the afternoon (btwn
09/16-23z), especially across the Cordillera Central/La Sierra de
Luquillo, creating mountain obscuration and frequent lightning.
This activity may impact JBQ/JSJ, and the VCTY of JPS/ISX/IST.
Winds will continue calm to light and variable, returning from the
E/ESE at 10- 15 kt with higher gusts and sea breeze variations.

&&

.MARINE...
Seas should remain at up to 5 feet, with occasional seas up to 6
feet over the offshore Atlantic waters. Moderate to locally fresh
trade winds are expected for the next several days. Scattered to
numerous showers are forecast through early next week across the
local waters. Locally higher winds and seas are possible near
showers and thunderstorms. Low to moderate risk of rip currents
will prevail for the local beaches.


&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...None.
VI...None.
&&

$$

SHORT TERM...CAM
LONG TERM....MRR

[underthwx]

Good morning Luis...I was looking at page 1 of your epic topic thread, (which you started in 2006)...you have many radar links available, are there any that are close to where Julia is?....thanks and have a great day.

[cycloneye]

Good morning Luis...I was looking at page 1 of your epic topic thread, (which you started in 2006)...you have many radar links available, are there any that are close to where Julia is?....thanks and have a great day.

I have the San Andrés radar but is not working now.

http://www.pronosticosyalertas.gov.co/archivos-radar

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
506 AM AST Tue Oct 11 2022

.SYNOPSIS...

A tropical wave will bring showers and thunderstorms across the
local waters and islands today. We anticipated the strongest
activity across the mountain areas and western locations of Puerto
Rico during the afternoon, where urban and small stream flooding
is likely. The available moisture with the diurnal heating will
result in heat index values near and above 100 degrees Fahrenheit
in urban and coastal locations. An air mass with suspended African
Dust Particles will create hazy skies tonight through Friday.
Unsettled weather conditions could be possible late in the weekend
into early next week.

&&

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

The dissipating low pressure in the upper levels and trailing
tropical moisture filtering into our region will continue to
influence the region today. Precipitable water values of around 2
inches, near to above-normal for this time of the year, will be
present until late tonight to early tomorrow. These conditions
will lead to a generally more active variation of the seasonal
weather pattern, due to additional instability and moisture,
morning showers will continue to affect the local waters and
eastern half of Puerto Rico and the Virgin Islands mainly during
the morning hours and diurnal and local effects will promote
shower and thunderstorm activity during the afternoon hours.

Generally east-southeast wind flow will lead to afternoon
activity mainly over the mountain areas and northwestern
municipalities with the San Juan streamer also developing and
affecting the San Juan metro area. These afternoon showers can
lead to urban and small stream flooding and persistent showers
over a particular area could cause flash flooding and mudslides.
Heat index values will continue reaching or surpassing the 100s
degrees Fahrenheit.

A ridge will build late tonight and by Wednesday with winds
becoming more easterly. GOES-East RGB products already detected an
air mass with suspended African Dust Particles. In addition, the
NASA/GMAO GOES Aerosol Model shows a drier air mass along with a
Saharan Air Layer (SAL) reaching the forecast area by late
tonight, Wednesday, and until the end of the short term forecast
period, promoting hazy skies and reduced visibilities. People
sensitive to these conditions should follow medical advice. The
presence of the ridge, drier air, and saharan dust will result in
more stable conditions and generally less active weather, with a
limited variation of the seasonal weather pattern Wednesday and
Thursday.

&&

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

The mid-level ridge will hold over the islands through at least
Saturday, when a polar trough approaching from the west may weaken
it. While at the surface, a cold front will exit CONUS moving
into the Western Atlantic Friday into the weekend. This frontal
boundary will approach the islands late Saturday through Monday,
inducing pre-frontal troughs and promoting moisture pooling over
the Northeast Caribbean.

PR and the USVI can expect hazy skies on Friday, with limited
shower activity. However, patches of moisture in the trades may
bring the typical passing showers during the morning and overnight
showers across the windward sections in PR/USVI. Diurnal heating
and the available moisture may result in limited afternoon
convection over western PR. Afternoon convection should become
stronger during the weekend due to the proximity of an upper-level
trough. An unstable weather pattern may seem possible on Sunday,
Monday, and even Tuesday, as pre-frontal troughs could be induced
near the region. The local winds would be influenced due to the
proximity of the front, becoming more from the south to east-
southeast, advecting additional moisture over the area.

