Caribbean - Central America Weather

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
505 AM AST Sun May 22 2022

.SYNOPSIS...

The Saharan dust concentration will slowly diminish throughout the
day. Today, a surface high pressure across the North Atlantic
Ocean will promote an easterly to northeasterly wind flow. Today
we have a better chance to observe scattered showers across the
windward sections of Puerto Rico and the U.S. Virgin Islands,
followed by afternoon convection across the interior and western
PR. A TUTT with shortwave perturbations will increase instability
early this week.

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

Surface analysis showed a high pressure over the western Atlantic.
This feature is inducing an east-northeastflow across the region.
Saharan dust is still present in our area but concentrations are
forecast to diminishlater today. In terms of moisture, GOES
Precipitable Water analysis indicated moisture levels near normal
about 1.5-1.6 inches upstream of the U.S. Virgin Islands. Also
latest TJSJ sounding suggests that the trade wind inversion has
weakened in the last 12 hours. As a result, conditional instability
has increased across the Northeast Caribbean due to less Saharan
dust, additional moisture, and a jet segment aloft. Based on these
factors, conditions have become more favorable for scattered showers
since midnight. For this morning, expect a few trade winds showers
affecting portions of the Virgin Islands and eastern Puerto Rico at
times. However, afternoon showers will likely be more intense and
last longer than yesterday due to additional instability and a
strong sea breeze convergence. Isolated thunderstorms can be
possibleonce again today, especially over the western interior and
west portions of Puerto Rico.

An upper trough/TUTT will deepennortheast of Puerto Rico and the
U.S. Virgin Islands early in the week.As this upper-level feature
remains near stationary to our northeast, a series of short-wave
troughs in the periphery of the TUTT will provide additional
instability to the region. This setup will favor an enhancement of
the trade wind showers each morning as well as strong thunderstorm
development during the afternoon hours. Although moisture remains
near normal, periods of heavy rainfall could lead to urban and small
stream flooding on Monday and Tuesday afternoons.

.LONG TERM...WEDNESDAY THROUGH SUNDAY...

The TUTT-low mentioned above and a shortwave trough will enhance
the trade wind showers early in the morning and the afternoon
convection. The TUTT-low is forecast to linger near the Northeast
Caribbean through Friday or Saturday. GFS/ECMWF has some
discrepancies on how fast this feature moves away from the region.
On Wednesday, a surface low over the Central Atlantic will relax
the local pressure gradient. However, a surface high pressure
moving from North America into the Western Atlantic will tight the
local pressure gradient again, increasing the winds from Thursday
onward.

Under the weather pattern mentioned above, expect scattered to
numerous passing showers with periods of moderate to locally heavy
rains overnight and early in the morning across the local waters,
the U.S. Virgin Islands, and eastern Puerto Rico each day. This
activity will be followed by afternoon convection across the
interior and western sections during the afternoon, where isolated
to scattered thunderstorms could develop each day. Urban and small
stream flooding will remain possible with the heaviest activity.

&&

.AVIATION...

VFR conditions will prevail thru the forecast period.
SHRA and ISOLD TSRA possible near TJMZ between 17Z-22Z. Mountains
obscurations are also possible over the western interior of Puerto
Rico. E to ENE winds will continue at 15-20 kt with higher gusts.
Hazy skies will continue but visibilities will improve as the day
progresses due to lower concetrations of Saharan dust.

&&

.MARINE...

A northerly swell will slowly fade through tonight. Mariners can
expect seas up to 5 feet and winds out of the east around 15
knots with higher gusts. However, local effects and sea breeze
variations will result in wind speeds between 15 and 20 knots
across the Atlantic Coastal waters. Winds are forecast to increase
by mid-week.

There is a high rip current risk for many of the north facing
beaches of Puerto Rico from Arecibo to Dorado.

&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
500 AM AST Mon May 23 2022

.SYNOPSIS...Relatively unstable conditions are forecast over the
next few days under the influence of an upper level trough/TUTT.
Surface high over the western Atlantic is supporting moderate
trade winds across the local islands. Max temperatures for the
week will be near normal, with highs in the upper 80s.

&&

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

Residents in Puerto Rico and the U.S. Virgin Islands can expect the
islands to move to a more unstable and wetter pattern than last
week. Expect more frequent passing showers moving across the
windward sections each day, followed by organized convection across
the interior and western areas.

Afternoon showers and thunderstorms will likely be more intense and
long-lasting due to a TUTT combined with a set of short wave
troughs, which are forecast to increase atmospheric instability,
especially today and Wednesday. Some instability parameters that
indicate favorable conditions for the formation of organized
convection are near to below-normal 250MB Heights, steep lapse rate
at low and mid-levels, below-normal temperatures at 500MB, the
disappearance of the trade wind cap, and MU CAPE ranging between
1500 and 2300, especially in the afternoon. Therefore, we are
anticipating the formation of thunderstorms, especially each
afternoon across the interior and western sections of Puerto Rico.
Also, we cannot rule out thunderstorm formation across the local
waters each night. This activity will produce periods of heavy
rainfall leading to urban and small stream flooding each afternoon.

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

An upper-level low/TUTT northeast of Puerto Rico and the U.S.
Virgin Islands will dominate the weather conditions. The proximity
of the TUTT will provide colder temperatures aloft, increasing the
instability late in the workweek. Although moisture will remain
near normal for this time of the year, high convective instability
associated with the TUTT will combine with the sea breeze convergence
to fuel afternoon showers and thunderstorms along the Cordillera
Central and western Puerto Rico. Aerosol models suggest some Saharan
Dust Thursday and Friday. This will limit the shower coverage but
the dust particles may enhance the thunderstorm activity as
concentrations are forecast to remain low. Another high pressure
builds over the western Atlantic late in the week into the
weekend, allowing the trade winds to veer from the east-southeast.
A drier and more stable pattern is possible during the weekend as
the upper-level trough moves away from the region. This will likely
result in mostly sunny conditions and warmer than normal temperatures
under a southeasterly flow from Saturday into early next week.

&&

.AVIATION...VFR conditions will prevail through much of the forecast period.
However, at times, quick passing SHRA with moderate to heavy rain
periods could lower VIS at JSJ/IST/ISX. TSRA will also form across
the mountain areas of PR and near JBQ during the afternoon, where
mountain obscurations are also expected. Expect calm to
light/variable winds overnight, returning from the E-ENE at 10-15 kt
with higher gusts and sea breeze variations after 23/13z.

&&

.MARINE...Moderate easterly winds of 10-15 kts and seas of 2-4
feet can be expected across the Atlantic and Caribbean waters most
of the week. Unstable conditions will increase the potential for
showers and thunderstorms across the regional waters. Moderate
risk of rip currents will continue for most of the beaches in
Puerto Rico and the U.S. Virgin Islands.

&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
518 AM AST Tue May 24 2022

.SYNOPSIS...Unstable conditions are forecast most of the workweek
under the influence of an upper level trough/TUTT. Surface high
over the western Atlantic is supporting moderate trade winds across
the local islands. Conditions will improve somewhat during the
weekend as upper level trough weakens resulting in more stable
pattern.

&&

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

Expect a wet and unstable weather pattern throughout the rest of
the workweek with shower and thunderstorm activity as a TUTT
amplify near Puerto Rico and the U.S. Virgin Islands. Showers will
move across the windward sections through the morning, and then
they will move into the interior and western Puerto Rico. Urban
and small stream flooding is expected with the heaviest activity.
Yesterday`s rainfall activity saturated the soils across the
Western Interior municipalities, and therefore persistent rains
over those areas could trigger mudslides.

Unstable atmospheric conditions will last through the short-term
period as the TUTT mentioned above linger near the islands. In
addition, GFS continues to bring a jet maxima between 40 and 60
knots, especially Wednesday and Thursday. Temperatures at 500 MB
are forecast to remain between -8 to -9 degrees Celsius. Moisture
will remain near normal to slightly above average values,
providing better potential to observe scattered to numerous
showers and isolated to scattered thunderstorms. Most
meteorological guidance suggests scattered to widespread rain
activity through Thursday. Please remain vigilant to the products
issued by your National Weather Service because the potential to
observe urban and small stream flooding will increase each day.
Also, if heavy rainfall events or downpours persist, rapid river
rises and mudslides will be more likely, especially across steep
terrains.

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

The aforementioned upper-level/TUTTwill move eastward and away
from the local region on Friday. However, a short-wave trough will
follow maintaining the conditions fairly unstable. Moisture
levels remain near normal, enough to sustain scattered to numerous
showers over the Cordillera Central and western Puerto Rico
during the afternoon. Thunderstorm potential diminishes somewhat
from scattered to isolated for Friday afternoon as 500mb returns
to normal around-7 C. NASA GEOS-5 aerosol model suggests low
concentrations of Saharan Dust that could result in isolated but
explosive thunderstorms on Friday afternoon hours.

During the weekend, a broad high pressure builds over the western
Atlantic allowing the trade winds to veer to the east-southeast.
A drier and more stable pattern is forecast for Saturday and
Sunday as the short-wave trough aloft weakens. As a result, the
shower and thunderstorm coverage will likely diminish compared to
the workweek. Next week, plenty of low-level moisture will favor
trade wind showers each morning across portions of the U.S. Virgin
Islands and eastern Puerto Rico, followed by the typical
afternoon convection over western Puerto Rico during the
afternoon.

&&

.AVIATION...VFR conditions will prevail through much of the
forecast period. However, at times, quick passing showers with
moderate to heavy rain periods could lower VIS at JSJ/IST/ISX.
TSRA/+TSRA are likely this afternoon across the mountain areas of
PR and near JBQ/JPS, where mountain obscurations are also
expected. Expect calm to light and variable winds overnight,
returning from the E-ENE at 13-18 kt with higher gusts and sea
breeze variations after 24/13z.

