Caribbean - Central America Weather

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
521 AM AST Sun Jun 26 2022

.SYNOPSIS...
The TUTT has continued to slowly lift out of our area and should
be replaced by a mid to upper level ridge for the next few days.
The main focus of shower activity should be in the afternoon in
the central-interior, northwest, and isolated areas in the San
Juan metropolitan area. Southeasterly winds will also bring hot
temperatures with maximum heat indices between 100 and 107 degrees
in northern coastal areas of Puerto Rico and upper 90s to near
100 degrees in the U.S. Virgin Islands. By late tonight into
Monday a tropical wave is forecast to cross the southeastern
Caribbean and should pass south of the area with most shower
activity remaining over the Caribbean Waters.

Another tropical wave (Invest 94L) continues to be monitored by
the National Hurricane Center. If the current forecast holds, no
direct impacts are anticipated from this feature, but some showers
and hazardous seas will be possible for the Caribbean and local
passages. Please monitor future forecasts for updates, including
future forecast discussions (AFDSJU) and Tropical Weather Outlooks
from the National Hurricane Center (TWOAT).


&&

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

A plume of low level moisture with areas of embedded showers
continued to cross the region overnight and into the early morning
hours. This brought periods of moderate to locally heavy rains and a
few isolated thunderstorm to the coastal waters and mainly the east
and south sections of Puerto Rico and the adjacent islands including
the U.S. Virgin Islands. So far the heaviest rains although brief,
were in the southeast sections of Puerto Rico where estimated
rainfall accumulations with the heaviest rains were around half an
inch of so. Recent satellite derived precipitable water products
suggests PWAT values ranging between 1.60-1.85 inches across the
region, while the doppler weather radar velocity wind profile
suggests a dominant southeast wind flow between 15-20 kts below 700
millibars. Therefore expect continued periods of passing showers for
the rest of the early morning hours.

Satellite imagery initialized well with the present conditions and
recent guidance and both suggest the TUTT continued to slowly lift
north and west of the area. This is to be replaced by a mid to upper
level ridging for the next few days. Meanwhile the broad and strong
surface high pressure ridge across the Atlantic continued to build
north of the region, while a tropical wave approached the Windward
Islands and will enter and cross the southeastern Caribbean later
today through Monday. This pattern will aid in increasing the
easterly wind flow through Monday, resulting in somewhat breezy
conditions especially along the coastal areas and during the
afternoon hours. In addition, the NAAPS Aerosol model guidance also
continued to suggest a low concentration of suspended Saharan dust
particulates.

For the rest of today expect sufficient moisture in low levels to
again support afternoon convection in and around portions of the
islands. The main focus of the afternoon showers and isolated
thunderstorms should be parts of the central interior and northwest
sections of Puerto Rico, including isolated areas around the San
Juan metro steered by the prevailing winds. Otherwise mostly fair
weather skies and isolated showers expected elsewhere as drier and
more stable airmass should filter in across the region. Some of the
enhanced afternoon shower activity may lead to minor urban and small
stream flooding, as well as ponding of water on roads and poor
drainage areas but in isolated spots. The prevailing southeasterly
winds will also bring warmer temperatures especially along the north
coastal areas of Puerto Rico where maximum heat indices should range
between 100 and 107 degrees. The U.S. Virgin Islands should feel
maximum heat indices in the upper 90s to near 100 degrees.

By late tonight through Monday, the aforementioned tropical wave is
forecast to cross the southeastern Caribbean and should pass south
of the area. However, peripheral moisture along with low level
convergence should increase the chance for showers and isolated
thunderstorm activity across the regional waters and portions of the
islands especially during the overnight and early morning hours. By
then expect more frequent passing showers with the best chance for
moderate to locally rains expected over parts of the east and south
coastal areas of Puerto Rico and the adjacent islands. During the
daytime, the afternoon convection should be focused over the
interior and north-northwest sections of Puerto Rico where minor
urban and small stream flooding will be possible with the periods of
locally heavy rains. A gradual improvement and erosion of moisture
is expected on Tuesday as drier air will filter in across the region
in advance of another tropical wave expected by mid-week. Fewer
streamer-like afternoon showers of short duration will remain
possible in the west interior and around the San Juan metro and
mainly downwind of the U.S. Virgin Islands where mostly isolated and
fair weather skies are so far forecast.

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

Winds should continue to be generally easterly by the start of the
long term period as a surface high pressure system seen over the
Atlantic. We are currently monitoring the potential development of a
tropical wave located over the the central tropical Atlantic. Models
continue to show the system passing south of the local area. This
system currently has a 70% chance to develop into a tropical
depression within the next five days. As the system moves south of
our region between Wednesday and Thursday, currently there are no
direct impacts anticipated. Even so, marine conditions should start
to deteriorate especially for the Caribbean and local passages
possibly causing hazardous seas. Showers associated with this
systems are possible for the Caribbean and could also reach the
islands. Precipitable water values should be at around 1.5 inches
during the time this system moves south of our area. We will
continue to monitor this tropical wave as it continues to move
westward and how potential effects develop as time progresses.
Please also monitor future forecasts by the National Hurricane
Center related to this system. A wetter weather pattern is also
expected to persist for the rest of the long term period. Our best
chance of shower activity seems to be on Saturday, with models
currently showing another tropical wave affecting our area. As an
air mass with precipitable water values of above 2 inches engulfs
the area through the end of the short term period.


&&

.AVIATION...VFR at all terminals. Wdly SCT SHRA ovr regional waters
and en route btw PR and the USVI. Ocnl SHRA ovr E interior of PR may
cause brief MVFR and Mtn Top obscr with SHRA/low clds til 26/14Z.
SCT ocnly BKN nr FL025...FL050. Brief prds of SHRA/Isold TSRA psbl
mainly across the interior and west-northwest sections of PR with
VCSH at TJSJ/TJMZ/TJBQ fm 26/17-23Z. Sfc wnds LGT/VRB bcmg fm E-SE
btw 12-18 kts and ocnly higher gusts and sea breeze variations aft
26/14Z.


&&

.MARINE...Increasing east southeast winds up to 20 kts are
expected. Small craft operators should exercise caution in these
areas. As a tropical wave moves across the southeastern Caribbean
tonight and into Monday, expect marine conditions to further
deteriorate tonight as winds increase and as seas reach up to 6
feet for most coastal waters. A high risk of rip currents is
currently in effect for all northern and eastern beaches in Puerto
Rico and should also extend to the beaches of St. Croix in the
evening.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 77 89 77 90 / 40 30 30 20
STT 82 85 82 85 / 40 30 30 30

[cycloneye]

 https://twitter.com/TTMetOffice/status/1541044157627629569

[cycloneye]

Area Forecast Discussion...DELAYED
National Weather Service San Juan PR
602 AM AST Mon Jun 27 2022

.SYNOPSIS...

A tropical wave moving well south over the Caribbean waters will
slightly increase the potential for localized shower activity
today and tonight, with the strongest activity in the afternoon
for western Puerto Rico. By the mid-part of the workweek, a
vigorous tropical wave, (Invest 94L) will also move south of the
forecast region, with most shower activity also being south of our
area, and by the weekend a third tropical wave should also affect
our area.

&&

.SHORT TERM...Today through Wednesday...
A vigorous tropical wave is moving south of the forecast area
with showers and thunderstorms. Some of this moisture will affect
the local area but currently very little shower activity is
occurring over the Caribbean waters and only a minimal increase in
the shower activity over Puerto Rico this afternoon is expected,
although this wave will probably mean the difference between
having some isolated thunderstorms rather than not.

Drier air in generally easterly flow will continue Tuesday and
Wednesday in the forecast area with some increase in stability
during the period. Low pressure in a tropical wave around 48 west
will enter the very southernmost part of the Caribbean on Wednesday
with almost no increase in moisture over Tuesday for out area on
Wednesday.

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

The main events during the long term period will be two tropical
waves that are approaching the area. With a surface high pressure
over the Atlantic, winds will be generally easterly at the start
of the long term period. The first tropical wave (Invest 94L) will
be moving south of the forecast area at the start of the long
term period. The majority of shower and thunderstorm activity
should also remain south our area. Even with this system currently
having a high chance to develop into a tropical depression within
the next five days, there are no direct impacts anticipated. Even
so, marine conditions should start to deteriorate especially for
the Caribbean and local passages possibly causing hazardous seas.
The seasonal pattern of afternoon showers in the western interior
will also be present. Marine conditions should start to
deteriorate especially for the Caribbean and local passages
possibly causing hazardous seas. Showers associated with these
systems are possible for the Caribbean and could also reach the
islands. Precipitable water values should be slightly above 1.5
inches during the time this system moves south of our area. We
will continue to monitor this tropical wave as it moves westward
for potential effects time progresses. A wetter weather pattern
is also expected to persist for most of the rest of the long term
period. Our best chance of shower activity continues to be on
Saturday, with another tropical wave affecting our area, as an air
mass with precipitable water values of above 2 inches engulfs the
area through the end of the long term period. This tropical wave
currently has a low chance of tropical cyclone formation during
the next five days. Even so, as it affects our area it should
increase chances of shower activity and thunderstorms for the
forecast area.


&&

.AVIATION...VFR at all terminals. Isold SHRA ovr regional waters and
ern PR. Aft 27/17Z SHRA dvlpg ovr wrn and interior PR with brief
MVFR and mtn obscr with SHRA/low clds til 27/23Z. Sfc wnds land
breezes less than 10 kt bcmg aft 27/13Z E-SE 12-18 kts with gusts to
26 kt in sea breezes. Max winds W 20-25 kt btwn FL385-400.


