Caribbean - Central America Weather

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
453 AM AST Tue Nov 5 2019

.SYNOPSIS...A surface trough is expected to linger over the area
for today, resulting in more shower activity. A drier and more
stable weather pattern will then take hold during the rest of the
work week and into the upcoming weekend. However, patches of low-
level moisture will be moving across from to time, bringing
rounds of trade wind showers. At this time, no significant weather
features that would bring widespread heavy rainfall activity to
the local area are anticipated during the long term period.

&&

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

A mid to upper level trough with its associated low will linger to
the east northeast of the local islands today as it weakens, then
slowly lifting by Wednesday. There is also a weak SFC trough over
the local area which as is slowly moves west, keeping abundant
moisture over the local area today. This weather pattern will cause
good instability across the local area albeit less than what we have
observed he past few days. Showers are expected in the morning and
nighttime hours, but in the afternoon the diurnal heating will play
a role and cause the development of significant showers and isolated
thunderstorms across the interior and western PR, with less frequent
showers elsewhere in PR. Given the amount of rainfall observed the
past few days, urban and small stream flooding is expected today,
especially across the interior and western sections of PR. The
instability decreases further for Wednesday and Thursday, and there
might even be small concentrations of Saharan dust, but isolated to
scattered showers are still expected in the overnight and morning
hours, while limited afternoon convection is forecast across western
PR. The wind speed is expected to increase for Wednesday, which
could cause even less afternoon shower activity across western PR as
the convection will quickly move offshore, same is expected for
Thursday but the winds will be lighter so there might be a bit more
shower activity over land areas in western PR. The USVI has a chance
of scattered showers today, but the accumulations are not expected
to cause much more than perhaps some ponding of water. Since the
instability decreases after today, mainly brief and isolated to
scattered showers, leaving minimal accumulations are expected for
the USVI on Wednesday and Thursday.

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

A mid to upper-level ridge pattern is expected to take hold over
the area during the long term period. This will result in mainly
stable conditions aloft and thus limit the potential for deep and
organized convective activity to materialize with moisture
expected to be limited to the lower levels. A surface high
pressure is expected to be entrenched across the central and
northeast Atlantic throughout the period. This feature will serve
to bring patches of low-level moisture into the area from time to
time. Therefore, some passing showers will be possible across
portions of eastern Puerto Rico, the USVI, and surrounding waters
during the overnight and early morning hours followed by the
development of some afternoon convection across the western half
of Puerto Rico. No significant rainfall event is anticipated in
the long term as conditions aloft look to remain unfavorable.

&&

.AVIATION...SHRA is expected in the morning hours across the local
flying area, causing at least VCSH across TJSJ, TIST, and TISX.
After 05/16Z, VCSH will remain a possibility for all of the local
terminals, but SHRA/TSRA is expected across western PR, which will
affect the vicinity of TJBQ, and TJMZ. Winds will be mainly from the
east at around 10-15KT with sea breeze variations developing after
05/13Z.


&&

.MARINE...Choppy seas of up to 6 feet are expected across most of
the regional waters for today. Therefore, small craft operators
are urged to exercise caution. A wind surge is expected by the
middle of the week. This will create rough seas of up to 7 feet,
starting late tonight and last through early Thursday across the
offshore waters and Mona Passage. Therefore, Small Craft
Advisories are in effect for these waters.

For beachgoers, a high risk of rip currents continues for most of
the northern beaches of Puerto Rico and Cramer Park Beach in
Saint Croix for today. Across the rest of the local beaches, there
is a low to moderate risk of rip currents.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 76 88 78 / 30 30 20 20
STT 88 77 88 78 / 40 20 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
420 AM AST Wed Nov 6 2019

.SYNOPSIS...Surface high pressure across the Central Atlantic will
result in brisk easterly trade winds through Thursday. Patches of
low-level moisture embedded within the easterly trade wind flow
will move across the area from time to time during the next
several days with trade wind showers expected. A weak tropical
wave is expected to affect the area late Saturday night and Sunday,
resulting an increase in shower activity. A drier weather pattern
follows during the first half of next week with more limited
shower activity expected.

&&

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

The upper level trough across the east northeast of the local
islands is slowly lifting. There is also drier air moving in in the
morning, but a patch of moisture is expected for the afternoon
hours. Scattered showers are expected in the morning across the
local waters and isolated across land areas, but in the afternoon,
the diurnal heating will combine with the expected patch of moisture
and local effects to cause the development of showers and isolated
thunderstorms across portions of the western sections of PR, with
less frequent showers elsewhere. The wind is expected to be a bit
stronger today, so the showers that do develop are not expected to
remain over land areas for too long, for that reason only ponding of
water on roadways and poor drainage areas is expected today. The
instability is decreasing and will continue to decrease into
Thursday, plus there might even be small concentrations of Saharan
dust, but isolated to scattered showers are still expected in the
overnight and morning hours, while limited afternoon convection is
forecast across western PR on Thursday as well. The USVI has a
chance of scattered showers today, but the accumulations are
expected to be minimal. This pattern of brief showers is expected
for the next few days for the USVI. However, on Friday, a weak upper
trough moves just to the west of PR, which may increase instability
for Friday afternoon while moisture also increases. For that reason,
the afternoon convection over PR may have more significant showers
over western PR, but elsewhere, the shower activity is still
expected to be isolated to scattered and brief.

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

A weak tropical wave is expected to move across the area late
Saturday night and during the day on Sunday with an increase in
rainfall activity possible as precipitable water values rise to
near 2.00 inches. Scattered showers will be possible across the
USVI and eastern Puerto Rico during the overnight and morning
hours of Sunday followed by the development of convection across
the western half of Puerto Rico on Sunday afternoon. At this time,
the upper-levels do not look particularly favorable for enhanced
thunderstorm activity as there will be some ridging aloft.

After the tropical wave exits to the west later Sunday night into
early Monday, a drier weather pattern will follow with ridging
aloft expected. Having said this, patches of low-level moisture
riding the easterly trade wind flow will move over the area from
time to time through the middle of next week. This will result in
some passing showers across portions of the USVI, eastern Puerto
Rico, and the USVI mainly during the overnight and morning hours
followed by the development of some afternoon convection across
the western half of Puerto Rico. However, under the influence of
the drier air mass and ridging aloft, significant rainfall
activity is not expected.

&&

.AVIATION...ISOLD SHRA expected in the morning hours across the
local area, causing VCSH across TJSJ, TIST, and TISX. After 06/16Z,
VCSH will remain a possibility for TIST, TJSJ, TJBQ and TJMZ, but
the more significant SHRA/TSRA is expected across western PR, which
will affect the vicinity of TJBQ and TJMZ. Winds will be mainly from
the east at around 10-15KT with sea breeze variations developing
after 06/13Z.

&&

.MARINE...Moderate to fresh easterly trade winds as a result of a
broad surface high pressure across the central Atlantic will
result in choppy seas across the regional waters. Seas are
expected to increase up to 7 feet across the offshore waters and
local passages, where small craft advisories are in effect. Across
the nearshore waters, seas of up to 6 feet are expected.
Therefore, small craft operators should exercise caution.

For beachgoers, there is a high risk of rip currents for Cramer
Park Beach in Saint Croix. Across most of the other beaches, the
rip current risk will be moderate.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 77 88 77 / 30 20 30 30
STT 87 77 87 77 / 30 30 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
459 AM AST Thu Nov 7 2019

.SYNOPSIS...Slightly drier air mass expected today across the
local area, but brief showers are still expected in the morning
hours, then locally induced showers expected across western PR in
the afternoon. The winds will be slightly lighter today, but still
near 15 mph across coastal areas and between 15 and 20 knots
across the local waters. Seas are subsiding slowly but still
choppy. Early morning and night time brief shower activity
expected across the USVI, local waters and eastern PR for the next
couple of days before a tropical wave moves in on Sunday and
Monday, increasing moisture and shower activity to the local area.

&&

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

A mid-level ridge is expected to prevail overhead during the short-
term period. This will result in subsidence aloft, which will serve
to hinder the development for deep and organized convective activity
from materializing. Meanwhile, at lower-levels, a broad surface high
pressure across the east-central Atlantic is expected to continue to
advect patches of low-level moisture into the forecast area from to
time through the period. Therefore, trade wind showers are expected
across the regional waters, with some of the activity affecting
portions of eastern Puerto Rico and the USVI mainly during the
overnight and early morning hours. Then, as the available moisture
combines with daytime heating and local effects, scattered showers
and isolated thunderstorms are expected across portions of western
Puerto Rico. Additional activity in the form of streamers are
possible downwind of the USVI and El Yunque, affecting portions of
the San Juan metro area. Given that the environment aloft is
expected to be unfavorable for any substantial rainfall activity
from materializing, significant rainfall accumulations are not
expected. As a result, the flooding potential is expected to remain
low with ponding of water on roadways expected to be the main hazard.

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

A tropical wave is forecast to move into the local area on Sunday
into Monday, causing an increase in moisture and in shower
activity. During that time, there will be an upper trough
approaching the local area as well, which would increase
instability and increase the chances for thunderstorms, but only
isolated thunderstorms are in the current forecast for Sunday
because there is a ridge in the mid levels that could work against
significant thunderstorm development. That said, if there is
consistency among the models for thunderstorm and significant
shower development on Monday, the forecast will reflect an
increase in shower and thunderstorm activity as well as in the
amount of rainfall expected. Thereafter, from Tuesday and for the
rest of the workweek, near normal moisture with an upper ridge
will dominate the local weather pattern, which would translate
into passing and brief showers in the night time and early morning
hours across the local waters, USVI, and eastern PR, while the
local and diurnal effects of PR could cause showers across western
PR in the afternoon hours.

