Caribbean - Central America Weather

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
501 AM AST Sun May 1 2022

.SYNOPSIS...
The influence from the inverted trough weakens as conditions
improve throughout the day with most of the activity over the
eastern portion of the region and the Atlantic Offshore waters.
Typical weather will prevail for the beginning of the week until
Thursday afternoon when an upper level trough passes over the
region increasing the likelihood of thunderstorms and shower
activity. The northerly swell previously affecting local waters is
decaying yet a High Risk of Rip Currents remain as breezy
conditions increase overnight.

&&

.SHORT TERM...TODAY THROUGH TUESDAY...

Conditions will slowly improve throughout the day with mostly
stratiform rain across the local waters and the coastal sections
of the eastern third of Puerto Rico, Vieques, Culebra, St Thomas,
St John, and St Croix. The strongest activity should remain across
the surrounding waters. Isolated thunderstorms cannot be ruled
out across the Atlantic Offshore waters. Drier air slowly filters
from the southeast and gradually fills over the region, tapering
off rain activity throughout the day. However, afternoon
convection will develop one more time across the interior and
north of the Cordillera Central of Puerto Rico and the northern
Virgin Islands.

A more seasonal weather pattern with an easterly wind flow will
return Monday and Tuesday. This wind flow will push the lingering
moisture across the islands each day. The seasonal weather pattern
consists of the combinations of clouds and sunshine and a few
passing showers in the night and morning hours, followed by
afternoon convection across the interior and western portions.


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

As a high pressure system at the surface in the Western Atlantic
promotes northeast flow, variable patches of moisture move through
the region providing passing showers and afternoon development in
the western portions of Puerto Rico with contribution from
diurnal heating and local effects. Upper level flow is mostly
zonal until around Thursday afternoon when an upper level short
wave trough passes through the Eastern Caribbean. Mid-level
heights are expected to fall, reaching the the lowest values on
Friday. By this time, winds begin to veer to the southeast as the
surface high pressure system reaches a position northeast of the
Islands. GFS model guidance is showing a bump in precipitable
water on Friday which in combination with these dynamics may
provide afternoon thunderstorms. If enough diurnal heating
combines with diffluence aloft, there is the chance of vertical
development late in the day on Thursday and Friday that could
result in exceptional amounts of rain and potential thunderstorms.

With southeast winds persisting into the weekend, most of the
afternoon development will concentrate in the northwest with
windward showers occuring throughout the day. Saturday through
Monday appears to appear normal with slightly above average
moisture. As a deep surface low develops in the Western Atlantic
late on Sunday, a short lived perturbation may exist over the
region. Since the GFS is quite fickle this far out, this
occurrence remains speculative. Therefore after the upper level
trough moves out of the region Saturday morning, a typical weather
pattern is expected with light winds from the southeast.


&&

.AVIATION...VFR but periods of MVFR conds will continue at times
with -SHRA/Low CIG. Mtn top obscr over ctrl mountain range of PR
will continue and should return between 01/17-22z. BKN-OVC lyrs nr
FL025...FL040... FL120. SHRA/Isold-TSRA could return mainly north
of the Cordillera Central (near JSJ) and near St Thomas terminal
(IST) during the afternoon (btwn 01/18-22z). SFC will continue
calm to light/VRB thru 01/13z, then returning from the E/ESE at
10-15 kt with higher gusts and sea breeze variations.


&&

.MARINE..A decaying northerly swell continues to influences wave
heights up to 5 feet. As moderate winds from the east become fresh
by tonight, choppy conditions will prevail. Isolated
thunderstorms and scattered showers are expected over local waters
throughout the day. As breaking wave heights reach up to 8 feet
for much of the coastline along the Islands, a High Risk of Rip
Currents remains in effect for Puerto Rico and the U.S. Virgin
Islands.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 82 74 82 74 / 60 40 50 40
STT 83 75 82 75 / 50 30 40 40

[cycloneye]

There was a tornado that occured in Puerto Rico this afternoon around 3 PM and preliminary data has it at EF-1. NWS crew will survey the area to see the duration, the trajectory it took and how strong it was officially. The good news is that nobody was hurt or died.



 https://twitter.com/CycloforumsPR/status/1520858408865472515




 https://twitter.com/RayTorres222/status/1520862796887597056




 https://twitter.com/CycloforumsPR/status/1520926071260127232

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
447 AM AST Mon May 2 2022

.SYNOPSIS...A set of upper-level short-wave troughs reaching the
northeastern Caribbean will become the dominant features, with the
first trough enhancing shower and isolated thunderstorm
development today. Since moisture levels are diminishing, it is
not until a second trough reaches the area by the end of the
workweek that a significant increase in shower activity under a
high moist environment and weak steering flow could lead to an
increased flooding risk. Moderate to fresh winds will maintain
choppy seas and life-threatening rip current conditions during the
next few days.


&&

.SHORT TERM...TODAY THROUGH WEDNESDAY...

The available moisture is expected to gradually decrease through the
short term period. The upper trough, currently just west of the
local islands, is expected to gradually become less pronounced on
Tuesday and Wednesday. This means that there is still a chance of
afternoon thunderstorms, especially this afternoon, but the global
models are more generous with the rainfall potential than the hi-res
models. The GFS model indicates a broad area of showers and
thunderstorms across the northern half of PR in the afternoon, with
northwestern PR having a chance of thunderstorms in the mid to late
afternoon. That said, the NBM and ECMWF ensemble are not very bullish
with the rainfall, particularly the NBM, having little to no rain
over land areas. This discrepancy could be because the thick layer
of clouds could inhibit convection over land areas, making the deep
convection to rely on the mid to upper level instability with a
weaker sea breeze convergence at the surface. Therefore, accounting
for uncertainty, we decided to go a bit more conservative in today`s
forecast, having scattered showers, but with isolated thunderstorms,
some of which could be heavy for brief periods.

A similar pattern is expected on Tuesday, but with drier air,
causing less shower and thunderstorm coverage. Therefore, isolated
to scattered showers are forecast on Tuesday, with a small area of
western PR having isolated thunderstorms in the afternoon. Even
drier air is expected on Wednesday, and the forecast models show
even less shower activity over the local islands. Therefore isolated
showers are in the forecast for Wednesday, which is a significant
change to the inherited forecast for that date. For Wednesday
afternoon, scattered showers are forecast for western PR, but no
thunderstorms are in the forecast.

As far as temperatures, the forecast is for near normal temperatures
both in daytime max temps and overnight min temps through the
forecast period.

.LONG TERM...THURSDAY THROUGH MONDAY...

Model guidance suggests that a mid-to-upper level short-wave
trough will become the dominant feature Thursday into Saturday,
with the associated jet enhancing ventilation across the
northeastern Caribbean and mid-level temperatures dropping as low
as -9 degrees Celsius. However, just below the trough, a weak high
to our east-southeast will maintain a weak trade wind cap,
pronounced southerly flow, and somewhat drier conditions through
the first half of the cycle. Despite these conditions, moisture
levels should remain at seasonal to slightly above seasonal,
ranging from 1.5 on Thursday to around 2.0 inches on Monday
afternoon, with secondary peak moisture of about 1.8 inches on
Saturday evening. At the surface, a high pressure migrating
eastward into the north-central Atlantic will cause winds to veer
from the east-southeast on Thursday, becoming more southeasterly
on Friday into the upcoming weekend while weakening. These
southeasterly winds will also lead to higher daytime temperatures
that could peak around 90 degrees, mainly across northern sections
of the local islands.

The expected shower activity should follow the seasonal pattern
with nocturnal/early morning showers moving inland over windward
areas, followed by afternoon convection across the interior and
western sections. So far, the best chance for shower development
and perhaps an increased risk for localized urban and small stream
flooding falls on Friday and Saturday, when favorable conditions
aloft, local and diurnal effects, abundant tropical moisture, and
a weak steering flow will lead to a higher chance for deep, slow-
moving shower development and a slight chance for isolated
thunderstorm development. Given the expected weak southeasterly
steering flow, the focus of the activity will favor central to
northern sections of the local islands. Increased moisture levels
and favorable conditions may envelop the forecast area again by
early next week as yet another short-wave trough approaches the
region, but confidence in this forecast remains low due to
uncertainties so far out in the cycle.


&&

.AVIATION...VFR conds expected in the morning across the local terminals. VCSH
forecast for TJSJ and TIST though the early morning hours. Winds
will be from the east at 10KT or less through 02/13Z, becoming a bit
stronger up to around 15KT with higher gusts after around 02/16Z,
sea breeze variations will play a role in wind direction. VCSH/VCTS
is expected across TJBQ after 02/17Z.


&&

.MARINE...Moderate to fresh winds up to 20 knots will maintain
choppy marine conditions, mainly across the Atlantic waters, where
small craft operators should exercise caution. Mariners can expect
seas of 5 feet or below and surface winds up to 15 knots elsewhere
across the local waters. For beachgoers, there is a high risk of
rip currents for beaches across the northwest to the northeast
coast of Puerto Rico and beaches of Vieques, Culebra, and the U.S.
Virgin Islands. For southeastern Puerto Rico, the risk will
elevate to high this evening.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 75 85 74 / 50 30 20 10
STT 86 75 86 74 / 50 30 20 10

[cycloneye]

The San Juan NWS did the full preliminary analysis of the tornado in Arecibo on May 1 at 3:10 PM. It lasted 5 minutes and the maximum winds were 107 mph and traveled 1 mile. They will do more analysis in the next few days. See in image the route in green.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
515 AM AST Tue May 3 2022

.SYNOPSIS...The entrance of a drier airmass will lead to improved
weather conditions, but lingering moisture and favorable
conditions aloft could still support shower and isolated
thunderstorm development today, mainly in the afternoon. Expect
limited shower activity through midweek with further erosion of
the available moisture. An upper-level trough will enhance shower
and isolated thunderstorm development by the end of the workweek
into the upcoming weekend, followed by another one early next
week, but under a higher moisture environment. Moderate to fresh
winds will maintain choppy seas and life-threatening rip current
conditions during the next few days.