&&

.MARINE...Moderate easterly winds of 10-15 kts and seas of 2-4
feet can be expected across the Atlantic and Caribbean waters
first part of the week. Then, a small northeasterly swell will
reach the local Atlantic waters increasing the seas to 3-5 feet
the second part of the week. Showers and thunderstorms are
possible across the regional waters most of the work week due to
the influence of an upper level trough. Moderate risk of rip currents
will continue for most of the beaches in Puerto Rico and the U.S.
Virgin Islands.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 76 88 76 / 40 60 60 60
STT 87 76 87 76 / 40 50 50 60

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
411 AM AST Wed May 25 2022

.SYNOPSIS...Unstable weather conditions will prevail across the
local area until the end of the workweek. Showers and
thunderstorms are expected once again along the central interior
and western Puerto Rico. A small northerly swell is expected to
move across the local waters, increasing the risk of rip currents
for the north-facing beaches of Puerto Rico.


&&

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

The wet and unstable pattern will continue due to the proximity of a
TUTT aloft. Therefore, expect showers and thunderstorms across
Puerto Rico and the U.S. Virgin Islands under the typical May
weather pattern with passing showers across the windward sections
through the morning, moving into the interior and western Puerto
Rico and downwind from the Virgin Islands in the afternoon. Also,
the land breeze and the prevailing northeast wind flow will enhance
showers and thunderstorms along the Atlantic Coastal waters of
Puerto Rico overnight. The heaviest activity will result in urban
and small stream flooding. Also, as rainy conditions persist, rapid
river rises and mudslides in affected areas cannot be ruled out in
the coming days.

The lingering TUTT will maintain unstable atmospheric conditions.
Model guidance has been consistent, indicating a jet stream between
50 and 60 knots, especially today and Thursday (TJSJ 25/00z sounding
observed it last night). Cold temperatures at 500 MB (between -8 to -
9 degrees Celsius) will promote the formation of thunderstorms.
Moisture will remain near normal to slightly above average values,
providing better potential to observe scattered to numerous showers
and isolated to scattered thunderstorms. Most meteorological
guidance suggests scattered to widespread rain activity through
Thursday. Please remain vigilant to the products issued by your
Weather Forecast Office in San Juan because the potential to observe
urban and small stream flooding will remain high.

Although the TUTT will move farther away from the region, leaving
the islands on its subsidence side by Friday, another shortwave
trough is forecast to swing by the islands during the maximum
daytime heating providing additional instability. This feature,
combined with local effects and sea breeze, could produce another
round of showers and thunderstorms on Friday.

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

As an upper level trough moves away from the local area, a
building high pressure in the western Atlantic will be in charge
of promoting fair weather conditions to the local islands. This
system will allow trades winds form the east-southeast. As a
result, expect morning showers across the U.S. Virgin Islands, and
eastern sectors of Puerto Rico from time to time. Much drier air
will filter into the region, leading to warmer temperatures along
Puerto Rico and the U.S. Virgin Islands. Nonetheless, because of
the daytime heating and local effects the atmosphere will be
conductive for mid-afternoon convection and will feed the
development of shower activity and isolated thunderstorms across
the interior, western and northwestern Puerto Rico. Streamers also
cannot be ruled out to form over El Yunque are and moving over
the metropolitan area of San Juan. Overall, fair weather
conditions likely to prevail.

&&

.AVIATION...VFR conds will prevail through much of the fcst prd. However,
SHRA/+SHRA will sometimes lower VIS at JSJ/IST/ISX, especially
around noon. TSRA/+TSRA will form this afternoon across the mountain
areas of PR, near JBQ/JPS, and downwind from the USVI (btwn 25/17z-
22z). Mnt obsc are also expected across the Cordillera Central and
Sierra de Luquillo. Calm to light, and variable winds will continue
until 25/13z. Winds will return from the E-ENE at 13-18 kt with
higher gusts and sea breeze variations.


&&

.MARINE...A small northerly swell will build seas up to 5 feet
across the Atlantic waters and local passages. Light to moderate
trade winds are expected to prevail until Friday, then are
expected to increase due to a building high pressure in the
central Atlantic. For beachgoers, there is a moderate risk of rip
currents across most of the local beaches. Later today, a high
risk of rip currents will be in effect for the north facing
beaches of Puerto Rico.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 76 88 78 / 60 60 60 60
STT 87 76 87 77 / 50 60 60 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
424 AM AST Thu May 26 2022

.SYNOPSIS...Rainy conditions with thunderstorms are forecasted
for today along the central interior and western Puerto Rico. This
pattern will linger across the area as an upper-trough moves over
the local area, increasing the potential for urban and stream
flooding. A small northerly swell spreading across the local
waters and passages will maintain a high risk of rip currents for
the north-facing beaches of Puerto Rico and Culebra until at least
Friday.


&&

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

Generally rainy short term period is expected, though each passing
day is expected to be a bit drier than the day before, and most of
the activity is expected to occur during the daytime hours. Urban
and small stream flooding could be expected each afternoon until
Saturday, and strong thunderstorms with frequent lightning and even
possible small hail can`t be ruled out, especially for this
afternoon.

There is a TUTT close to the local area that will maintain some
instability over the area today, but will gradually move away and
weaken. However, a weak upper trough will develop to the west of the
local area on Friday and Saturday, which will continue to promote
instability, just not quite as much as is expected today. There is
also colder than normal temperatures at 500 MB (nearly -9 degrees
Celsius), which normally promotes strong thunderstorms and perhaps
some small hail. Moisture will remain near normal to slightly above
normal, with Precipitable Water values ranging between 1.6 to 1.9
inches, but some areas over the local waters and around the USVI
could reach 2.0 inches. This amount of moisture, combined with the
instability that is expected, would be enough to cause numerous
showers with isolated to scattered thunderstorms across the local
area, especially today. The hi-res guidance is quite bullish in the
amounts of rainfall across many sectors of PR, most of which is
expected starting in the late morning into the afternoon hours.

By Friday, with the weaker upper trough expected to our west,
showers and thunderstorms are also expected in the afternoon,
especially across mainland Puerto Rico, with western PR having the
highest chance of rain, while the USVI may observe scattered showers
and isolated thunderstorms. The 500mb temps will still be colder
than normal, but slightly warmer than today. A similar pattern is
expected on Saturday, but with slightly less moisture, so the
coverage area of showers and thunderstorms is expected to be smaller
than that on Friday.

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

Unstable weather conditions aloft and sufficient moisture will
persist across the local area. More active afternoons can be
expected with the diurnal convective activity. GFS model is
suggesting an active day on Sunday then conditions will start to
improve slowly. A building surface high pressure over the Atlantic
waters will be the main feature, at least for the first half of the
long period. The tightening of the pressure gradient leads to the
acceleration of the trade winds over the Caribbean Basin. In the
low levels of the atmosphere moisture remains nearly saturated and
will provide the necessary fuel for shower activity across the
islands. This pattern will enhance the potential for morning
passing showers over portions the U.S.Virgin Islands and eastern
Puerto Rico from time to time. Daytime heating and local effects
will help for the development of afternoon convection over the
central interior and western Puerto Rico. The latest GFS model
guidance is forecasting another upper level trough and moving into
the local area by the end of the workweek. Patches of moisture
pulled from the Caribbean will place over the islands, enhancing
once again unstable conditions aloft and shower formation. Expect
warmer temperatures and rainy afternoons.


&&

.AVIATION...VCSH is expected at different times through the forecast period. The
USVI terminals may observe VCSH through the entire period, but
occasional -SHRA could affect the terminals. At least VCTS is
expected for the terminals in PR, as TSRA will develop today. No
TEMPO TSRA was put in TAF due to uncertainty on the timing and
location of TS, but TSRA are likely today across PR, possibly
affecting the local terminals. Winds will increase to around 15KT
from the East with sea breeze variations after 26/13Z.


&&

.MARINE...A small northerly swell will continue to build seas up
to 5 feet across the Atlantic waters and local passages. Light to
moderate trade winds are expected to prevail until Friday. Then
are expected to increase due to a building high pressure in the
central Atlantic. For beachgoers, there is a high risk of rip
currents along the north-facing beaches of Puerto Rico, including
Culebra. There is a moderate risk of rip currents elsewhere,
except for some beaches on the west coast of Puerto Rico where the
risk is low.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 76 87 76 / 60 60 50 30
STT 86 75 86 76 / 50 50 40 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
459 AM AST Fri May 27 2022

.SYNOPSIS...Showers and thunderstorms are expected today, as a
short-wave trough maintain conditions favorable for afternoon
convection over Puerto Rico. There is a small northerly swell
spreading across the regional waters and passages. Therefore,
there is a high risk of rip currents for the north-central and
northwest beaches of Puerto Rico and Culebra until at least
late tonight.

&&

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

Showers and thunderstorms are expected through the short term
period, but each passing day is expected to be a bit drier than the
day before. Urban and small stream flooding could be expected each
afternoon, and strong thunderstorms with frequent lightning and even
possible small hail can`t be ruled out this afternoon.

There is a TUTT moving to the northeast and away from the area, but
a weak upper trough is developing to the west of the local area,
which will continue to promote instability. 500 MB temperatures are
colder than normal (nearly -9 degrees Celsius), which could once
again promotes strong thunderstorms and perhaps some small hail.
Moisture, however, will be slightly below normal today, but overall
in the short term period will remain near normal, with Precipitable
Water values ranging between 1.6 to 1.9 inches, though around 1.4
inches today. The available moisture, combined with the instability
that is expected, would be enough to cause numerous showers with
isolated to scattered thunderstorms across the local area,
especially across the northwestern quadrant of PR, with isolated to
scattered showers elsewhere. The hi-res guidance strongly favors
activity across the northwestern quadrant of PR with little rain
elsewhere today.

By Saturday and Sunday, showers and thunderstorms are also expected
in the afternoon, especially across mainland Puerto Rico, with
western PR having the highest chance of rain, while the USVI may
observe scattered showers and isolated thunderstorms. The 500mb
temps will still be colder than normal, but slightly warmer than
today.