&&

.AVIATION...Mainly VFR conditions expected to prevail across the
flying terminals through the forecast period. Passing SHRA may
result in VCSH across TJSJ and USVI terminals through 07/14z with no
significant impacts to operations expected. SHRA/TSRA expected
across western PR between 07/17z and 07/23z, affecting mainly the
vicinity of TJMZ. TEMPO MVFR conditions are possible. Winds light
and variable through 07/12z, increasing to 10 and 20 kts with sea
breeze variations after 07/14z.

&&

.MARINE...The local seas are subsiding and the buoy observations
confirm the ongoing wave height forecast. The small craft advisory
continues in effect until 8 AM for the Anegada passage and until
2 PM for the offshore Atlantic waters due to seas up to 7 feet.
Elsewhere, small craft operators are urged to exercise caution
with seas up to 6 feet and winds up to 20 knots. There is now a
moderate risk of rip currents for many of the local beaches.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 77 88 76 / 40 40 20 30
STT 88 77 87 78 / 30 30 20 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
515 AM AST Fri Nov 8 2019

.SYNOPSIS...A slightly drier than normal air mass is expected
today across the local area, with even drier air moving in this
afternoon, but brief showers are still expected in the morning
hours across the local waters, USVI, and eastern Puerto Rico. Locally
induced showers are expected across western PR in the afternoon.
A surface high pressure across the east central Atlantic will
continue to promote moderate easterly winds across the local area
today. A tropical wave will move in on Sunday into Monday,
increasing moisture and shower activity to the local area,
especially on Monday when the deeper moisture is expected to move
in.

&&

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

A fairly stable weather pattern is expected to prevail across the
local area through most of the short-term period as a ridge aloft
will continue to suppress the development of deep and organized
convective activity, thus limiting the potential for any significant
rainfall activity from materializing. However, patches of low-level
moisture embedded within the easterly trade wind flow will
occasionally move across the local area. This will generate some
trade wind showers across the surrounding waters, with some of the
activity affecting portions of eastern Puerto Rico and the USVI
during the overnight and early morning hours, followed by the
development of some afternoon convection across western Puerto Rico
due to diurnal heating and local effects. Given that significant
rainfall accumulations are not expected, the flooding potential will
continue to remain low with ponding of water on roadways being the
main hazard with these showers.

The latest model guidance have delayed the arrival of the deeper
moisture associated with a tropical wave until Sunday night.
Therefore, it is not until then when shower activity is expected to
increase in coverage, especially across the eastern half of Puerto
Rico and the USVI. Given this latest scenario, fairly tranquil
weather conditions are expected across most of the forecast area
during the majority of Sunday, although as it is normally the case
climatologically speaking, showers and isolated thunderstorms can be
expected across interior and western portions of Puerto Rico during
the afternoon hours.

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

By Monday, a tropical wave is expected to be near or just passing
through the local islands, with most of its associated moisture
over the local islands. However, some of the moisture will linger
into Tuesday, but drier air is forecast for Wednesday. During this
period a broad upper trough will develop and help with the
thunderstorm development. That said, the mid level temps will be
near normal and the relative humidity will be slightly higher than
normal. Therefore, although nothing impressive in the mid to upper
levels is expected, there will be higher than normal moisture on
Monday with Precipitable Water values near 2 inches and the
forecast soundings indicate some instability. For that reason, we
followed up on yesterday`s analysis and increased the rainfall
forecast for Monday and included isolated thunderstorms as well.
The weather conditions are expected to gradually improve through
the early part of the week thereafter even though some moisture
will linger into Tuesday. Below normal moisture will start moving
in on Wednesday and much drier air by Friday as a strong SFC high
pressure moves into the western Atlantic, causing NE winds across
the local area, while a mid and upper ridge is over the local
area, causing more stable conditions.


&&

.AVIATION...Mainly VFR conds expected to prevail across the flying
terminals. Passing SHRA will result in VCSH across TJSJ and USVI
terminals through 08/12z. SHRA/TSRA expected across western PR
between 08/16z and 08/22z, affecting the vicinity of TJMZ/TJBQ.
TEMPO MVFR conditions cannot be ruled out. Winds light and variable
through 08/12z, increasing from the E between 10 and 15 kts with sea
breeze variations after 08/14z.

&&

.MARINE...Seas have subsided but are still choppy, up to 6 feet
across the Atlantic waters and the Anegada Passage. Elsewhere,
seas will be up to 5 feet and the winds will be generally between
10 and 15 knots. These choppy seas will continue for the next
several days. Most of the local beaches will have a moderate risk
of rip currents today.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 76 88 76 / 30 20 20 30
STT 87 77 86 77 / 20 20 20 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
410 AM AST Sat Nov 9 2019

.SYNOPSIS...Ridge aloft is expected to maintain fairly stable
weather conditions across the local area during the next couple of
days. A weak tropical wave is expected to move over the area late
Sunday night through Monday, increasing the shower activity
somewhat. A drier and more stable weather pattern will follow
starting on Tuesday and lasting through the rest of the week.

&&

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

Overall stable mid to upper level ridge pattern is to persist
through most of the period. However, a weak tropical wave is to
enter the eastern Caribbean later today, then cross the region
Sunday through early Monday. This will bring sufficient low level
moisture across the region to favor isolated to scattered showers
over the coastal waters and most of the islands. The exception will
be in the west sections of Puerto Rico during the afternoon, where
scattered to numerous showers will remain possible with a slight
chance for isolated thunderstorms. Expect the shower development to
be short lived and suppressed due to the fairly strong cap inversion
forecast to remain in place for most of the weekend.

The moderate trade winds will bring patches of low-level moisture
across the area form time to time ahead and trailing the
aformentioned tropical wave. As a result, periods of moderate to
locally heavy rains of short duration will be likely. Some showers
will affect portions of eastern Puerto Rico as well as the U.S.
Virgin Islands during the overnight and early morning hours. This
will be followed by locally and diurnally induced afternoon
showers across western Puerto Rico. A few showers may also form
and quickly stream across parts of the San Juan Metro during the
late afternoon hours, but significant rainfall is not anticipated
at this time. For this reason, the flood potential is still
forecast to remain low during the period, with ponding of water on
roadways and poor drainage areas being the main hazard with the
shower activity.

Recent model guidance initialized fairly well and continued to
suggest most of the moisture to trail the tropical wave now expected
to arrive late Sunday into early Monday. Therefore, it is not until
then when shower activity is expected to a bit more widespread
especially across the eastern half of Puerto Rico and around the
USVI. Otherwise, fairly tranquil weather conditions are expected
across most of the forecast area during the majority of Sunday and
by Monday afternoon. Although the typical locally and diurnally
induced afternoon showers and isolated thunderstorm activity will
remain possible each day over parts of the interior and west
sections of Puerto Rico steered by the prevailing trade wind flow.

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

After the tropical wave passage on Monday, drier and more stable
weather conditions are expected to follow starting on Tuesday and
lasting through the rest of the work week and into the following
weekend as a mid to upper level ridge builds overhead. This will
hinder the development of deep and organized convective activity
from materializing. Therefore, significant rainfall activity is
not expected during this period. An east northeast to northeast
wind flow is expected to dominate during the middle and latter
half of next week and extending into next weekend as a surface
high pressure moves off the eastern seaboard of the United States
and into the western Atlantic. Under this pattern, patches of low-
level moisture will move over the area from time to time,
resulting in some passing trade wind showers across portions of
northern and eastern Puerto Rico and the USVI during the overnight
and early morning hours followed by the development of some
afternoon convection across southwest Puerto Rico due to daytime
heating and local effects.

&&

.AVIATION...VFR at all terminals. SCT lyrs nr FL025...FL040... with
isold SHRA ovr regional waters and en route btw islands. Sfc wnds
Lgt/Vrb to Calm bcmg mainly fm E 10-15 kt with sea breeze variations
aft 09/14Z. Few SHRA vcty TJSJ/TIST/TISX/TNCM/TKPK til 09/14z. Aftn
convection mainly ovr ctrl interior and NW PR...with VCSH/Isold TSRA
psbl vcty TJMZ/TJBQ fm 09/17Z-09/22Z.

&&

.MARINE...Seas of up to 5 feet and winds of up to 15 knots are
expected to prevail across the majority of the regional waters.
However, across portions of the local offshore Atlantic waters,
choppy seas of up to 6 feet are possible. Therefore, small craft
operators should exercise caution. A northwesterly swell is
forecast to move across the regional waters late Sunday night into
Monday. This is expected to result in choppy and rough seas of up
to 6-7 feet across portions of the Atlantic waters and local
passages. A small craft advisory may be needed, especially for the
local offshore Atlantic waters, during this period.

For beachgoers, the rip current risk is expected to be moderate
for most of the northern and southern beaches of Puerto Rico,
Vieques, Culebra, and Saint Croix for today. The rip current risk
is expected to increase to high across portions of the northern
beaches of Puerto Rico on Monday with the arrival of the
northwesterly swell.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 76 88 76 / 40 30 30 30
STT 86 81 86 80 / 30 40 40 40

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
336 AM AST Sun Nov 10 2019

.SYNOPSIS...
A weak tropical wave will move over or south of the area later
tonight and Monday, causing an increase in shower activity across
the area. Afternoon shower development remains possible across the
interior and western Puerto Rico as well as across the San Juan
metro area.

&&

SHORT TERM...Today through Tuesday...
Mid to upper level ridge is forecast to hold across the area
today, but will gradually weaken on Monday and Tuesday as a short
wave trough moves across the southwest Atlantic. In the meantime
expect fairly stable conditions aloft with the trade wind cap
inversion to hold across the area and therefore limit and suppress
convective development.