&&

.SHORT TERM...TODAY THROUGH THURSDAY...

The surge in moisture that affected the northern portions of PR late
last night into early morning caused long lasting showers and
thunderstorms that caused flash flooding across some areas in the
San Juan Metro. This shower and thunderstorm activity is expected to
diminish significantly as the day progresses. The latest guidance,
both the hi-res and the global models indicate a drying trend in
shower activity today and also on Wednesday.

As the drier air moves in today, mainly isolated to scattered
showers are forecast today, with a small area of western PR having
isolated thunderstorms in the afternoon. There is also some Saharan
dust still in the area. That said, slightly drier air is expected on
Wednesday, though with less Saharan dust, and the forecast models
show even less shower activity over the local islands. Therefore
isolated showers are in the forecast for Wednesday, but we kept a
small area of isolated thunderstorms across western PR for Wednesday
afternoon, while only isolated light showers expected across the
USVI. Some moisture increase and also an increase in instability is
forecast over the local area on Thursday. Therefore, scattered to
locally numerous showers with isolated thunderstorms are in the
forecast for PR, but isolated to scattered brief showers are
forecast for the USVI. As far as temperatures, the forecast is for
near normal temperatures both in daytime max temps and overnight min
temps through the forecast period.

.LONG TERM...FRIDAY THROUGH TUESDAY...

Although the overall expected pattern has not changed, the model
guidance now suggests a delay in peak moisture to early next week
with slightly drier weather conditions through most of the
weekend. Below seasonal moisture levels as low as 1.25 inches are
expected on Friday and Sunday, separated by a sharp and brief
increase in moisture content to about 1.7 inches by Saturday
evening. A gradual increase in moisture will follow early next
week, with model-estimated precipitable water values rising to
around 2 inches late Tuesday night.

A mid-to-upper level short-wave trough will remain the dominant
feature into Saturday, with the associated jet enhancing
ventilation across the northeastern Caribbean, and causing mid-
level temperatures to drop as low as -10 degrees Celsius by Friday
evening. Another short-wave trough will follow, supporting
favorable conditions for deep convective development by the latter
part of the cycle. At the surface, a high pressure migrating
eastward into the north-central Atlantic will cause winds to veer
to the southeast and diminish to 10-15 mph Friday into the
weekend, but becoming more south-southeasterly at ten mph or less
by early next week. The southeasterly component in the general
wind flow will also lead to higher daytime temperatures that could
peak around 90 degrees, mainly across northern sections and urban
areas of the local islands.

Despite moisture variations, showers and possible isolated
thunderstorm development are expected every day, even on the
driest days, following the seasonal pattern with nocturnal/early
morning showers moving inland over windward areas and afternoon
convection across the interior and western sections. Following the
most recent update, the best chance for shower development and
perhaps an increased risk for localized urban and small stream
flooding has now shifted to Saturday and Monday night into
Tuesday, when favorable conditions aloft, local and diurnal
effects, abundant tropical moisture, and a weak steering flow will
lead to a higher chance for moderate to heavy rains from deep,
slow-moving showers. Given the expected weak southeasterly
steering flow, the focus of the activity will favor central and
northern to northwestern sections of the local islands. Confidence
in this forecast remains low due to increasing uncertainties so
far out in the cycle, particularly for the potential of wetter
conditions early next week.


&&

.AVIATION...VCSH expected across the local terminals in the
morning hours, with TEMPO SHRA at TJSJ and TJBQ through at least
03/10Z. East winds to prevail today at around 15 KT with higher
gusts, decreasing after 03/22Z. SHRA/TSRA forecast across W-PR
after 03/16Z could cause VCSH/VCTS at TJBQ.


&&

.MARINE...Moderate to fresh winds up to 20 knots will maintain
choppy marine conditions, mainly across the offshore waters and
local passages, where small craft operators should exercise
caution. Mariners can expect seas of 5 feet or below and surface
winds up to 15 knots elsewhere across the local waters. For
beachgoers, there is a high risk of rip currents for beaches
across the northwest to the northeast coast of Puerto Rico,
northern and eastern Culebra, northwestern Saint Thomas, and
eastern Saint Croix.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 73 85 76 / 40 20 30 40
STT 86 73 86 74 / 30 10 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
422 AM AST Wed May 4 2022

.SYNOPSIS...
As breezy easterly winds and average moisture values prevail, a
relatively typical rainfall pattern is expected with passing
windward showers and afternoon development in western regions due
to seabreeze convergence and local effects. Precipitable water
values are expected to fall over the weekend and then will slowly
rise throughout the week as a surface low in the Western Atlantic
will promote southeast flow that will pull tropical moisture over
the Islands. A High to Moderate Risk of Rip Currents continues
throughout the day into tonight.

.SHORT TERM...TODAY THROUGH FRIDAY...

The available moisture is expected to be near to below normal for
the most part over the short term period. There is however a
developing trough in the mid and upper levels, that could cause an
increase in instability. This increase in instability will
support locally induced thunderstorm development across western PR
due to sea breeze convergence. The little bit of Saharan dust
that appears to be lingering today will gradually move out of the
area, and the latest guidance is suggesting that any sort of dust
would be out of the area late Thursday and Friday. A surface high
pressure across the southwestern Atlantic will move slowly to the
east over the short term period, tightening the local pressure
gradient and thus causing somewhat breezy conditions today, with
winds possibly reaching 15 to 20 mph across coastal areas. Winds
are expected to diminish slightly on Thursday and then even more
on Friday.

Overall, a relatively typical rainfall pattern is expected. Isolated
to scattered showers are forecast across the local waters, USVI, and
eastern PR in the overnight and early morning hours each day in the
short term period. Then showers and twhen the risk thenhunderstorms
are forecast across portions of western PR in the afternoon hours
each day due to the aforementioned sea breeze convergence and
local effects. The ENE winds may help keep the daytime high temps
in the mid 80s across the northern sections of the local islands,
but the south coastal sections of PR may see temps in the upper
80s. However, easterly winds are expected to return on Friday, and
the daytime high temps across the north coastal areas could also
reach the upper 80s, or even 90 degrees.

.LONG TERM...Saturday though Wednesday...

Over the weekend, a surface high pressure system in the Central
Atlantic steers a southeasterly flow over the Islands. Currently,
Saturday appears to be quite dry in comparison to the following days
regardless of an upper level trough east of the region. Sunday
onward, lower to mid level columnar moisture begins to rise as
variable patches of moisture advects though with the prevailing
flow. This southeast wind flow will become reinforced early in the
week when a surface low develops in the Western Atlantic. GFS model
guidance suggest that precipitable water values will progressively
increase until reaching exceptional values on Wednesday as
tropical moisture moves into the region. This surface low may
also produce a northerly swell that could raise local wave
heights.

Upper levels remain mainly zonal throughout this period until
Wednesday when the flow become southwesterly. With this, upper level
tropical moisture will fill into the region, most likely resulting
in lots of cloud coverage. This all being said, a typical pattern of
passing showers and afternoon developmwhen the risk thenent is
expected with the chance of overnight showers as patches of
moisture combine with local effects until Wednesday onward, when
moisture values are expected to surge. Throughout the week,
surface to 850 mb wind flow will prevail from the southeast,
therefore windward areas and the northwestern region of Puerto
Rico is expected to receive the bulk of activity.

&&

.AVIATION...VFR conds expected across the local terminals today.
However, there may be VCTS/VCSH at TJBQ after 04/17Z since
SHRA/TSRA is forecast to develop across W-PR, which may affect the
vicinity of TJBQ for a brief period. ENE winds are expected
today, which could reach 15 KT or slightly higher with occasional
gusts. Winds at TJPS will be from the ESE after 04/14Z due to sea
breeze variations.

&&

.MARINE...Moderate to fresh easterly winds continue to promote
choppy seas. A small northerly swell remains in the water adding
height to breaking waves. As choppy conditions continue, small
craft operators should exercise cautiowhen the risk thenn. A High
Risk of Rip Currents remains until late tonight and then becomes
moderate for most beaches of Puerto Rico and the U.S. Virgin
Islands.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 85 75 86 74 / 20 40 40 20
STT 87 75 86 74 / 20 30 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
448 AM AST Thu May 5 2022

.SYNOPSIS... A typical weather pattern is expected to prevail
today. Passing showers across the windward sections of the
islands, then followed by afternoon convection, including
isolated thunderstorms over the central interior and western
Puerto Rico. Marine conditions are improving with seas up to 5
feet or less and a moderate risk of rip currents will continue
across the local beaches for the next several days.

