Caribbean - Central America Weather

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cycloneye
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Re: Caribbean - Central America Weather

#20241 Postby cycloneye » Sun Jun 21, 2020 5:00 am

Area Forecast Discussion
National Weather Service San Juan PR
438 AM AST Sun Jun 21 2020

.SYNOPSIS...

The big story for the next several days will the dense Saharan
dust event. Along with the dust, dry air will lead to fairly calm
weather for the next several days. The next tropical wave is
expected to arrive Thursday night. Marine conditions will be
choppy due to moderate to fresh easterly winds associated with the
tropical wave leaving the region today and a fairly strong
surface high in the central to east Atlantic.

&&


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

A drying trend will continue as the lingering moisture of
yesterday`s tropical wave exits the region. A dense air mass with
suspended African dust particles will create hazy skies and poor
visibilities across the northeast Caribbean through the morning
hours, reaching the U.S. Virgin Islands and Puerto Rico by this
afternoon into the first part of this week. The peak of this event
is forecast between late tonight and early Monday, lasting until at
least mid-week. This weather pattern will promote above-normal
overnight temperatures (in the low-80s), making it easier to reach
high temperatures in the low to mid-90s each afternoon.

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

By Wednesday, the worst of the dust should be behind us, though
moderate amounts of dust are expected for the full duration of the
long-term period. Some moisture will drop in for Wednesday and
Thursday from the north associated with an old front. The moisture
does not look like much at this point, but showers should be able to
develop over southwest PR under northeasterly flow for Wednesday,
though these showers will likely be unimpressive. Thursday however
looks better for showers and thunderstorm development. A trough at
upper levels is still expected to develop to our west, that will
enhance shower and thunderstorm activity. With winds switching more
from the southeast, winds will converge over the northwestern
portion of PR in the afternoon, so that is where the activity should
be.

Friday looks even more interesting as a tropical wave is expected to
move through the area, and may also be enhanced by the upper-
level trough to the west. The GFS model is projecting a more
robust wave compared to yesterday, but the European model has a
less impressive wave than what it was simulating yesterday with
most of the moisture exiting the region by Friday afternoon. With
still plenty of time before its arrival, more changes to the
forecast of this wave are probable. Thereafter however, dry
conditions are once again expected to prevail through the weekend
and into the next week with only weak patches of moisture riding
in on the easterly trade winds.

&&


.AVIATION...

VFR conditions will prevailed. However, a dense Saharan air mass
will reduce VIS after 21/18z across the local flying area between 6-
9 SM and diminishing overnight into Monday. Calm to light and VRB
winds will prevail thru 21/13z, then will return from the ESE at 10-
20 kt with higher gusts and sea breeze variations.

&&


.MARINE...

Moderate to fresh winds will continue for the next several days,
leading to choppy seas up to 5 to 6 feet. At this point, it
appears Small Craft Advisory conditions may be met for Monday
night and into Tuesday due to the windy conditions, and the
decision to put that advisory out will be made in the next 24
hours. Regardless, small craft operators are urged to exercise
caution. Finally, expect lower visibility due to Saharan dust.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 92 79 91 80 / 20 20 20 20
STT 92 82 91 80 / 20 20 10 20
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Re: Caribbean - Central America Weather

#20242 Postby cycloneye » Mon Jun 22, 2020 6:03 am

Area Forecast Discussion
National Weather Service San Juan PR
515 AM AST Mon Jun 22 2020

.SYNOPSIS...

Suspended African dust particles will peak today, creating very
hazy and low visibilities over the islands. Overnight
temperatures will remain in the low-80s, making it easier to rise
into the 90s during the afternoon hours. These conditions will
prevail through at least Tuesday. However, the aerosols leftovers
will linger through much of the workweek. A tropical wave is
forecast to reach the islands by Friday.

&&

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

Saharan dust concentrations are expected to peak today and tomorrow.
Visibilities near and even below 6 miles are likely across the
region, with the dust concentrations declining during the day on
Wednesday, though still remaining quite high. Along with the dust, a
very dry airmass has invaded the region, with precipitable water
values well below average at 1.3 to 1.5 inches. Furthermore high
pressure will dominate the region at all levels, resulting in
subsidence and further warming/drying aloft. This is plainly evident
in model soundings with warmer than average 500 mb temperatures and
an inversion at 850 mb. With these specific conditions lasting today
and tomorrow, very little rainfall is expected. High resolution
model guidance does suggest a chance for some showers in west to
northwest Puerto Rico tomorrow and Tuesday afternoons. However,
these showers will have very minimal impact. Winds will stay fairly
breezy due to surface high pressure strengthening the central
Atlantic.