A weak tropical wave with axis now crossing the eastern Caribbean
and approaching the local Islands is forecast to move over or just
south of the the area later tonight into Monday. Therefore expect a
slight increase in low to mid level moisture along with periods of
shower activity especially during the overnight and morning hours
today and on Monday. Afternoon shower development will remain
possible but mainly over parts of the central interior and northwest
sections of Puerto Rico, as well as around parts of the San Juan
metro. Some afternoon showers of short duration will remain possible
over the U.S. Virgin islands but should be mainly on the west end
and downwind of the islands. A more stable weather pattern is
forecast by Tuesday as winds become more east to northeast and a
drier airmass filters in across the region.

.LONG TERM...Wednesday through Monday...
A predominantly east-northeast wind flow is anticipated for most
of the long-term period. Although a drier air mass is anticipated
in general, groups of showers are expected to move over the
region from time to time. Under this pattern, passing showers
will mainly affect the northern and eastern coast of Puerto Rico
as well as across the U.S. Virgin Islands. In the afternoon, due
to a combination of local effects, available moisture and diurnal
heating, showers are expected across the interior and southwestern
Puerto Rico. In the mid-levels, a ridge building over the western
Caribbean should begin to influence the local weather by Thursday
through the upcoming weekend. This feature should limit the
intensity and coverage of the afternoon convection across western
Puerto Rico. However, low level patches of moisture will still
result in passing showers across sections of eastern Puerto Rico
and the U.S. Virgin Islands, mainly during the overnight and early
morning hours.


&&

.AVIATION... VFR durg prd. SCT lyrs nr FL025...FL050. Isold SHRA en
route btw islands and ovr regional waters. Sfc winds lgt/vrb bcmg fm
E 10-15 kt with sea breeze variations. VCSH at TJSJ/TIST/TISX with
VCTS psbl at TJBQ/TJMZ fm 10/17Z-10/22Z.


&&

.MARINE...
A tropical wave over the eastern Caribbean seas is expected to
bring an increase in shower and isolated thunderstorm activity
over the local waters. A northwesterly swell will reach the
Atlantic waters tonight, creating hazardous marine conditions.
Seas will increase up to 7 feet, therefore, a small craft advisory
will be in effect for the Atlantic offshore waters.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 77 87 75 / 40 20 20 30
STT 86 77 87 76 / 30 40 40 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
453 AM AST Mon Nov 11 2019

.SYNOPSIS...
Mid to upper level short wave trough across the southwest Atlantic
will continue eastward and slightly erode the ridge aloft today
through Tuesday, then strengthen and reestablish overhead by
Wednesday and during the latter part of the work week. A broad and
strong surface high pressure across the east central Atlantic and
a frontal trough over the west Atlantic will promote moderate
easterly winds across the local area through most of the week.
Trade wind moisture trailing a tropical wave will move across the
region today, resulting in periods of isolated to scattered
showers and isolated thunderstorms across the regional waters and
portions of the islands today. This overall weather pattern of
passing trade wind showers should remain in place through most of
the work week.

&&

.SHORT TERM...Today through Wednesday...
A short wave trough will move north of the islands today. However,
no major impacts are expected in association with this system other
than a slight erosion of the upper ridge. Patches of moisture will
move over the region today, bringing showers to portions of eastern
Puerto Rico and the U.S. Virgin Islands. In the afternoon, due to
a combination of available moisture and local effects, showers
are expected with possible isolated thunderstorm across western
portions of Puerto Rico. For Tuesday and Wednesday, a drier air
mass is expected to filter in, promoting a fair weather pattern
for the islands. As a result, the latest GFS-sounding is showing a
trade wind inversion holding on over the region, which should
limit the coverage in shower activity across western Puerto Rico.
However, patches of moisture embedded in the trade winds will move
in from time to time, with passing shower activity across eastern
Puerto Rico and the U.S. Virgin Islands mainly during the
overnight and early morning hours.

.LONG TERM...Thursday through Tuesday...
A predominantly east-northeast low level wind flow is anticipated
for most of the period. Although a drier air mass is anticipated
at least through the end of the work week, groups of trade wind
showers are forecast to move over the region from time to time.
Under this pattern, the passing showers will mainly affect the
northern and eastern coast of Puerto Rico, as well as across the
U.S. Virgin Islands. During the afternoon hours, the combination
of local effects, available moisture and diurnal heating will give
way to shower development mainly across the interior and west to
southwest sections of Puerto Rico. Mostly isolated showers are so
far expected in and around the San Juan metro and the U.S. Virgin
Islands. In the mid-upper levels, a ridge building over the western
Caribbean should again begin to influence the local weather by
Thursday and into the upcoming weekend. This feature should limit
the intensity and coverage of the afternoon convection across
western Puerto Rico and the rest of the islands. However, occasional
patches of low level moisture will still result in passing showers
across sections of eastern Puerto Rico and the U.S. Virgin Islands,
mainly during the overnight and early morning hours.

The weather pattern is forecast to change by late Sunday and into
the early part of the following week as a tropical wave is expected
to approach the region and interact with a frontal trough which
is to linger west and north of the region, along with an amplifying
Tutt which is to move across the west Atlantic and sink southwards
across the region. This in turn will increase instability aloft
as well as enhance low level tropical moisture convergence. As a
result, and based on latest model guidance, a wetter pattern is
in store during the latter part of the period. however, this is
subject to change and will continue to monitor how and if this
pattern unfolds. Stay tuned.

&&

.AVIATION...Mainly VFR conditions are anticipated through the
forecast period. Passing showers under a ESE wind flow out of the
east at 10 to 15 knots. VCTS are expected for TJMZ/TJBQ after
11/16Z.

&&

.MARINE....Northwest swell will continue to increase and spread
across the Atlantic and local passages today. This will cause
large breaking waves along the Atlantic coastline of Puerto Rico.
Therefore, a high surf advisory was issued for the northern beaches
of mainland PR until later this evening. A high risk of rip
currents continues through Tuesday for the northern beaches. Seas
up to 7 feet are expected across the Atlantic beaches and small
craft advisories will remain in effect.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 76 87 75 / 20 30 30 30
STT 87 77 87 76 / 30 30 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
456 AM AST Tue Nov 12 2019

.SYNOPSIS...
Recent satellite imagery and satellite derived precipitable water
product both suggest a gradual depletion of low to mid level
moisture across the region this morning. However, few passing
showers were noted crossing the local waters and brushing parts of
the islands from time to time. High pressure over the central
Atlantic and a weak frontal trough northwest of the area will help
to maintain gentle to moderate east northeast winds today and
through the end of the work week. Mid to upper level ridge will
build and reestablish itself once again across the region later
today and into the weekend. This help stabilize the local airmass
and suppress convective development through Friday.

&&

.SHORT TERM...Today through Thursday...
As a frontal trough remains to the northwest of the area, some mid
to upper level clouds are expected to work their way into the
forecast area. At the lower levels, however, drier air is
anticipated to reach the area by midday into the afternoon hours.
This should limit the rainfall activity over the islands.
Nonetheless, afternoon convection is still anticipated across
western Puerto Rico due to local effects. In the mid-levels, high
pressure will begin to build over the western Caribbean, taking
control of the weather pattern for the rest of the short-term
forecast period. As this system establishes and migrates closer to
the area, the wind flow will shift more from the east-northeast with
a slight increase in speed. Therefore, groups of passing showers
will affect portions of northern and eastern Puerto Rico and the
U.S. Virgin Islands, mainly during the overnight and early morning
hours. In the afternoon, as usual, shower and thunderstorm formation
should be focused across the southwestern quadrant of the main
island of Puerto Rico with possible streamers forming from the isles
and El Yunque.

.LONG TERM...Friday through Wednesday...
A mid to upper level ridge will build and remain anchored across
the region on Friday and through most of the upcoming weekend to
maintain a fairly strong trade wind cap inversion. This will result
in limited showers development across the islands and coastal waters
during the fist half of the period. The upper ridge is then forecast
to gradually erode by late Sunday into early next week as a short
wave trough moves across the southwest Atlantic accompanied by a
cold front which is forecast to stall northwest of the region. A
broad low level low trough and tropical wave is also forecast to
develop and approach the region by late Sunday or Monday. This overall
scenario will bring an increase low level moisture convergence to
the region along with the expected instability aloft. If this unfolds,
a much wetter weather pattern can be expected with increased potential
for enhanced showers and thunderstorm activity beginning on Monday
and continuing through at Tuesday and possibly into Wednesday,


&&

.AVIATION...Mainly VFR conditions are expected across all terminals
through the forecast area. VCTS are possible across TJMZ/TJBQ
after 12/18Z, which could result in brief MVFR/IFR conditions,
with VFR conditions returning after 12/22Z. Winds will be out of
the east at 10 to 15 knots.

&&

.MARINE...A slowly fading northerly swell will continue to create
hazardous seas across the offshore Atlantic waters during the
early morning hours. Seas of up to 7 feet will therefore continue
during the morning but will continue to gradually subside to 6
feet or less throughout the day. Small craft advisory will remain
in effect for the offshore Atlantic until 8:00 AM AST, and small
craft operators should exercise caution elsewhere due to seas of
up to 6 feet during the rest of the day.