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

The available moisture is expected to be slightly below normal for
the short term period, with precipitable water values between 1.3 to
1.4 inches, and low RH values at the 800-600mb levels. There is
however a trough in the mid and upper levels, that could cause an
increase in instability today and Friday, but we should be in the
subsident side by Saturday. This instability will support locally
induced thunderstorm development across western PR when it combines
with diurnal heating and sea breeze convergence. With respect to
Saharan Dust, the latest guidance is suggesting that any sort of
dust should be out of the local area by this afternoon if not
already since the latest observations have not reported haze. A
surface high pressure north of the local area will continue moving
slowly to the east over the short term period, causing somewhat
breezy conditions today, with winds possibly reaching 15 to 20 mph
across coastal areas. Winds are expected to diminish slightly on
on Friday, and then even more on Saturday.

Isolated showers are forecast across the local waters, USVI, and
eastern PR in the overnight and early morning hours each day during
the short term period. Then scattered showers and isolated
thunderstorms are forecast across portions of western PR in the
afternoon hours each day. That said, locally numerous showers and
isolated thunderstorms are in the forecast for this afternoon. The
daytime high temps will be in the mid to upper 80s across the
coastal sections of the local islands today. However, the daytime
high temps could be in the upper 80s to near 90 across the coastal
areas on Friday and Saturday.

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

A broad high pressure in the Atlantic will continue to dominate
the area for much of the long term period. Drier air mass will
filter into the local area, with trades winds that are favorable
for the development of morning showers across the U.S. Virgin
Islands, and eastern sectors of Puerto Rico from time to time.
Warmer temperatures are expected as this dry weather pattern will
prevail throughout the work-week. Nonetheless, the atmosphere is
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 are
also expected 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 expected across the local terminals today.
VCTS/VCSH possible at TJBQ after 05/17Z since SHRA/TSRA is
forecast to develop across W-PR. E winds expected today, which
could reach 15 KT or slightly higher with occasional gusts to 25
KT or slightly higher. Winds at TJPS will be from the ESE after
05/14Z due to sea breeze variations.

&&

.MARINE...Seas up to 5 feet or less will continue across the local
waters, with winds ranging between 15 and 20 knots. Mariners
should exercise caution across the waters and passages. There
is a moderate risk of rip currents for all the beaches of Puerto
Rico and the U.S. Virgin Islands.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 85 74 88 75 / 40 20 20 20
STT 86 75 84 74 / 30 20 20 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
455 AM AST Fri May 6 2022

.SYNOPSIS...Seasonal weather pattern is expected to prevail
across the islands today. Passing showers across the windward
sections of Puerto Rico and the U.S. Virgin Islands, then followed
by afternoon convection, including isolated thunderstorms over
the central interior and western Puerto Rico. Marine conditions
continue to improve with seas up to 5 feet or less. There is a moderate
risk of rip currents across the local beaches for the next
several days.

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

The available moisture continues to be expected slightly below
normal today and Saturday, with precipitable water values between
1.2 to 1.4 inches, increasing up to almost 1.5 inches on Sunday. RH
values at the 800-600mb levels are forecast to be on the lower end,
which may help inhibit thunderstorm development this afternoon.
There is a trough in the mid and upper levels, that could cause an
increase in instability today, but the air may be just a bit too dry
to cause prolonged and deep convection, and the hi-res models seem
to agree. That said, we should be in the subsident side of the
troughs by Saturday, then zonal flow is expected in the upper levels
by Sunday. A surface high pressure north northeast of the local area
will continue moving slowly to the east over the short term period,
expecting for it to be in the central Atlantic by Sunday. By Sunday,
a surface low pressure will enter the western Atlantic, causing the
local winds to shift to a SE direction. Easterly winds of 10-20 mph
are expected today, decreasing a little on Saturday as they gradually
shift to the SE at 10-15 mph on Sunday.

Isolated showers are forecast across the local waters and eastern PR
in the overnight and early morning hours each day during the short
term period. Then scattered showers are forecast across portions of
western PR in the afternoon hours each day, but isolated
thunderstorms are also forecast for Sunday afternoon. That said, the
USVIs are expected to have isolated to brief scattered showers
during the day and nighttime hours with little to no rainfall
accumulations. The daytime high temps will be in the mid to upper
80s across the coastal sections of the local islands today. However,
the daytime high temps could be in the upper 80s to near 90 across
the coastal areas on Saturday, and especially across northern PR on
Sunday due to the expected SE winds.

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

A relatively wetter pattern is expected to prevail across the local
area for most of the period. A surface to mid level trough will
start to bring bands of tropical moisture into the forecast area for
the beginning of the term. This pattern will support the development
of nighttime and morning showers in the windward side of Puerto
Rico, and afternoon convection in the central interior and western
portions. Winds will turn more from the southeast suggesting an
increase of the precipitable water values until the end of the work
week. From Friday onwards, latest GFS model suggest a high surface
pressure intensifying over the Atlantic and much drier air will
filter into the local area promoting stable conditions aloft.
Nonetheless, the atmosphere will still 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 are also expected to form over El Yunque are
and moving over the metropolitan area of San Juan.


&&

.AVIATION...VFR conds expected across the local terminals today. VCSH possible
at TJSJ after 06/14Z, then at TJBQ after 06/17Z. Winds will be light
and easterly until 06/13Z, gradually increasing up to around 15KT
with occasional gusts and sea breeze variations.

&&

.MARINE...Moderate easterly winds with seas up to 5 feet are expected to
prevail today and into Saturday. Winds will turn more southeast
while weakening as we head towards the weekend. For beachgoers, there
is a moderate risk of rip currents for most beaches of Puerto
Rico and the U.S. Virgin Islands, except for the western beaches
of Puerto Rico where the risk of rip currents is low.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 74 89 76 / 30 10 10 20
STT 85 75 85 77 / 20 10 10 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
455 AM AST Sat May 7 2022

.SYNOPSIS...A seasonal weather pattern is expected to prevail
across the islands throughout the weekend, with a patch of
moisture increasing cloud coverage and shower activity on Sunday.
A wetter pattern over northeastern Caribbean is anticipated by
next week as tropical moisture increases across the area. However,
some uncertainty persists with location and timing of impacts.
Improving marine conditions with seas up to 5 feet or less are
forecast through the weekend. There is a moderate risk of rip
currents across the local beaches for the next several days.


&&

.SHORT TERM...Saturday through Monday...

A broad surface high pressure ridge spread across the north central
Atlantic and extending southwards into the northeastern Caribbean,
will maintain a light to moderate east southeast wind flow today
through Saturday, becoming more southeasterly on Sunday. Mostly
sunny and fair weather skies will prevail into early Sunday,
followed by a slight increase in trade wind moisture by late Sunday
through Monday. Mid to upper level ridge will however build and hold
across the area through the period to maintain dry and stable
conditions aloft.

As aforementioned ,an overall dry airmass will prevail today into
Sunday. Few passing morning showers may affect the coastal waters and
reach parts of the east coastal sections of Puerto Rico and the
adjacent islands. Lesser shower activity is expected around the U.S.
Virgin Islands, as a drier conditions and mostly fair weather will
persist. For the rest of today, low level winds are forecast to
gradually become more east southeast except for local sea breeze
variations. Lingering pockets of moisture along with local and
diurnal effect will support some afternoon shower development,
mainly over parts of the west interior and northwest sections of
Puerto Rico steered by the east-southeast low level wind flow.
Elsewhere mostly sunny skies and somewhat breezy conditions will
prevail. Similar weather conditions expected on Sunday with limited
shower activity across the region as an overall dry airmass is
expected to prevail. However passing tradewind showers can be ruled
out, followed by afternoon showers focused mainly over the northwest
sections Puerto Rico. The San Juan metro may see a few quick passing
showers which may develop and stream across the area. Elsewhere
mostly sunny skies are expected based on recent model guidance. A
slight increase in low level moisture is however expected by late
Sunday into Monday as a weak easterly perturbation will cross the
region a the southeasterly wind flow increases. A gradual warming
trend is also expected over the weekend through Monday especially
along the north coastal municipalities as well as for the USVI.

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

Uncertainty characterizes the long-term forecast mainly due to the
placement of an advected moist plume from the south across
northeastern Caribbean. Both GFS and ECMWF models show very similar
patterns throughout the week, but akin to recent events, GFS
continues to be more bullish regarding moisture content across the
area. Tuesday starts with a strong low pressure system reflected
at all pressure levels in the atmospheric column over western
Atlantic as the subtropical jet at upper-levels covers the
forecast area. Additionally, a strong surface high pressure and
mid- to upper- level ridge will dominate the north central
Atlantic. The evolution of these features will determine the
overall impacts in Puerto Rico and U.S. Virgin Islands throughout
the workweek into the weekend.

As the week advances, the pressure system at the surface is expected
to move gradually westward towards the eastern coast of the U.S.
While doing so, it will induce southeasterly winds over Puerto Rico
and U.S. Virgin Islands, pulling tropical moisture across north and
eastern Caribbean. At upper-levels the subtropical jet will
intensify west of the area which should promote favorable weather
conditions aloft for deep convective activity as the ridge over
north central Atlantic amplifies. Past model runs for both GFS and
ECMWF show a similar evolution, however, the positioning of all
these weather components change slightly from cycle to cycle. In
the most recent GFS 07/00z run, Puerto Rico and U.S. Virgin
Islands are on the edge of the above normal moisture plume with
the bulk centered over Hispaniola as the strong low pressure
system moves westward towards the Florida Peninsula. On the other
hand, the 07/00z ECMWF model run has the plume even farther west,
with drier airmass affecting the forecast area. Therefore, given
its moisture uncertainty, the forecast combines both model
solutions.