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

Relative unstable weather conditions are forecasted for the first
half of the period. A surface high pressure over the central
Atlantic will tight the pressure gradient that will lead to an
acceleration of the trade winds over the Caribbean Basin and the
local area. At 850 mb, moisture content remains nearly saturated,
enhancing the potential for shower activity across the islands.
Bands of moisture along with the trade winds, will be the
responsible for trade wind showers over the windward portions of
Puerto Rico and the U.S. Virgin Islands. Daytime heating and local
effects will help for the development of afternoon convection
over the central interior and western Puerto Rico. GFS latest run
suggest a slightly drier pattern for the second half of the
period with more stable conditions. Warmer temperatures and rainy
afternoons are also expected. Moving towards the end of the
period, tropical moisture pulled from the Caribbean will enter the
local area, enhancing shower and thunderstorm development.

&&

.AVIATION...VCSH is expected at different times through the forecast period. At
least VCTS is expected for the terminals in PR today. No TEMPO TSRA
was put in TAF due to uncertainty on the exact timing and location
of TS, but TSRA are likely today across W-NW PR, and possible
elsewhere. TEMPO will be written as confidence increases. Winds will
increase to around 15KT from the East with sea breeze variations
after 27/13Z.


&&

.MARINE...A small northerly swell will remain across the regional
waters. Hazardous coastal conditions are expected to continue
throughout the weekend. There is in effect a high risk of rip
current for all the north-central and northwestern beaches of
Puerto Rico, including the northeastern beaches of Culebra. Seas
will remain up to 5 feet across the Atlantic waters and up to 4
feet across the Caribbean waters. An increase in winds up to 20
knots is expected by Saturday, mainly over the Caribbean waters.
Therefore, small craft should exercise caution.


&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
422 AM AST Sat May 28 2022

.SYNOPSIS...Unstable conditions are expected today with showers
and thunderstorms expected. Moisture aloft continue near normal,
and a seasonal weather pattern will persist for the next few days.
Marine conditions with seas up to 5 feet and winds up to 20 are
expected today across the regional waters. There is a high risk
of rip currents for the north-central and northwest beaches of
Puerto Rico and small craft should exercise caution.

&&

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

Showers and thunderstorms continue to be expected through the short
term period. Though Sunday looks a bit drier than today or Monday.
Urban and small stream flooding could be expected each afternoon
due to the strong thunderstorms that are forecast.

A weak upper trough over the local area, will continue to promote
instability. 500mb temperatures are still colder than normal (nearly
-9C), which will continue to promote strong thunderstorms and
perhaps some small hail. The 500mb temps are expected to remain
between -8 and -9C through the short term period, while lapse rates
are also expected to be stronger than normal, especially in the 700mb-
500mb level. Moisture will increase slightly today, then decrease
slightly on Sunday, only to increase once again on Monday. The
available moisture, combined with the instability that is expected,
would be enough to cause numerous showers with a few thunderstorms
across the local area, especially across the northwestern quadrant
of PR, with isolated to scattered showers elsewhere through the
short term period. That said, some of the hi-res guidance favors not
only some activity across the northwestern quadrant of PR, but also
some showers and thunderstorms across the north eastern into north
central PR today. However, the hi-res ECMWF is much less bullish
with the rainfall today. Also, the hi-res guidance does not like
much activity on Sunday and Monday. Although Sunday overall looks
drier, the global models are not as dry as the hi-res models, so
there seems to be some uncertainty with regards to rainfall.
However, given the moisture, local effects, and some instability
present, and lack of Saharan dust; it would be difficult to have
completely dry days over the local area. Therefore, isolated to
scattered showers across the general area, including the USVI, with
isolated thunderstorms for western PR are in the forecast for Sunday
and Monday.


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

A surface high pressure over the central Atlantic will maintain the
wind flow from the east-southeast for most of the term, with bands
for a tropical moisture approaching from the Caribbean. A very
seasonal scenario is expected with relative stable weather
conditions. At 850 mb, moisture content remains nearly saturated,
enhancing the potential for shower activity across the islands.
Tightening of the pressure gradient in the low levels from 800 to
700 mb will lead to an acceleration of the trade winds over the
local area. As a result, trade wind showers can be expected every
morning over the windward portions of Puerto Rico and the U.S.
Virgin Islands. Then, due to the wind component from the east-
southeast and daytime heating, convective activity is expected each
afternoon over northwestern Puerto Rico. Forecast global models
(GFS and ECMWF) suggest a drier weather pattern at the end of the
term with limited rainfall activity across the islands. Warmer
temperatures and sunny days will be expected as well.

&&

.AVIATION...VFR cons are expected in the morning across the local
terminals. At least VCTS is expected for the terminals in PR
after 28/16Z. No TEMPO TSRA was put in TAF due to uncertainty on
the exact timing and location of TS, but TSRA is likely this
afternoon across PR, which could impact the vicinity of TJSJ, TJPS
and TJBQ. TEMPO will be written as confidence increases later
today. Winds will increase to around 15KT from the East with sea
breeze variations after 28/13Z.


&&

.MARINE...A building high pressure over the central Atlantic
will cause an increase of the trade winds up to 20 knots.
Moderate to fresh winds will maintain choppy marine conditions
with seas up to 5 feet across the regional waters for the next
several days. A High Rip Current risk remains in effect for the
north-central and northwestern beaches of PR through late Saturday
night. Small craft should exercise caution.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 76 88 78 / 60 20 30 40
STT 87 77 88 78 / 50 30 30 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
429 AM AST Sun May 29 2022

.SYNOPSIS...Active weather with showers and thunderstorms will
continue for the next few days. The expected activity will be
limited to the northwestern sectors of Puerto Rico during the
afternoon hours. Increasing winds up to 20 knots will maintain
choppy marine conditions and seas between 4-6 feet across the
local waters and passages. There is a high risk of rip current in
effect for the north-facing beaches of Puerto Rico, including
Culebra.

&&

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

Showers and thunderstorms continue to be expected through the short
term period. Though perhaps slightly drier than what we have
observed the past few days, and also the heavy rain is expected to
be limited to the northwestern quadrant of PR. That said, urban and
small stream flooding is expected each afternoon due to the strong
thunderstorms that are forecast, especially for the northwestern
quadrant of PR.

Surface high pressure over the Atlantic will keep easterly winds
over the local area, with speeds that could reach 15-20 mph with
higher gusts over the coastal areas, especially during the daytime
hours. A weak upper trough over the local area will continue to
promote instability today as it weakens for Monday, but then
strengthens lightly on Tuesday. 500mb temperatures are still colder
than normal (between -8 and -9C) and are expected to remain in that
range through the short term period, which will continue to promote
strong thunderstorms and perhaps some small hail. The latest
guidance also suggests that the lapse rates are also expected to be
stronger than normal, especially in the 700mb-500mb level. Moisture
will decrease slightly today, then increase once again on Monday and
Tuesday. The available moisture, combined with the instability that
is expected, would be enough to cause numerous showers with a few
thunderstorms across the local area, especially across the
northwestern quadrant of PR, with isolated to scattered showers
elsewhere through the short term period. This is in agreement with
the hi-res models in terms of location of rainfall. The NBM and
ECMWF ensemble both have rainfall in the same locations, but the
amounts in the model output is very minimal, which seems unlikely
given the moisture and local effects that would occur. The global
models are not as dry as the hi-res models, so there seems to be
some uncertainty with regards to rainfall, but we are leaning more
with the global models and then adjusting for local effects; since
given the moisture with the local effects, some instability present,
and lack of Saharan dust; it would be difficult to have completely
dry days over the local area. Therefore, isolated to scattered
showers across the general area, including the USVI, with isolated
thunderstorms for the northwestern quadrant of PR are in the
forecast for the short term period.

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

A strong surface high pressure over the central Atlantic will
continue as the dominant feature for most of the period. Winds will
remain from the east-southeast, bringing patches of moisture to the
local area from time to time. A very seasonal scenario is expected
for the first half of the term, with morning passing showers over
the windward portions of the islands, and afternoon convection
over the western and northwestern portions of Puerto Rico. At 850
mb, moisture content remains nearly saturated, enhancing the
potential for shower activity across the islands. Friday into
Saturday, a mass of drier air will entrain and will linger across
the islands until at least Sunday, limiting the formation of
shower activity. By Sunday onwards, the GFS model suggest a shift
on the winds to a southerly component due to the possible
development of a tropical system between Cuba and the Bahamas. In
the meantime, shower activity will be very limited, and warmer
temperatures with mostly clear skies could be expected.

&&

.AVIATION...VFR cons are expected in the morning across the local terminals. At
least VCTS is expected for the TJBQ terminal after 29/16Z. TEMPO
will be written in the TAF as confidence in timing and exact
location increases later today. But be aware that TSRA development
is forecast. Winds will increase to around 15 - 20KT from the East
with frequent gusts and sea breeze variations after 29/13Z.

&&

.MARINE...Moderate to fresh winds up to 20 knots will maintain
choppy marine conditions for the next several days. Seas for most
of the regional waters will be around 5 feet or less, and up to 6
feet in the offshore Atlantic waters. There is a high risk of rip
currents in effect for the north-facing beaches of Puerto Rico and
the northeastern beaches of Culebra until Tuesday. Therefore,
small craft should exercise caution. The remaining beaches have a
moderate risk of rip currents.

&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
428 AM AST Mon May 30 2022

.SYNOPSIS...
A typical weather pattern of morning passing showers and diurnally
induced afternoon showers will prevail for the next few days. On
Tuesday, a weak surface trough is expected to increase
instability, enhancing rainfall with the potential for minor
flooding in isolated areas. A drier airmass will arrive on Friday
right before a wet trend begins on the weekend due to a
developing low in the western Caribbean. Until late tonight,
there remains a High Risk of Rip Currents for several beaches
along the coastline of Puerto Rico and the eastern coastline of
St. Croix.