A high risk of rip currents will remain in effect for the north
facing beaches of PR and some northern beaches in Culebra into
the late afternoon hours.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 75 87 76 / 20 30 30 30
STT 86 76 87 76 / 20 30 10 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
438 AM AST Wed Nov 13 2019

.SYNOPSIS...Apart from overnight and early morning trade wind
showers and limited afternoon convection, a generally stable
weather pattern is expected to hold over the region through the
upcoming weekend due to unfavorable conditions aloft. By early
next week, there is a chance for an increase in shower and
thunderstorm activity as an the combination of an upper-level
trough and tropical wave generates favorable conditions aloft and
enhances low-level convergence across the region. Across the
regional waters...A northeasterly swell is forecast to generate
hazardous marine conditions Friday into Saturday.


&&

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

Broad surface high pressure ridge anchored across the north central
Atlantic and a weak lingering frontal trough across the west central
Atlantic, will induce and maintain an light to moderate east to
northeast wind flow through the period. Mid to upper level ridge
will build and remain in place across the region through Friday.
This will maintain dry and stable conditions aloft while limiting
convective development due to the fairly strong cap inversion across
the forecast area. The dominant easterly winds will become more
northeasterly and slight increase by Friday into the upcoming
weekend.

Fragments of shallow low level moisture brought in by the easterly
trades will bring passing showers to the coastal waters. Some
showers will reach portions of the north and east coastal areas of
the islands from time to time but no significant rainfall is
anticipated. During the afternoon local terrain effects and daytime
heating will support isolated to scattered shower development over
Puerto Rico. The showers and isolated thunderstorms if any should be
focused mainly over the central interior and western Puerto Rico.
Mostly sunny skies should prevail elsewhere but an isolated
afternoon shower cannot be ruled out.

Thursday through Friday, more of the same fair weather pattern is
expected with an overall dry airmass and seasonal daytime and
overnight temperatures expected, as high pressure and subsidence
aloft will hold over the region. Nevertheless, quick passing trade
wind showers will remain possible across eastern Puerto Rico and the
U.S. Virgin Islands each morning, followed by limited showers and
only a slight chance of isolated thunderstorm development during the
afternoons across the interior and western Puerto Rico. Afternoon
convection will be mainly due to local sea breeze convergence and
diurnal effects. No significant weather or flooding impacts are
forecast at this time during the period.

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

Ridging aloft accompanied by a strong trade wind cap and drying
at mid-levels will maintain relatively stable weather conditions
on Saturday and Sunday. However, overnight and early morning
trade wind showers streaming over the regional waters into
windward areas nor limited afternoon convection cannot be ruled
out each day. By late Sunday night into early next week, the
ridge is forecast to erode as it is replaced by an upper-level
trough that moves in from the north-northeast. In the meantime, a
broad surface low and tropical wave will increase low-level
moisture convergence over the region, favoring a wetter weather
pattern that could hold through at least mid week. Although there
is medium confidence in this forecast due to timing uncertainties
and dependence on various weather features, interests in the
northeastern Caribbean should monitor this tropical wave since any
development of this system could generate hazardous marine
conditions across the region.


&&

.AVIATION...VFR conds durg entire prd at all terminals. However,
SHRA/ slght chc of Isold TSRA over western PR with brief MVFR psbl
VCTY TJMZ/TJBQ fm 13/17z-13/22Z. Isold SHRA VCTY TJSJ/TJPS durg aftn
til 13/23z. Wnds calm to lgt/vrb bcmg fm E at 10-15 knots with sea
breeze variation til 13/22z. No sig operational wx impacts across
flying area attm.


&&

.MARINE...Tranquil marine conditions with seas up to 5 feet and
east winds up to 15 knots will prevail across most of the regional
waters through late Thursday night, except for the offshore
Atlantic waters where small craft operators are urged to exercise
caution due to seas up to 6 feet. A northeasterly swell is
forecast to arrive and spread across the regional waters Friday
into Saturday. As a result, Small Craft Advisories may be
required, especially for the Atlantic waters and local passages.

There is a moderate risk of rip currents for beaches along the
north coat of Puerto Rico, Culebra and Saint Thomas, as well as
for Cramer Park beach in Saint Croix.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 75 87 76 / 30 30 30 40
STT 87 77 87 77 / 20 30 30 40

[hurricanes1234]

Down here in Trinidad, I can attest to the very dry, hot and uneventful weather produced by this ridging. I'm hoping the approaching low pressure system still manages to bring some rain to the islands.

We've had a lot less rain than usual this year and temperatures have soared to the mid and upper 30's daily. Our reservoirs are currently far from full capacity and with dry season slowly approaching, I'm just hoping the islands can get at least a bit more rain from this rainy season before it ends.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
506 AM AST Thu Nov 14 2019

.SYNOPSIS...Although a generally stable weather pattern is
expected to hold through the weekend, patches of low-level
moisture will bring overnight and early morning showers into
windward areas of Puerto Rico and the U.S. Virgin Islands, as well
as support limited afternoon convection across the interior and
western sections of Puerto Rico each day. By early to midweek next
week, the combination of favorable conditions aloft and enhanced
low- level convergence due to an approaching upper-level trough
and meandering tropical wave will support an increase in shower
and thunderstorm activity across the region. Across the regional
waters...A northeasterly swell is forecast to create hazardous
seas and dangerous surf conditions Friday into Saturday.


&&

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

Upper level ridge will remain over the Central Caribbean Sea and
maintain northwest to north northwest flow over the local area
through Saturday. Mid level dryness persists through the period in
high pressure just west of the area. East northeast flow persists
at low levels as weak low pressure forms deep in the tropical
Atlantic east of the ABC Islands and moves north northwest to just
east of the Windward Islands by late Saturday. This brings in
bands of moisture out of the Atlantic that are a little wetter
each day. Scattered showers are expected overnight and early
mornings in northeast Puerto Rico and the northern U.S. Virgin
Islands, with showers likely in the southwest and interior
portions of the island during the afternoons. Temperatures will
vary little from day to day, but remain at or just above normal
for mid-November. At this time stability and mid level moisture
does not seem favorable for thunderstorms and they have not been
included in the forecast.

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

Model guidance continues to suggest that ridging aloft will
support a strong trade wind cap and drying conditions at mid-
levels that will help maintain relatively stable weather
conditions through at least Wednesday. However, patches of low-
level moisture and the passage of a weak tropical wave will bring
overnight and early morning showers across the waters into
windward areas. Lingering moisture and local effects will support
limited afternoon convection, especially across the western
interior and western sections of Puerto Rico. Ridging aloft is
forecast to somewhat erode as a weak upper-level trough moves
north of the region on Monday, but relatively unfavorable
conditions aloft should persist until a strong upper-level trough
moves in and generates favorable conditions aloft by the end of
the work week. In the meantime, a tropical wave and broad surface
low will increase low-level moisture convergence with model-
estimated precipitable water vapor generally between 1.6 and 1.9
inches, but expected to peak above 2.0 inches by Friday afternoon.
The combination of sufficient low-level moisture and favorable
conditions aloft will favor a wetter weather pattern as early as
Wednesday afternoon with a potential to hold through the end of
the workweek. Although there is medium confidence in this forecast
due to changes in the timing of patches of low-level moisture and
intensity of the aforementioned weather systems in recent model
solutions, interests in the northeastern Caribbean should monitor
the surface low since any development of this system could
generate hazardous marine conditions across the region.


&&

.AVIATION...Sct SHRA from TJNR east...mainly ovr lcl waters will
continue to move west. Ern mtns lcly obscured in cld and ocnl SHRA.
SHRA dvlpg acrs interior/SW PR aft 14/16Z with lcl MVFR and mtn
obscurations there and arnd TJMZ till 14/23Z. All other TAF sites
will have prevailing VFR conds thru 15/12Z. Sfc flow ENE less than
10 kt dominated by land breezes, bcmg aft 14/13Z 5-15 kt with sea
breezes and hir gusts. Max winds NNW 20-30 kt FL300 to abv FL540.


&&

.MARINE...Tranquil marine conditions with seas up to 5 feet and
east winds up to 15 knots will prevail across the regional waters
today. There is a moderate risk of rip currents for beaches along
the north and southeast coast of Puerto Rico, Culebra and Vieques,
as well as for most beaches of Saint Thomas and Saint Croix.

A northeasterly swell is forecast to arrive and spread
across the Atlantic waters Friday into Saturday, resulting in
hazardous seas and dangerous surf conditions. As a result, a
Small Craft Advisory and a High Rip Current Risk will be in
effect by Friday morning.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 76 85 76 / 30 70 60 50
STT 87 77 87 77 / 30 40 40 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
421 AM AST Fri Nov 15 2019

.SYNOPSIS...Patches of low-level moisture will continue to bring
overnight and early morning showers across the local waters into
windward areas. Although ridging aloft will generate unfavorable
conditions aloft, lingering moisture and local effects will still
support the development of showers across the interior and western
sections of Puerto Rico each afternoon. A wetter weather pattern
is expected due to the combination of favorable conditions aloft
and enhanced low-level moisture convergence by early to midweek
next week. Across the regional waters...A northeasterly swell
will create hazardous seas and dangerous surf conditions today
into Saturday.


&&

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

Upper level ridge from SW Caribbean to Hispaniola will move east
over the local area on Sunday. Mid level dryness persists through
the period in high pressure just west of the area. Northeast to
east northeast flow persists at low levels as an inverted trough
near 55 degrees west in the tropical Atlantic moves north and
west, crossing the windward Islands by Sunday afternoon. This
brings in bands of moisture out of the Atlantic that are a little
wetter each day. Scattered showers are expected overnight and
early mornings in northeast Puerto Rico and the northern U.S.
Virgin Islands, with showers likely in the southwest and interior
portions of the island during the afternoons. Temperatures will
vary little from day to day, but remain at or just above normal
for mid-November. At this time stability and mid level moisture is
not favorable for thunderstorms and they have not been included
in the forecast but locally heavy rain is expected in southwest
Puerto Rico that may cause urban and small stream flooding in a
few places.