Dynamically speaking, both models are a bit more consistent on
unsettled weather conditions at upper-levels through at least
midweek of next week with a gradual increase in stability aloft as
the low pressure system moves westward and a building ridge
dominates the northeastern Caribbean by Saturday. The potential
for flooding due to rainfall and widespread thunderstorm activity
can be expected throughout the week but confidence is low due to
lack of detail in timing and location of these features. We will
continue to monitor the progress of this weather pattern as it
evolves throughout the week.


&&

.AVIATION...VFR conds at all terminals durg prd. Few SHRA ovr
regional waters en route btw islands...Mstly SCT lyrs nr FL025
...FL050. Aftn SHRA psbl mainly ovr W interior and NW PR with only
slght chc of Isold TSRA fm 07/18-21z. Sfc wnds lgt/vrb to
calm...bcmg mainly fm E at 10-20 knots with higher gusts and local
sea breeze variations after 07/14z. No sig operational wx impacts
to AVN attm.

&&

.MARINE...Moderate easterly winds continue to raise local seas up
to 4 feet. Wind speeds will reach their strongest values in the
afternoon throughout the next few days. There is a slight chance
of passing showers over the local waters. A moderate risk of rip
currents remains for most coastlines of Puerto Rico and the U.S.
Virgin Islands.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 76 90 77 / 10 20 20 30
STT 81 77 81 77 / 10 20 30 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
429 AM AST Sun May 8 2022

.SYNOPSIS...A diurnal weather pattern will continue to prevail today
through early in the week, with passing showers affecting portions
of the southeastern Puerto Rico and the USVI during the overnight
and morning hours followed by afternoon convection across
northwestern Puerto Rico. By midweek, tropical moisture could move
across the area, with more widespread shower and thunderstorm
activity possible. Seas below 4 feet with low to moderate risk of
rip currents will continue through at least Tuesday.


&&

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

Surface high pressure spread over the north central Atlantic and
extending southwards across the northeastern Caribbean, will
maintain an east southeast low level wind flow across the area
today. The winds are forecast to veer below 500 millibars and become
more southerly during the period. This will result in good warm air
advection leading to warmer temperatures especially in urban areas
along the northern half of Puerto Rico and the U.S. Virgin Islands.
This will also cause heat indices to near 100 degrees in these
areas. In addition, a plume of low level trade wind moisture will
sweep across the region later today into Monday and therefore
increase the change for periods of isolated to scattered showers
across portions of the islands. In the mid to upper levels, a weak
ridge is to hold across the region into Monday, but will erode by
Tuesday as a trough is forecast to move eastwards across the west
Atlantic and gradually destabilize the upper levels resulting in
better ventilation aloft.

In the meantime, expect overall dry and stable conditions aloft
today through Monday. This should aid in limiting enhanced daytime
convection across the islands. However, the combination of the
anticipated warmer temperatures and good heating each day, along
with the aforementioned moisture plume, should be sufficient to
favor locally induced afternoon showers as well the chance for
isolated thunderstorms. This activity should be focused mainly over
the west interior and northwest sections of Puerto Rico, with lesser
activity expected around the San Juan metro. Minor ponding of water
on roads and in poor drainage areas will therefore be possible in
isolated areas but mainly in northwest Puerto Rico. Brief early
morning and afternoon showers will remain possible around the USVI
especially around St Croix, but no significant rainfall
accumulations are expected as a mix of sunshine and passing clouds
is forecast each day.

By Tuesday, expect a gradual erosion of low level moisture, however
with the continued southerly low level wind flow and erosion of the
ridge aloft, expect the development of locally and diurnally induced
afternoon showers over portions of the islands. This should be
focused over portions of the central interior and northwest sections
of Puerto Rico, but with the increasing chance for some afternoon
showers in the form of streamers around the San Juan metro as well.
Limited showers activity is expected during the overnight and early
morning hours during that time.

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

The long-term forecast continues to struggle regarding moisture
content across the area. Both GFS and ECMWF models, however, are
slightly in better agreement for Wednesday, with discrepancies
gradually increasing for Thursday onwards. The strong low pressure
system across western Atlantic is still expected to slowly move
westward approaching the Carolinas in the United States while
inducing southeasterly winds at low levels. Under this wind
influence, tropical moisture is expected to get advected across
the northeastern Caribbean with precipitable water values
increasing from 1.5 inches on Wednesday to almost 2.0 inches by
Thursday. At upper-levels, the subtropical jet over the CWA will
slightly round the strong cut-off low and position itself
northwest of the area while generating a jet maxima during this
period. The proximity of this jet maxima should maintain favorable
conditions aloft for convective development. The 500 mb
temperatures will also remain below normal to normal
climatological levels, between -6 to -9 degree Celsius. Therefore,
expect a gradual increase in cloud coverage and the potential for
isolated to scattered thunderstorms across the CWA, especially
for Thursday if high moisture content is retained.

On Wednesday, the strongest activity will be focused across
northwestern quadrant of Puerto Rico in the afternoon as high
moisture content combines with induced surface heating and sea
breeze convergence. Streamers downwind of El Yunque could affect the
San Juan Metropolitan area. By Thursday, the rainfall and
thunderstorm activity will become more widespread, but might be
strongest over the Mona Passage and northwest of Puerto Rico, across
the Atlantic waters extending to western municipalities due to the
positioning of the jet maxima at upper-levels. This wetter weather
pattern will increase the potential for urban and small stream
flooding. In localized areas with the heaviest showers, flash
flooding events cannot be ruled out, especially roads and buildings
in flood prone areas. Confidence in this forecast is still low as
location of the advected plume of moisture continues to shift with
latest 08/00z ECMWF model run putting it more west than previous
model runs.

Uncertainty greatly increases on Friday through Sunday as ECMWF
suggests a rapid drying trend compared to GFS model, the latter
indicating the continuation of wetter conditions through the
weekend. Despite the fact that both models differ greatly in
moisture content, they agree on a building ridge at upper levels
and the amplification of a surface high pressure over north
central Atlantic into northeastern Caribbean. Therefore, although
agreement in moisture content across the CWA continues to
fluctuate between models, it seems that dynamics will become more
seasonal for the latter part of the forecast period. We will
continue to monitor de evolution of this forecast as we get closer
to the forecast period.


&&

.AVIATION...VFR conds at all local terminals. Few-Isold SHRA/-SHRA
ovr regional waters and enroute btw islands. SCT-BKN lyrs nr
FL025...FL040..FL080 btw E-PR and the USVI with brief SHRA psbl at
TIST/TISX/TJSJ til 08/14Z. Brief Mtn Top obscr ovr E PR til 08/12Z.
Aftn SHRA w/chc of Isold TSRA btw 08/18-21z ovr the west interior
and northwestern sections of PR. SFC wnds calm to lgt/vrb ..bcmg fm
ESE at 10-20 knots with higher gusts and sea breeze variations aft
08/13Z. No sig operational wx impacts attm.


&&

.MARINE...Recent buoy observations continue to show seas below 4
feet at the nearshore. These conditions are expected to prevail
through Tuesday, when a northerly swell will invade the waters.
Winds will remain moderate, at 5 to 15 knots, with stronger gusts
near the coastal areas. For the beaches, there is a moderate rip
current for most of the local beaches across the local islands.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 75 90 76 / 20 30 40 30
STT 84 77 84 77 / 30 50 50 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
451 AM AST Tue May 10 2022

.SYNOPSIS...
Very warm to hot temperatures will linger along the area today.
Heat indexes are expected to reach above 100s mainly over north-
central municipalities by late morning through early afternoon.
Please exercise caution. An increase in moisture for the middle to
latter part of the workweek could result in increasing shower
activity. Marine conditions will deteriorate by the end of the
workweek.


&&

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

Overall mostly sunny and hot weather conditions will prevail
today under a relative dry and stable airmass which continued to
filter in across the region along with a dominant southeast low
level wind flow. The region continued to be wedged between a
strong high pressure ridge across the north central Atlantic and a
broad area of low pressure and associated cold front now
meandering across the west Atlantic. Recent satellite imagery and
doppler weather radar both suggest an even drier drier air mass
spreading across the area. Satellite derived precipitable water
values ranged between 1.25-1.38 inches which remains below the
normal climatological values. Consequently, expect mostly fair
weather conditions to prevail in most areas. However, there is
slight potential for brief afternoon shower development and an
isolated thunderstorm over the northwest sections of Puerto Rico.
This will be mainly due to local winds and terrain effects and
good daytime heating. Any activity that do develop will be of
short duration,as recent satellite imagery and derived local
precipitable water content suggests only shallow and and limited
moisture availability. The mid to upper level ridge should
therefore continue to suppress significant convective development.
The dominant southeasterly winds flow will however promote warmer
temperatures along the north coastal areas of Puerto Rico and
this will cause heat indices to range between 100 and 107 in some
areas. The local public and visitors are urged to please take the
necessary protective precautions and stay hydrated if outdoors.

On Wednesday and Thursday expected a gradual change in the overall
weather pattern as the Atlantic high pressure ridge is forecast to
lift northwards and the area of low pressure across the western
Atlantic and associated frontal boundary induces a weak low level
trough just west of the region. This will support better low level
moisture convergence while the mid to upper level ridge is forecast
to erode in response to a polar trough slowly lifting eastwards
across the west Atlantic. This overall scenario will support
unstable conditions aloft and thus provide good ventilation,
resulting in isolated areas of enhanced convection, based on the
most recent model guidance which so far appeared to be in good
agreement for the short term. That said the potential for overnight
and enhanced afternoon convection is moderate to high for mainly
parts of the east interior and northern half of Puerto Rico where
urban an small stream flooding will be possible in isolated areas.