&&

.MARINE...Small craft will need to exercise caution as winds and
seas continue around 4 to 6 feet and winds 15 to 20 knots. Small
craft advisory conditions are anticipated as a strong tropical
wave moves south of the area.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 76 90 77 / 30 20 20 40
STT 88 81 89 82 / 10 30 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
543 AM AST Tue Jun 28 2022

.SYNOPSIS...Mainly fair weather conditions are expected to prevail
today with warmer temperatures. Expect passing showers during the
morning hours across eastern PR and the USVI, followed by
afternoon convection across the western portions of PR. Potential
Tropical Cyclone Two will pass well south of the local area. No
impacts associated with this system are expected for the local
islands.

&&

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

A tropical wave moved across the Caribbean south of Hispaniola as
dry air followed it. However, an area of scattered showers has moved
into the forecast area from the east northeast and was approaching
Puerto Rico and the northern U.S. Virgin Islands as of 5 AM AST. It
will spread showers across eastern Puerto Rico this morning. After
this moisture passes a second area of moisture associated with a
developing tropical disturbance will brush the area on Wednesday and
remain through Thursday. At upper levels high pressure will
generally dominate the area during the period, although on Thursday
a lobe of the TUTT low to our northeast will approach the area from
the north northwest on Thursday. Currently divergence aloft is
indicated for Saint Croix more than for Puerto Rico which may see
some additional shower activity. Temperature variations other than
diurnal will be limited during the mostly easterly flow, but this
flow will carry some Saharan dust that will increase today through
Thursday.

The chances for thunderstorms are considered lower today than
yesterday and since thunderstorms were not seen yesterday, they have
been removed from today's forecast. 500 mb temperatures will drop on
Wednesday again, so will leave thunderstorms in western Puerto Rico
then.

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

A surface high pressure dominating in the Atlantic will continue to
induce an easterly wind flow across the local area. A tropical wave
is being monitored for potential impacts across the local area on
Saturday. At this time this system has a 20% chance of development
during the next 5 days. The latest GFS-20 model guidance shows a
trend of development before the system cross the Lesser Antilles.
Further development can be expected due to conducive
environmental conditions, and a tropical depression or a weak
tropical storm could be expected. As for now the possible track
shown by the GFS-20 model, this system should stay south of the
local area. However, impacts associated with this system could
lead to thunderstorms, heavy rainfall, gusty winds, hazardous
marine and coastal conditions, and urban and small streams
flooding. We will continue to monitor this tropical system as it
moves west-northwest for more potential effects as time
progresses. By Monday onwards a more seasonal weather pattern will
return, with the morning passing showers over eastern Puerto Rico
and the U.S. Virgin Islands followed by the afternoon convection
over western Puerto Rico.

&&

.AVIATION...VFR at all terminals. Isold-sct SHRA ovr regional waters
and ern PR movg in from ENE. Aft 27/17Z SHRA dvlpg ovr wrn and
interior PR with brief MVFR and mtn obscurations with SHRA/low clds
til 27/23Z. Sfc winds land breezes less than 10 kt bcmg aft 27/13Z E
12-20 kts with gusts to 26 kt in sea breezes. Max winds SW 20-25 kt
btwn FL360-390.

&&

.MARINE...Wind driven seas will create choppy marine conditions
across most of the regional waters. Seas up to 6 feet and winds in
excess up to 20 kts will prevail. Therefore, small craft should
exercise caution. There is a high risk of rip currents in effect
for the north-central and northwestern beaches of Puerto Rico, and
the eastern corner of Saint Croix. A moderate risk of rip current
remains in effect elsewhere. Further deteriorating marine
conditions could be expected due to the pass of a vigorous
tropical wave south of the local area, over the Caribbean Sea.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 77 89 77 / 30 40 40 40
STT 88 81 88 81 / 20 30 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
528 AM AST Wed Jun 29 2022

.SYNOPSIS...Stable weather conditions are expected to prevail
today. Winds will increase today up to 25 mph. More moisture is on
the way and will enhance the formation of the afternoon shower
activity across the central interior and western Puerto Rico.
Potential Tropical Cyclone Two will continue its track south of
the area, no impacts are expected.

&&

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

Potential Tropical Cyclone Two is in the Caribbean sea and hugging
the northern coast of Venezuela, but the best moisture is and
will remain in the southern half of the Caribbean. Surface winds
will reach a maximum during the day as the gradient between
Potential Tropical Cyclone Two and the central Atlantic high
climaxes. Sustained winds up to 25 mph are expected along a few
coastal regions with gusts to 35 mph possible today. Columnar
moisture will increase today through Friday, and will peak just
shy of 2 inches before a "dry" slot moves through Friday night.
High pressure at the surface will continue just west of the
Azores. High pressure will form in the western Atlantic on
Thursday to maintain moderate to locally strong trade winds across
the local area. At mid levels. low pressure about 1500 miles
northeast of San Juan Puerto Rico will retreat slowly northward
and high pressure in the eastern and western Atlantic horse
latitudes will join north of the forecast area. At upper levels a
cut-off low will drop south and pass just northeast of the British
Virgin Islands on Friday at 12Z and this should enhance showers
and thunderstorms over western Puerto Rico on Friday. Near normal
temperatures will continue through the period.

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

A tropical wave located over the Central Atlantic continues to be
monitored, as this system could move close to the local area. At
this time this system has a 30% chance of development during the
next 5 days. Further development can be expected due to conducive
environmental conditions. The latest GFS-20 model guidance shows a
trend of induced heavy rainfall across the islands starting on early
Saturday. The eastern portions of Puerto Rico and the U.S. Virgin
Islands could receive the majority of the rainfall. Therefore,
impacts associated with this system could lead to strong winds with
gusts, thunderstorms, heavy rainfall, hazardous marine and coastal
conditions, and urban and small streams flooding. Wetter weather
conditions will persist until at least Monday. We will continue to
monitor this system as it west-northwest to the local area. By
Monday, fourth of July the moisture fields associated to the
tropical wave will continue to linger across the islands, leaving
unstable conditions with showers from time to time. By Tuesday
onwards, a more seasonal weather will establish. Passing showers
during the morning hours across the eastern portions of Puerto
Rico and the U.S. Virgin Islands, then the afternoon convection
across the central interior and western portions of Puerto Rico.
Warmer temperatures expected as well the return of Saharan Dust.

&&

.AVIATION...VFR at all terminals. Isold-sct SHRA ovr regional waters
and ern PR movg in from the E. Aft 29/17Z SHRA dvlpg ovr wrn and
interior PR with brief MVFR and mtn obscurations with SHRA/low clds
til 29/23Z. Sfc winds land breezes less than 10 kt bcmg aft 28/13Z E
15-25 kts with gusts to 30 kt in sea breezes. Max winds ENE-E 20-25
kt btwn FL150-210 and E 20-23 kt btwn FL027-042. Winds less than 20
kt btwn FL210-540.

&&

.MARINE...Increasing winds across the local area will result in
choppy and hazardous marine conditions starting today. Seas up to
7 feet are expected over the offshore Atlantic and Caribbean
waters and the Anegada Passage. There is a high risk of rip
currents for the northern and southeastern beaches of Puerto Rico,
including Vieques, Culebra and Saint Croix. Small craft
advisories are also in effect across the local waters.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 77 89 77 / 20 40 40 40
STT 88 81 88 82 / 20 20 20 30

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
544 AM AST Thu Jun 30 2022

.SYNOPSIS...Moisture associated to the Potential Tropical Cyclone
Two will continue to bring group of clouds and showers across the
area today. Models continue to show and increase in precipitable
water for the next several days due to the proximity of a strong
tropical wave. Hazardous marine conditions will continue today.
Small craft advisories are in effect for most of the local waters.


&&

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

Potential Tropical Cyclone Two is in the Caribbean sea and hugging
the northern coast of Colombia, and the best moisture continues
to be in the southern half of the Caribbean. The highest surface
winds today will be less than yesterday but will still be stronger
than average due to the stronger gradient between the high
pressure building in the western Atlantic east of Virginia and
North Carolina and Potential Tropical Cyclone 2. Also momentum of
the trade winds driven by the high west of the Azores will assist.
Sustained winds up to 25 mph are expected along a few coastal
regions. Gusts up to 32 mph are possible today with stronger gusts
near heavy showers. Gusts up to 40 mph were reported in Guayama
earlier this morning already. Columnar moisture will continue
today through Friday night between 1.5 and 1.8 inches, but will
rise dramatically to above 2.3 inches, according to the GFS, as
moisture in a vigorous tropical wave drives into the area on
Saturday. High pressure at the surface just west of the Azores
will be found north of the Azore Islands by Saturday night. But,
the vigorous tropical wave will bring the best moisture of several
months into the area Saturday with winds of 15 to 25 mph at the
surface and up to 40 knots at 850 mb. At mid levels, low pressure
about 1900 miles northeast of San Juan, Puerto Rico will retreat
slowly northward allowing high pressure to spread east out of the
western Atlantic north of the area. At upper levels, a cut-off low
will drop south and pass just northeast of the British Virgin
Islands on Friday at 12Z and this may enhance showers and
thunderstorms over western Puerto Rico on Friday. Near normal
temperatures will continue today and tomorrow, but the arrival of
rain on Saturday will mute high temperatures in the eastern half
of the forecast area including the U.S. Virgin Islands. That rain
will likely trigger urban and small stream flooding in many areas
and may be heaviest in southeast Puerto Rico this time.