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

Model guidance continues to suggest that a wetter pattern will
prevail through most of the long-term forecast period with model-
estimated precipitable water values ranging between 1.6 and 1.9
inches. This will be the result of lingering moisture, associated
to a tropical waves and a surface induced trough, confined across
the region between a series of surface high pressure. So far,
shallow shower activity is expected to dominate through the first
part of the next week due unfavorable conditions aloft. However,
environmental conditions are forecast to turn favorable for
deep convection and thunderstorm development by the latter part of
the week of the workweek as an upper- level trough moves in from
the north- northwest and meanders over the region into the
weekend. Nevertheless, any showers or thunderstorms that develop
across the region will be slow-moving and could result in
significant rainfall accumulations. There is medium confidence in
this forecast since model solutions continue to delay the timing
of high moisture content and intensity of the aforementioned
weather systems.


&&

.AVIATION...Sct SHRA ovr lcl waters movg onshore from the NE and
dissipating til arnd 15/14Z. SHRA dvlpg acrs interior/SW PR aft
15/15Z with lcl MVFR and mtn obscurations there and arnd TJMZ till
15/23Z. All other TAF sites will have prevailing VFR conds thru
16/12Z. Sfc flow ENE less than 10 kt dominated by land breezes,
bcmg aft 14/13Z 5-15 kt with sea breezes and hir gusts. Max winds
NNW 25-35 kt FL350 to abv FL450 diminishing aft 15/12Z.


&&

.MARINE...A northeasterly swell will spread across the local
waters today, resulting in hazardous marine conditions. As a
result, a Small Craft Advisory is in effect for the outer Atlantic
waters starting at 2 PM AST this afternoon. In the meantime,
small craft operators are urged to exercise caution across the
Atlantic waters and local passages due to seas up to 6 feet.
Elsewhere, seas up to 5 feet and winds up to 15 knots are
expected.

There is a High Rip Current Risk for the north-facing beaches of
Puerto Rico and Culebra today. As marine conditions continue to
deteriorate, a high risk of rip currents will be in effect for
beaches along the north coast of Saint Thomas tonight. A moderate
risk of rip currents will prevail for beaches of southeastern
Puerto Rico, as well as for most beaches of Vieques and elsewhere
in the U.S. Virgin Islands.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 76 86 76 / 60 60 60 60
STT 87 76 87 77 / 50 40 40 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
518 AM AST Sat Nov 16 2019

.SYNOPSIS...Low pressure advancing toward the area will continue
to bring areas of clouds and showers over the weekend and into
next week. It will split around the area, passing south and north
of the area by Tuesday. An upper level trough will enhance shower
activity on Friday and Saturday of next week when another low
level trough will approach the area, steering moisture in the
lower levels toward the local area Thursday and Friday.

&&

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

A surface induced trough located around 60 degrees west will
continue to maintain a light to moderate northeasterly wind flow
across the region through at least Sunday morning, shifting to a
more easterly flow as the trough moves into the eastern Caribbean by
Sunday afternoon into early next week. Under this flow and triggered
by the trough, overnight and early morning showers will continue to
stream across the local waters into portions of northern and eastern
Puerto Rico and the U.S. Virgin Islands. As the day progresses,
sufficient low-level moisture and local effects will favor the
development of showers across the interior, but favoring
southwestern sectors on Saturday and northwestern sectors on Sunday
and Monday as the winds shift to a more easterly flow. Lack of upper
level support due to ridging aloft and mid-level dryness will limit
the intensity and areal coverage of this activity during the
weekend, but a slight increase in low-level moisture content and
somewhat favorable conditions aloft will allow for a slight increase
of diurnal convection by early next week. Model-estimated
precipitable water vapor values will range around 1.3-1.5 inches on
Saturday and Sunday, increasing to around 1.7-1.9 inches on Monday
afternoon. Although somewhat improved conditions aloft and increased
moisture content are expected, thunderstorm development is not
anticipated during this cycle since model-estimated 500 mb
temperatures will remain at or above -5 degrees Celsius.
Nevertheless, moderate to locally heavy rains resulting from slow-
moving showers may generate localized urban and small stream
flooding each afternoon. Across coastal areas...daytime temperatures
will remain around mid to upper 80s, while overnight low
temperatures will drop into the low to mid 70s each day.

.LONG TERM...Tuesday through Saturday...
The weak low pressure at lower levels will have split into two
parts during the weekend. By Tuesday the more southerly part will
have transited the Caribbean Sea south of us, while the northern
portion will continue moving north and away from the area. This
will leave a weak ridge on Wednesday that rapidly dissolves as
another weak trough over the Lesser Antilles drifts through the
eastern Caribbean, and finally, the local area by Saturday night.
This brings bands of moisture, but also pockets of drier air
through the area. Total precipitable water, however, will peak on
Friday at close to two inches and then fall off.

Mid level dryness will persist through Thursday and return on
Saturday night. The break occurs when a passing trough to our
north at 500 mb weakens the pressure field over the area for a day
or two. Instability also increases then, as 500 mb temperatures
cool and approach minus 7 degrees Celsius.

At upper levels, Tuesday will find a ridge extending northeast
over the local area. It will slide east over the tropical Atlantic
as a sharp trough makes its passage late Friday night.

The combination of the cooler mid levels accompanied by the best
moisture of the week and the approach and passage of the upper
level trough will make Friday and early Saturday the most
unsettled of the period, with scattered to numerous showers.
These showers will likely lead to urban and small stream flooding
in localized areas, but will for the most part will not be
particularly impressive in coverage or amount. Otherwise the
general patter of scattered showers in our typical diurnal pattern
will continue.

Drier weather returns over the weekend that follows.

&&

.AVIATION...
Mainly VFR conditions are expected during the next 24 hours.
However, SHRA moving onshore from the waters will result in VCSH
at TJSJ and TJBQ through at least 16/14Z, and TIST and the Leeward
terminals through the entire cycle. Afternoon convection will
bring VCSH and BKN between FL030-040 to TJMZ and TJPS, resulting
in brief MVFR conditions between 16/16-23Z. Light and variable
winds expected overnight, turning from the ENE between 5-15 knots
after 16/14Z. Maximum winds WNW 25-35 kt btwn FL400-500.

&&

.MARINE...Seas are subsiding. Although the outer buoy--41043--is
still running between 7 and 8 feet, local seas appear to be less
than 7 feet at this time and will let the small craft advisory for
the outer Atlantic waters expire at 8 AM AST this morning. 7 foot
seas are expected again on Tuesday and again on Friday in the
waters just north of our forecast area, but small craft advisories
are not at this time predicted Atlantic waters in our area.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 76 87 76 / 40 50 40 40
STT 89 77 88 76 / 40 40 30 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
506 AM AST Sun Nov 17 2019

.SYNOPSIS...Weak trough passages on Monday and Monday night and
Friday will bring slightly enhanced showers to the local area,
otherwise winds will be light with generally below normal
precipitation and slightly above normal temperatures.


&&

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

Overall, a light low-level steering flow is expected to hold
throughout the short-term forecast period. However, the direction of
this flow will change as various features move across the region.
First, a surface trough, now moving across the eastern Caribbean,
will maintain a northeast wind flow this morning. As this feature
continues to move westward, winds are expected to shift to the east
this afternoon. Then, a surface trough, located east of the
Leeward Islands, and a frontal boundary out of the northeast,
across the western Atlantic, will merge with each other and winds
are expected to shift into a more south-southeasterly flow by
Tuesday morning and hold through the end of this period.

Under the influence of this flow and triggered by the aforementioned
features, overnight and early morning showers are expected to stream
across the local waters into portions of northern and eastern Puerto
Rico and the U.S. Virgin Islands. As each day progresses, sufficient
low-level moisture and local effects will favor the development of
showers across the interior today, but favoring the northwestern
quadrant on Monday and Tuesday. Showers developing downwind from El
Yunque and the local islands cannot be ruled out. An increase in low-
level moisture convergence and the erosion of the trade wind cap
will allow for a gradual increase of diurnal convection during the
next few days.

Model-estimated precipitable water vapor values will peak around 1.5
inches today, rising to around 1.7 and 1.8 inches by Monday and
Tuesday afternoon, respectively. Although somewhat improved
conditions aloft and increased moisture content are expected,
thunderstorm development is not anticipated during this cycle since
model-estimated 500 mb temperatures are expected to remain at or
above minus 5 degrees Celsius. Nevertheless, moderate to locally
heavy rains resulting from slow-moving showers will generate
localized urban and small stream flooding each afternoon. Across
the USVI, only some isolated to scattered shower activity is
expected. Daytime temperatures will remain around mid to upper 80s
across coastal areas, while overnight low temperatures will drop
into the low to mid 70s each day. Slightly higher temperatures are
expected on Tuesday due to the southerly flow.

.LONG TERM...Wednesday through Monday...
After the passage of an upper level ridge on tuesday that moves
into the tropical Atlantic, flow will turn southwesterly Thursday
and Thursday night ahead of an approaching upper level trough.
Previous model runs had been taking this trough through on Friday,
however the latest run of the GFS from 17/00Z shows the trough
stalling over Hispaniola and a low pinching off to the southwest,
with only upper level clouds to show over the local area. The low
pressure is re- absorbed and the high builds back over the local
area over the following weekend.

Mid level dryness still extends through Thursday, but moisture
appears to be more feeble above 850 mb and fades on Saturday.