Heading into Wednesday, some moisture is expected to drop in from
the northeast during the daytime associated with an old front. The
low level inversion is expected to erode, so conditions should be
more conducive for shower and isolated thunderstorm development
for western Puerto Rico in the afternoon. Furthermore, an upper
level trough will begin developing to our west during the day,
which may aid in enhancing thunderstorms.

.LONG TERM...Thursday through Monday

An upper-level trough will amplify over the Windward Passage and
slowly drift eastward Thursday into the weekend. The leftovers of
today`s African dust event will make its way into the long-term
period in combination with patches of low level moisture embedded
in the trade winds. Moisture will slowly ramp-up over the
Northeast Caribbean producing a few passing showers and afternoon
convection each day. However, at this time, no significant
rainfall event is anticipated over the islands until the arrival
of the next tropical wave on Friday.

Both GFS and ECMWF are indicating the arrival of a tropical wave
on Friday. This tropical perturbation will interact with an
upper-level trough centered over Jamaica and extending into our
region. If the models are right, the aforementioned upper-level
feature could enhance upper-level ventilation hence thunderstorm
formation and downpours over the county warning area. After this
wave, a fast-drying trend is forecast on Saturday. Then, another
trade wind perturbation will be advecting over the islands by
Sunday. A second tropical wave is forecast to swing by the region
on Tuesday. Keep in mind that sometimes models have high
uncertainty in the humidity field, especially during the long-
term.

&&

.AVIATION...
The Saharan dust event will continue to impact visibilities at all
terminals through tomorrow at least, ranging from 4-8 miles. E winds
will pick up to 10 to 20 kts by 15z, and slow down to 5 to 15 kts
by 00z. VCSH possible for TJBQ, otherwise dry conds will prevail.

&&

.MARINE...
Mariners can expect moderate to fresh winds between 15 and 20 kts
and therefore choppy seas between 3 and 6 feet across the
regional waters through at least the middle of the workweek. Fresh
winds will create seas up to 7 feet across the Mona Passage this
evening. Therefore, a Small Craft Advisory in in effect until at
least Tuesday morning. Elsewhere, small craft operators should
exercise caution. Visibilities will be limited between 4 and 7
nautical miles in a Saharan dust episode through Wednesday.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 92 83 91 80 / 10 10 10 20
STT 92 83 91 79 / 10 10 10 20

&&
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Re: Caribbean - Central America Weather

#20243 Postby cycloneye » Wed Jun 24, 2020 5:00 am

AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
430 AM AST Wed Jun 24 2020

.SYNOPSIS...

Hazy skies will continue today. However, as the Saharan Air Layer
moves westward, gradual improvement and lesser concentrations are
expected through at least Thursday. A trade wind perturbation
will bring showers and thunderstorms across the islands today. A
tropical wave is forecast to cross the local islands late Thursday
night into Friday, followed by a fast drying trend on Saturday.

&&

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

We will definitely see lighter amounts of Saharan dust today
compared to yesterday, but light to moderate amounts of dust are
expected for the rest of the week. Visibilities are expected to stay
at or above 6 miles for the rest of the week as well. Showers have
once again returned to the region and even some robust thunderstorm
activity is expected during the next few days.

At mid to upper levels, a trough of low pressure is currently
developing to our west, which will work to increase instability over
our forecast area and enhance the threat for thunderstorms for the
next few days. High surface pressure is dominating the central
Atlantic and extending into our region, driving easterly winds at 10
to 20 mph. In fact, low level steering winds will be fast enough
that showers ought to move along fairly quickly for the next few
days. Still however, flooding could be a threat where persistent
showers develop over a given location. Finally, the last thing to
consider is that moisture is increasing across the region as the
dust moves out. In fact, a decent patch of moisture is moving
through this morning and will help showers develop this afternoon
over western Puerto Rico. Less moisture will be available tomorrow
until a fairly fast and thin tropical wave moves in tomorrow night
and into Friday.