&&

.SHORT TERM...TODAY THROUGH WEDNESDAY...
A seasonal weather pattern is expected across much of the islands
today, with the typical early morning passing showers across the
regional waters, followed by locally and diurnally induced afternoon
convection in isolated spots. This activity should be mainly focused
over parts of the interior and west sections of Puerto Rico. Some
afternoon showers and possible an isolated thunderstorm may produce
locally heavy rains which may cause ponding of water on roads and in
poor drainage areas with a slight chance of minor urban flooding in
isolated areas. However, no significant or widespread rainfall
accumulations are so far anticipated for today.

Tuesday through Wednesday, mostly fair weather conditions and sunny
skies expected over much of the islands, however a weakly induced
surface trough is forecast to cross the northeast Caribbean. This
should bring a slight increase in low level moisture through early
Wednesday and therefore favor an increase in shower development over
the local waters. Consequently, there will be sufficient moisture
available to aid in the development of late evening and early
morning showers over the coastal waters, with some reaching parts of
the east and southeast coastal areas areas at times. Afternoon
shower development each day should be focused mainly over the
central and west interior sections of Puerto Rico. Mostly isolated
shower activity is so far forecast elsewhere but the activity should
be in the form streamers steered by the prevailing east to southeast
winds. Some of the afternoon convection may also affect parts of the
San Juan Metro during the afternoon and again the potential for
minor ponding of water on roads and poor drainage areas will remain
possible with the locally heavy rains and isolated thunderstorm
activity. A gradually warming trend is also expected on Wednesday as
winds becoming more southeasterly by Wednesday afternoon, resulting
in temperatures along the north coastal areas of Puerto Rico
reaching the upper 80s to near 90 degrees.

.LONG TERM...Thursday through Tuesday...
A typical advective and afternoon convective weather pattern is
expected for Thursday as breezy easterlies continue to move air
masses with decent moisture values over the region. On Friday, the
winds will veer due to a short wave trough existing over The Bahamas
and this will introduce drier air into region, were low precipitable
water values will limit shower development. Prevailing southeast
winds will cause temperatures along the northern coast to rise in
the 90s. Expect the least amount of rain this day as a wet trend
lies ahead.

GFS guidance suggest that on Saturday a developing low over Cuba
will enhance the southeast flow, pulling tropical moisture into the
region. The Euro Model (ECMWF) is not incorporating this bump of
moisture for Saturday yet it seems likely if this low develops. This
may produce a noticeable amount of precipitation for the weekend
as moisture values are expected to remain above climatological
average. However, strong ridging aloft will dominate the upper
levels of the Caribbean, potentially limiting vertical
development. Overall, it seems that a wet trend is expected for
the end of the long term. If the aforementioned low does develop
north of the region by Tuesday, we may see impacts such as
increased surf heights and enhanced moisture values throughout
next week, yet the uncertainty is high.



&&

Aviation...Few passing showers will reach E-PR and the USVI
terminals at times but VFR conds will prevail. SCT ocnl BKn lyrs nr
FL025...FL050 en route btw E PR and USVI and mainly ovr Caribbean
waters. SHRA/Isold TSRA fcst to develop across ctrl mtn range and
and W PR mainly btw 30/17z-30/22z, with VCTS psbl at TJBQ/TJMZ and
VCSH at TJSJ. The aftn convection may result in brief MVFR conds due
to SHRA/Isold TSRA. SFC wnds calm to LGT/VRB...bcmg fm E/ENE at 15-
18kt with higher gusts and sea breeze variations after 30/14z.


&&

.MARINE...Moderate to fresh easterly winds and a fading
northerly swell will continue to produce choppy seas up to 6 feet,
and occasionally greater, across the local waters. Until late tonight,
there remains a High Risk of Rip Currents for several beaches
along the coastline of Puerto Rico and the eastern coastline of
St. Croix. The risk of rip currents is moderate elsewhere along
the local islands. Small craft operators should exercise caution
as breezy conditions will prevail for the next few days.


&&

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

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
505 AM AST Tue May 31 2022

.SYNOPSIS...
A typical regime of passing windward showers and afternoon
development over the interior and western portions of Puerto Rico
is expected with an enhancement on Wednesday into Thursday as an
induced low level trough passes by. A warming trend is expected by
Wednesday onwards as the low level wind flow becomes more
southeasterly. Over the weekend, a wetter pattern begins as a
developing low pressure system in the Western Caribbean promotes a
southeast flow, introducing moist air into the region. A High
Risk of Rip Currents continues for several beaches across Puerto
Rico and St. Croix.


&&

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

An upper level trough will continue to lift northwards and weaken,
while a mid level ridge will build and hold across the area through
the period. This will therefore limit afternoon convective
development. A surface high pressure ridge across the west and
central Atlantic and a weakly induced trough northeast of the region
will maintain an light to moderate east northeast wind flow across
the area. Shallow fragments of tradewind moisture will continue to
be advected across the area during the morning hours with brief
passing showers expected to affect parts of the north and east
coastal areas of the islands from time to time. A gradually clearing
in cloud cover and diminishing shower activity is expected by late
morning with a mixture of sunshine and cloud expected thereafter.
The combination of local effects, diurnal heating and sea breeze
variations will promote afternoon convection mainly over the
interior and west to southwest section of Puerto Rico, as well as
downwind from the Virgin Islands. Some locally induced showers may
also affects parts of the San Juan Metro during the afternoon but
the activity should be of short duration with no significant
accumulations expected. The afternoon shower activity in the west
may cause ponding of water in roadways and in low-lying areas with
the possibility of minor urban and small stream flooding in
localized a gradually warming trend is also expected by Wednesday onwards as
the low level wind flow becomes more southeasterly as with the
heaviest rains and isolated thunderstorms activity.

For Wednesday into Thursday the approach of an induced low level
trough will increase low level convergence and bring a slight
increase in moisture to the region. By then winds are expected to
become east to southeast. This will result in better potential for
more early morning passing showers as well as continued afternoon
convective development over the central interior and west section of
Puerto Rico. Some shower activity can also be expected around the
U.S. Virgin Islands, especially during the morning hours, followed
by limited afternoon showers mainly on the west end and downwind of
the islands. Some of the afternoon shower activity over the interior
and west sections of Puerto Rico may also promote ponding of water
in roadways and in low-lying areas with the possibility of minor
urban and small stream flooding in localized areas but in isolated
areas.

A gradually warming trend is also expected by Wednesday onwards as
the low level wind flow becomes more southeasterly, resulting in
temperatures along the north coastal areas of Puerto Rico reaching
the high 80s to near 90 degrees with heat indices above 100 degrees.


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

A developing low pressure system in the Western Caribbean
promotes a southeast flow over the region while the influence of a
surface high pressure system weakens as it moves further east
into the Atlantic. This flow will support the advection of typical
tropical air with a dry patch arriving on Friday afternoon,
shortly limiting the development of afternoon and evening showers.
Saturday afternoon is the beginning of a wetter pattern as
southeast winds will pull tropical air through the region
increasing the chance for widespread rainfall. As the surface low
migrates over South Florida, GFS guidance shows that a large
tropical airmass is expected to pass through the region causing
moisture values to spike well over climatological averages.

However, a mid to upper level ridge over the Central Caribbean
will last throughout the long term period, supporting atmospheric
stability. High relative humidity values in the upper levels
indicate the possible abundance of cloud coverage, delaying
diurnal heating which may lead to more of a passing shower regime.
By Sunday, the low pressure system begins to make its way into
the Atlantic, slowly moving east-northeast until arriving north of
the region on Tuesday. Southeast winds will continue to prevail,
with precipitable water values maxing out on Tuesday. No major
features will be present in the upper levels by Wednesday to
enhance instability as a ridge continues to dominant the Central
Caribbean yet with excessive moisture over the region, a wet week
should be expected.


&&

.AVIATION...VFR conds through fcst prd. Passing clds and tradewind
showers will continue to affect the regional waters. Some showers
may reach eastern PR and the USVI at times, with SHRA/+SHRA til
31/14z. Fm 31-17Z-22z, SHRA will also develop across interior and
western PR btwn with psbly Isold TSRA. Some SHRA may affect or be in
the vicinity of TJBQ and TJMZ. Brief MVFR conds can be expected with
the aftn convection. Sfc wnd calm to LGT/VRB...bcmg fm E-NE at 15-
20kt with higher gusts and sea breeze variations after 31/14z.


&&

.MARINE...Moderate easterly winds continue to generate wind waves
raising sea heights up to 5 feet. A minor northerly swell lingers
in the local waters, slowly diminishing. There is a High Risk of
Rip Currents for beaches of Northern Puerto Rico until the
morning and until tonight for Northwest Puerto Rico, the eastern
tip of Culebra and St. Croix. The risk afterwards remains
moderate for most coastlines with the exception of a low risk for
the southwest beaches of Puerto Rico.



&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 77 88 77 / 40 50 60 20
STT 87 76 87 77 / 40 60 40 20

[cycloneye]

Area Forecast Discussion...CORRECTED
National Weather Service San Juan PR
549 AM AST Wed Jun 1 2022

.SYNOPSIS..
A seasonal weather pattern will prevail with passing windward
showers and afternoon development in the interior and western
regions of Puerto Rico. Winds will gradually turn more
southeasterly throughout the week, promoting a warming trend with
heat indices near 100 degrees or greater across northern urban regions.
Starting on Saturday, a wet pattern begins as southeast flow
advects tropical moisture to the region. A developing low pressure
system in the Western Atlantic is main determining factor for
rainfall next week. Today is the first day of the 2022 Atlantic
Hurricane Season, see the National Hurricane Center (NHC) for more
information.


&&

.SHORT TERM...Today through Friday...
A overall seasonal weather pattern will prevail today into Thursday
with passing trade wind showers to affect the regional waters and mainly
portions of northeast and east sections of PR and some of the USVI during
the early morning. This will be followed by some shower development over
parts of the interior and west portions of Puerto Rico as an induced low
level trough crosses the region. Improving weather conditions and a warming
trend will continue for the rest of the period as the low level winds become
more southeasterly and the mid to upper level ridge builds and holds in place.
This will create a moderate cap inversion and lead to gradual erosion of the
tradewind moisture. Along with warmer temperature, increasing maximum heat
indices near 100 degrees or slightly higher can be expected in isolated and
urban areas along the north coastal sections of Puerto Rico.