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

Friday will start with a ridge north of the forecast area in the
mid- to upper levels, this ridge should prevail until around
Monday near the end of the long term period. For Friday, winds
will be from the east southeast becoming more southeast by Sunday.
There is discrepancy between the GFS and the ECMWF models
regarding the amount of humidity affecting our area during Friday
and the rest of the long term period with the ECMWF showing a much
drier atmosphere above 850 mb. They do seem to agree more on
moisture availability for Saturday with both showing mid-level
relative humidity between 60-80% through most of the day. The 500
mb temperatures should reach between -6C to
-5C by Friday which is normal to above normal values for this time
of the year. The GFS somewhat maintains these 500 mb temperatures
through the long term period while the ECMWF increases the 500 mb
to close to -4C by Sunday. Along with the effects of the ridge,
the increase in 500mb temperatures can limit thunderstorm
activity. However, isolated thunderstorms during afternoon hours
cannot be ruled out. By Tuesday at the end of the long term
forecast period a tropical wave should bring moisture to our
region, with precipitable water values reaching above 2 inches.
This can result in increased rain chances for the eastern region
of Puerto Rico and the local islands. This could cause ponding of
water in roads and poorly drained areas. However, forecast
confidence is low due to the discrepancies regarding available
moisture, therefore the forecast will continue to be monitored.

&&

.AVIATION...

VFR. Few SHRA E coastal areas til 10/12Z w/ brief Mtn
top obscr psbl ovr E interior of PR due to low clds and -SHRA. Winds
less than 10 kts with land breezes..bcmg mainly SE 10-15 kts with
limited sea breeze variations aft 10/14Z. Low level winds fairly
light fm the SE 5 to 15 kts BLO FL100..bcmg fm W and incr w/ ht ABV.
No sig operational wx impact fcst durg prd for the local terminals.


&&

.MARINE...

Nearshore observations show seas less than and around 3 feet.
These conditions should maintain through at least tonight, then
choppy to hazardous seas are expected through the end of the
workweek due to increasing winds and a small northerly swell. For
the beaches, a high risk of rip currents is expected for some
northern beaches by tonight, then the high risk of rip currents will
extend to most local beaches.



&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 91 77 90 76 / 30 30 50 50
STT 81 80 81 79 / 30 30 50 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
509 AM AST Wed May 11 2022

.SYNOPSIS...

Isolated thunderstorms are developing across the eastern and
northern regional waters, this activity should continue through
the next few hours. Heat indexes are expected to reach above 100s
for the north-central municipalities by late morning through early
afternoon. Increasing winds in combination with a small northerly
swell will deteriorate marine conditions, as seas become choppy
to hazardous, through the end of the workweek. Increasing moisture
today and tomorrow can result in increasing shower and
thunderstorm activity.


&&

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

Variably cloudy skies will prevail for the rest of the morning hours
due to a low and high level clouds streaming across the region.
Passing showers will continue to affect the regional waters during
the rest of the early morning hours, as a surge of moisture is
steered across the region by the prevailing southeast wind flow.
Occasional showers of mostly light to moderate intensity will affect
the south and east sections of Puerto Rico as well as the San Juan
metro, parts of Culebra, Vieques and mainly the island of St Croix.
So far rainfall accumulations were not expected to be significant as
the showers will be fast moving and of short duration.

For the rest of today and through Thursday, a fairly moist
southeasterly wind flow will prevail. This is due to a surface high
pressure across the north-central Atlantic and a meandering broad
area of low pressure with the associated cold front across the
western Atlantic. This dominant southeasterly wind flow will
continue to promote warmer and slightly above normal temperatures
especially along the along the north coastal areas of Puerto Rico.
Therefore the maximum heat indices are still forecast to fluctuate
between 100 to 103 in isolated areas. As a result, the local public
and visitors are still urged to please take the necessary protective
measures and stay hydrated if going or working outdoors.

Recent model guidance continue to suggest a somewhat wetter pattern
today and through at least Thursday due to the waning mid to high
pressure ridge aloft and the broad polar trough crossing the west
Atlantic, which is to relocate just northwest of the region. In
addition, the good low level moisture convergence and cooler mid
level temperatures will result in better chance for enhanced
afternoon convection over parts of the islands, especially over the
interior and northwest to north central sections of Puerto Rico.
Some brief shower activity may also affect the San Juan metro during
the afternoon but should be of short duration in the form of
streamers. The proximity of the mid and upper level trough and the
subtropical jet just north and west of the area will also favor
increasing instability aloft with good potential for isolated
thunderstorm development during the next few days especially during
the afternoon hours. Due to the expected periods of heavy rains,
there is moderate potential for ponding of water on roads and in
poor drainage areas as well as the chance for minor urban flooding
today and on Thursday.

By Friday, weather conditions are expected to gradually improve as
the mid to upper ridge will reestablish across the region and low
level moisture continues to erode. In the meantime, the tradewinds
winds increase and become more easterly. However lingering moisture
along with local and diurnal effect will result in early morning
passing showers , followed by isolated to scattered afternoon
convection over parts of the interior and west sections of Puerto
Rico as well as on the west end and downwind of the U.S. Virgin
Islands. Therefore during the afternoon hours there will be lesser
chance for urban and small stream flooding , however ponding of
water on roads and poor drainage areas will remain possible. Also
the increasing trade winds a will also lead to breezy conditions
during the day.

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

A mid- to upper- level ridge north of the forecast area will be
prevailing on Saturday and should continue to prevail through
Monday. For Saturday, winds will be from the east southeast becoming
more southeast by Sunday. There continues to be discrepancy between
the GFS and ECMWF models with respect to the amount of humidity
affecting the forecast area during the long term period. While
the GFS is showing a slightly drier atmosphere than yesterday and
the ECMWF is showing a slightly more humid atmosphere than
yesterday, the ECMWF is still showing a generally drier atmosphere
above 850mb through the long term period. Both models continue to
agree on moisture availability for Saturday as they both show
mid-level relative humidity values between 50-80% through most of
the day. By Saturday, the 500 mb temperatures should be within -6C
to -4C, normal to above normal values. An increase in wind speed
is expected on Saturday at around 18Z, as the pressure gradient
tightens, with winds of around 20 kts. This wind flow should bring
patches of moisture to our forecast area, but the effects of the
ridge and the increase in 500mb temperatures can also limit
thunderstorm activity. However, isolated thunderstorms during the
afternoon hours cannot be ruled out. Nevertheless, shower activity
is expected with showers affecting mainly windward coastal areas
during morning hours and scattered to numerous showers over
western portions of Puerto Rico. A tropical wave will pass mainly
south of the forecast area, however some low level moisture should
filter in across the forecast area by the latter part of the long
term period. This can result in increased rain chances for the
eastern region of Puerto Rico and the local islands. This could
cause ponding of water in roads and poorly drained areas. However,
forecast confidence is low due to the discrepancies regarding
available moisture, therefore the forecast will continue to be
monitored.


&&

.AVIATION...
VFR conds at all terminals. SCT-BKN lyrs nr FL025...
FL050...FL090...BKN-OVC nr FL200. Wdly SCT SHRA ovr regional waters
and enroute btw islands w/Isold TSRA ovr ATL waters NW of PR til
11/10Z. Isold tops nr FL250 with TSRA. VCSH at TJPS/TJSJ and the
USVI terminals during the rest of the morning hours...with MTN top
obscr ovr E PR due to low cig and SHRA til 11/12Z. Low level winds
fm SE 10-15 kts BLO FL120 then veering and incr w/ht ABV. Wnds
mainly fm SE at 10KT or less, but incr to around 15 kts and gusty
after 11/14Z. SHRA/Isold TSRA psbl vcty TJBQ fm 11/17Z-11/22Z.


&&

.MARINE...
Nearshore observations show seas less than and around 3 feet, with
a southern nearshore observation showing 3.5 ft. Choppy to hazardous
seas are expected into the weekend due to increasing winds and a
small northerly swell. For the beaches, a high risk of rip
currents is expected through Thursday afternoon for most
northern, western and eastern beaches including Culebra. A Small
Craft Advisory is expected to be in effect from thursday afternoon
through late thursday night for the offshore Atlantic Waters.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 77 87 77 / 40 50 50 20
STT 81 80 81 79 / 30 50 40 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
445 AM AST Thu May 12 2022

.SYNOPSIS...
Patches of moisture will move across the island bringing showers
at times. Thunderstorms are expected in the afternoon today and
tomorrow. Seas will be choppy to hazardous across the offshore
waters due to increasing winds.


&&

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

A strong upper low in the western Atlantic east of the
Florida/Georgia border will retrogress and move onshore in the
United States on Friday and then move slightly northeast on
Saturday. This will allow a ridge, also at upper levels, to build
east of the area. At mid levels, high pressure just east of
Guadeloupe will move over the area by Saturday evening. At lower
levels, a high over the west central Atlantic will hold a ridge over
the northeastern Caribbean and maintain southeasterly flow. This
will carry bands of moisture into the area obliquely and keep clouds
and showers over the area. Mid level temperatures are relatively
cool today and will dip to minus 9 degrees C this afternoon, but
will warm to minus 4.5 degrees C by Saturday evening, hence
stability will increase during the period. Isolated thunderstorms
are expected this afternoon and will be possible on Friday, but are
not expected on Saturday.