Maximum temperatures in coastal and urban areas will continue to
peak in the upper 80s and low 90s. Combined with the relative
humidity, this will result in heat index values of 100s degrees
Fahrenheit or more each day during the maximum heating. &&

.AVIATION...
(06Z TAFS)

Mainly VFR conditions will prevail with -SHRA/SHRA moving over
the terminals from time to time. SHRA/+SHRA will continue
impacting JSJ, IST and ISX mainly during the morning hours. During
the afternoon hours +SHRA/TSRA will develop mainly over central-
int/W-PR, impacting JBQ, with additional streamers impacting JSJ
(btwn 11/16-22z). VCSH can also affect ISX/IST at that time. Winds
will be at 10-15 knots with higher gusts and sea breeze
variations aft 11/13z, bcmg calm to light/vrb after around
11/21Z.

&&

.MARINE...

Moderate easterly winds between 10 and 18 knots will prevail across
the local waters. Seas will range at 4 ft or less across most of
the local waters. However, mariners should exercise caution due
to showers and thunderstorms associated with a tropical wave,
which will result in gusty winds and locally hazardous marine
conditions.

There is a low risk of rip currents for most of the local beaches
in Puerto Rico and the U.S. Virgin Islands.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...None.
VI...None.
&&

$$

SHORT TERM...MRR
LONG TERM....CAM
AVIATION...MRR

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
507 AM AST Wed Oct 12 2022

.SYNOPSIS...

The trailing moisture of yesterday's tropical wave will gradually
decrease today, not without first bringing occasional trade wind
showers across the windward sections of Puerto Rico and the Virgin
Islands. Then, local effects, diurnal heating, and sea breeze
variations will promote pulse storms across the interior and
western locations during the afternoon. Nevertheless, an air mass
with suspended African Dust Particles will create hazy skies
through the end of the work week. Once again, heat index values
will reach and surpass 100 degrees Fahrenheit in urban and coastal
areas each afternoon. A moist and unstable weather pattern would
be possible late in the weekend into early next week.

&&

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

Moisture from a weak tropical wave and patchy showers will gradually
decrease as a drier air mass with a Saharan Air Layer (SAL) continues
to move into the region, as detected by GOES-East RGB products. This
will cause precipitable water values to drop to at or below normal
values for this time of the year. The NASA/GMAO GOES Aerosol Model
shows this SAL persisting during the rest of the workweek. These
suspended African Dust Particles will promote hazy skies and, reduced
visibility and air quality. People sensitive to these conditions should
follow medical advice. Heat index values will continue reaching or
surpassing the 100s degrees Fahrenheit during short term period.

A ridge will also continue to build resulting in increased stability
over the atmosphere. Winds will be generally from the east during the
next few days at up to around 15 mph with higher gusts and sea breeze
variations. The presence of the ridge, drier air, and saharan
dust will result in more stable conditions and a limited variation of
the seasonal weather pattern, Wednesday through Friday. This includes
patchy moisture mostly affecting the eastern forecast region and
diurnal and local effects promoting afternoon convection, including
scattered showers and isolated thunderstorms this afternoon, mainly
over western Puerto Rico.

&&

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

The mid-level high pressure will slowly erode Saturday when a
polar trough approaches from the west. While at the surface, a
cold front will move westward across the Western Atlantic,
approaching the northeast Caribbean till it dissipates off to the
north of the islands by next week. This frontal boundary may
promote moisture pooling and could induce pre-frontal troughs over
the Northeast Caribbean.

Under the weather pattern explained in the previous paragraph,
expect the arrival of moisture embedded in the trades promoting
passing showers across the local waters and windward sections of
PR/USVI in the morning and evening hours. The influence of sea
breeze and diurnal heating will promote thunderstorms across the
interior and western areas Saturday and Sunday. However, the
proximity of the frontal boundary and the trough aloft will be
combined to enhance afternoon convection from Sunday through
Tuesday. GFS-Total Precipitable Water (TPW) is forecast to be near
2 inches or more Sunday through Tuesday, eroding by Wednesday. If
model guidance is correct, unsettled weather conditions may
affect the islands through that period.

Maximum temperatures in coastal and urban areas will continue to
peak in the upper 80s and low 90s. Combined with the relative
humidity, this will result in heat index values of 100s degrees
Fahrenheit or more each day during the maximum heating.

&&

.AVIATION...

Mainly VFR conditions will continue to prevail. -SHRA/SHRA will
impact the terminals from time to time. During the afternoon hours
+SHRA/TSRA will develop mainly over central-int/W-PR, which can
impact JBQ. VCSH can also affect ISX/IST/JSJ at that time. Winds
will be at 10-15 knots with higher gusts and sea breeze variations
aft 12/13z, bcmg calm to light/vrb after around 12/21Z. A weak
tropical wave and an area of Saharan dust will impact the
terminals, this dust can reduce visibilities to as low as 6
statute miles.