As aforementioned, the mid to upper ridge will build and hold across
the area and therefore limit afternoon convective development. A surface
high pressure ridge will continue across the west and central Atlantic
while an induced low level trough crosses the region today into Thursday.
The prevailing winds will bring a shallow plume of low level moisture
across the region through early Thursday and consequently periods of passing
showers can be expected to affect the islands from time to time during the
morning hours. Thereafter, local effects, diurnal heating and sea breeze
variations will support afternoon convection mainly over the interior and
west sections of Puerto Rico, with lesser activity if any expected around
the U.S. Virgin Islands. The afternoon shower activity in west interior of PR
may cause ponding of water in roadways and in low-lying areas with the chance
of of minor urban and small stream flooding in isolated areas.

For the latter part of the period, a gradual improvement more of the seasonal
scenario is expected as the low level trough exits the area and winds become
more southeasterly. Limited early morning passing showers are forecast with
warmer temperatures during the day especially along the north coastal areas of
Puerto Rico. However, the intense heating along with local effects may result in
shower development across parts of the central interior and northwest sections of PR.
Elsewhere mostly sunny skies will prevail.

.LONG TERM...Saturday through Thursday...
Surface to 700 MB southeast flow will prevail from the influence of
low level ridging northeast of the region and a developing low in
the Western Caribbean. Embedded in this flow will be abundant
moisture with Precipitable Water values trending toward above
average. However, an upper level ridge will exist over the Caribbean
throughout the long term period enhancing stability yet as diurnal
heating and local effects occur, thunderstorms are possible. Over
the weekend, this southeast moist flow will bring hot and humid
conditions to the islands and heat indexes are expected to rise near
the 100s especially along the northern regions of Puerto Rico. A
passing shower and afternoon convective regime is expected with most
precipitation occurring in the northwest and interior regions of
Puerto Rico with the possibility of streamers developing off of the
upstream islands and El Yunque.

A wetter pattern is expected for the beginning of next week as
moisture values continue to rise as tropical air gets pulled
through the region due to the development of a low pressure
system in the Western Atlantic, close to the Floridian Peninsula.
GFS and ECMWF model guidance differs with how this system will
progress with the ECMWF having a more aggressive deepening by
midweek. If this occurs, we could expect greater moisture
advection over the region and a possible northerly swell. Tuesday
is expected to be the wettest day with exceptional moisture
values across the region. Meanwhile, ridging in the upper levels
prevails until Wednesday as a TUTT develops east of the Leeward
Islands. This may cause unstable weather and prolong the ongoing
wet pattern. Overall, the development of the aforementioned low
pressure system is main determining factor.


&&

.AVIATION...Passing showers overnight into early morning but mainly
over the regional waters with a few SHRA/-SHRA affecting mainly the
north and east coastal sections of the islands from time to time.
SCT ocnl BKN lyrs nr FL025...FL050 with wdly Sct SHRA en route btw
islands til 01/13Z but no operational impacts at terminals. Aftn
convection fcst ovr west and central interior PR, with VCSH and
Isold TSRA psbl at TJBQ/TJMZ fm 01/17Z-22Z. SFC wnds light/vrb bcmg
fm E-NE at 12 to 18 knots, with sea breeze variations and ocnly
hir gusts.


&&

.MARINE...Choppy conditions prevail across the local waters with
seas up to 4 feet from moderate trade winds up to 15 knots with
occasionally stronger gust. A small northerly swell is expected
to arrive on Thursday, however wind waves will continue to have
the greatest influence on surf heights. Winds are expected to turn
southeast by the end of the week. A moderate risk of rip currents
exist for most coastlines across Puerto Rico and the U.S. Virgin
Islands with the exception of a low risk for beaches between
Anasco and Cabo Rojo.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 76 89 78 / 20 20 30 20
STT 87 77 87 77 / 20 30 30 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
516 AM AST Thu Jun 2 2022

.SYNOPSIS...
Mainly overall dry and stable conditions will prevail at least
through Friday. As winds turn southeasterly, northern urban areas
may experience heat indices near 100 degrees. On Saturday, a
tropical wave is expected to cross south of the islands,
resulting in a better potential for early morning and afternoon
convection. A wet pattern is expected for the weekend onward as a
tropical system in the Western Atlantic promotes a moist southeast
flow across the region, however the system having no direct
impacts on Puerto Rico and the U.S. Virgin Islands. A Saharan Air
Layer and a Tropical Upper Tropospheric Trough will effect the
region by next Wednesday onward.

&&

SHORT TERM...Today through Saturday...
A building mid to upper level ridge will hold across the region
during the period to maintain overall dry and stable conditions at
least through Friday. Recent satellite derived precipitable water
product as well as model guidance also suggest a drier trend with
limited convection expected for the next few days. However local
and diurnal effects along with a good warming trend as the wind
become more southeasterly will favor only some brief afternoon
convection, mainly over parts of the central interior and
northwest quadrant of Puerto Rico. Elsewhere mostly sunny and the
typical hot summertime conditions can be expected.

The mid-to upper ridge and a southeasterly wind flow will be the
dominant features through most of the short term period. Also, the
expected warmer temperature and increasing humidity will bring
maximum heat indices to near 100 degrees or slightly higher in
isolated and urban areas along the north coastal sections of
Puerto Rico. A thunderstorm or two cannot be ruled out during the
afternoon hours each day but should be mainly over the central and
west sections of Puerto Rico. Significant organized afternoon
convection and rainfall accumulations are not likely for the
period.

The seasonal weather pattern is anticipated except for Saturday when
a tropical wave is expected to cross the southeast Caribbean mainly
south of the area. This may bring some peripheral low level tropical
moisture to the region a while models also suggest a gradual erosion
of the upper level ridge. This pattern may also increase instability
aloft while increasing moisture convergence in the low levels,
resulting in better potential for early morning and afternoon
convection on Saturday.

.LONG TERM...Sunday through Friday...
A tropical system situated over The Bahamas supports a southeast
flow over the local region. Embedded in this flow is moist air with
above average climatological moisture values. Ridging aloft over the
Caribbean will enhance atmospheric stability, however as diurnal
heating and local effects contribute, numerous showers and isolated
thunderstorms are possible especially over the interior and western
regions of Puerto Rico. This weather pattern continues early into
the week as the aforementioned low pressure system moves with a
northeast track into the Western Atlantic, without any direct
impacts to Puerto Rico and the U.S. Virgin Islands. Upper level
ridging will promote a northerly 250 mb flow that will advect
remnant moisture in from the tropical system and as a result, high
relative humidity values will be present in the mid to upper
levels from Sunday to Tuesday, increasing the cloud coverage.

A plume of Saharan Dust is expected to reach the region by late
Tuesday and Precipitable Water values are expected to drop starting
Wednesday with Thursday having the lowest values of this long term
period. This Saharan Air Layer (SAL) may provide a strong capping
inversion however there is a Tropical Upper Tropospheric Trough
(TUTT) replacing the upper level ridging on Thursday and this may
counter the dynamical influences of the SAL. These conditions may be
quite favorable for strong afternoon thunderstorms. Winds will
back slightly becoming more easterly on Friday and a large plume
of moisture will move in while the TUTT aloft continues to exist over
the region. Overall, it seems that a typical wet weather pattern
is expected for the beginning of next week with passing windward
showers and afternoon convective development and then a wet trend
for the weekend.

&&

.AVIATION...VFR conds is fcst for all terminals. Mstly SCT lyrs nr FL025...
FL050...Isold trade wind SHRA en route btw islands and ovr the
regional waters. Sfc wnds calm to LGT/VRB bcmg 10-15 kts with sea
breeze variations and ocnly hir gusts btw 20-24 kts psbl. VCSH in TAF
for TJMZ/TJBQ aft 02/17Z. No sig operational wx impacts attm.


&&

.MARINE...Seas remain up to 4 feet, occasionally 5 feet from a
mix of wind waves and a small northerly swell. Moderate easterly
winds will continue with stronger gust occurring in the
afternoon. Passing showers are possible over the local waters
throughout the day and isolated thunderstorms cannot be ruled out
over the Mona Passage during evening hours.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 77 90 78 / 30 20 30 40
STT 86 77 87 79 / 30 30 20 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
515 AM AST Fri Jun 3 2022

.SYNOPSIS...
Dry and stable conditions will prevail with a southeast wind
flow. However, locally and diurnally induced afternoon shower
development is still possible over parts of the central interior
and northwest quadrant of PR. A typical weather pattern of
windward showers and afternoon development is expected for the
weekend with warmer temperatures as heat indices reach near 100
degrees in urban zones across north central regions of the PR.
Expect a wet pattern next week as a Tropical Upper Tropospheric
Trough erodes the ridge aloft throughout the week.


&&

SHORT TERM...TODAY THROUGH SATURDAY... A building mid to upper level
ridge and the dominant Atlantic surface high pressure ridge will
continue to maintain and overall dry and stable airmass across the
region, as well as a prevailing southeast low level wind flow.
Recent satellite imagery and the NWS doppler weather doppler radar
suggest scattered low level clouds with isolated showers mostly over
the offshore coastal waters with little or no and shower activity so
far reaching the islands. Recent satellite derived blended
precipitable water product, as well as previous TJSJ 03/00Z sounding
both suggests precipitable water values ranging between 1.50 to 1.70
inches across the forecast area, much of which was with a patch of
shallow moisture moving across the region. Otherwise mostly fair
weather and sunny skies expected for today except for some locally
and diurnally induced afternoon shower development still possible
over parts of the central interior and northwest quadrant of PR.
Some of the heavy rains may lead to minor ponding of water on roads
and in poor drainage areas. Through the week a typical weather
pattern is expected and the prevailing wind flow will be from the
southeast promoting warmer temperatures with maximum heat indices
reaching near 100 degrees in urban zones across north central
area of the PR.