With lower level lows fading into the distance both to the north
and the west, flow from the southeast flips to the northeast on
Wednesday with the approach of an easterly wave. Pockets of
moisture at lower levels continue to transit through the area but
substantially drier air is forecast to enter the area Saturday
through Monday on the southeast flow behind the trough that
although much weakened should pass through the area on Friday.

This scenario will bring improving weather conditions on Wednesday
and Thursday, with enhanced shower activity on Friday, but
gradual drying Saturday through Monday. Even on Friday, widespread
rains are not expected and amounts will generally light with only
pockets of heavy showers or isolated thunderstorms on Friday as
500 mb temperatures briefly cool below minus 7 degrees.

&&

.AVIATION...Mainly VFR conds are expected during the next 24
hours. However, SHRA moving onshore from the waters will result in
VCSH at TJSJ, TJBQ, USVI and Leeward terminals through at least
17/14Z. Afternoon convection will bring VCSH and ocnl BKN
ceilings between FL030-040 to TJMZ/TJBQ, resulting in brief MVFR
conditions between 17/16-23Z with mtn obscurations. Light and
variable winds expected overnight, turning from the ENE between
5-15 knots after 17/14Z. Max winds W-WNW 20-25kt btwn FL380-490.

&&

.MARINE...Marine conditions have improved over the last 24 hours
and all advisories and cautions have been taken down. Seas will
fade slightly until the next event Monday night and tuesday bring
6 foot seas back to the outer Atlantic waters. Seas in the
caribbean will generally remain between 2 and 4 feet. Small craft
advisories are not expected in the local waters during the next 7
days.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 76 87 77 / 40 30 30 40
STT 88 76 87 76 / 40 30 30 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
526 AM AST Mon Nov 18 2019

.SYNOPSIS...

Passing showers will continue this morning over local waters, some
of which may push onshore over local islands. This afternoon,
sufficient low-level moisture will combine with local effects and
diurnal heating to bring scattered to numerous showers to the
area, especially in western and interior Puerto Rico, though
thunderstorms are unlikely. However, there is the potential that
locally heavy rainfall, and the fact that showers are likely to be
slow-moving could conspire to cause urban and small stream
flooding. This pattern is expected to persist into midweek, after
which an upper-level low moving near Hispaniola could result in
increased shower activity, as well as the potential for a return
of thunderstorms.

&&

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

A weak surface trough will continue to move west and away from the
region today. Moisture associated to the trough is expected to
linger through at least Tuesday with the GFS showing between 1.80 to
near 2 inches of precipitable water. The peak of low level moisture
is today. At upper levels, a weak ridge is building from the west
and is forecast to prevail through at least late Wednesday. Although
no upper level support is expected, scattered to locally numerous
showers are expected to develop due to the combination of the
available moisture, day time heating and sea breeze convergence
along the interior and west/northwest sections of PR. Steering winds
are forecast to remain under 7 knots with an east to southeast
component. This will cause slow moving showers and increase the
potential for urban and small stream flooding. Steering winds are
expected to gradually diminish through Wednesday as an area of low
pressure a few hundred miles east-northeast of the Leeward Islands
is forecast to move north and merge with a frontal system. Diurnally
induced afternoon convection is expected each day over the islands,
with the higher rainfall amounts over the interior and western
portions of PR.

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

On Thursday, there will remain seasonally normal levels of moisture
over the area; however, the bulk of the moisture will be limited to
lower levels of the atmosphere. With this moisture at low levels,
passing trade wind showers are anticipated over local waters, with
some making their way onshore in windward portions of Puerto Rico
and the U.S. Virgin Islands, during the morning hours, and again
overnight. During the afternoon, showers are likely, caused by
local effects and diurnal heating, in southwestern and interior
Puerto Rico with winds out of the northeast, as well as downwind
of the major islands east of mainland Puerto Rico. Stability aloft
is expected to have begun to erode somewhat, as well; with this
in mind, there is the potential for an isolated thunderstorm in
southwestern and/or interior Puerto Rico.

On Friday, a weak upper-level trough to the west of the region will
deepen somewhat, possibly with the development of a cut-off low into
Saturday. With the forecast position of this feature, divergence
aloft is anticipated, which could aid in the development of
afternoon convection, especially over western and interior Puerto
Rico; isolated thunderstorms are possible. Potentially moderating
this influence, however, is a mid-level ridge stretching into the
area from the west. Furthermore, the mid-levels are expected to
remain dry through the weekend, and overall moisture levels are also
anticipated to decrease during this time period. The upper-level
trough is expected to weaken later in the weekend as it pushes over
the region as well. Therefore, the potential for thunderstorms
diminishes into the latter half of the weekend, and into early next
week. Elsewhere in the region, overnight and morning showers remain
likely over the local waters, pushing onshore in windward portions
of the local islands - generally northeastern and eastern
Puerto Rico as well as the U.S. Virgin Islands - through the weekend.

Increasing moisture is expected starting during the day next Monday,
as a weak wave makes its way past the area to the south, pushing
moisture northward. This enhanced moisture will extend well into the
mid-levels of the atmosphere by Tuesday morning. Furthermore,
another weak upper-level trough is forecast to stretch southward to
our west late Monday into Tuesday; though the confidence in the
location of this feature is relatively low, should the guidance from
the GFS be correct, divergence aloft would be anticipated over the
area increasing instability. With this wave to our south, the flow
is expected to generally be out of the east to southeast on Tuesday.
With this in mind, as well as the potential for somewhat more
favorable conditions for convection aloft, showers are forecast for
Tuesday afternoon, caused by local effects and diurnal heating, for
western and interior Puerto Rico, as well as downwind of major
orographic features such as the U.S. Virgin Islands, Vieques,
Culebra, and El Yunque, with the potential for an isolated
thunderstorm here or there.


&&

.AVIATION...

Mainly VFR conditions are expected to prevail across all
terminals through the forecast period. However, MVFR to brief IFR
conditions are possible between 16z-22z at TJMZ/TJBQ due to +SHRA.
RA/VCSH expected at TJSJ/TJPS this afternoon. East-southeast low
level winds expected at 5-10 kt with sea breeze variations after 14z.

&&

.MARINE...

Relatively tranquil conditions continue again today, with seas
generally less than 5 feet. Tomorrow, a small swell from the
northeast will impact the local Atlantic waters, bringing a slight
increase in wave heights. However, at this time, this swell is not
forecast to cause small craft advisory criteria to be met. There
remains a moderate risk of rip currents at north-facing beaches of
mainland Puerto Rico, as well as a low to moderate risk of rip
current at beaches of St. Croix.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 76 87 76 / 30 30 40 30
STT 86 77 86 76 / 20 30 40 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
520 AM AST Tue Nov 19 2019

.SYNOPSIS...

Passing showers continue this morning over local waters, with some
pushing onshore in the east. This afternoon, scattered to
numerous showers are expected again, with isolated thunderstorms
possible as well; peak activity is anticipated for northwestern
and interior Puerto Rico, but showers will be seen elsewhere as
well. Locally heavy rainfall and slow-moving showers are possible
again this afternoon, which could lead to urban and small stream
flooding. A small northeasterly swell is forecast to impact local
waters today and tonight, with hazardous marine conditions in
offshore Atlantic waters expected starting this afternoon.

&&

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

Light east to southeast steering winds will continue through at
least Wednesday as the area remains under the influence of a trough
to the north and a low pressure area a few hundred miles northeast
of the Leeward Islands. A weak ridge aloft is not expected to
inhibit afternoon convection today or tomorrow. Precipitable water
content is expected to continue between 1.50-1.75 inches through the
short term period. As steering winds are forecast to drop under 5
knots today and tomorrow, diurnally induced afternoon showers and
thunderstorms influenced by the sea breezes will cause urban and
small stream flooding, especially over the interior and northwestern
sections of PR each day. Across the rest of the islands, isolated
shower activity is expected. An upper level trough is forecast to
move later on Thursday and an a surface high pressure building over
the southwestern Atlantic will push a frontal boundary and
associated low level moisture under a moderate east to northeast
steering wind flow across the region. This will favor an advective
pattern along the northern portions of PR and across the USVI during
the morning hours, followed by afternoon convection over the
interior and southwestern sections of PR.

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

There will remain enhanced moisture across the forecast area on
Friday, under the effects of the tropical wave merging with a mid-
latitude trough to our north/northeast. Meanwhile, an upper-level
trough is forecast to be in place over Hispaniola; this suggests
decreasing stability aloft, with upper-level divergence could
bolster convective activity. As such, showers are expected during
the afternoon, with isolated thunderstorms, especially in western
and interior Puerto Rico. Scattered showers are also possible
downwind of the major islands east of mainland Puerto Rico.

Decreasing moisture is expected through the weekend, mostly at mid-
and upper-levels. At low-levels, patches of moisture continue to be
carried into the region, embedded in the trade winds. Sufficient
moisture is expected to allow for the development of passing showers
overnight and into the morning, as well as for afternoon showers
caused by local effects and diurnal heating. At the same time,
conditions aloft will become less favorable to convective activity
as the upper-level trough sweeps over the area to our east, putting
us on the subsidence side of the feature. Associated with this
change is a decrease in potential for thunderstorm activity through
the weekend and into early next week.

On Tuesday, an increase in moisture is anticipated. However, model
guidance has backed off on the amount of moisture expected, as well
as its vertical extent... The majority of the moisture is forecast
to remain in the low to lower-mid-levels. Some weak troughing
develops in the upper-levels to our west late Monday into Tuesday,
as well. These factors are likely to combine with local effects and
diurnal heating to cause afternoon showers and the potential for an
isolated thunderstorm here or there. The flow is expected to be
generally out of the southeast, placing the peak level of activity
in northwestern and interior Puerto Rico, and there is the potential
for streamers downwind of major orographic features. This enhanced
shower and convective activity may be relatively short-lived, as the
upper-level trough makes its way eastward over the local islands,
decreasing support aloft for convection, while moisture begins to
slowly decrease slightly during the midweek.