&&

.MARINE..

Moderate easterly winds between 10 and 18 knots will prevail
across the local waters. Seas will range at 4 ft or less across
most of the local waters. However, mariners should exercise
caution due to showers and thunderstorms especially during the
afternoon, which will result in gusty winds and locally hazardous
marine conditions.

The beaches from Aguadilla to Dorado have a moderate risk of rip
currents. Elsewhere, the risk is low.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...None.
VI...None.
&&

$$

SHORT TERM...MRR
LONG TERM....CAM
AVIATION...MRR

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
456 AM AST Fri Oct 14 2022

.SYNOPSIS...

Hazy conditions are expected to linger today. Despite the drier
air, though, local effects will combine with the available
moisture to result in showers and isolated thunderstorms.
Increasing shower activity is expected for the first part of next
week, as a deep-layer polar trough approaches from the northwest,
providing instability over the area. A decrease in activity is
likely by midweek next week.

&&

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

Slightly below normal moisture with some Saharan dust is expected
today across the local area. Isolated to scattered showers are
forecast across the local waters, USVI and eastern PR in the
morning hours, leaving some accumulations across eastern PR, but
little to no accumulations elsewhere. Showers and thunderstorms
are expected this afternoon across central to western PR. Some
showers could be heavy at times, which could lead to urban and
small stream flooding in some areas.

The Saharan dust is expected to move out of the local area by late
tonight, and the available moisture is expected to increase through
the weekend. The shower activity is also expected to increase this
weekend with the additional moisture. That said, the overall pattern
is expected to be close to normal, just with a bit more coverage,
with scattered showers across the local waters, eastern PR and the
USVI, while afternoon thunderstorms develop across central to
western PR. However, for Sunday, there is the potential for more
persistent thunderstorms over central PR, due to an approaching
upper trough from the northwest, causing an increase in instability
over the local area.

As far as temperatures, daytime high temperatures will be near
normal, with highs in the upper 80s to low 90s across the lower
elevations. The heat index values will continue reaching or
surpassing the 100s degrees Fahrenheit during short term period,
especially across north central Puerto Rico.

&&

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

A deep-layer polar trough is expected to continue to dig into the
tropics through the first part of the week next week. Model guidance
has been backing off somewhat in recent runs on how far it will
stretch over the region, but it is likely to be either over the area
or just north of it on Monday morning. From there, it is forecast to
shift southeastward, making its way northeast of the Windward
Islands by Tuesday. Increased instability is expected for Monday,
but then decrease as the mid- to upper-level ridge re-asserts itself
over the region. Moisture will remain on the low end of normal for
Monday. Beyond that, moisture content is expected to decrease over
the region, especially in the mid-levels, through at least midweek.

Overall, expecting active weather conditions for Monday, maintaining
a typical shower pattern but with enhanced activity. The steering
flow is forecast to be quite weak, likely around 5 to 10 knots out
of the east to east-northeast. Above around 600 hPa, however, the
flow backs quickly with height, becoming more west-northwesterly.
So, on the whole, showers will be slow-moving. Because of this,
locally higher rainfall totals are likely, providing a further
increase to the potential for localized flooding impacts, mostly in
the form of urban and small stream flooding. Decreasing shower
activity is expected through at least Wednesday. That being said,
the light steering flow will persist through the week, and could
lead to isolated areas with high rainfall totals.

A modest increase in moisture over the region starting as early as
late Thursday could result in an increase in shower activity.

&&

.AVIATION...
(06Z TAFS)

VFR conditions will prevail. VCSH expected across the local
terminals in the morning hours. VCTS is expected at TJBQ after
14/17Z, with the possibility of TEMPO TSRA. TJSJ may have brief
VCTS/VCSH at some point between 14/17 and 14/20Z, as SCT SHRA/ with
possibly brief TSRA develops south and west of the terminal. Winds
will be generally easterly at around 10KT with sea breeze variations
developing after 14/13Z. Some HZ will be present due to Saharan
Dust, but VIS should remain P6SM.

&&

.MARINE...

Winds of up to 10 to 15 knots out of the east are expected across
the waters. Seas of 4 feet or less are anticipated. Showers and
isolated thunderstorms are expected, especially near western Puerto
Rico in the afternoon, with which locally deteriorated conditions
are possible. There is a low risk of rip currents.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...None.
VI...None.
&&

$$

SHORT TERM...JA
LONG TERM....CRS
AVIATION...JA