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

Moisture associated to a tropical wave is expected to linger across
the area during the first half of the period. A this time this
tropical wave has a 10% chance of development during the next five
days. However, it will reach the local islands as a strong and
vigorous wave. The latest GFS-20 model guidance shows a trend
moisture content causing heavy rainfall across the islands. The
eastern portions of Puerto Rico and the U.S. Virgin Islands are
expected to receive most of the rainfall activity, increasing the
potential of thunderstorms and flooding. Unstable conditions
aloft will persist at least until late Monday. Associated impacts
with this system could lead to strong winds with gusts,
thunderstorms, heavy rainfall, hazardous marine and coastal
conditions, and urban and small streams flooding. On Monday, the
moisture content will continue high across the local area,
increasing the potential for another round of showers and
unstable conditions. Tuesday onwards, weather conditions will
star to improve as the tropical wave moves out of the region. A
mass of dry air will filter into the area and a ridge will place
near the region. A seasonal weather pattern will return with
passing showers during the morning hours across the windward
portions of the islands, followed by the afternoon convection in
the west. Winds will return form the east-southeast. Expect an
increase in temperatures and more Saharan Dust.

&&

.AVIATION...MVFR conds at TJPS and the S central coast in +SHRA till
30/10Z, othw VFR at all TAF sites through 30/16Z. Isold-sct SHRA ovr
regional waters and the nrn coastal plains of PR are movg from the E
at 35-40 kt. Aft 30/16Z SHRA dvlpg ovr wrn and interior PR will
generate brief MVFR and areas of mtn obscurations with SHRA/low clds
til 30/23Z at TJMZ and TJBQ. Sfc winds land breezes less than 10 kt
bcmg aft 30/13Z E 15-23 kts with gusts to 28 kt in sea breezes. Max
winds E 25-35 kt btwn FL025-110.

&&

.MARINE...A surface high pressure and the Potential Tropical
Cyclone Two will continue to promote locally strong easterly winds
across the regional waters. Seas up to 7 feet are expected over the
offshore Atlantic and Caribbean waters Passages. There is a high
risk of rip currents for the northern and southeastern beaches of
Puerto Rico, including Vieques, Culebra and Saint Croix. Small
craft advisories are also in effect across most of the local
waters.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 77 90 78 / 50 40 30 40
STT 89 79 89 80 / 20 30 40 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
546 PM AST Fri Jul 1 2022

.SYNOPSIS...

A strong tropical wave approaching the islands, will lead to
increasing shower and thunderstorm activity. The strongest
events will be from Saturday heading into Sunday. The tropical
wave should also bring breezy conditions with surface winds of 15
to 25 mph with higher gusts, especially near showers and
thunderstorms. Rainfall accumulations during the weekend should
range between 1-4 inches with higher localized amounts, mainly in
eastern and southeastern Puerto Rico, and the San Juan metro
area. Small craft advisories are currently in effect for offshore
waters besides the Atlantic waters. A high rip current risk is
currently in effect for northern, eastern and southeastern beaches
in Puerto Rico, and the beaches of Vieques, Culebra and St.
Croix. Areas with small craft advisories and high rip current
risk should increase as the weekend progresses.

&&

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

Main shower activity this afternoon was concentrated in the southwest
sector of Puerto Rico and is currently moving mainly off the coast
of Cabo Rojo. According to satellite data, precipitable water values
are currently right below normal values for this time of the year,
at around 1.4 inches. Precipitable water values should rise
significantly to above normal values, peaking at around 2.3 inches due
to moisture from a vigorous tropical wave moving approaching our area
on Saturday. Even with this tropical wave having a low chance (10%)
to develop into a tropical cyclone will continue to affect the region
through this weekend. The tropical wave will also interact with
an upper-level trough, resulting in more favorable conditions for
shower and thunderstorm activity. Moisture and rain chances will
increase as the system approaches our area late tonight. This
system will bring widespread shower and thunderstorm activity for
tomorrow and heading into Sunday with the most active day being
tomorrow. On Sunday conditions should start to improve but
moisture associated with the wave will continue to filter in.
Widespread shower and thunderstorm activity will mainly over the
eastern areas but afternoon convection will also develop in
western areas. Rainfall accumulations should range between 1-4
inches with higher localized amounts, mainly in eastern and
southeastern Puerto Rico, and the San Juan metro area. This will
lead to urban and small stream flooding with rapid river rises in
many sectors later in the day. The tropical wave should also bring
breezy conditions with surface winds of 15 to 25 mph with higher
gusts, especially near showers and thunderstorms.

.LONG TERM...Monday through Thursday...
.FROM PREV DISCUSSION... /issued 535 AM AST Fri Jul 1 2022/

A tropical wave will move out of the local area, but associated
moisture will linger across for the fist half of the period. The
latest GFS- 20 guidance shows a trend moisture content causing
rainfall across the islands. The eastern portions of Puerto Rico
and the U.S. Virgin Islands are expected to receive most of the
rainfall activity, increasing the potential of thunderstorms and
flooding. By Tuesday onwards, weather conditions will start to dry
out across the region and stable weather is expected to prevail.
Nonetheless, trade wind showers can be expected over portions of
the U.S. Virgin Islands and eastern Puerto Rico from time to time
overnight through the morning hours. A surface high pressure in
the Atlantic, will dominate and is expected to induce strong east-
southeast wind flow across the local area. Diurnal heating and
local effects result in heavy rainfall and isolated thunderstorms
across central and western interior during the afternoon hours. A
Saharan Air Layer will slowly increase, deteriorating the air
quality across the region.

&&

.AVIATION...VFR conditions are expected the rest of today. However,
TSRA will develop across W/SW PR thru this evening (01/23z).
Winds will continue from the E/ENE between 15 and 20 knots with
higher gusts. Weather conditions will deteriorate early Saturday
morning (02/09z) onward as a tropical wave reach PR/USVI flying
area. Expect MVFR or even IFR condtions across USVI/E-PR
terminals. Winds will shift from the E-ESE at 10 overnight
increasing between 15-25 knots with higher gusts after 02/13z.


&&

.MARINE...The tight pressure gradient will continue to sustain
moderate to fresh and locally strong winds. Seas of up to 7 feet
persist, building late tonight into Saturday to up to 8 to 10 feet
for offshore waters and local passages due to a tropical wave
that will be approaching our area. Small craft advisories are
currently in effect for offshore waters besides the Atlantic
waters. A high rip current risk is currently in effect for
northern, eastern and southeastern beaches in Puerto Rico, and
the beaches of Vieques, Culebra and St. Croix.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 78 87 76 85 / 60 90 90 60
STT 80 86 78 85 / 60 90 80 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
533 AM AST Sat Jul 2 2022

.SYNOPSIS...The passage of a strong tropical wave will lead to
increased wind speeds and widespread shower and thunderstorm
activity today into Sunday. This scenario will increase the
potential for urban and small stream to localized flash flooding
and mudslides. In addition, moderate to locally strong winds will
maintain choppy to hazardous marine and surf zone conditions. As a
result, Small Craft Advisories and High Risk of Rip Currents
remain in place for most local waters and beaches, respectively.
Weather and marine conditions will gradually improve by early next
week.


&&

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

The best convection of a tropical wave approaching the area is about
290 miles southeast of San Juan. The wave is expected to pass
through the U.S. Virgin Islands today and Puerto Rico overnight. The
forecast for this wave has changed very little in the past 24 hours.
The 850 mb winds forecast both before and after the wave reach 30-35
knots over Puerto Rico and the USVI. Precipitable water values are
expected to peak twice, once at 6 AM Sunday and again just after 6
PM AST at 2.3 inches. There will be a rapid ramp-up on Saturday to
these maximum values, however during the day today. This will
provide more than adequate moisture for heavy rains. Although not
very unstable, 500 mb temperatures are expected to be around minus 7
degrees today, dropping to minus 6 on Sunday. Moisture and showers
will move into the area from the southeast, and are already
affecting Saint Croix. Only scattered showers in southeast and
eastern Puerto Rico are expected before dawn, but showers should
spread rapidly across the area during the morning. Currently rain
amounts for the next 48 hours should range from 1 to 4 inches--
lowest northwest and highest southeast. This will likely provoke
urban and small stream flooding with rapid river rises later in the
day and overnight. As flow turns southeasterly after the passage of
the wave, good moisture will continue to stream across the area
tonight and into Sunday with the threat of minor flooding
continuing, but low-level moisture drops off quickly by Sunday
morning. Heavy showers will likely form during the day Sunday, but
will move quickly. More typical summer weather conditions will
return in a breezy scenario Monday.

The upper level low in the long wave trough is quickly lifting
northeast of the British Virgin Islands but is also dissipating.
Some troughiness will remain across eastern Cuba and Hispaniola as
the main trough feels the presence of the cut-off low south of
Florida and Cuba. This will produce a slightly more favorable
environment for enhanced shower and thunderstorm activity today and
Sunday, though its effects are waning. High pressure will move in
over the Antilles on Monday as the atmosphere begins to dry.

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

At the surface, a strong high pressure across the north Atlantic
will induce a generally east to southeast wind flow of around
10-20 mph and locally higher through the cycle. Variations in the
general wind flow will result from a weak tropical wave crossing
the northeastern Caribbean by Wednesday. Lingering moisture from a
departing strong tropical wave will maintain above-normal moisture
levels of 2.0 inches or above through Tuesday night. After that, a
patchy weather scenario and somewhat drying trend will follow,
promoting a more stable weather pattern. Even considering a slight
increase in tropical moisture with the passage of a weak tropical
wave, the moisture content will remain at normal seasonal levels,
ranging between 1.4 and 1.9 inches.