Putting this all together, as the current patch of moisture moves
across the region this morning, isolated to scattered showers can be
expected with occasional lightning. This afternoon should be fairly
active over western Puerto Rico given these condtions, particularly
for areas near Mayaguez. Moderate to heavy showers, localized
flooding, and frequent lightning will be the threats for this
afternoon in western PR. The lingering dust may also help enhance
the amount of lightning seen this afternoon. With less moisture in
place for tomorrow, showers and isolated thunderstorms are again
possible over western PR, but they should be less impactful. Then,
the tropical wave arrives overnight Thursday and into Friday, that
will induce scattered showers and isolated thunderstorms across the
region. At this point, it looks like Friday afternoon should be
active over northwestern Puerto Rico as lingering moisture from the
wave will combine sea breeze convergence effects to drive numerous
showers and isolated thunderstorms. The aforementioned upper level
trough will move westward Thursday and into Friday, so it should not
be a factor for Friday afternoon.

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

A somewhat dry air mass is forecast to produce a fast-drying
trend from Saturday into early Sunday. Then, another trade wind
perturbation induced by a mid- to upper-level trough over the
Central Atlantic will move into the region, increasing passing
showers and convection during the afternoon. This upper-level
feature and a surface high pressure centered over the Atlantic
will promote the advection of low-level moisture early next week.

The leading edge of a second tropical wave is forecast to reach
the islands late Tuesday night and crossing Puerto Rico and the
U.S. Virgin Islands on Wednesday. There is high uncertainty about
the evolution of this weather pattern because it is close to the
end of the forecast cycle, but stay tuned to see if it
materialize.

&&

.AVIATION...

Saharan dust concentrations are declining across the region, so P6SM
expected at all terminals after 12z. However, light to moderate HZ
expected for the rest of the week. Winds will be out of the east at
around 10 to 20 kt with sea breeze modifications, and slowing down
to 5-10 mph after 00z. TSRA likely for TJMZ this afternoon. VCTS
possible for TJBQ, and possible but less likely for other terminals.
Gusty winds will accompany any nearby thunderstorms.

&&

.MARINE...
Moderate to fresh winds between 10 and 20 kts will continue to
result in seas of between 3 and 6 feet across most of the regional
waters through most of the work week. Therefore, small craft
operators should exercise caution. Visibilities across the area
should improve as the Saharan Air Layer exit the local waters.
Afternoon thunderstorms should not be ruled out each day over
western Puerto Rico.

A tropical wave is forecast to increase the potential for showers
and thunderstorms across the local waters late tomorrow night into
Friday.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 80 89 79 / 40 30 30 60
STT 89 80 89 79 / 40 30 40 50
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Re: Caribbean - Central America Weather

#20244 Postby cycloneye » Thu Jun 25, 2020 4:45 am

Area Forecast Discussion
National Weather Service San Juan PR
521 AM AST Thu Jun 25 2020

.SYNOPSIS...
Moisture associated with a tropical wave will move over the region
today. Therefore, an increase in shower and thunderstorm activity
is expected for the afternoon hours. The heaviest showers with
isolated thunderstorms are expected mainly over western sections
of Puerto Rico, elsewhere isolated to scattered showers are
expected. On Friday, the same weather pattern is expected. A more
dry airmass is forecast to reach the region for the weekend and
will produce less shower activity and more fair weather
conditions. A wind speed increase is expected over the local
waters resulting in choppy marine conditions with seas up to 7
feet in the Atlantic and Caribbean waters as well the local
passages.


&&

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

A slot of dry air will be moving in today across the local area,
causing a decrease in the shower activity through the mid morning
hours. However, the local effects will combine with the diurnal
heating and some instability from an upper-level low to cause
afternoon shower and thunderstorm activity. The most significant
shower activity will be across the western sections of Puerto Rico.
The Saharan dust concentration will continue to decrease today. For
Friday, a tropical wave will be moving in, which will cause a
significant increase in moisture and shower activity across the
local area. The latest model guidance suggests that the tropical
wave will move in the morning across the USVI and then over PR for
the afternoon hours. This tropical wave will also come in with a
surge in winds from the east, causing wind speeds to be near 20 mph.
This will could cause the shower and thunderstorm activity to move a
bit more inland across eastern PR and into the eastern interior
sections, though the high res models are not suggesting too much
rain, partly because of the fast moving showers. As far as the USVI,
the expectation is the same, where showers and thunderstorms are
expected, but may be brief as the showers could be moving quickly.
However, later in the afternoon, the shower activity will be more
significant for central and western PR. One thing to note is that
there will be an increase in Saharan dust on Friday, which could
inhibit some of the convection. Then on Saturday, a return of
relatively dry air is expected, with the presence of Saharan Dust,
though not as much as we observed early in the week, but shower
activity will be limited mainly to locally induced showers across
western PR.