&&

.AVIATION...

Mainly VFR conditions are expected to prevail across all
terminals through the forecast period. However, MVFR to brief IFR
conditions are possible between 16z-22z at TJMZ/TJBQ due to
TSRA/SHRA. Also, RA/VCSH expected at TJSJ/TJPS through this period.
East-southeast winds expected at 5-10 kt with sea breeze variations
after 14z.

&&

.MARINE...

In the outer Atlantic waters, a small northeasterly swell will bring
hazardous marine conditions, starting this afternoon and lasting
until 2 am AST tomorrow. Coastal Atlantic waters as well as portions
of the Anegada Passage are also expected to see a rise in wave
heights due to this swell, but seas are not expected to reach the
advisory criteria in those areas. Elsewhere, relatively tranquil
marine conditions will continue today, with wave heights up to 3
to 5 feet. There is a moderate to high risk of rip currents at
northern beaches of mainland Puerto Rico. Northern beaches of St.
Croix and Culebra have a moderate risk of rip current, and there
is a low to moderate risk of rip current at the beaches of St.
Thomas.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 77 87 77 / 40 30 20 30
STT 86 77 86 77 / 40 40 20 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
508 AM AST Wed Nov 20 2019

.SYNOPSIS...

Active weather will continue today and for the next few days.
Light steering winds and the potential for locally heavy rainfall
and thunderstorms bring a persisting risk of localized urban and
small stream flooding, especially in areas that have already seen
copious quantities of rain over the last several days. The
northerly winds expected today into the latter half of the week
will see decreasing temperatures over the local islands. In the
local waters, another northeasterly swell is forecast to arrive
tomorrow night.

&&

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

Light northerly steering winds will prevail today as the region
remains under the influence of Tropical Storm Sebastien located a
few hundred miles northeast of the Leeward Islands and a trough
north of Hispaniola. This wind flow will bring shallow moisture and
passing showers with minor rainfall accumulations over portions of
the USVI and the northern sections of PR through the day. Sea breeze
variations along the southern coast will aid in the development of
afternoon convection along the Cordillera Central and the southern
slopes of PR. Soils across some areas are saturated from previous
days rainfall and any heavy shower today could lead to urban and
small stream flooding.

Although moisture content is forecast to gradually decrease during
the next few days, the 500mb temp is forecast to reach -7 degrees C
as an upper level trough moves from the west later on Thursday and
on Friday. Meanwhile a ridge is expected to build over the western
Atlantic and into the local area by the end of the short term
period. This will increase the trade winds and bring the remnants of
an old frontal boundary across the region. Brisk northeasterly
trades and an advective pattern should bring down by a few degrees
the max temps on Friday.

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

On Saturday, a large ridge to our northwest will act to inhibit
the amount of moisture that makes its way over the area from a
weak broad trough that is forecast to be to the southeast. Aloft,
a cutoff upper-level low is anticipated over the western
Caribbean; this will likely keep the environment somewhat
favorable for convection. Sufficient moisture is anticipated at
low levels to aid in the development of showers and isolated
thunderstorms due to local effects and diurnal heating, especially
in western, southwestern and interior Puerto Rico, though showers
remain possible elsewhere.

On Sunday, the winds are forecast to become more east-
northeasterly, and patches of moisture embedded in the trade winds
will begin to filter into the region, and will continue to do so
through Monday. The upper-level low to our southwest is expected
to weaken, leaving a lingering weak trough to the west of the
local islands. This trough will make its way across the area
Monday as it continues to weaken, and there will be decreasing
favorability for convection. Passing showers are possible over
local waters and windward portions of the islands during the
overnight and morning hours both days. Sunday afternoon, showers
are expected, with the peak activity over western and interior
Puerto Rico, and a risk of isolated thunderstorms. Showers are
expected again on Monday, with the most-affected area being
northwestern and interior Puerto Rico as winds shift to out of the
southeast.

Tuesday will bring increased moisture to the area as a weak
disturbance passes by the forecast area to the south. At the same
time, a small upper-level trough is expected to be near
Hispaniola. These features will serve to enhance afternoon shower
and convective activity. Showers and isolated thunderstorms due to
local effects and diurnal heating are most likely over
northwestern and interior Puerto Rico, though other areas will
still see showers, especially downwind of major orographic
features, such as the major islands east of mainland Puerto Rico,
and El Yunque. This enhanced shower and thunderstorm activity may
be relatively short-lived, as the upper-level trough progresses
eastward over the local islands, decreasing support aloft for
convection, while, at the same time moisture levels decrease for
Wednesday. Patches of moisture, generally in the lower levels of
the atmosphere, will continue to stream into the area on the trade
winds Wednesday and Thursday. Winds are expected to shift to out
of the northeast during this time as well. Passing showers are
possible during the overnight and morning hours both days over the
local waters, with some pushing onshore in windward areas of the
local islands. During the afternoons, thunderstorms again seem
less likely; but, showers are still likely due to local effects
and diurnal heating, especially in western and interior Puerto
Rico.

&&

.AVIATION...

Mainly VFR conditions are expected to prevail across all
terminals through the forecast period. However, MVFR to brief IFR
conditions are possible between 16z-22z at TJMZ/TJPS due to
TSRA/SHRA. Light winds with a northerly component are expected to
prevail with sea breeze variations after 14z.

&&

.MARINE...

Marine conditions are improving in the offshore Atlantic waters, as
the swell from yesterday subsides. Seas are expected to be around
4 to 6 feet in Atlantic waters today, and up to 3 to 5 feet in
the Caribbean. Another northeasterly swell is expected to arrive
overnight tomorrow night or early on Friday morning; hazardous
marine conditions are currently forecast for local Atlantic waters
associated with this swell, lasting through the weekend. There
remains a moderate to high rip current risk at northern beaches of
Puerto Rico today, with a low to moderate risk at the beaches of
the U.S. Virgin Islands and Culebra.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 78 86 77 / 20 30 30 50
STT 86 78 86 77 / 30 30 30 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
536 AM AST Thu Nov 21 2019

.SYNOPSIS...

Passing showers continue over local waters, pushing onshore in
northern portions of the local islands this morning. This afternoon
will bring active weather, similar to yesterday, with the greatest
shower and thunderstorm activity in southern Puerto Rico. A front is
expected to push by the region, bringing slightly cooler
temperatures for the end of the week. Decreasing shower and
convective activity is expected as we head into the weekend, picking
up again early- to mid-week next week. A northerly swell is expected
to bring hazardous seas to local Atlantic waters and passages, which
will last well into the weekend.

&&

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

Tropical Storm Sebastien located a few hundred miles northeast of
the Leeward Islands and a cold front north of Hispaniola and across
the central Atlantic will continue to promote north to northwest
winds today. A low to mid level ridge building behind the front will
promote a moderate to fresh north to northeast wind flow later
tonight and through Saturday. This wind flow will push the remnants
of the front across the islands to promote an advective pattern,
with showers increasing along the northern half of Puerto Rico
tonight into early Friday morning. At upper levels, a trough
extending from the western Atlantic into the central Caribbean is
expected to move over and to the northeast of the region through
early Saturday.

For this afternoon, under the influence of the northerly wind flow
and the sea breeze over the coastal sections of southern PR, showers
with isolated thunderstorms are expected to develop once again,
causing urban and small stream flooding along the southern slopes of
PR. For Friday, moisture content is expected to gradually decrease
as the remnants of the front are pushed over the Caribbean waters,
and the building ridge promotes drier air and fair weather
conditions that are to persist into the weekend. Slightly cooler
temperatures are expected during this period.

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

A relatively dry air mass will be in place on Sunday, with a strong
ridge to the northwest. Local effects and diurnal heating are still
likely to lead to the development of afternoon showers, especially
in western and interior Puerto Rico. Moisture will increase slightly
on Monday and Tuesday as patches of moisture are carried in on the
trade winds; a disturbance passing by the region to the south is
unlikely to provide significant moisture to the area. Aloft, an
upper-level trough is expected to move over the area and to the east
Sunday and Monday. A weak upper-level trough is forecast to set up
near Hispaniola Tuesday. These features are likely to result in
convergence aloft for Sunday and Monday, leading to conditions
unfavorable for convection; therefore, thunderstorms are unlikely.
On Tuesday, conditions will become less unfavorable. Afternoon
showers are likely both Monday and Tuesday, due to local effects and
diurnal heating, especially in western and interior Puerto Rico;
there is the potential for isolated thunderstorms as well on
Tuesday. Elsewhere in the local islands, there is the potential for
afternoon showers downwind - northwest - of orographic features,
including the major islands east of mainland Puerto Rico as well as
El Yunque.

On Wednesday, the remnants of an old frontal boundary will make
their way into the area. Meanwhile, the aforementioned upper-level
trough over Hispaniola will be absorbed by a stronger one making its
way into the area. As such, divergence aloft is anticipated, which
will aid in the development of afternoon convection. Afternoon
showers with the potential for isolated thunderstorms is expected,
especially in western and interior Puerto Rico. For Thursday,
conditions favorable for convection are forecast to persist, and
once again scattered showers are anticipated for the afternoon, with
isolated thunderstorms, especially in southwestern and interior
Puerto Rico, as well as possibly downwind of orographic features.
Friday will see the upper-level trough pushing east of us, and
conditions aloft will become increasingly unfavorable for
convection. Afternoon showers caused by local effects and diurnal
forcing are still expected, and the potential for an isolated
thunderstorm here or there cannot be ruled out, especially in
southwestern and interior Puerto Rico.