The seasonal weather pattern is anticipated for most of the short
term period, however a tropical wave is still expected to cross the
southeast Caribbean passing mainly south of the area. This may bring
some peripheral low level tropical moisture to the region on
Saturday, while model guidance also suggest a slight erosion of the
upper level ridge by Sunday. This pattern may also increase
instability aloft while increasing moisture convergence in the low
levels, resulting in better potential for a bit more early morning
and afternoon convection at least on Saturday. On Sunday , the upper
ridge reestablishes and holds across the region while low level
moisture erodes and will be dominated by a southeast low level wind
flow which is also influenced by a tropical system in the west
Atlantic. That said, again only limited locally and diurnally
induced afternoon convection is forecast over parts of the interior
and west PR on Sunday as mostly fair weather an sunny skies will
prevail elsewhere.

.LONG TERM...Monday through Saturday...
A potentially developed tropical system north of the region
near 30 N latitude continues to promote a southeasterly flow,
without any direct impacts to Puerto Rico and The USVI. Tropical
air with variable moisture values around climatological average
will promote a typical weather pattern until late Thursday when a
great surge of moisture fills in lasting through the weekend. In
the upper levels a Tropical Upper Tropospheric Trough (TUTT)
starts to erode the ridge over the Caribbean early in the week,
enhancing instability. The exact arrive of this TUTT is not
certain as the flow is subject to change with the progression of
Potential Tropical Storm One. However, at the current
moment the TUTT arrives east of the region on Monday afternoon
and lingers around all week until decaying around Friday.
This feature should promote divergence aloft throughout the week,
increasing the likelihood of afternoon thunderstorms and heavy
rainfall.

North/northeasterly flow will mainly prevail above 400 mb from
Monday to Wednesday as the ridge to the west and TUTT to the east
accelerates air over the region. This will advect upper level
remnant moisture from the tropical system in the Western Atlantic
and as a result, cloudy conditions are expected. A Saharan Air
Layer (SAL) is expected to arrive around Tuesday, yet no
significant reduction to visibly is likely as dust concentrations
are moderate. A northerly swell is possible mid week if the
aforementioned tropical system maintains a tight structure once it
is in the Western Atlantic. Wind speeds are expected to
strengthen by the end of the week as a surface ridge in the
Central Atlantic develops, enhancing breezy easterlies. Overall, a
wet pattern will prevail next week due to atmospheric stability
eroding from a TUTT and a spike of moisture arriving on Friday,
lasting into the weekend.




&&

.AVIATION....AVIATION...VFR conds durg prd. Very ISOL SHRA ovr
regional waters and en route btw islands with mstly SCT lyrs nr
FL025..FL050. Brief VCSH psbl at the TIST/TISX/TJSJ til 03/12z. SFC
wnds calm to lgt and vrb, bcmg fm SE 12 to 15KT with occasional
gusts and local sea breeze variations. Fm 03/16Z-03/22Z Isold to SCT
SHRA psbl ovr ctrl mtn and NW PR. This may cause VCSH mainly
TJBQ/TJMZ. No other operational impacts attm.



&&

.MARINE...Moderate southeast winds prevail with speeds up to 15
knots with occasionally stronger gust. Sea heights will be up to 4
feet due to wind waves and a small northerly swell. The risk of
rip currents remains moderate for most north facing coastlines and
low for most southern facing coastlines of the local islands. No
significant swell or noticeable increase in wind speeds is
expected for the short term.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 92 78 90 79 / 30 40 40 30
STT 87 79 87 79 / 20 40 40 20

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
459 AM AST Sat Jun 4 2022

.SYNOPSIS...

A typical shower pattern is expected across the region over the next
several days, sustained by patchy moisture. An increase in moisture
over the region is possible around Tuesday.

&&

.SHORT TERM...Today through Monday... Low-level winds from the east
southeast to southeast are carrying very isolated strings of showers
across the local waters. Precipitable water values are plummeting and
are expected to bottom out around 1.35 inches this morning at 12Z.
By 05/15Z the GFS is forecasting them to recover to nearly 1.85
inches as a broad band of moisture moves across the area. Dew points
on the north coast were running around 75-78 degrees and even Ponce
had 79 degrees after midnight. The southeast winds expected will
lead to very warm temperatures along the north coast and some higher
relative humidities along the south coast for the next several days.
Ridging from the east central Atlantic will keep the flow
southeasterly with some help from Potential Tropical Cyclone 1 as it
moves rapidly northeast across Florida today and into the western
Atlantic. High pressure at upper levels will extend east northeast
from the northwest Caribbean and maintain mostly northerly flow.

As might be expected, the very warm temperatures and relatively
good moisture will provoke showers and isolated thunderstorm across
northwest and interior Puerto Rico each day with rainfall
probabilities increasing through the period.

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

Moisture convergence is likely over the region on Tuesday, as a
southeasterly flow carries tropical moisture into the area, while a
frontal boundary approaches from the northwest (but does not reach
the islands). This frontal boundary will be off of whatever remains
of what is currently Potential Tropical Cyclone 1 by the time it
reaches the central Atlantic. On Wednesday, moisture levels will
decrease. And, for the rest of the week, patchy moisture is likely
to stream across the region from time to time. The frequency and
moisture content of these patches is likely to increase into the end
of the week. For the second half of the week into early next week,
precipitable water values within moisture patches is expected to
remain within seasonally typical values; between the patches,
though, below-normal values are possible. Forcing/instability aloft
is expected to be relatively neutral for much of the period.
However, an upper-level trough may dip far enough south to bring a
modest increase in instability for the end of the workweek.
Presently, the day most likely to be affected by this increase looks
to be Friday. As such, an increase in shower activity, especially in
terms of afternoon convection, is likely.

With the decrease in moisture at midweek, shower activity will also
decrease. The patches of moisture will sustain shower activity over
the region, in a typical pattern. An increase in showers is likely
near the end of the week, with an increase in moisture and
instability around Friday. Another decrease in activity is likely
during the weekend.

&&

.AVIATION...

VFR conds thru 04/16Z. Aft 04/16Z sct SHRA/isold TSRA to dvlp in
central and NW PR. Tops of TSRA to FL400-500. These will likely
mov offshore to the NW and slowly dissipate aft 05/01Z. Sfc winds
bcmg SE 10-15 kt with hir gusts in sea breezes, then, aft 04/22Z
winds bcmg less than 10 kt in mostly SE flow.

&&

.MARINE...

Winds out of the east to east-southeast at up to 15 knots will help
to sustain some choppy conditions across the local waters. Seas of 4
feet or less are anticipated.

There is a moderate risk of rip currents for most local beaches,
including beaches of Culebra and the north coast of Puerto Rico, as
well as some beaches of the USVI, Vieques, and southwestern and
southeastern Puerto Rico.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 91 77 92 76 / 30 20 20 20
STT 87 79 89 79 / 30 20 20 30

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
458 AM AST Sun Jun 5 2022

.SYNOPSIS...

A typical shower pattern is expected across the region for the
next several days, though likely somewhat drier than normal. On
the whole, this drier-than-typical season is likely to persist at
least into the second half of the week. There is the potential
for an increase in moisture and therefore shower activity around
the end of the week. However, confidence is still quite low for
the weekend.

&&

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

Low-level winds from the east southeast to southeast are carrying
very isolated strings of showers across the local waters.
Precipitable water values will fluctuate between 1.6 and 1.8
inches. Dew points on the north coast were running around 75-78
degrees and even Ponce had 81 degrees after midnight. The
southeast winds expected will lead to very warm temperatures along
the north coast and some higher relative humidities along the
south coast for the next several days, however there will be some
high and mid clouds from the north out of tropical storm Alex that
may keep temperatures from reaching 94 degrees and most certainly
not a record today which would have to be 97 degrees to tie.
Ridging from the east central Atlantic will keep the flow
southeasterly with some help from Tropical Storm Alex as it moves
into the western Atlantic. High pressure at upper levels will
extend east northeast from the northwest Caribbean and maintain
mostly northerly flow with considerable help from a cut-off low
that will sink due south in to the western tropical Atlantic a few
hundred miles east of the Leeward Islands.

As might be expected, the very warm temperatures and relatively good
moisture will provoke scattered showers with a slight chance of
thunderstorm across northwest and interior Puerto Rico each day with
rainfall probabilities appearing to be the best in Tuesday. The
relatively dry air at around 8000 feet will keep convection from
become as vigorous as otherwise would be expected.

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

Wednesday and Thursday are expected to bring seasonally typical
conditions to the region, if perhaps somewhat drier than normal. In
terms of forcing aloft, conditions are likely to be less conducive
to convective development. An upper-level trough is forecast to
remain to the northeast to east during this time, with ridging at
the mid-levels. This will inhibit afternoon shower activity over the
region. Patchy moisture, however, is expected to sustain shower
activity regardless. Forecast confidence through this point is
medium-high.

As we approach the weekend, the forecast confidence decreases.
Models are generally trending towards bringing more moisture into
the area late Friday into Saturday, but the extent to which varies
between model runs. The GFS suggests that a tropical wave will move
through the area during this time, and the Euro does show some
agreement. This is a marked change from what model guidance
suggested yesterday for the region, though the shift in the wave`s
location is relatively unspectacular for this time range. Even if
the wave does not reach the area, remaining south over the
Caribbean, it could still push an increase in moisture over the
area. This is reflected in the forecast, which now has a more active
trend starting on Friday and lasting through the weekend. Dynamics
aloft still remain neutral to unfavorable for the most part.
Confidence is low, and this is more of a possible than a probable
kind of thing.

A drying trend is expected late Sunday through Monday. Patchy
moisture is likely to sustain shower activity, however, in a typical
pattern over the area. There could be more significant drying on
Monday, with the potential for a dry slot moving over the area ahead
of an induced trough approaching from the east. Confidence remains
low into next week.