.LONG TERM...Sunday through Thursday

The long term period start with a more drier mass over the region
limiting the development of well convection specially in the
afternoon hours. This weather patter si expected through at least
on Monday when fragments of moisture reach the local area embedded
in a east northeasterly wind flow. This will enhance the chance
of rain activity in the central and southwestern sections of
Puerto Rico in the afternoon hours. Late Tuesday into Wednesday, a
tropical wave is expected to move over the region. This wave will
bring enough moisture to increase the shower well convective
development for at least Thursday. Therefore, isolated to
scattered showers are expected over eastern sections of Puerto
Rico and the U.S. Virgin Islands in the morning hours and the
afternoon convection over the interior sections and northwestern
quadrant of Puerto Rico. This weather pattern is expected for at
least Thursday.




&&

.AVIATION...
Aviation...
VFR conditions will prevail through 25/16Z with SCT SHRA across the
area, causing VCSH. After 25/16Z, VCTS could affect TJBQ, though
ISOL/SCT SHRA is expected elsewhere. Approaching tropical wave will
bring NMRS SHRA / ISOL TSRA to the local area after 26/06Z. Winds
will be from the East at 15 to 20 knots with occasional gusts after
25/13Z, but winds will remain around 10kt or so after 25/23Z. Some
Saharan dust is still present, therefore HZ could be observed, but
VIS is expected to be P6SM.


&&

.MARINE...
Moderate to fresh easterly wind flow will continue for at least
Friday late night resulting in choppy marine conditions with sea
up to 6 feet over the local water. Therefore, a small craft
advisory is effect from this evening to Saturday afternoon.There is
a moderate risk of rip currents for most Puerto Rican beaches
including Culebra and Vieques.Showers and isolated thunderstorms
are possible across the regional waters due to a tropical wave
forecast to move over the region today.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 80 89 79 / 20 60 60 20
STT 90 80 90 80 / 40 50 50 20
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Re: Caribbean - Central America Weather

#20245 Postby cycloneye » Fri Jun 26, 2020 4:53 am

Area Forecast Discussion
National Weather Service San Juan PR
508 AM AST Fri Jun 26 2020

.SYNOPSIS...
A tropical wave is moving over the region today. This will
enhanced the shower activity over the local islands. In the
morning hours, isolated to scattered showers and thunderstorms
are expected over eastern sections of Puerto Rico and the U.S.
Virgin Islands. In the afternoon hours the shower and
thunderstorms activity is expected over the northwestern quadrant
of Puerto Rico. Urban and small stream flooding cannot be ruled
out with the heaviest showers. For the weekend, another episode
of Saharan dust is expected over the area limiting the shower
activity. Across the regional waters, choppy marine conditions
are expected to continue with seas up to 7 feet and winds up to
20 knots. Therefore, a small craft advisory is in effect for the
local waters.

&&

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

For today, a tropical wave will be moving through the local area,
which will cause a significant increase in moisture and shower
activity across the local area. As of this writing, some rain bands
have caused heavy rain and strong gusty winds across the U.S. Virgin
Islands and eastern Puerto Rico, and this is expected to continue at
least through the early afternoon hours across the local area. This
tropical wave will also come in with a surge in winds from the east,
causing wind speeds to be near 20 mph and gusty. Even though the
rain bands are causing heavy rain, the duration is short as these
bands are moving quickly to the west, so the rainfall totals have
been so far less than a half an inch of rain. That said, some areas
could observe an inch of rain or more today. As far as the USVI, the
expectation is the same, where showers and thunderstorms are
expected, but may be brief as the showers could be moving quickly,
and mostly in the morning hours. For this afternoon, the shower
activity will be mostly focused across the central and western
portions of Puerto Rico. One thing to note is that there will be an
increase in Saharan dust right after this tropical wave passes. Then
on Saturday and Sunday, a return of relatively dry air is expected,
with the presence of Saharan Dust, though not as much as we observed
early in the week, but shower activity will be limited mainly to
locally induced showers across western PR.

.LONG TERM...Monday through Friday

A surface high pressure located over the central Atlantic will
produce a east-northeasterly wind flow over the region for at
least Tuesday. In comparison with the yesterday, the GFS model
guidance suggest less fragments of moisture embedded in the east
northeasterly wind flow reaching the forecast area on Monday and
Tuesday. On wednesday, another tropical wave is forecast to each
the region increasing the potential of shower activity over the
region. The focus of the heaviest showers are expected over the
northwestern quadrant of Puerto Rico in the afternoon hours. Considerable
moisture will linger in the region until at least Friday. For
that reason, isolated to scattered showers may occur over the
eastern sections of Puerto Rico and the U.S. Virgin Islands
during the morning hours and then in the afternoon hours over the
interior and northwestern Puerto Rico each day. Urban and small
streams flooding is possible with the heaviest showers. Also,
temperatures are expected to remain between the mid 80s to the low
90s across the coastal sections.