Despite variations in surface winds and moisture content, a set of
mid-to-upper level lows streaming across the northeastern
Caribbean will maintain a weak trade wind cap and somewhat
favorable conditions for deep convective development through most
of the cycle. Aided by local and diurnal effects, this scenario
will enhance afternoon showers and isolated thunderstorm
development mainly across the interior to western sections of
Puerto Rico, even during the driest periods expected on Wednesday
and Thursday. Streamer-like showers could also affect portions of
eastern Puerto Rico and the San Juan metropolitan area each
afternoon. Although limited, overnight and early morning trade
wind showers will offer the chance for measurable rainfall amounts
across the U.S. Virgin Islands and eastern Puerto Rico. Saharan
Dust concentration will maintain hazy conditions, with the
highest impact expected during the driest periods.


&&

.AVIATION...SHRA are increasing ovr the SE portion of the FA and
just north of TSJU. Winds of 10-20 kt cont and will increase to 15-
25 kt as trop wave passes today. Gusts to 30 kt psbl nr TSRA. Aft
01/15Z SHRA/isol-sct TSRA spread ovr PR and will generate areas of
MVFR/IFR and mtn obscurations with SHRA/low clds til byd 03/08Z. Max
winds bcmg S 20-30 kt btwn FL330-490.


&&

.MARINE...Increasing winds up to 20 knots and locally higher,
gusting up to 35 knots, will maintain choppy to hazardous marine
conditions, with building seas up to 10 feet expected today. As a
result, Small Craft Advisories remain in effect for most of the
local waters. Seas will gradually subside but remain choppy to
hazardous through at least Tuesday. There is a high risk of rip
currents for beaches across the northern, eastern, and southern
coasts of Puerto Rico and most beaches of Vieques, Culebra, and
the U.S. Virgin Islands.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 76 86 78 / 90 90 60 50
STT 86 78 86 81 / 90 90 60 30

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
531 AM AST Sun Jul 3 2022

.SYNOPSIS...Lingering moisture from a departing tropical wave will
bring showers and isolated thunderstorms today. Periods of
moderate to locally heavy rains could lead to urban and small
stream flooding, with localized flash flooding and mudslides
possible in areas with saturated soils from previous rains.
Moderate to fresh winds will maintain hazardous marine conditions
and life-threatening rip currents today. Weather, marine, and surf
zone conditions will improve early next week.


&&

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

At 03/08Z the tropical wave was found moving across Hispaniola at
about 20 knots. Drier air is still a considerable distance upstream
and winds are diminishing. This will keep showery weather in the
forecast. Showers quickly developed across the U.S. Virgin Islands
just before dawn and are moving toward Puerto Rico. Precipitable
water values are expected to remain above 1.9 inches through
tonight. Even the upper level pattern with a weak building high over
the forecast area will promote divergence aloft that will offset the
the limited heating at the surface due to cloud cover.

Moisture decreases considerably during the period and by Tuesday
night forecast precipitable water values are below 1.7 inches. This
is still favorable for showers, but the pattern for Monday and
Tuesday will be more typical of a regular summer day. A weak trough
at 700 mb moves through on Tuesday and a sharp trough at 250 mb
approaches the island at the same time so some additional
shower and thunderstorm activity is expected Tuesday afternoon.

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

The most recent model guidance suggests a drier weather pattern
during the long-term forecast cycle, with two prolonged periods of
below-normal seasonal moisture levels, as low as 1.4 inches, by
Thursday and Friday afternoon into Saturday. Overall, a patchy
weather scenario will dominate, with a weak tropical wave and a
set of easterly perturbations embedded in the general wind flow
bringing moisture levels to normal seasonal levels. These features
will lead to the relatively wettest periods on Wednesday and
Friday morning, when precipitable water values will peak at around
1.7-1.9 inches. Model guidance suggests a steady increase in
moisture content into above-normal seasonal levels of 2.0 inches
or higher by the end of the cycle into the upcoming weekend.

Variations in the general wind flow will result from the passage
of the tropical wave early in the period, but overall, a strong
high pressure centered across the north Atlantic will remain the
dominant feature at the surface, leading to a generally east to
southeast wind flow at around 10-20 mph through the cycle. At the
mid-to-upper levels, a set of lows approaching the northeastern
Caribbean Region from the northeast will maintain a weak trade
wind inversion and somewhat favorable conditions for deep
convective development through the end of the workweek before a
mid-level high briefly leads to hostile conditions aloft on
Saturday. Despite variations in surface winds, moisture content,
and mid-to-upper level conditions, local and diurnal effects will
support afternoon showers and possible isolated thunderstorm
development, mainly focused across the interior to western
sections of Puerto Rico, where a potential for urban and small
stream flooding will be likely during any wet period. Streamer-
like showers could also affect portions of eastern Puerto Rico and
the San Juan metropolitan area each afternoon. Although limited,
overnight and early morning trade wind showers will offer the
chance for measurable rainfall amounts across the U.S. Virgin
Islands and eastern Puerto Rico. Saharan Dust concentration will
maintain hazy conditions, with the highest impact expected during
the driest periods.


&&

.AVIATION...SHRA are increasing ovr the E portion of the FA--
spcly ovr the nrn USVI. Winds of less than 12 kt in easterly flow
are present and will increase to 10-20 kt aft 03/13Z. Gusts to 25 kt
psbl nr TSRA. Aft 03/15Z SHRA/isol TSRA spread ovr PR and will
generate areas of MVFR and mtn obscurations with SHRA/low clds til
byd 04/01Z. Max winds SE 15-30 kt blo FL110.


&&

.MARINE...Moderate to fresh winds of up to 20 knots will maintain
choppy to hazardous seas today, up to 10 feet. As a result, Small
Craft Advisories remain in effect for the offshore Atlantic
waters, Caribbean waters, and Mona Passage through this evening.
Seas will continue to subside but will remain choppy through at
least Monday. There is a high risk of rip currents for beaches
across the southwestern to southeastern and eastern coasts of
Puerto Rico, Vieques, Culebra, and Saint Croix through this
afternoon.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 78 88 77 / 40 40 40 40
STT 86 81 88 81 / 40 20 20 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
511 AM AST Mon Jul 4 2022

.SYNOPSIS...A typical seasonal shower pattern will prevail during
the next few days, with the highest impact expected across the
interior to western sections of Puerto Rico each afternoon, where
urban and small stream flooding will be likely on Tuesday and
Wednesday. Drier and hazy conditions will dominate the latter part
of the workweek before another tropical wave generates increased
shower and thunderstorm activity later this weekend. Small craft
operators should exercise caution due to choppy marine conditions
across most local waters. There is a high risk of rip currents for
beaches across the north- central to the northwestern coast of
Puerto Rico, with a moderate risk for most of the remaining local
beaches.


&&

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

Flow at 700 mb is now turning NE ahead of an easterly wave currently
about 560 miles east of Saint Croix. At this time the best moisture
is ahead of the wave and will be arriving during the day on Tuesday.
At the same time a sharp upper level trough will be rotating
through Puerto Rico and the northern U.S. Virgin Islands during the
afternoon. Another weaker lobe of the upper level low moves through
late on Wednesday in time for a second band of moisture also late
Wednesday. Precipitable water values at this time will range between
1.5 and 1.85 inches. This would indicate a good chance for urban and
small stream flooding, mainly in Puerto Rico, for both Tuesday and
Wednesday afternoons.

For today a blob of dust will affect the local area--mainly Puerto
Rico and the northern U.S. Virgin Islands. Although visibilities
will not likely drop below 9 miles some whitening of the skies is
likely to be noticed this afternoon. Daytime winds will generally
continue between 10 and 20 mph in the east to northeast flow with
higher gusts in sea breezes.

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

A strong high pressure centered across the north Atlantic will
remain the dominant feature at the surface, leading to a generally
east to southeast wind flow at around 10-20 mph through the
cycle. A mid-to-upper level low to our west will maintain
favorable conditions for deep convective development through the
end of the workweek before a mid-level high briefly leads to drier
air entrainment and development of the trade wind cap inversion
on Saturday. While the entrance of drier air may lead to mainly
fair weather conditions on Thursday and early Friday into Friday
night, with model-estimated precipitable water values below-normal
seasonal levels as low as 1.4 inches, a weak tropical wave
streaming across the Caribbean Sea and south of the local islands
and fast-moving easterly perturbations embedded in the general
flow will bring moisture to normal seasonal levels at about 1.8
inches by Friday morning and Saturday morning into Saturday
evening. Despite variations in moisture content and mid-to-upper
level conditions, local and diurnal effects will support a typical
seasonal pattern each day, with the highest impacts expected from
afternoon convective development across the interior to western
portions of Puerto Rico during the wettest periods. Saharan Dust
concentration will maintain hazy conditions, especially during the
driest periods.

By Sunday and continuing early next week, the passage of a
tropical and associated trailing moisture will lead to above-
normal seasonal moisture levels as high as 2.2 inches. If this
scenario materializes under the influence of yet another mid-to-
upper level trough to the northwest, the resulting moderate to
heavy rains could enhance the potential for flooding across the
local islands. Although this forecast has low to medium
confidence, given the event`s timing far out in the cycle, model
guidance has remained relatively consistent during the last few
solutions.


&&

.AVIATION...ESE flow of 5-10 kt is carrying minor SHRA around the
USVI and PR. A few of these will mov onshore til 04/15Z with ocnl
mtn topping in ern PR. Winds will increase to 10-15 kt with hir
gusts aft 04/13Z. SHRA will dvlp and spread across interior and wrn
PR aft 04/15Z with lcl MVFR conds and mtn topping and also sct SHRA
psbl downstream from El Yunque till 04/21Z. Max winds E-ESE 20-30 kt
btwn FL007-070 and WSW-W 20-30 kt btwn FL400-480.