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

Next week will start off with the mid- to upper- level ridge north
of the forecast area. As a surface high pressure continues to move
through the Atlantic a general southeast wind flow at 15-20 kts is
expected to continue. This wind flow can bring patches of moisture
into the area at times. Both GFS and ECMWF have started to shown
more agreement for the moisture content on Sunday, with both showing
drier mid-levels during that day, adding more confidence level to the
forecast. In addition, temperatures at 500mb should warm up to be
within -5C to -4C for most of the long term period, which is above
normal for this time of the year, before cooling to close to -6C on
Thursday. Due to these 500mb temperatures and the effects of the
ridge, any thunderstorm activity will be limited. This can leave the
seasonal pattern of showers affecting windward coastal areas in the
morning and showers affecting western portions of Puerto Rico in the
afternoon, isolated thunderstorms during the afternoon hours cannot
be ruled out.

A transition into a wetter pattern is expected by Tuesday as some
low level moisture filters into the forecast area as a tropical wave
passes mainly south of our region through the day. As the wave moves
westward, a lingering pocket of moisture should reach the area late
Wednesday into Thursday. This can result in increased rain chances
for the eastern region of Puerto Rico and the local islands. This
could cause ponding of water in roads and poorly drained areas and
increase the likelihood of urban and small stream flooding.


&&

.AVIATION...
Areas of SHRA are expected throughout the day with local
MVFR conds and mtn topping in ern PR and dvlpg in wrn and interior
PR btwn 12/15-17Z. Isold TSRA psbl. Sfc winds bcmg by 12/15Z SE 10-
18 kts with gusts to 28 kt psbl alg the north and south coasts.
Winds subsiding to arnd 10 kts aft 12/22Z. Max winds W 80-90 kts
btwn FL410-500 diminishing somewhat durg the day.


&&

.MARINE...
Increasing winds will result in choppy to hazardous seas across
the offshore waters and local passages. This conditions are
expected to linger at least until tomorrow. Seas up to 7 ft and
winds up to 20 kts with smaller gusts are anticipated.

There is a high rip current risk for most of the local beaches
and local islands except the beaches around Ponce and vicinity.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 75 88 76 / 50 20 50 50
STT 85 77 85 77 / 40 40 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
521 AM AST Fri May 13 2022

.SYNOPSIS...
Breezy conditions will maintain choppy to hazardous seas through
the weekend. Patches of clouds will move across the local islands
at times, bringing passing showers. Warm temperatures are expected
to return by next week, with heat indices again just above 100
degrees.

&&

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

At mid and upper levels a ridge is found east of the windward
islands early today and will move westward over the area Saturday
and Sunday as the trough over the western Atlantic retrogresses into
the southeastern United States. Flow at lower levels is and will
continue to be east southeast driven by the high that remains in the
northwest central Atlantic. In this pattern, the atmosphere over the
local area remains dry just above 700 mb. Temperatures at 500 mb
will warm from minus 7 to almost minus 4 by Saturday evening and
stability will increase over the area. Hence the chances of
thunderstorms forming with the dry layer just above 700 mb and the
limited instability are quite limited and will not be included in
the forecast for any of the next 3 days. Showers, however, will be
found in the lower layers through the period even though their
energy source is limited by the cloud cover in the area including
the persistent cirrus and some mid cloud layers seen from the last
several days.

.LONG TERM...Monday through Friday

The mid- to upper-level ridge north of the forecast area will
continue to affect us as we enter the workweek. A surface high
pressure in the Atlantic will promote winds from the southeast to
reach our area. This wind flow can bring patches of moisture into
our area at times. This wind flow can also bring warmer air into our
forecast area, causing hot days especially for the north-central
sector of the island, urban areas and areas of low elevation. During
most of the forecast period the temperatures at 500 mb will be
relatively warm between -5C to -4C, which is above normal
temperatures for this time of the year. The 500mb temperatures are
expected to cool to -6C to -5C, from Thursday to Friday. Due to
these 500mb temperatures and the ridge affecting our forecast area,
thunderstorms are unlikely. This should leave the normal seasonal
pattern of showers affecting windward coastal areas in the morning
and showers affecting the western area of Puerto Rico in the
afternoon hours. As a tropical waves passes mainly south of our
region through Tuesday, some low level moisture will filter into our
forecast area. As the wave moves westward, a lingering pocket of
moisture should also reach the area Wednesday into Thursday. This
can result increased rain chances for the eastern area of Puerto
Rico and the local islands. This could cause ponding of water in
roads and poorly drained areas and increase the likelihood of urban
and small stream flooding. On Friday as a relatively drier airmass
filters into the region, rain chances are expected to be limited.


&&

.AVIATION...
Mainly VFR conditions are expected to prevail across all
terminals through the forecast period. However, sct SHRA will dvlp
ovr wrn and interior PR arnd 13/16Z and cont thru 13/23Z. Sfc winds
will bcm ESE 12-18 kts aft 13/14Z.

&&

.MARINE...
Moderate to fresh winds will maintain choppy to hazardous seas
through Saturday. Seas up to 7 feet are expected for the offshore
Atlantic waters through late tomorrow. Elsewhere, seas up to 6
feet are expected. For the beaches, the risk of rip currents is
high for the northern and eastern coast of Puerto Rico, Vieques,
Culebra and many beaches in the U.S. Virgin Islands.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 76 87 77 / 30 50 40 30
STT 85 76 85 78 / 30 30 20 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
516 AM AST Sat May 14 2022

.SYNOPSIS...East southeast to southeast flow will bring areas of
moisture and passing showers across the local islands in a
generally seasonal pattern that will favor the southeast coast of
Puerto Rico during the overnight and morning hours and the west
and northwest portions during the afternoons. The U.S. Virgin
Islands will be less favored, but may experience some passing
showers during the upcoming 7 days. Conditions will become
generally less cloudy across the area later next week.

&&

.SHORT TERM...Tonight through Monday...

A mid to upper level trough exiting the eastern coast of the United
States, along with a mid to upper ridge centered just to the east-
northeast of the northeastern Caribbean is generating winds
out of the west southwest at upper levels. This is spreading
cirrus clouds out of a surface trough over the western Caribbean
Sea. The GFS forecast soundings indicate passing areas with saturation
above 400 mb through Sunday, which will create some periods of
passing high clouds.

At the low levels, a surface high pressure over the central Atlantic
will maintain a tight gradient along the area, resulting in breezy
conditions with a steering flow out of the east-southeast at around
20 knots. This wind flow is dragging patches of moisture across the
islands, with passing showers affecting eastern Puerto Rico and the
U.S. Virgin Islands through at least the early morning hours. This
area of moisture should combine with local effects to generate
additional shower activity. However, due to the strong breeze, all
the high resolution and global models have the bulk of the activity
this afternoon over the northwestern corner of Puerto Rico and over
the Mona Channel. Additionally, the mid to upper level high will
maintain the mid-levels dry and stable, so neither heavy rainfall
nor thunderstorm development are anticipated. As a drier air mass
filters in later this afternoon and in the evening, the activity
is expected to gradually taper off. This dry air mass should
linger into Sunday, but a seasonal pattern of early morning
showers in the eastern half of the County Warning Area, and
afternoon convection developing in the west are still expected.

By Monday, the wind flow veers from the southeast as a tropical
waves moves well south of the region. The bulk of the moisture of
this feature is expected to remain over the waters, but some showers
could reach the islands at times, especially by the end of the day.
It will become warmer as well, with temperatures expected to climb
into the low 90s and heat indices around 100 degrees. The aerosols
models also show slight amounts of Saharan dust reaching the region
by the start of the workweek, causing skies to look a little hazy
at times.

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

High pressure at upper levels will be found on the north coast of
Venezuela on Tuesday and will shift to just west of Jamaica on
Saturday. This will hold the area under an upper level ridge
through Saturday with west or northwest flow. A mid level ridge
will persist across the Caribbean out of Africa throughout the
period. At lower levels, high pressure in the central Atlantic
will drift eastwards and then northeast to just east of the Canary
Islands. But, by Thursday another high pressure will form in the
western Atlantic north of the local islands.

Precipitable water values will be fairly high Tuesday through
Thursday with values of around 1.8. With the above synoptic
pattern in place this will bring scattered night and morning
showers to eastern Puerto Rico that will spread and form over west
and northwestern Puerto Rico during the afternoons. Moderate to
fresh winds will keep these showers moving and only modest
accumulations are expected. Of course ponding on roadways and
low-lying areas cannot be ruled out each day. After Thursday
moisture values diminish to around 1.5 inches of columnar water
and shower activity is expected to be reduced. However the weekend
may see some thunderstorm activity in the west and interior
sections of Puerto Rico as 500 mb temperatures approach minus 8
degrees C.

Beginning Tuesday night the northern edges of a plume of Saharan
dust centered along 10 north latitude will begin to brush Puerto
Rico and the U.S. Virgin Islands and skies will become somewhat
hazy Wednesday and Thursday.

&&

.AVIATION...Mainly VFR conditions expected to prevail through the
forecast period. Passing SHRA will continue for TJSJ and the USVI
terminals through the morning, which could result in brief periods
of reduced VIS and low ceilings. Winds will continue out of the ESE
at 15 to 20 knots, with ocnl gusts to 30 kt psbl. Maximum winds W
45-55 kt btwn FL380-490.