&&

.AVIATION...
VCSH/VCTS is expected across the local terminals as a tropical wave
moves through the area. Conditions to gradually improve after
26/21Z. TEMPO MVFR conds will affect the terminals as the rain bands
affect the VIS and CIG today. Winds from the east at around 15kt
with higher gusts expected, but VRB winds and gusts to 30kts
possible near the SHRA/TSRA. After 27/00Z the local winds are
expected to decrease to around 10kts or less.


&&

.MARINE...

High pressure located over the north central Atlantic will
generate moderate to fresh easterly winds up to 20 knots across
the regional waters. Choppy marine conditions with seas up to 7
feet are expected. Therefore, a small craft advisory is effect
through at least Saturday over the most of the local waters.There
is a high risk of rip currents for Cramer Park beach in St.
Croix. Additionally, a moderate risk of rip current for most
beaches of Puerto Rico including Culebra and Vieques as well as
the U.S.Virgin Islands. Showers and isolated thunderstorms are
possible across the regional waters due to a tropical wave.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 79 90 79 / 60 20 30 30
STT 90 80 90 80 / 50 20 20 20
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Re: Caribbean - Central America Weather

#20246 Postby cycloneye » Sat Jun 27, 2020 5:28 am

Area Forecast Discussion
National Weather Service San Juan PR
513 AM AST Sat Jun 27 2020

.SYNOPSIS...
Mostly fair weather conditions are expected for Puerto Rico and
the U.S. Virgins Islands today. The presence of a Saharan dust air
layer will result in hazy skies and warm temperatures. Therefore,
limiting shower activity is expected for the morning hours. In
the afternoon hours, local effects will produce light to moderate
showers focus across western Puerto Rico. In general, for the rest
of the area mostly hazy skies. Early next week, the chance of
widespread showers are expected with another tropical wave enter
the region. Choppy marine conditions are expected to continue
today with seas up to 7 feet and winds up to 20 knots.

&&

SHORT TERM...Today through Monday...

For today and Sunday, the return of Saharan dust and relatively dry
air is will cause mostly fair weather and hazy skies, though not as
much haze as we observed in the previous Saharan dust event. That
said, shower activity will be limited, but western PR has a chance
of locally induced showers in the afternoons. Sunday may have a bit
more rain than Saturday as a brief patch of slightly higher moisture
is expected to move through early on Sunday afternoon while an upper
trough starts to position itself in a favorable area for instability
and convection. However, the upper trough strengthens and positions
itself north of the local area, instability will increase for Monday
and so will the chances of showers. In addition, the concentration
of Saharan dust is expected to be lower by Monday. Therefore the
forecast has scattered to numerous showers on Monday afternoon for
central and western PR, and scattered showers elsewhere during the
evening on Monday as Saharan dust further decreases and moisture
increases into Tuesday.

.LONG TERM...Tuesday through Saturday

A upper trough low will result in favorable conditions and
instability for upper motion across the region. This will likely
result in light to moderate shower and thunderstorm activity over
Puerto Rico. Once again, the GFS model guidance suggest less
moisture embedded in the wind flow for Tuesday through Thursday.
On late Friday into Saturday, the models suggest an increase in
moisture associated with a tropical wave moving into the area.
Given the expected weather features, the long period forecast is
expected to be active for Puerto Rico and the US Virgin Islands.
In the morning hours, isolated to scattered showers over eastern
Puerto Rico and the U.S. Virgin Islands. Then in the afternoon
hours thunderstorms over the interior and western sections of
Puerto Rico are expected. Urban and small stream flooding is
expected with the heaviest showers. In term of temperatures, a
easterly southeasterly wind flow will result in warmer
temperatures reaching the upper 80s to low 90s over the coastal
sections of Puerto Rico.


&&

.AVIATION...
Fair weather with Haze due to Saharan dust is expected across the
local terminals for the next 24 hours. VIS is expected to remain
P6SM, but could be down to 5-6SM at times, but uncertainty at this
time kept prevailing MVFR from the TAFs. Winds will be from the east
at around 15 knots with higher gusts and sea breeze variations.

&&

.MARINE...