&&

.MARINE...Small craft operators should continue to exercise
caution due to moderate to locally fresh easterly winds of up to
20 knots and choppy seas of up to 6 feet across most local waters,
except for the coastal waters of southern and western Puerto Rico
and northern U.S. Virgin Islands, where winds and seas should
remain at or below 15 knots and 5 feet. There is a high risk of
rip currents for beaches across the north-central to the northwest
coast of Puerto Rico, while a moderate risk of rip currents
remains in place for most remaining local beaches.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 77 89 77 / 40 30 40 50
STT 88 81 89 82 / 20 30 30 50

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
343 AM AST Tue Jul 5 2022

.SYNOPSIS...
A weak tropical wave will be moving across the area, while a
surface trough crosses the region by tomorrow and Wednesday. These
surges in moisture should increase the frequency of showers and,
along with an upper level trough, enhance the potential for
thunderstorms, especially along the interior and western Puerto
Rico. Temperatures will stay near or above normal, with heat
indices at 102 to 105 degrees.

&&

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

A high pressure system across the north-central Atlantic will
remain the dominant feature, maintaining east to east-southeast
winds ranging between 10 and 20 mph through the cycle. A Tropical
Upper Tropospheric Trough (TUTT) will continue to travel
southwestward and anchor between Puerto Rico and Hispanola through
midweek, supporting a weak trade wind inversion and favorable
conditions for deep convective development across the local
islands. In the meantime, a weak tropical wave and the associated
plume of moisture will move across the area, boosting precipitable
water values into normal to above-normal moisture levels as high
as 2.0 inches today. A patch of drier air will briefly filter the
area this evening, causing precipitable water values to fall near
below-normal seasonal levels. Still, another band of tropical
moisture and weak perturbations in the general wind flow will
cause precipitable water values to range between 1.6 and 1.8
inches from Wednesday into Thursday.

The proximity of the TUTT combined with local effects, diurnal
heating, and sufficient available moisture will support shower and
isolated thunderstorm development. So far, the heaviest rains will
cluster across the interior to western sections of Puerto Rico
this afternoon, with a potential for urban and small stream
flooding. Showers may quickly dissipate westward around sunset
with the entrance of drier air. Yet, increased tropical moisture
and favorable dynamics aloft may lead to enhanced showers and
possible isolated thunderstorm activity tonight, favoring portions
of eastern Puerto Rico and the U.S. Virgin Islands, where ponding
of water to localized urban and small stream flooding is likely.
Despite variations in moisture content, similar weather conditions
will prevail through Thursday, with the potential for urban and
small stream flooding with any prolonged period of moderate to
heavy rains.

Daytime high temperatures will peak into the upper 80s to around
90 degrees across lower elevations, while overnight low
temperatures will fall into the upper 60s across higher
elevations. Winds will remain from the east to east-southeast at
10-20 mph with higher gusts and sea breeze variations, becoming
light and variable at nighttime. Southeasterly trade winds and a
high moist environment will lead to heat indices of 102 degrees or
higher, mainly across northern and western sections of Puerto
Rico.

.LONG TERM...Friday through Wednesday...
An upper level low will linger north of Hispaniola, maintaining a
wind flow out of the south at these levels. Additionally, the GFS-
forecast soundings for Friday show saturation from 400 to 200 mb,
indicating upper level clouds over the islands. At the surface, a
high pressure system centered over the eastern North Atlantic
maintain a wind flow out of the southeast, with a dry air mass
filtering in from the east between 700 and 500 mb. For Friday and
Saturday, shower activity should be focused in the afternoon hours
across northwestern Puerto Rico and in form of streamers downwind
from El Yunque and from the Virgin Islands. However, the dry air
mass could be a limiting factor in the intensity and coverage of the
rainfall activity.

By Sunday into the first half of the workweek, another upper level
low will begin to retrograde from the northeast. This will cause 500
mb temperatures to cool down, increasing instability aloft. At the
same time, a tropical wave will be moving across the southeastern
Caribbean. The bulk of the moisture should remain south of the local
islands, but still, precipitable water values are expected to climb
to near 1.8 inches on Sunday and just above 2.0 inches on Monday. As
a result, widespread showers could develop across the area,
increasing the potential for urban and small stream flooding, and
water surges along the rivers. Afterward, for Tuesday and
Wednesday, the upper level low moves westward into the western
Caribbean, while a layer of Saharan dust filters in. Therefore,
expect hazy skies to prevail along with generally dry conditions for
Puerto Rico and the U.S. Virgin Islands.

&&

.AVIATION...
Mainly VFR conditions across all local terminals. However, trade
wind SHRA may result in brief MVFR conditions at TJSJ and USVI
terminals through 05/13Z and after 05/22Z. Afternoon convective
development may bring TSRA to TJBQ and VCSH to the remaining
terminals between 05/16-22Z. Light and variable winds will
continue through at least 05/13Z, increasing to 10-20 knots with
gusts up to 30 knots and sea breeze variations by mid-morning.

&&

.MARINE...
Recent buoy observations show seas at 2 to 3 feet with winds out
of the east at 10 to 15 knots. Winds will become a little
stronger by mid-week, and these choppy conditions should linger
through the weekend. For the beaches, the risk of rip currents is
high for the north-central northwest coast of Puerto Rico and
moderate elsewhere.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 77 90 77 / 50 50 50 50
STT 89 80 89 80 / 40 40 50 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
337 AM AST Wed Jul 6 2022

.SYNOPSIS...
Very warm temperatures are expected to persist across the local
area under a southeasterly wind flow. Heat indices are expected to
remain between 102 to 107 degrees for the urban areas and coastal
municipalities. Conditions are still favorable for shower and
thunderstorm activity across the interior and western Puerto Rico
each afternoon.

&&

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

The short-term forecast is on track. As the dominant feature, a
high pressure system across the north-central Atlantic will
maintain east to east-southeast winds ranging between 10 and 20
mph through the cycle. A Tropical Upper Tropospheric Trough (TUTT)
anchored to the west over La Hispanola will support a weak trade
wind inversion and favorable conditions for deep convective
development over the northeastern Caribbean. Although a patchy
weather pattern will cause variations in moisture content,
moisture from a departing tropical wave and weak perturbations in
the general wind flow will boost precipitable water values into
normal to above-normal levels. Periods of high moisture content as
high as 1.9 inches are expected today into late tonight and again
on Friday, separated by a somewhat drier period with precipitable
water values declining to as low as 1.6 inches. Despite variations
in moisture content, a typical seasonal shower pattern will
dominate, accentuated during the wettest period.

An area of high moisture content, now moving over the northern
Leeward Islands as depicted in the GOES-19 Total Precipitable
Values estimates product, will reach the local islands today,
causing precipitable values to range between 1.8 and 1.9 inches
into late tonight. The TUTT`s proximity, local effects, diurnal
heating, and sufficient available moisture will support shower and
isolated thunderstorm development, with the highest impact
expected across the interior and western to northwestern sections
of Puerto Rico this afternoon. Showers developing downwind from
the local islands and el Yunque may also affect eastern Puerto
Rico and the San Juan metropolitan area throughout the day.
Increased tropical moisture advection and favorable environmental
conditions could also lead to showers activity during the
overnight and early morning hours, favoring eastern Puerto Rico
and the U.S. Virgin Islands. Any prolonged period of moderate to
heavy rains, either from the afternoon convection or nighttime
activity, could lead to ponding of water on roadways and poorly
drained areas with a slight chance for urban and small stream
flooding. Drier conditions will inhibit the potential for heavy
rains between Thursday and Friday. Still, as tropical moisture
increases from Friday afternoon onwards, the potential for
enhanced shower and isolated thunderstorm activity will also
increase.

.LONG TERM...Saturday through Thursday...
A surface high pressure over the central Atlantic will maintain
moderate winds along the islands for the weekend, with a low level
steering flow out of the southeast at 10 to 15 knots. At the upper
levels, a Tropical Upper Tropospheric Trough (TUTT) will begin to
retrograde into the area, while an induced trough a 700 mb
approaches from the east by Sunday. This will make 500 mb
temperatures to drop to around -7 to -8 Celsius degrees and
instability to increase. Additionally, a tropical wave will be
moving across the eastern Caribbean, with the bulk of the moisture
remaining south of the region. Although these feature should not
move directly over the islands, they will still aid in the
generation of afternoon convection, especially along northwestern
Puerto Rico, and downstream from el Yunque and the Virgin Islands.
On Monday, while the upper level trough lingers, precipitable water
values are expected to climb above climatological values, surpassing
the 2.0 inches. Therefore, the intensity and coverage of the shower
and thunderstorm activity is expected to increase. After the
tropical wave departs toward the central Caribbean, a Saharan Air
Layer will follow, with hazy skies expected and the potential for
reduced visibilities. There is another tropical wave approaching the
area by Thursday, both under the presence of the Saharan dust, the
global models are not too enthusiastic with rainfall accumulation
for the middle and latter part of the workweek.


&&

.AVIATION...Mainly VFR conditions across all local terminals.
However, trade wind SHRA may result in brief MVFR conditions at
TJSJ and USVI terminals through 06/13Z and after 06/22Z. Afternoon
convective development may bring TSRA to TJBQ and VCSH to the
remaining terminals between 06/16-22Z. Light and variable winds
will continue through at least 06/12Z, increasing to 10-20 knots
with higher gusts and sea breeze variations by mid-morning.