&&

.MARINE...Seas of 6 to 7 feet are being seen in the northern outer
Atlantic waters with areas of wind driven waves moving through the
area. Seas are expected to subside to 3 to 6 feet on Sunday and
continue through the week in this way. Some protected areas will
see seas even less than 3 feet during the next 7 days.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 77 89 76 / 50 30 30 30
STT 87 78 87 78 / 30 40 30 20

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
508 AM AST Sun May 15 2022

.SYNOPSIS...Moisture and winds will decrease slowly through the
week this week. East southeast wind flow will prevail until
around Friday and then become mostly easterly. The typical diurnal
shower pattern will persist through the next 7 to 10 days. A
tropical wave will pass mostly to the south on Tuesday with some
additional shower activity followed by a steadily drying
atmosphere through Friday.

&&

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

A mid to upper level ridge continues to hold over the
northeastern Caribbean. This feature is promoting a dry air mass
at the mid levels, and 500 mb temperatures warmer than normal--
around -4 to -5 degree Celsius. Under this stable air layer, heavy
rainfall and thunderstorms are not favored through the short-term
forecast period. There is some moisture trapped below 850 mb, as
shown on the Total Precipitable Water product from GOES-16, with
values around 1.4 inches over the area. The trade winds will carry
these showers along the eastern half of the forecast area through
the day, then generating additional activity this afternoon
across the northwestern corner of Puerto Rico, and downwind from
the Virgin Islands and from El Yunque. At the surface, a high
pressure over the Central Atlantic will maintain a wind flow out
of the east southeast, at around 20 knots. Due to the strong
breeze, any shower activity that develops is expected to be fast
moving, further diminishing the risk for flooding.

Moving into the first part of the workweek, the wind flow will veer
from the southeast to the south all the way into 700 mb, as a
tropical wave enters the southeastern Caribbean Sea. At first, under
this wind flow temperatures will warm up, with highs reaching the
low or even the mid-90s, especially along the northern half of
Puerto Rico. Heat indices around the 100 degree mark are
anticipated for both Monday and Tuesday. Additionally, the aerosol
models are showing some Saharan dust making it into the islands,
which should result in hazy skies. In terms of rainfall, although
the bulk of moisture is expected to stay over the waters, the
northern periphery of the tropical wave is expected to bring an
increase in shower frequency by late Monday and on Tuesday.
However, the mid and upper level ridge will continue to hold, so
rainfall amounts are expected to remain on the moderate side, and
mainly focusing around the eastern third of Puerto Rico, including
Vieques and Culebra, and around the U.S. Virgin Islands.

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

High pressure at upper levels will be found in the southern and
central Caribbean. It will drift slowly westward during the
period. At mid levels high pressure also dominates the tropical
Atlantic and the local area through Friday. Then a wide, but weak
trough will invade the western tropical Atlantic, divide and push
the high over us to the west. The trough will rotate west to over
the local area by Sunday. At lower levels, the tropical wave that
moved into the area on Tuesday will move into Hispaniola on
Wednesday and begin an overall drying trend that should last
through Sunday. Showers during the long term period will follow
the usual diurnal pattern for winds out of the east southeast.
Meaning scattered showers with modest accumulations on the east
southeast side of Puerto Rico during the overnight and early
morning hours, followed by showers over central and western Puerto
Rico during the afternoon. Shower activity over the U.S. Virgin
Islands will generally be sparse. Beginning Friday winds will
gradually back to the east and the shower pattern--considerably
diminished-- will follow. As the mid and upper level trough gains
more influence over the area over the weekend, showers will
increase somewhat. By Saturday, mid level temperatures at 500 mb
will drop to between minus 8 and 9 to renew the chances of
afternoon thunderstorms, mainly over western Puerto Rico during
Saturday and Sunday afternoons.

And finally, the Goes GEOS model from NASA indicates that dust
from the Sahara will begin to be seen in trace amounts on Tuesday
and increase each day through Sunday until a noticeable reduction
in visibilities will be noticed by the weekend. This will also
have a dampening effect on showers and convective activity.

&&

.AVIATION...Mainly VFR conditions expected to continue through the
forecast period. It will stay breezy, with FL050 winds out of the
ESE at 11 to 19 knots and gusts around 25 knots. VCSH are expected
for TJBQ after 17Z, which could result in reduced VIS and low
ceilings. Maximum winds 40-50 kts btwn FL410-490.

&&

.MARINE...Seas will gradually diminish today and Monday, such that
by Tuesday, most seas will be below 5 feet. Some northeast swell
of 2 to 3 feet will persist during the week. Seas are expected to
remain benign through next Sunday.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 76 90 75 / 40 30 30 40
STT 87 78 86 79 / 50 40 20 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
505 AM AST Mon May 16 2022

.SYNOPSIS...

Variably skies will prevail for this morning over the forecast
area, a scattered showers are forecast for the interior and
western Puerto Rico. On Thursday, a tropical wave moving over the
Caribbean Sea will increase the shower activity over the forecast
area. On wednesday, GOES model NASA suggest a slightly intrusion
of Saharan Dust Particles, increasing more on Friday into the
upcoming weekend.

&&

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

A mid to upper level ridge will continue to promote drier air and
stable conditions aloft through the short term period. However, a
tropical wave moving across the Caribbean Sea and southeasterly
trades will bring an increase in moisture content overnight and
through Tuesday. Breezy trades will continue today as a surface high
pressure continues to build just northeast of the region.
Precipitable water content (PWAT) is forecast to drop today to
around 1.50 inches and increase around 2 inches by 12z Tuesday.
Therefore, similar conditions to yesterday are expected to continue
across the forecast area with a drying trend under the trade wind
cap. Showers are still expected to develop this afternoon, with
rainfall amounts generally under 1 inch of rain over northwestern PR.

Showers are expected to increase by early Tuesday morning across the
Caribbean waters and across portions of the U.S. Virgin Islands and
south/eastern PR as moisture lifts over the region from the
Caribbean Sea. Ponding of water in low-lying areas and poor drainage
areas can be expected with this activity, while urban and small
stream flooding is possible across west/northwest PR in the
afternoon hours. Winds will gradually decrease as the high moves
further east into the Tropical Atlantic by midweek. Then, a Saharan
Air Layer is expected to gradually filter by Wednesday, but there
will be enough low-level moisture content to trigger diurnally
induced afternoon showers over western Puerto Rico.

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

A drying trend is forecast for the CWA during the long term period.
At the surface, a building high pressure located just west at the
central Atlantic will induce a east-southeasterly over the forecast
area. Meanwhile, at the upper level, a shortwave trough will sink
just east of the forecast area, inducing some instability and
resulting in cloudiness and low level moisture near the area. This
fragments of moisture with precipitable water values around 1.40
in, which is below climatological normals will reach the local
islands embedded in the southeasterly wind pattern. This patches
will increase in somewhat the showers over the forecast area
mainly in the afternoon hours on Thursday into Friday over the
northwestern Puerto Rico and some coastal sections of the U.S.
Virgin Islands. However, minimal rainfall accumulations are
forecast due to the stability across the mid and upper levels and
the presence of Saharan Dust in the area.

According to GOES model from NASA, particles of Saharan Dust
will reach the Caribbean and will invade the forecast area from
Thursday into the weekend. As the week ends,an increase in
Saharan Dust particles is forecast, and the thick layer of
will filter into the area on Friday into the weekend. This event
will enhance noticeable reduction in visibilities and heat indices
around 90s. Additionally, given the drier conditions over the
forecast area, shower activity, if any, will leave minimal
rainfall accumulations.

&&

.AVIATION...
Mainly VFR conditions are expected to prevail across all
terminals during the next 24 hours. However, showers are expected to
develop over northwest PR btw 16z-22z, which may cause tempo MVFR
conditions at TJBQ. Low level winds will continue E-ESE at 12-16 kt
with higher gusts and sea breeze variations aft 14z.

&&

.MARINE...

Across the regional waters, a surface high pressure located over
the central Atlantic will continue to result in a moderate to
locally fresh winds over the area. Therefore, mariners are urge to
exercise cautions across most of the local waters due to choppy
wind driven seas. By midweek, conditions should improve across
most of the local waters, and mariners can expected seas up to 5
feet and winds up to 15 knots. There is a high risk of rip current
only for two local beaches; Culebrita In Culebra, Puerto Rico and
Kramer Park in St. Croix, USVI. The rest of the local beaches
will observed moderate risk of rip current.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 75 91 75 / 20 50 60 30
STT 86 79 87 79 / 40 40 40 50

[cycloneye]

AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
456 AM AST Wed May 18 2022

.SYNOPSIS...
The presence of a Saharan Air Layer (SAL) will turn hazy skies
across all the forecast area today into the upcoming weekend. As a
result, mostly hot and hazy conditions are forecast for most of the
short and long term period. However, the local effects with the
available moisture will result in some afternoon showers over the
northwestern quadrant of Puerto Rico each afternoons. Tranquil
marine conditions will prevail across most of the local waters for
today into tomorrow.

&&

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

A Saharan Air Layer (SAL) will continue across the local area
through the short term period. Therefore, hazy skies are expected to
prevail across the islands. The peak of this moderate dust event is
from Thursday through Saturday, and limited rainfall is expected
through this period. However, both GFS and ECMWF are indicating a
100% to 120% precipitable water (PWAT) anomaly over Puerto Rico
today. Therefore, mostly isolated showers are expected early in the
morning hours between the USVI and eastern sections of PR. Then,
diurnally induced afternoon showers are expected to develop once
again over the northwestern quadrant of Puerto Rico, while hazy
skies and limited shower development is expected elsewhere.