&&

.AVIATION...

Mainly VFR conditions are expected to prevail across all
terminals through the forecast period. However, SHRA under a
northerly wind flow across the Atlantic waters will move at times
across the northern PR terminals and across the USVI terminals
through the forecast period. MVFR to brief IFR conditions are
possible between 16z-22z at TJPS due to TSRA/SHRA. Northerly winds
are forecast to prevail between 7-14 kts with the exception of a
light southerly sea breeze at TJPS after 14z.

&&

.MARINE...

A northerly swell pushing into the area later today will see
increasing wave heights through Friday morning in Atlantic waters
and local passages. Hazardous marine conditions are expected for
these areas, lasting into the weekend; in offshore Atlantic waters
they are forecast to persist into Sunday night. There is a high
risk of rip currents at northern beaches of mainland Puerto Rico
today. At the beaches of Vieques, the risk is moderate; in the
U.S. Virgin Islands and Culebra, there is a moderate to high risk
of rip current.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 77 84 75 / 50 50 20 20
STT 86 76 85 75 / 50 50 30 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
411 AM AST Sat Nov 23 2019

.SYNOPSIS...

Relatively tranquil weather conditions are expected to prevail
over the next several days. A high pressure to the north and a
weakening frontal boundary to the south of Puerto Rico will cause
an increase in winds through the weekend. A few showers are
possible during the afternoon as a result of local and diurnal
effects. Early next week moisture is expected to lift from the
Caribbean waters across Puerto Rico, and increase rain chances
through Wednesday.

&&

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

The frontal boundary has left a relative stable and dry air mass
over Puerto Rico and the U.S. Virgin Islands. TPW of 1.35 inches was
recorded last night (23/00z), which is below the 25th percentile for
November climatology. Although stable and dry weather conditions
will prevail, passing showers, mainly over the windward sections,
should not be ruled out today and Sunday. A high pressure moving
westward across the Atlantic Ocean will promote a moderate to fresh
northeasterly wind flow across the northern and elevated sections of
Puerto Rico, and the U.S. Virgin Islands. This wind flow and a dense
layer of mid-level clouds will promote pleasant temperatures
throughout the weekend.

For Monday, high pressure moving into the Central Atlantic will
bring a moist E-ESE wind flow across the islands. Although, moisture
and showers are expected to increase, this activity will be
shallow due to the presence of a mid-level-High pressure.

&&

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

Tuesday and Wednesday, current guidance shows moisture associated
with the frontal boundary in the southern Caribbean which has gone
through frontolysis moving northward across Puerto Rico. The GFS as
well as the EURO model shows this boundary draped over Puerto Rico
through Wednesday. The boundary will increase low to mid-level
moisture across the region, and combine with local and diurnal
effects to develop showers during the afternoon. Thunderstorm
development is not likely due to modest 500 mb temperatures and
divergence aloft, however, an isolated thunderstorm can`t be ruled
out. Wednesday afternoon the moisture begins to wane before falling
to 1.1 inches which is near 2 standard deviations below normal for
this time of the year. Also, a shortwave trough is forecast to
developed, and deepen across the central Atlantic waters, and cause
weak troughiness aloft across the region. This feature will continue
to move to the east before phasing out across the central Atlantic
waters.

Thursday through Friday, the GFS and Euro has a slight drying trend
with a few patches of moisture embedded in the easterly trades
pushing over the area from time to time. Friday afternoon guidance
shows moisture increasing as patches of moisture move into the
region. During the afternoons shower activity will be driven by
local and diurnal effects; with relatively light rainfall
accumulations. Late Saturday into early Sunday morning both the GFS
and Euro have a cold front across the Atlantic waters moving into
northern areas of Puerto Rico. If this scenario materializes it will
increase rain chances as well as winds across Puerto Rico. At this
time it`s best to take a wait and see approach, and see if the GFS
and Euro continue to show this solution over the next several days.
Nevertheless, showers will develop during the afternoons across the
western and interior and areas of Puerto Rico during the long-term
period. While scattered to isolated showers are possible during the
mornings hours across the U.S Virgin Islands and eastern Puerto
Rico. Additionally, marginal instability and relatively limit
moisture will inhibit thunderstorms development during the
afternoons. This is depicted by the GFS and EURO 500 mb temperatures
with values only reaching minus 6 degrees Celsius on Wednesday,
while other days the 500 mb temperatures are forecast to remain
above minus 5 degrees Celsius.

&&

.AVIATION...

VFR conds will prevailed through most of the forecast
period. N-NE winds between 10 and 15 knots with brief gusty winds
will continue today. -SHRA/SHRA and ceilings btwn FL050-FL070 should
not be ruled out at times, mainly across the windward sections. In
general, fair and stable weather conditions will prevail.

&&

.MARINE...

A weakening northerly swell will continue to cause hazardous seas
of up to 7 to 8 feet across the Atlantic waters and local passages
through early Sunday morning. Thus, a small craft advisories are
in effect. Also, there is a high risk of rip currents for the
northern, northwestern beaches of Puerto Rico, and the northern
beaches of Culebra and Saint Thomas.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 85 73 85 75 / 10 20 30 20
STT 87 75 83 78 / 10 10 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
424 AM AST Sun Nov 24 2019

.SYNOPSIS...

Mostly quiet weather is expected today with a few showers possible
during the afternoon. Southerly flow on Monday will pull moisture
from the Caribbean across the region, and increase rain chances.
During the middle of the workweek scattered to isolated showers
are possible during the afternoons due to local and diurnal
effects.

&&

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

A ridge aloft will continue to promote dry air at mid and upper
levels today. This will inhibit the vertical development of showers
across the islands. A surface high pressure moving across the
Atlantic Ocean will promote an easterly wind flow and cool air
advection. As a result, pleasant temperatures, stable and fair
weather conditions will continue in Puerto Rico and the U.S. Virgin
Islands. Afternoon convection, if any, will be shallow and limited
to portions of the western PR. But, passing showers should not be
ruled out over the windward sections of E-PR/USVI.

Model guidance has backed off, and now the increase in moisture
should begin later on Monday afternoon/evening. Therefore, a similar
weather pattern is forecast for the first part of Monday. The
increase in moisture associated with a trade-wind perturbation will
enhance the potential for shower development late Monday
afternoon/evening into Tuesday. The lack of upper-level support will
continue to inhibit vertical development, consequently, the
intensity and areal coverage of this activity.

&&

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

Long-term guidances continues to show a relatively quiet period with
a few passing showers over the U.S. Virgin Islands and eastern
Puerto Rico during the morning. Followed by isolated to scattered
showers during the afternoons across northern, interior, and western
areas of Puerto Rico. The shower activity will be driven by local
and diurnal effects. Thursday, morning surface and 700 mb winds will
be mainly from east to northeast. This will lead to shallow moisture
from the Atlantic moving into the region from the north. The GFS and
EURO models continues to depict marginal instability and relatively
limit moisture which is needed for thunderstorm development.
Therefore, thunderstorms where not put in the long-term forecast.

Wednesday, guidances continues to show a weak trough passing through
the area, then deepening across the central Atlantic on Thursday.
Moisture from the Caribbean is forecast to lift north across Puerto
Rico; the added moisture will aid in the development of isolated to
scattered showers during the afternoon. Late Wednesday night the GFS
and EURO shows a drier air mass filtering into the region from the
central and eastern Atlantic waters. The GFS has precipitable water
values peaking at 1.72 Wednesday afternoon, then falling through the
remainder of the day. Similar to yesterday`s guidance the GFS and
EURO keeps 500 mb temperatures warm and shows limited divergence
aloft. Therefore thunderstorm development is not anticipated at
this time.

Thursday through Friday, the GFS and Euro has a slight drying trend
with a few patches of moisture embedded in the easterly trades
pushing over the area from time to time. During the afternoons
shower activity will be driven by local and diurnal effects; with
relatively light rainfall accumulations. The next weather maker for
the area will be a front that guidance shows moving into the western
Atlantic on Thursday. Current guidance shows several jet streaks
with winds ranging from 115 to 140 kts will round the base of the
trough Friday through Saturday. The jet streaks will help deepen the
trough with a frontal passage across Puerto Rico possibly late
Saturday night or early Sunday morning. If the frontal passages
comes to fruition this could lead to the development of
thunderstorms as a result of increased instability and upper-level
forcing. At this time the current thinking is scattered to isolate
showers will develop during the afternoons mainly across northern,
interior, western areas of the islands.

Monday, southeast winds will draw moisture from the southern
Caribbean waters across the U.S. Virgin Islands and Puerto Rico.
This will result in an increase in showers across the region on
Monday.

&&

.AVIATION...

VFR conds will continue across the local flying area.
Passing -SHRA/SHRA should not be ruled out at times, mainly across
JSJ/IST/ISX/NCM/KPK thru the fcst period, and across JBQ/JMZ during
the afternoon. But, fair and stable weather conditions will prevail.
Calm to light/vrb winds, returning from E-ESE at around 10kt with
sea breeze variations.

&&

.MARINE...

Seas will continue to improve across the region as the northerly
swell continues to dissipate over the area. Today seas up to 5
feet with easterly winds of 10 to 15 kts. Small craft operators
are urged to exercise caution. There is a high risk of rip
currents for northern beaches of Puerto Rico today.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 75 89 75 / 10 20 30 40
STT 86 78 87 78 / 10 30 30 40