&&

.MARINE...
A surface high pressure maintains a moderate wind flow across the
area, up to 15 knots. Winds are expected to increase by Thursday,
resulting in choppy conditions. There is a moderate rip current
risk for much of the local beaches.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 77 88 77 / 40 50 50 40
STT 87 79 89 78 / 40 40 30 30

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
508 AM AST Thu Jul 7 2022

.SYNOPSIS...
Another round of showers and thunderstorms are expected for each
afternoon this week across western Puerto Rico, and also
downstream from El Yunque and from the Virgin Islands. Urban and
small stream flooding will be possible with this activity.
Temperatures are expected to increase to the low 90s with heat
indices just above 100 degrees.

&&

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

This morning, conditions will remain calm, with the skies mostly
clear to partly cloudy, mainly due to overnight rains across the
Virgin Islands and most of Puerto Rico. Therefore, expect a mixture
of sunshine and clouds. However, the east south-easterly winds will
sometimes push a few clouds and showers across eastern PR.

A Tropical Upper Tropospheric Trough (TUTT) lingering near the
islands will provide favorable environmental conditions (good
dynamic aloft) for the next few days. The instability combined with
diurnal heating, local effects, and sea breeze variations will
result in afternoon showers and thunderstorms over the interior and
western PR and downwind from the Virgin Islands and El Yunque. El
Yunque streamer could produce periods of moderate to heavy showers
across the San Juan Metropolitan area. This activity could result in
urban and small stream flooding. Under an east-southeast wind flow,
expect heat indices surpassing the 100s degrees Fahrenheit across
coastal and urban areas, especially north of the Cordillera Central.
During the nighttime, cool air advection over warm waters combined
with land breeze convergence could result in another round of
showers and possibly a few isolated thunderstorms across the
Atlantic Coastal Waters. A similar weather pattern will persist on
Friday too. The limiting factor for the conditions mentioned above
is the lack of moisture which could reduce the frequency and
coverage of this activity. Traces with African Dust Particles will
also result in some haziness through the next few days.

Another tropical wave will move into the Caribbean Sea by late
Friday or Saturday, increasing the intensity and frequency of
showers across the islands.

.LONG TERM...Sunday through Friday...
The forecast for the upcoming workweek remains on track. A (TUTT)
will continue to advance into the region. At the same time, an
induced surface to mid level trough will move from the eastern
Caribbean and move north of the islands, while a tropical wave
crosses the southeastern Caribbean. The surface features will not
move directly over the forecast area, but they will increase
moisture, while the upper level feature will cause 500 mb
temperatures to cool down. This increase in instability will
increase the potential of showers and thunderstorms for Sunday and
Monday. However, the position of the TUTT and the available
moisture appears to favor further coverage and intensity of the
activity on Monday.

The upper level trough lingers through Wednesday across the region,
but late on Monday, a Saharan Air Layer will begin to filter in from
the east, resulting in hazy skies, and also reducing the available
moisture for shower production. By the end of the week, the global
models shows a well defined tropical wave at 700 mb advancing over
the area. However, with the dry air layer between 700 to 500 mb,
shower activity should be limited in term of intensity and coverage,
and with a seasonal behavior of morning showers over eastern Puerto
Rico and the U.S. Virgin Islands, and afternoon convection along the
western municipalities of Puerto Rico.


&&

.AVIATION...
VFR Conditions will persist today. However, SHRA/TSRA
will affect the interior and western PR btwn 07/16-22z, sometimes
this activity could move in/around TJSJ/TJBQ/JPS. SHRA will also
develop downwind from the USVI which could impact IST/ISX during the
afternoon. Winds will be from the E-ESE at 10-15KT with higher gusts
after 07/13Z with variations due to sea breeze. Winds will diminish
overnight to around 10 KT or less.

&&

.MARINE...
Winds are expected to increase by tonight due to a surface high
pressure centered over the eastern Atlantic. Seas will increase up
to 6 feet with winds out of the east up to 20 knots. These choppy
conditions are expected to continue through early next week.

&&

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

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
507 AM AST Fri Jul 8 2022

.SYNOPSIS...Although decreasing moisture and instability are
expected, local effects and diurnal heating will still support a
typical seasonal shower pattern. The highest impact will focus
across the interior to western sections of Puerto Rico each
afternoon, where urban and small stream flooding is likely. A
tropical wave and favorable conditions aloft will enhance the
potential for heavy rains by Sunday into Monday, followed by drier
and hazy conditions through midweek. Increasing winds will
maintain choppy marine conditions and life-threatening rip
currents during the next few days. Above-normal heat indices are
also expected.


&&

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

Today expect the typical summer weather pattern with a mixture of
sunshine and clouds and showers moving across the local waters, some
of them sometimes moving quickly across the Virgin Islands and the
windward sections of Puerto Rico. Then, local effects, diurnal
heating, and sea breeze variations will provide the conditions to
aid in afternoon showers and thunderstorms across the interior and
northwest quadrant of Puerto Rico and downwind from El Yunque. Rain
showers will also develop downwind from the Virgin Islands during
the afternoon, moving mainly over the surrounding waters. Maximum
temperatures will reach the low 90s, and combined with relative
humidities, the heat indices will surpass 100s degrees Fahrenheit
across coastal and urban areas this afternoon. Skies will also
remain hazy as African Dust Particles` traces move across the local
skies. Urban and small stream flooding could not be ruled out,
especially across the northwest quadrant of PR and in the San Juan
Metropolitan area (if El Yunque streamers develop).

An induced perturbation will bring good moisture on Saturday,
increasing the frequency of showers and afternoon convection across
Puerto Rico and the Virgin Islands. Then, a retrograding Tropical
Upper Tropospheric Trough (TUTT) will reach the islands with a weak
tropical wave late Saturday night into Sunday, increasing the
likelihood of observing isolated to scattered thunderstorms. Under
this weather pattern, expect the environmental conditions to become
more favorable each day through the weekend to have unsettled
weather conditions.

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

A Tropical Upper Tropospheric Trough (TUTT), maintaining a weak
trade wind cap inversion and cooler mid-level temperatures
dropping as low as -11 degrees Celsius, will support thunderstorm
development through at least midweek. Ridging will briefly yield
to hostile conditions for deep convective development by the end
of the work week, but another TUTT will favor somewhat favorable
environmental conditions by the end of the forecast cycle. While
model guidance suggests various periods of drier than normal
conditions, a set of tropical waves and surface-induced
perturbations embedded in the general flow will boost precipitable
water values into normal to above-normal levels as high as 2.1
inches.

Despite variations in moisture content, local and diurnal effects
will support a typical seasonal pattern each day. So far, the
highest impacts are expected during the wettest periods on Monday
morning and Wednesday evening into late Thursday night. However,
favorable conditions generated by the TUTT could lead to localized
isolated thunderstorm development even during the driest periods.
This activity will be accentuated by overnight and early moderate
to heavy rains affecting eastern Puerto Rico and the U.S. Virgin
Islands, followed by afternoon convective development across the
interior and western sections of Puerto Rico. Saharan Dust
concentration will maintain hazy conditions, especially during the
driest period between Monday evening and Wednesday morning and
from Friday onwards. As the dominant feature, a strong high
pressure centered across the north Atlantic will maintain a
generally east to southeast wind flow at around 10-20 mph through
the cycle. Variations in the general flow will result from
tropical waves and a surface-induced trough streaming across the
northeastern Caribbean.


&&

.AVIATION...VFR Conditions will persist today with passing SHRA.
SHRA/TSRA will develop over the interior and NW-PR btwn 08/16-22z,
this activity will in/around TJBQ. SHRA will also develop downwind
from the USVI and El Yunque which could impact sometimes IST/ISX and
JSJ, respectively. Expect calm to light/Var winds thru 08/13z, when
winds will return from the E-ESE at around 15KT with higher gusts
and sea breeze variations. Winds will diminish overnight to 10 KT or
less.


&&

.MARINE...Small craft operators should continue to exercise
caution due to moderate to locally fresh easterly winds of up to
20 knots and choppy seas of up to 6 feet across most local waters,
except for the coastal waters of southern and western Puerto Rico,
where winds and seas should remain at or below 15 knots and 5
feet, respectively. There is a high risk of rip currents for
beaches across the north-central to the northwest coast of Puerto
Rico, while a moderate risk of rip currents remains in place for
most remaining local beaches.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 78 88 78 / 40 60 60 60
STT 88 79 89 78 / 20 50 50 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
455 AM AST Sat Jul 9 2022

.SYNOPSIS...

An induced perturbation embedded in the trades will reach the U.S.
Virgin Islands today and Puerto Rico. An upper-level trough will
approach from the northeast westward, making its way over the
region through late Tuesday. A tropical wave will reach the
islands on Sunday. A Saharan Air Layer will create hazy skies from
Monday onward. Unstable weather conditions could be possible
Friday through Saturday of next week.

&&

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

Total Precipitable Water from GOES-16 indicates small pockets of
moisture around the northeastern Caribbean. This product shows
values around 1.8 inches, which is very similar to the GFS-forecast
soundings, meaning that the model initialized well. An upper level
low is located northeast of the islands, with an induced surface
trough just underneath. At the surface, high pressure dominates the
eastern Atlantic and it is generating a moderate east-southeast wind
flow across the local islands. The upper and mid-level trough will
continue to produce these patches of moisture that will frequently
cross the area, increasing the potential for shower activity today.
In fact, the high resolution and global models agree in a pattern of
advective showers over eastern Puerto Rico and the U.S. Virgin
Islands, followed by stronger activity developing in the afternoon
over the interior and northwestern Puerto Rico. Instability is
enough to support thunderstorms, and with these periods of heavy
rain, urban and small stream flooding will remain possible.