&&

.AVIATION...

VFR conds thru 05/17Z. Aft 05/17Z sct SHRA/slgt chc TSRA to dvlp
in central and NW PR. Tops of TSRA to FL350-450. These will likely
dissipate aft 05/23Z. Sfc winds bcmg SE 10-15 kt with hir gusts
in sea breezes, then, aft 05/22Z winds bcmg less than 10 kt in
mostly SE flow.

&&

.MARINE...

Light to moderate southeasterly winds are expected over the area,
which will sustain some choppy conditions over the waters. Seas of 4
feet or less will persist across the local waters.

There is a moderate risk of rip currents for nearly all local
beaches.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 92 76 91 76 / 20 10 10 20
STT 88 79 88 76 / 20 20 20 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
453 AM AST Mon Jun 6 2022

.SYNOPSIS...Dry and hazy conditions prevail in east southeasterly
flow. Weak low level troughing Thursday through Saturday and
cooler mid level temperatures could lead to isolated afternoon
thunderstorms on Thursday and Saturday, but moisture remains
limited on Thursday and on Saturday local dynamics and an
intervening drier layer at low to mid levels will resist
widespread showers and thunderstorms then.

&&

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

Dry, warm, and hazy continues to be the theme through midweek.
Unfortunately, relief for drought conditions seems unlikely during
this time. Another increase in dust is anticipated for later today,
likely starting in the afternoon in St. Croix and spreading
northwestward. And yet another increase is forecast for tomorrow
night into Wednesday morning. Stable conditions will continue aloft,
as well; mid-level ridging supports stability, while an upper-level
low is forecast to stay to the east of the islands, promoting
subsidence. Despite the fact that moisture levels are likely to
remain at near-normal levels based on precipitable water values,
shower activity is expected to be significantly inhibited. The
typical shower pattern will nominally be maintained, but the extent
of the showers will be lower. Because of the southeast winds,
higher dew points and mostly sunny conditions the heat indices
along the northern central coast will reach advisory levels for a
few hours during the early afternoon today.

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

A cut-off low in the upper atmosphere that dug south into the
Greater Antilles Tuesday and Wednesday will begin to return north
Thursday through Saturday. High pressure at mid levels will
continue across the Atlantic just north of the local area, but a
slow moving trough will undercut it and reach the area by
Thursday. Weak low pressure at mid levels will remain in the area
through Saturday. A tropical wave induced, or at least sustained
by the upper level TUTT low, will move through the area on
Thursday but will have limited moisture. Better moisture will
accompany another wave that moves through on Saturday. Conditions
then return to their drier state Sunday. Since flow remains
southeasterly, isolated showers should occur most nights and early
morning in eastern Puerto Rico and over the local waters with
some showers developing in the the west northwest and interior
areas of Puerto Rico during the afternoons. Cooler 500 mb
temperatures forecast for Thursday and Friday could lead to
isolated afternoon thunderstorms there as well.

&&

.AVIATION...Generally VFR conds are likely across all terminals for
the next 24 hours. However, haze will continue to be a concern,
as well. Observed CIGs at TISX are likely artificially lower than
reality, based on satellite imagery, which is due to the effects
of haze. Additional Saharan dust from the southeast starting after
about 06/20Z could cause visibilities to dip, possibly into MVFR.
Afternoon SHRA likely to be limited, but cannot entirely rule out
one or two near TJBQ.

&&

.MARINE...Seas are mostly reacting to moderate winds with very
localized areas of fresh winds generating seas above 4 feet, and
hence the need for exercise caution statements. However pulses of
northerly swell will begin to be seen Wednesday and build to
almost 7 feet by Saturday. This will also cause rip currents along
the north central coast of Puerto Rico Wednesday that will spread
to many beaches by Saturday night.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 91 76 90 77 / 10 20 20 10
STT 88 76 88 77 / 20 20 20 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
506 AM AST Tue Jun 7 2022

.SYNOPSIS...Mostly dry, very warm and hazy conditions are expected
through at least Monday in southeasterly flow that will bring
scattered showers to the area through the period. No overriding
features are present to trigger unusual events.

&&

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

Additional dust is making its way into the region from the
east/southeast. This will cause persisting hazy conditions across
the area. Moisture is also decreasing; a tropical wave passed by to
the south, and there is a decrease in precipitable water values in
its wake. Patchy moisture will help to sustain some shower activity,
but it will be inhibited. This has been evidenced by conditions
overnight, which have had very sparse coverage of showers over the
local waters, and only one or two that made their way over the
islands. For the afternoon, showers are expected for northwestern
and interior Puerto Rico again today. Thunderstorms have been left
out of the forecast for today, based on the lower amount of moisture
available, with generally similar conditions dynamically. A
thunderstorm or maybe two still cannot be wholly ruled out.

Continuing through midweek, the haze will remain a concern over the
region. However, the higher dust concentrations are only forecast to
just barely make it over the islands tomorrow, so a small shift
southward of the dust plume could leave us with a little less dust
than anticipated. That being said, it will still be hazy regardless.
Aloft, an upper-level low will continue to churn to our
east/southeast, which will promote subsidence over the area.
However, a modest increase in instability is expected by Thursday,
as 500 hPa temperatures cool to around -8C to -9C. Though drier air
and dust are still expected to be over the region on Thursday, the
increase in instability brings a higher potential for thunderstorms
during the afternoon on Thursday. But the potential for
precipitation remains relatively low.

The result is that warm, dry, and hazy conditions are likely to
persist through the short-term period. A few showers are possible,
however, with patches of moisture making their way through the
region from time to time.

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

The vigorous upper level low over the northern end of the Leeward
Islands will move northeast from Friday only to loop back over
the weekend and be found in a similar position on Monday. It then
moves south and returns to the same position on Tuesday night. A
trough at mid levels will slowly drift over the area by Friday and
bring a pool of cooler air with it. High pressure dissipates
somewhat and allows warmer air to prevail until late on Monday.
This cool pool of air will give a little boost to local
instabilities on Friday and again on Monday. At lower levels east
to east southeast flow will prevail carrying areas of modest
moisture with alternating patches of relatively dry air. The moist
patches will bring scattered showers during the overnight and
morning periods to eastern Puerto Rico and some streamer activity
with showers each afternoon in west northwest Puerto Rico and
isolated thunderstorms during the unstable periods mentioned
above. Otherwise no overriding features are seen with exception of
the plume of Saharan dust that stretches across the Atlantic and
into the Caribbean. The northern edge of the plume is over the
local Caribbean waters with fairly high concentrations of Saharan
dust just south of the edge toward the center of the plume. The
plume is forecast to continue from the Windward Islands to the
Dominican Republic and Cuba through at least Sunday.
concentrations will diminish over the weekend and early next week.

&&

.AVIATION...VFR conditions expected to prevail next 24 hours across all
aerodromes. Afternoon showers focused on northwestern/interior PR,
with VCSH for TJBQ; cannot entirely rule out potential for TS, but
unlikely. Hazy conditions continue, which are impacting CIG observations
at TISX. Based on satellite data, reports at TISX have
artificially low ceilings. Wind east-southeast today at 10 to 15
knots, with sea breeze variations and stronger gusts possible.
Maximum winds N-NE 35-45 kts btwn FL380-515.

&&

.MARINE...Marine conditions continue at 2 to 4 feet through Friday
with local seas up to 6 feet under wind maximums around the island
of Puerto Rico. Also seas in the Caribbean and the Anegada
passages will increase Saturday through Monday, but so far small
craft advisory conditions are not anticipated. High rip current
risks are still expected to be gin spreading around Puerto Rico
Wednesday night and around Saint Croix on Friday night.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 91 78 89 78 / 20 10 20 10
STT 88 78 87 78 / 20 20 20 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
518 AM AST Wed Jun 8 2022

.SYNOPSIS...East southeast flow at lower levels will persist
through the period. Saharan dust continues across the Caribbean
and will be seen across Puerto Rico and the U.S. Virgin Islands
from time-to-time. Heat and local low-level convergent flow will
generate thunderstorms in west northwest and interior Puerto Rico
most days, otherwise mostly isolated showers with limited
accumulations will be seen.


&&

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

Another warm day is expected today. Moisture levels across most of
the region will be below normal levels, with precipitable water
values of around 1.3 to 1.5 inches, based on satellite estimates.
During the afternoon, however, some moisture convergence is
anticipated to aid in the development of convection for northwestern
and interior portions of Puerto Rico. Currently, it looks like
today`s activity will be less than what was seen yesterday, but
isolated thunderstorms are still expected, and locally heavy
rainfall is possible. Dust concentrations are expected to be lower
than they have been for the few days, though a little haze is
possible, especially in areas along the south coast and over the
Caribbean waters; the bulk of the dust plume is expected to stay
generally south of the CWA, though.

An upper-level low is expected to continue to churn to the east of
the region, north of the Windward Islands. This will promote
convergence aloft, and therefore subsidence over the area. Though
this will inhibit convective development, it will not halt it, much
like yesterday. With additional drying expected for tomorrow,
another decrease in shower activity is expected. Still, showers and
maybe an isolated thunderstorm or two, are expected for
northwestern/western and interior portions of Puerto Rico. By midday
on Friday, the strong upper-level low is forecast to cause an
induced trough to form in the mid-levels. Instability will increase
on Friday. Meanwhile, increasing patches of moisture are expected to
make their way through the region. As such, a more active weather
pattern is expected for Friday.


.LONG TERM...Saturday through Wednesday...
The tropical wave entering the area on Saturday will also receive
some amplification as it passes under the upper level low just
east of the area and the induced trough at mid levels. Moisture
between the marine layer and the mid levels will be weak so this
is expected to produce only a limited increase in showers and some
reduction in the Saharan dust seen. On Sunday and through the
rest of the forecast period, despite having upper level troughing
in the vicinity, convective activity will be limited with
thunderstorm activity a little more favored on Monday and
Wednesday in the west northwest and interior sections of Puerto
Rico. Low level flow will continue to be east southeast through
the entire period, but the GFS indicates that significant warming
will commence on Wednesday. Hence the generally dry period except
for the afternoon convection over west northwest and interior
Puerto Rico will continue.