SAL intrusion and low to mid-level ridging will promote erosion of
the available moisture content through Friday, and showers with
limited vertical development should develop mainly over western PR
in the afternoons. Heat indices between 102-108 are possible each
day across the northern and western portions of PR, as well as above
normal minimum temperatures along coastal areas, including the USVI.

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

A surface high pressure over the central Atlantic will continue to
result in a more east to southeasterly wind flow over the region.
Embedded in this trade wind, according to GOES NASA model, a
dense plume of Saharan Air Layer will continue to filter into the
region. This Saharan Air Layer (SAL) will turn hazy skies across
most of the islands. Additionally, the islands will experience a
noticeable reduction in visibilities and heat indices near the 105
degrees. Despite the drier and hostile conditions for Saturday
into Monday, a few showers are possible across the northwestern
quadrant of Puerto Rico. However, this activity will be short-
lived and no major impacts are forecast so far. As the weekend
progresses, the SAL will slightly diminishing over the region.

Conditions will start to slightly change on Tuesday into Wednesday,
when both model guidances, GFS and ECMWF, agree with a minor
increase in some pockets of moisture trapped in the low-levels.
This moisture is forecast to reach the local islands, by the end
of the period and will enhance some shower activity over the
interior sections in the afternoon hours. Given the presence of
very stable conditions provided from an established mid to upper
level ridge, widespread and long-lived shower activity is not
anticipated.

Daytime temperatures for most of the period are forecast to remain
from the low 80s to the mid 80s across the interior sections of
Puerto Rico, and up to the low 90s across the coastal sections of
Puerto Rico and the U.S. Virgin Islands. These temperatures will
also result in heat indices in the upper 90s to near 105 degrees,
and even higher in isolated spots.

&&

.AVIATION...
Mainly VFR conditions are expected to prevail across all
terminals through the forecast period. However, showers are expected
to develop in and around TJBQ from 18/16z-23z, which may cause tempo
MVFR cigs. Low level winds will continue E-ESE at 10-15 kt with
higher gusts and sea breeze variations aft 18/14z. HZ due to
suspended Saharan dust will continue across the region into the
weekend. VSBY could drop to 6-8 SM today. False MVFR cigs continue
due to dust event across the USVI terminals.

&&

.MARINE...
A surface high pressure over the central Atlantic will continue
to result in moderate east-southeasterly winds across the region.
As a result winds up to 15 knots are expected across most of the
local waters, with seas up to 5 feet. There is moderate risk of
rip currents for most of the local exposed beaches, the risk will
remain low across south beaches of Rincon.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 77 90 77 / 20 10 10 10
STT 87 78 87 77 / 30 30 20 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
515 AM AST Fri May 20 2022

.SYNOPSIS...Saharan Air Layer (SAL) will continue to promote
hazy skies into the weekend. Limited shower activity will continue
through at least Saturday. An upper level trough pattern across
the northeastern Caribbean, and pooling of low-level moisture is
expected by early next week.


&&

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

Mid level ridge will continue to promote stable conditions across
the Northeast Caribbean. At low levels, a warm layer associated with
the Saharan Air will favor a strong cap around 850mb. These
environmental conditions will limit the shower development across
Puerto Rico and the U.S. Virgin Islands through at least Saturday.
The moderate concentrations of Saharan dust will persist over the
next 48 hours, lowering the visibilities and maintaining a poor air
quality. Aerosol models suggests that higher concentration of the
Saharan Dust will be passing over the Caribbean Sea just south of
the local islands over the next day or so, as the dust extends to
the Florida Peninsula. Afternoon convection over western Puerto Rico
can not be ruled out as sea breeze convergence and available
moisture could induce a few short-lived showers. In terms of winds
and daytime temperatures, the TAFB/OPC surface analysis shows an
elongated high pressure over the tropical Atlantic that is promoting
a east-southeast trade wind flow across the eastern Caribbean. This
will favor hot temperatures across Puerto Rico and the U.S. Virgin
Islands especially the north central and the San Juan Metro Area.
Heat indexes will range between 100-105 degrees throughout the day.

Weather conditions will become more favorable for showers on Sunday
as an upper low/TUTT develops over the central Atlantic weakening
the ridge and the trade wind cap. Moisture will increase as well as
the instability under the influence of the TUTT. Therefore, morning
showers and afternoon convection will likely affect more areas in
Puerto Rico. Also some thunderstorms may also develop due to cooler
temperatures at mid-levels.

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

A TUTT-low over the central Atlantic is expected to linger through
at least Wednesday, when it is forecast to merge with a polar
trough over the north-central Atlantic. In response, a long wave
trough pattern is expected to prevail from the central Atlantic
into the northeastern Caribbean through the long term period. Weak
low to mid-level ridging should remain mainly over the western
Atlantic, while a surface low meanders over the central Atlantic
through at least midweek. This will promote light to moderate
east to southeast trades across the region. During the second part
of the workweek, moderate to locally fresh trades will return as
the surface ridge over the western Atlantic strengthens.

Precipitable Water content is forecast to increase between
1.75-2.00 inches through the period, and 500 mb temperatures are
expected to drop between -8/9 degrees Celsius. Therefore, a more
seasonable weather pattern is expected during the long term
period. Expect trade wind showers to increase during the nighttime
and early morning hours between the USVI and eastern sections of
PR, followed by diurnally induced afternoon convection over
portions of the interior and western PR each day. Urban and small
stream flooding is expected with this activity.


&&

.AVIATION...VFR conditions are forecast to prevail through at
least late Saturday. Low level winds will continue ESE at 10-15 kt
with higher gusts and sea breeze variations. Saharan dust will
continue to affect the visibilities across the local islands,
ranging between 6-8 SM. False low ceilings have been observed
overnight at the USVI terminals due to the presence of dense Saharan
Dust.


&&

.MARINE...Seas are expected to continue between 2-5 feet in
general through the weekend, with the highest seas expected across
the Atlantic waters due to the combination of locally higher winds
and the arrival of a small northeasterly swell. Light to moderate
trades should prevail across the rest of the local waters. The
risk of rip currents will increase along the northern beaches of
Puerto Rico during the weekend.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 77 87 76 / 10 10 10 20
STT 87 78 86 75 / 10 10 10 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
501 AM AST Sat May 21 2022

.SYNOPSIS...

The Saharan Air Layer will continue to produce hazy skies
throughout the day. Warmer temperatures and heat indices in the
low 100s are also possible each day, especially for north-central
Puerto Rico and urban areas of the islands. A surface high
pressure over the Atlantic Ocean will promote an easterly wind
flow across Puerto Rico and the U.S. Virgin Islands. A TUTT will
slowly erode the ridge aloft, increasing instability early next
week.

&&

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

Surface high pressure over the western Atlantic will maintain an
easterly flow across the Northeast Caribbean. Embedded in the trade
winds are the Saharan dust particles that will continue to spread
across the local islands today. However, higher concentrations will
remain just south of Puerto Rico and St. Croix, over the Caribbean
Sea. Aerosols models suggest that the dust will diminish on Sunday.
Therefore, visibilities will gradually improve over the next 24-36
hours. In terms of moisture and stability, dry and stable conditions
associated with a mid-level ridge will prevail most of the day
across most of the forecast area. However, sea breeze combined with
available moisture produce some showers over the western interior of
Puerto Rico, but those showers will be short-lived under the
influence of the mid-level ridge. Elsewhere, hazy skies with little
or no shower activity are expected.

An upper-level trough/TUTT will erode the high pressure at mid-
levels allowing more moisture andinstability to pull over the area
Sunday into early next week. Fragments of moisture over the western
Atlantic will be pulled over the local area tomorrow, enhancing the
trade wind showers during the morning hours on Sunday. Then, a
subtropical jet will provide better dynamic aloft to sustain longer
the showers over western Puerto Rico on Monday afternoon.

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

A lingering TUTT-low will promote a long wave trough pattern from
the central Atlantic into the northeastern Caribbean through much
of the long-term period. A surface low pressure over the Central
Atlantic will relax the local pressure gradient, weakening the
local winds. A surface high pressure moving from North America
into the Western Atlantic will tight the local pressure gradient
increasing the winds after Wednesday onward.

A seasonal weather pattern will dominate the local weather
conditions next week. The seasonal weather pattern consists of
passing showers with periods of moderate to locally heavy rains
overnight and early in the morning across the Virgin Islands and
eastern Puerto Rico. This activity will be followed by afternoon
convection across the interior and western sections during the
afternoon, where isolated 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. Easterly
winds will continue at 15-20 kt with higher gusts. Hazy skies
associated with Saharan dust particles will keep the visibilities
across the flying area between 6-8 SM.

&&

.MARINE...

Seas will remain at 5 feet or less across the local waters and
passages. A surface high pressure over the central Atlantic will
maintain gentle to moderate east to southeast winds across the
local waters and passages, and local effects will increase local
winds each day. A small northerly swell is forecast to arrive
across the local Atlantic waters today.

Beachgoers, a high rip current risk is expected for the beaches
of the north central Puerto Rico.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 76 89 77 / 10 20 30 50
STT 86 77 86 76 / 10 20 20 50