On Sunday, the upper level low will continue to retrograde
into the area. The trough will move in tandem with it, but should
remain north of the local islands. At the same time, a tropical wave
will be crossing the southeastern Caribbean Sea. Moisture is
expected to converge over the area, with precipitable water values
ranging between 1.8 to 2.0 inches. As a result, another round of
showers and thunderstorms is expected to develop. Once the tropical
wave departs toward the Dominican Republic on Monday, a dense cloud
of Saharan Air Layer will filter in from the east. This will result
in hazy skies as well as reduced visibilities. The drier air mass
will also support a trade wind cap inversion at 850 mb, and shower
activity is expected to be less widespread and mainly focused across
western Puerto Rico in the afternoon hours.

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

A retrograding tropical upper tropospheric trough (TUTT) will
linger aloft Tuesday and Wednesday, replaced by a ridge Wednesday
and Thursday. However, the lack of moist air due to an extensive
Saharan Air Layer will limit rain activity, promoting hazy skies
through at least Thursday. Thunderstorms could develop across the
western sections of Puerto Rico and downwind from La Sierra de
Luquillo each afternoon. Above-normal temperatures, with heat
indices above 100 degrees Fahrenheit will be possible each
afternoon too.

The ridge will erode as another retrograding TUTT swings by the
islands Friday through Saturday. While at the surface, a tropical
wave will increase the available moisture on Friday, followed by a
trade wind perturbation (wind surge) on Saturday. Consequently, a
moist and unstable weather pattern could be possible by Friday
into the following weekend.

&&

.AVIATION...

VFR conditions are expected to prevail through the forecast
period. VCSH are expected for TJSJ and the USVI terminals through
the period, while VCTS are expected after 17Z for TJBQ. These
should result in brief periods of reduced VIS and low ceilings.
Afternoon convection may cause mountain obscuration across the
Cordillera Central and western Puerto Rico. Winds are out of the
ESE at 10 to 15 knots, with strong gusts at times.

&&

.MARINE...

Mariners can expect breezy trades promoting choppy seas up to 6
feet across portions of the Atlantic waters and the Anegada
Passage through the weekend. The winds will be mainly from the
east at 15 to 22 knots but gusty near thunderstorms. Therefore,
small crafts should exercise caution.

Beachgoers, there is a high risk of rip currents from Aguadilla to
Dorado and at Cramer Park, and a moderate risk elsewhere across
the rest of the islands.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 77 88 77 / 50 40 60 60
STT 89 79 88 79 / 40 30 50 60

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
456 AM AST Sun Jul 10 2022

.SYNOPSIS...

A tropical wave and an upper-level trough will bring showers and
thunderstorms across the local islands today. The retrograding
tropical upper tropospheric trough (TUTT) will linger aloft
through late Tuesday. A Saharan Air Layer (SAL) will create hazy
skies from Monday onward. Unstable weather conditions will return
Friday through Sunday.

&&

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

An upper level low is currently located northeast of the islands,
while a tropical wave approaches the Lesser Antilles. In the middle
of the Atlantic, a surface high pressure remains anchored, creating
a moderate wind flow out of the east-southeast. The instability
provided by the upper level low will combine with the moisture
provided by the wave and local effects to result in another active
afternoon across the interior, northern and western Puerto Rico.
Some of these storms could be strong at times, with periods of heavy
rain, gusty winds and frequent lightning. Urban and small stream
flooding are expected.

By late Sunday or early Monday, the tropical wave will part ways
into the central Caribbean Sea, and a Saharan Air Layer will follow.
Skies will turn hazy and visibilities will be reduced at least
through mid-week. Moisture content is expected to drop to around 1.6
inches, which is near normal. Although shower activity is expected
to be reduced to the lack of low level moisture, it will not be
completely dry. The upper level low will induce small pockets of
moisture that will be advected into the area at times. Additionally,
this low will dig even closer to the area, dropping 500 mb
temperatures to around -12 degrees Celsius. With this increased
instability aloft, and with strong diurnal heating, isolated, but
strong thunderstorms are expected each afternoon. However, the
activity should not be widespread, focusing along northwestern
Puerto Rico in the afternoon hours.

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

A mid to upper-level ridge will replace a TUTT and reinforce a
trade wind inversion Wednesday and Thursday. In addition, an
extensive Saharan Air Layer will also limit the available moisture
and rain activity, promoting hazy skies through at least Thursday.
However, due to local effects, diurnal heating, and sea breeze
variations, thunderstorms could develop across the western
sections of Puerto Rico and downwind from La Sierra de Luquillo
each day. The SAL will reduce nighttime cooling resulting in
above-normal minimum temperatures each day, which will be easier
for the highs to reach the 90s each day. Although moisture content
will be less than normal, heat indices could surpass 100 degrees
Fahrenheit each afternoon.

The ridge will erode as another retrograding TUTT swings by the
islands Friday through Saturday. While at the surface, a tropical
wave will increase the available moisture on Friday, followed by a
trade wind perturbation (wind surge) on Saturday and a strong
tropical wave on Sunday. Although ECMWF and GFS have some
discrepancies regarding the position of the TUTT, which could
impact the frequency and intensity of the convective activity, we
are putting more weight on GFS (because its solution is closer to
what is happening now). Consequently, a moist and unstable
weather pattern could be possible by Friday into the following
weekend.

&&

.AVIATION...

VFR conditions are expected to prevail through the forecast period.
SHRA will continue to move across the U.S. Virgin Islands and TJSJ
terminals through the period. After 17Z, VCTS are expected at TJBQ,
and these conditions could result in periods of reduced VIS and low
ceilings. Afternoon convection will cause mountain obscuration
across the Cordillera Central and western Puerto Rico. Winds will be
out of the ESE at 10 to 15 knots with stronger gusts and sea breeze
variations.

&&

.MARINE...

Mariners can expect breezy trades promoting choppy to
hazardous seas up to 7 feet across portions of the Atlantic
waters, where a Small Craft Advisory is in effect until 2 PM AST,
this afternoon. Elsewhere, small craft operators should exercise
caution due to choppy seas up to 6 feet and easterly winds of 15
to 22 knots but gusty near the thunderstorms.

Beachgoers, there is a high risk of rip currents from Aguadilla to
Dorado and at Cramer Park, and a moderate risk elsewhere across
the rest of the islands.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 77 90 79 / 60 60 50 40
STT 88 80 88 80 / 50 60 30 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
421 AM AST Tue Jul 12 2022

.SYNOPSIS...
Mostly fair weather conditions are forecast today across the
area. Although the presence of Saharan air Layer will continue to
promote fair weather conditions, showers with isolated
thunderstorms are forecast for the interior to western sections
of Puerto Rico in the afternoon hours. Today into Wednesday, a
strong upper level trough will move over the islands into
Hispaniola, causing unstable conditions aloft. Another tropical
wave is forecast to move near the area on Sunday into Monday,
increasing the potential for more widespread shower activity.
Daytime temperatures are forecast to reach the lower 90s across
some north coastal sections of Puerto Rico, as well the coastal
sections of the U.S. Virgin Islands.

&&

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

A strong surface high pressure remains anchored in the north central
Atlantic, and is expected to continue dominating through the short
term period. This will continue to cause easterly winds. There is a
weak mid level ridge over the local area, and there is a strong
upper level low over the local islands, which is moving to the west
and should be over Hispaniola by tonight. As the upper level low
retrogrades, the instability in the upper levels will increase,
heights will drop, and the temperatures in the mid levels will be
much below normal. This would normally cause very strong
thunderstorms over the area, but in this case there are other
factors in place that may limit convection. There is still a
moderate concentration of Saharan dust over the area, which will
remain over the local islands through Wednesday, so the dust and dry
air will limit convection. The forecast soundings indicate a decent
temperature inversion, that may be difficult to break, though not
impossible, especially across western PR where there may be higher
moisture locally due to sea breeze convergence.

Although shower activity is expected to be somewhat limited overall,
it is possible for brief showers with isolated thunderstorms each
afternoon over the short term period. Given the current setup, there
may be limited coverage of showers and thunderstorms, but the
thunderstorms that do develop may be strong, with gusty winds and
frequent lightning.

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

As the upper level trough moves westward over the western
Atlantic, more favorable conditions aloft will prevail on Friday
into Saturday over the local area. At the low-levels, a strong
surface high pressure located over the central Atlantic extended
to the eastern Atlantic will promote fresh easterly winds over the
forecast area. According to NASA Goddard Earth model, on Friday
into Saturday some presence of Saharan dust could promote drier
weather conditions and warmer temperatures. Nevertheless the
presence of the Saharan dust, embedded in the wind pattern and an
increase in moisture from a wind surge will promote some showers,
mostly for the afternoon hours as this moisture combines with the
local effects. This activity will be localized and mostly over
the interior and western sections of Puerto Rico, were some
ponding of water is possible.

On Sunday, conditions will start to deteriorate, as more moisture
from a tropical wave arrives into the region. According to GFS
model guidance, the bulk of the moisture content will stay to the
south of the Islands. Additionally, conditions aloft would turn
more favorables as a some divergence aloft from a upper level
trough at our north and the northeastern sections of an
anticyclone. Additionally, colder temperatures at the 500 MB
between the -6.5 and -7 Celsius could aid thunderstorm
development. The combination of these conditions and the
available moisture with PWat values near or above normal will, so
far, increase the shower frequency. Some moisture will be in
place on Monday, as the tropical wave moves to the western
Caribbean, given that similar conditions are forecast for Monday
across all of the local islands, with the typical morning showers
over the east and the U.S Virgin Islands, follow by the afternoon
activity over the western sections of Puerto Rico.