&&

.AVIATION...VFR conditions are expected to prevail across all
terminals. Some haze is possible, especially over the Caribbean
waters, but operational impacts at aerodromes is likely to be
limited. Afternoon showers and potentially isolated thunderstorms
for NW and interior PR bring VCSH to TJBQ; cannot entirely rule
out VCTS/TSRA for TJBQ between 08/17Z and 08/22Z. Winds pick up
out of the east at 12 to 16 knots with sea breeze variations and
stronger gusts possible, subsiding after sunset. Maximum winds NE
40-50 kts btwn FL330-470.

&&

.MARINE...A small northerly swell continues to invade the local
waters that will peak early next week. Nevertheless with quiet
seas the rip current risk for today dropped to moderate for all
waters and will only be high starting tonight for zone 5. Small
craft will need to exercise caution for winds up to 20 knots in
localized area of the near shore Atlantic waters of Puerto Rico.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 77 90 77 / 20 10 10 20
STT 87 78 87 78 / 20 20 10 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
421 AM AST Thu Jun 9 2022

.SYNOPSIS...

Briefly passing showers will prevail across all the local waters
and windward sections during the morning hours. After that,
afternoon convection will develop over the interior and western
areas of Puerto Rico. Deteriorating weather conditions are
forecasted for the first part of the weekend as a tropical wave
moves over the local islands on late Friday into Saturday. On
Sunday, once again, a drying trend is forecast as a bulk of
Saharan Dust particles filter into the region. There is a high
risk of rip current for all the north- central exposed beaches of
Puerto Rico.

&&

.SHORT TERM...Today trough Saturday...

Upper-level trough/TUTT over the Leeward Islands will continueto
promote subsidence air over Puerto Rico and the U.S. Virgin Islands
over the next day or so, before weakens and pulls northeast over the
Central Atlantic. This current setup is keeping the mid-levels
fairly dry. The 00Z TJSJ sounding shows mid-level RH in the lower
30s and the overall moisture around 1.5 inches of precipitable
water. Moisture levels are forecast to drop even more through the
day today with precipitable water values reaching a minimum of
around 1.25 inches by mid-morning. Not a lot of instability is
anticipated today and Friday, however, strong sea breeze convergence
will favor convection over the western interior of Puerto Rico this
afternoon and over northwest Puerto Rico on Friday afternoon as the
low-level winds veer to the southeast.

Maximum temperatures will remain near normal today in the upper 80s,
however on Friday temperatures will be slightly above normal with
highs in the low 90s due to the southeasterly flow. Most of the
Sarahan dust will remain over the Caribbean Waters south of Puerto
Rico and the U.S. Virgin Islands over the next few days, increasing
again over the local islands late in the weekend.

Conditions will become wetter and unstable on Saturdaywhen a
tropical wave approaches the islands. As a result, scattered to
numerous showers are forecast for Saturday as the wave moves across
the U.S. Virgin Islands, Culebra, Vieques, and Puerto Rico. The
tropical wave should bring some beneficial rains to most of the area
that is currently in abnormally dry or drought conditions. Rain
accumulations could serve as a relief and not will change
drastically the drought conditions across the islands because the
wave will move relatively fast across the local area.

.LONG TERM...Sunday trough Thursday...

On Sunday into Monday, conditions will turn more favorables for less
shower activity. At the surface, a high pressure will continue to
result in east-southeasterly winds over the area. Embedded in this
trade wind, particles of Saharan Dust will filters into the area,
turning hazy skies for most of the forecast area. According to
GOES 16 Satellite Imagery, the bulk of the Saharan Dust will be on
late Sunday into Monday. Additionally, ridging aloft will aid
drier and stable conditions in the mid to upper levels. Weather
conditions would slowly change on Tuesday. As the drier air moves
out of the region, fragments of low-level moisture embedded in
the winds will each the local islands. This increase in
cloudiness and moisture into the area, will enhance the potential
for showers, mainly in the afternoon hours over the interior.

Conditions will deteriorate on Wednesday, when both model guidances,
GFS and ECMWF, agree with a significant increase in moisture across
all the levels. Meanwhile, a upper the upper level moving westward
will establish over the forecast area on Wednesday into Thursday.
The presence of this aforementioned feature will enhanced
instability aloft, and colder temperatures at the 500 MB. As a
result, an increase in the widespread shower activity is
anticipated due to the combination of the instability aloft and
the available moisture. So far, if the forecast still on track,
some isolated thunderstorms are forecast with the heaviest
activity, and over the local waters in the nighttime hours.

&&

.AVIATION...VFR conditions are expected to prevail across all
terminals through the forecast period. SHRA over the western
interior may produce mountain obscurations across portions of the
Cordillera Central this afternoon. Easterly winds will continue
around 10-15 kt and occasional gusts of 20-25 kt. Sea breeze
variations will occur between 15Z-21Z, then lighter winds at night
and overnight.

&&

.MARINE...
The combination of moderate easterly wind and a small northerly
swell will continue to result in choppy conditions across
all the north coast of Puerto Rico and the U.S. Virgin Islands.
Therefore, seas will remain up to 5 feet across the Atlantic and
Caribbean waters with winds up to 15 knots. Therefore, a high risk
of rip current for all the northern exposed beaches of the
forecast area.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 77 90 79 / 20 20 20 40
STT 87 78 88 78 / 20 20 20 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
449 AM AST Sat Jun 11 2022

.SYNOPSIS...A tropical wave moving across the region today could
bring a few roundsof showers and thunderstorms across Puerto
Rico and theU.S. Virgin Islands through tonight. Wetter conditions
will be short-lived as moisture associated with the wave will
move fairly quickly across the region, giving way to drier and
stable conditions as well as the hazy skies through early next
week. Anotherperiod of unsettled conditions isforecast between
Wednesday and Thursday under the influence of an upper trough.

&&

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

At the surface, a high pressure will continue to promote moderate to
fresh easterly winds across the forecast area. Embedded in this wind
pattern, cloudiness and moisture from a tropical wave arriving the
local islands will create more frequent passing showers in the
morning hours. As the day progress, weather conditions should
deteriorate mainly over the interior and western sections of Puerto
Rico. Isolated thunderstorms are included in the forecast, due to
colder temperatures at 500 MB. A significant change in the weather
conditions is forecast for Sunday, when a big pulse of Saharan Air
Layer (SAL) moves into the area and erode most of the present moisture
over the region. This drier conditions will promote very stable
conditions. However, the local effects with the daytime heating
could result in localized shower activity over the interior and
western sections of Puerto Rico. But no significant rainfall accumulations
are expected due to stable conditions aloft. On Monday, the surface
high pressure will move into the central Atlantic resulting in easterly
trade winds that will push fragments of low level moisture over the
area. Nevertheless, the presence of the SAL will limit the shower
coverage across the region. Additionally, stable conditions aloft
will erode the moisture in the mid levels, limiting the vertical
development of the afternoon shower Sunday and Monday.

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

Surface high pressure over the north-central Atlantic will promote
east to east southeast winds across the local area early in the week.
Some Saharan dust particles will still be embedded in the trade
winds on Tuesday but concentrations will be much less than Monday.
GFS forecast soundings suggest precipitable water values slightly
below normal around 1.5 inches on Tuesday afternoon due to the
presence of the Saharan Air Layer at mid-levels. Therefore, expect
a few morning showers on the windward side of the islands followed
by isolated to scattered afternoon convection over the northwest
quadrant of Puerto Rico.

Then, conditions will become wetter and unstable by midweek. An upper-
level trough/TUTT will slowly move westward and position west-northwest
of the region on Wednesday. As the TUTT becomes near stationary north
of Hispanola, deep tropical moisture is forecast to surge from the
eastern Caribbean into the local islands late Wednesday into Thursday.
The high moisture content will combine with enhanced instability associated
with the TUTT to support organized convection in the Caribbean waters
and portions of Puerto Rico and the U.S. Virgin Islands. At this time,
operational modelssuggest that the most active day will be on Thursday
as moisture and instability peak across the local region. However, the
exact timing of the unsettled period may be adjusted early in the week
as operational models still show some discrepancies in the intensity
and the position of the TUTT low. Beside of the uncertainty in
the forecast, there is a decent chance to experience showers and
thunderstorms between Wednesday and Thursday. Afterwards, drier
and more stable conditions are forecast for Friday into next
weekend as the TUTT weakens significantly and mid-level high
pressure expands over the eastern Caribbean. As the ridge spreads
westward into the local region, dry air aloft will limit the
shower coverage as well as the vertical development of the showers
late in the workweek and the weekend. There is a lot of Saharan
dust in the tropical Atlantic between Africa and the Caribbean,
therefore hazy skies will probably accompany the stable conditions
during the weekend.

&&

.AVIATION...Mainly VFR conditions will prevail at all TAF terminals
during the period. VCSH will prevail for TIST,TISX & TJSJ TAF sites
due to the arrival of a tropical wave until 06/18Z. Showers at
10/16Z could add VCTS over TJBQ and more lower ceilings. SFC winds
will increase up to 15 knots and winds gust at 10/14Z to 10/22Z.
Winds will slightly diminish around 10/22Z.

&&

.MARINE...Moderate to locally fresh winds have resulted in choppy
seas of 4-6 feet. Therefore, small craft operators should exercise
caution across most of the local waters. Also, the small northerly
swell has combined with the wind waves to produce a high risk of
rip current for the north coast beaches of Puerto Rico and Culebra
as well as the east coast beaches of St. Croix through at least
Sunday afternoon. For the rest of the local beaches, the risk will
remain moderate except the beaches of Anasco, Mayaguez and Cabo
Rojo where the risk is low.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 78 89 79 / 50 20 20 20
STT 88 79 89 78 / 50 20 20 20