&&

.AVIATION...VFR conditions are expected through the forecast period. Saharan
dust over the area will cause HZ, but VIS should be P6SM as reported
by nearby stations. After 12/17Z, SHRA/TSRA is possible near TJBQ.
Winds will be out of the E at 10 to 15 knots with stronger gusts and
sea breeze variations.

&&

.MARINE...
A broad surface high pressure across the central Atlantic will
continue to promote moderate easterly winds across the local
Atlantic waters. As a result seas up to 6 feet across the Atlantic
waters and up to 5 feet across the Caribbean waters and local
passages are expected. Therefore, small craft operators should
exercise cautions across the Atlantic waters. By midweek, conditions
should deteriorate more due to an increase in winds across the
local waters. As a result, seas up to 7 feet and winds up to 20
knots are forecast on Wednesday night into the end of the
workweek.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 78 89 78 / 20 40 40 40
STT 90 77 90 77 / 20 30 40 40

[cycloneye]

 https://twitter.com/TTMetOffice/status/1546862845840789504

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
452 AM AST Wed Jul 13 2022

.SYNOPSIS...
An upper level trough and an increase in moisture will promote
shower and thunderstorm activity today. This activity could result
in ponding of water and minor flooding, especially with the heaviest
shower activity. Weather conditions are forecast to remain
unstable until Friday, when the upper level trough shift more to
the western and a Saharan Air Layer filters into the region. For
the long term period, a typical weather pattern is forecast for
the CWA.



&&

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

The strong TUTT to the west of the local area is causing cloudiness
over the local islands, as well as an induced surface trough that is
causing scattered showers across the local area. Blended
precipitable water imagery indicates that the precipitable water is
above normal over the USVI and the northern Leewards, and model
guidance suggests that the increase in moisture will move west
today. This increase in moisture and the TUTT is expected to cause
an increase in shower activity across the local islands today. But
in the afternoon, especially in the mid afternoon hours onward,
numerous showers and isolated thunderstorms are forecast across the
southwestern quadrant of PR. Some of the storms can have heavy rain
and cause urban and small stream flooding, while ponding of water in
poor drainage areas can be expected elsewhere.

There is however some level of uncertainty. Considering that there
is still some Saharan dust in the area, there is lots of cloudiness
which also limits the daytime heating which normally helps
convection, the 500mb temps are very low but are expected to
increase sharply as the day progresses, heights will increase also.
But the hi-res models are very aggressive with the amounts of rain,
especially across SW-PR, the forecast soundings indicate a good
environment for thunderstorm development with a relatively low
convective temperature, which would be easy to reach. Therefore, we
decided to nudge today`s forecast wetter than we inherited, with
scattered to numerous showers and isolated thunderstorms through the
local area, especially in the afternoon hours, when the Saharan dust
concentration is expected to decrease. Scattered showers and
isolated thunderstorms are also forecast for the USVI today.

For Thursday and Friday, we still expect decent moisture to move in,
and there will be a smaller concentration of Saharan dust, but the
TUTT would have moved away and the upper levels will have a weak
high pressure over the area. Therefore, afternoon convection may be
limited to trade wind showers, affecting the USVI and eastern PR, and
locally induced thunderstorms in the afternoon across western PR.

The daytime high temps today may be a couple of degrees below normal
due to the cloudiness expected today. Therefore highs in the mid to
upper 80s are forecast across the lower elevations, and only very
isolated areas in PR are expected to reach heat index values of 102
degrees, while most areas are expected to be below that value over
PR and the USVI.


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

A variable pattern is forecast for the upcoming weekend.
According to the latest NASA Goddard Earth model, the presence of
a Saharan Air Layer intrusion will erode most of the available
moisture on Saturday into early Sunday. However, a considerable
increase in water content is expected on Sunday into early Monday,
as the proximity of a tropical wave will aid the typical shower
activity, but accumulations are not forecast to be significant due
to the SAL intrusion. Additionally, a mid level ridge will favor
stable conditions.

On Monday into Wednesday, conditions will turn more favorables for
shower activity across the Islands. A Tropospheric upper level
trough will establish well at north of the CWA, increasing the
divergence aloft. Meanwhile, at the surface, as the building high
pressure establish over the central Atlantic, will promote a
moderate to fresh easterly winds. Embedded in this trade wind
pattern, several patches of low level moisture from the Caribbean
with PWat near or above climatological normals will enhance the
potential for more frequent passing showers and more widespread
afternoon activity. Colder temperatures at 500 MB would aid some
isolated thunderstorms, especially in the afternoon hours with the
heaviest activity.


&&

.AVIATION...SHRA/TSRA activity expected to increase today across
the local flying area. This will cause VCSH across the local
terminals today. After 13/16Z, the chance for TSRA increases in
areas near TJPS, but SHRA also increases elsewhere, maintaining at
least VCSH across the local terminals. Winds will be from the
east at around 15 knots with occasional gusts and sea breeze
variations.


&&

.MARINE...
A broad surface high pressure located over the Central Atlantic will
continue to promote moderate easterly wind flow over the local
waters, increasing slightly over some waters up to 20 knot.
Therefore small craft operators should exercise caution mainly
across the Anegada Passage. For the rest of the waters, seas will
remain up to 5 feet and winds up to 15 knots. marine conditions
are forecast to deteriorate by the end of the workweek, when small
craft advisories could be in effect for some local waters. There
is a low to moderate risk of rip current for most of the exposed
beaches of the region. The risk will increase on Thursday to high
across some of the northwestern coast of Puerto Rico.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 80 89 78 / 40 40 50 60
STT 90 80 89 78 / 40 50 50 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
442 AM AST Thu Jul 14 2022

.SYNOPSIS...
Variable weather conditions will prevail today, passing showers
during the morning hours and afternoon convection over the
western interior. Typical weather conditions will prevail for the
rest of the forecast period. Another pulse of Saharan Dust will
filter into the forecast area on late Friday into Saturday, this
particles will erode the available moisture and will limit the
shower activity. Choppy to hazardous marine conditions are
forecast for the next several days.

&&

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

The strong TUTT continues to move west and away from the local area,
allowing for a weak upper high pressure to move over the local
islands, which will stay over the area until late Friday. Then a
tilted upper trough will move over the local area on Saturday. The
available moisture will decrease today but moisture will still be
enough to allow locally induced thunderstorms int he afternoon
across western PR. That said, a weak tropical wave will cause a
quick increase in moisture by the late afternoon hours today. This
increase in moisture is expected to cause scattered to locally
numerous showers across the USVI and eastern PR into the evening
hours.

Drier air returns for Friday during the day with some possible
Saharan dust, but once again with enough moisture to allow
afternoon convection across western PR. Then by Saturday, even
though some Saharan dust may still be present, another quick
tropical wave will cause an increase in moisture over the local
area. By Saturday afternoon, the aforementioned tilted upper
trough may be positioned favorably for sustained thunderstorm
development in areas of sea breeze convergence across western PR.

Temperatures are expected to be near normal, with highs in the upper
80s to low 90s across the lower elevations of PR and the USVI. Heat
index values could reach the low 100s in PR, while the USVI may
remain mainly in the mid to upper 90s. Across the highest elevations
of PR, the daytime temps will be in the low to mid 80s.

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

A variably weather pattern is forecast for Saturday. Early in the
morning, a wind surge embedded in the easterly trade will filters
into the region increasing the passing showers. After that, by noon
into the night hours, an big pulse of Saharan Dust will move into
the area eroding al the available mostly and result in hazy skies.
Additionally, conditions at the mid to upper levels will remain
stables, therefore, only limited and localized shower activity is
included in the forecast for Saturday. This drier conditions due to
the presence of the Saharan Dust will prevail throught the rest
of the weekend, increasing the water content on later Monday due
to the arrival of a tropical wave.

For the upcoming workweek, conditions at the upper level would
change when a retrogressing upper level trough drifts more into
the area with the axis over the CWA. Meanwhile, at the surface,
several patches of low level moisture with precipitable water
values above normals from a passing tropical wave will increase
the potential for widespread shower activity. As the surface high
pressure sinks more into the Central Atlantic, a more east-
southeasterly wind flow will prevail on Tuesday into Thursday.
This wind flow will drift all the shower activity over the
northwestern sections of Puerto Rico, and could enhance the San
Juan Metro Area streamer each day. A slight increase in the
temperatures is forecast for Tuesday into Thursday for the north
coastal sections of the islands.


&&

.AVIATION...SHRA/TSRA activity expected today across the local flying
area. This will cause VCSH across the local terminals through the
day, possibly brief SHRA at the terminals. After 14/16Z, the
chance for TSRA increases in areas near TJBQ and TJPS possibly
causing VCTS. Winds will be from the east at around 15 knots with
occasional gusts and sea breeze variations.


&&

.MARINE...
A broad surface high pressure over the Central Atlantic will promote
moderate to fresh easterly winds over the local waters. This will
result in choppy seas up to 6 feet for all the Atlantic waters for
today, increasing up to 7 feet tonight. Therefore, small craft
operators are urge to exercise caution across all the local
waters today, then a Small Craft Advisory will go into effect this
evening for the offshore Atlantic waters. There is a high risk of
rip current for all the northwestern exposed beaches of Puerto
Rico, the risk will extend for the rest of the north coast,
Culebra and St. Croix this evening into the upcoming weekend. For
the rest of the exposed beaches, the risk will remain low to
moderate.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 78 87 78 / 50 60 50 60
STT 89 79 88 79 / 40 40 40 40