A surface high pressure will continue to promote moderate to fresh
easterly wind flow over the region. Therefore, choppy marine
conditions are expected to continue through at least late today
with seas up to 7 feet and winds up to 20 knots. A small craft
advisory still in effect for he Atlantic and the Caribbean waters
of Puerto Rico and the U.S. Virgins Islands. An improve in winds
and seas are expected on Sunday for all the regional waters.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 91 80 90 78 / 20 20 30 30
STT 91 80 90 77 / 20 20 20 30
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Re: Caribbean - Central America Weather

#20247 Postby cycloneye » Sun Jun 28, 2020 4:58 am

Area Forecast Discussion
National Weather Service San Juan PR
518 AM AST Sun Jun 28 2020

.SYNOPSIS...Saharan dust will remain over the local area today and
therefore hazy skies are expected. Surface high pressure will
cause east to east northeast winds today, becoming mainly
easterly by Monday. Upper trough will cause instability and
thunderstorm activity through the first half of the workweek and a
weak tropical wave could approach the local islands by Thursday.

&&

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

The presence of Saharan dust over the region will maintain
relatively tranquil weather today. However, there is some low
level moisture that could combine with the local effects,
resulting in shower activity in the afternoon across central to
southwestern PR due to an ENE wind flow. For Monday, the pattern
changes, an upper-level trough and induced surface perturbation
will approach the northeastern Caribbean. These features will
enhance upward motion and an will increase the shower and
thunderstorm activity. Therefore, starting on Monday, isolated to
scattered showers are expected mostly over eastern sections of
Puerto Rico and the U.S. Virgin Islands in the morning. Then,
afternoon convection with moderate to heavy showers and isolated
thunderstorms are expected over the interior and western sections
of Puerto Rico in the afternoon. Also, showers will not be ruled
out across the San Juan Metro area. Urban and small stream
flooding is expected with the heaviest showers. This instability
due to the upper trough, is expected for the first few days of the
workweek, therefore a similar pattern in expected on Tuesday. In
term of temperatures, warmer than normal temperatures are expected
aross the coastal sections and urban areas with heat index values
that could be in the 100 to 105 degree range.

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

A slot of dry air is expected on Wednesday, ahead of a tropical
wave that could reach the local islands on Thursday. That said,
there may still be the influence of the upper trough, which will
help develop showers and thunderstorms across central to NW-PR on
Wednesday afternoon. The weak tropical wave that could reach the
area on Thursday may cause a significant enough increase in
moisture to cause showers and a few thunderstorms across a more
generalized area, with the latest GFS guidance favoring
development across the north half of PR. This pattern however is
trending different than what the model was suggesting yesterday,
so not too much confidence is put in the long range forecast. For
the next weekend, patches of moisture will be moving through, but
by then, the upper low may not be positioned in a location to
provide good dynamics for generalized convection over the local
islands, so locally induced convection would be favored starting
on Friday and Saturday. However, some deeper moisture could cause
an increase in shower activity again on Sunday and Monday.

&&

.AVIATION...Some haze is expected to continue today with visibilities
staying P6SM across all TAF sites. VFR conditions are expected
across the local TAF sites, but SHRA is possible at TJPS after
28/18Z. Winds out of the E-ENE between 10 and 15 kt with sea
breeze variations and occasional gusts.


&&

.MARINE...Winds of 10 to 15 knots are expected today with choppy
seas up to 6 feet. However, from this afternoon onward, most of
the local waters are expected to have wave heights up to 5 feet as
seas gradually subside. There is a moderate risk of rip currents
today across many of the local beaches, especially across northern
and southeastern Puerto Rico, Vieques and Culebra, west and south
Saint Thomas, south Saint John, as well as north, eastern and
southeastern Saint Croix.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 79 87 77 / 30 40 40 50
STT 91 78 88 77 / 20 40 40 60
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Re: Caribbean - Central America Weather

#20248 Postby cycloneye » Mon Jun 29, 2020 4:41 am

Area Forecast Discussion
National Weather Service San Juan PR
338 AM AST Mon Jun 29 2020

.SYNOPSIS...
Unsettle weather conditions are expected to continue through the
next few days. Today, the heaviest showers and thunderstorms are
expected over the interior and the southwestern quadrant of Puerto
Rico, then on Tuesday and Wednesday, over northwestern Puerto Rico.
A tropical wave could bring widespread rainfall on Thursday.

&&

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

Broad upper level trough will become amplified while sinking
southwards across the region through Wednesday. This will maintain
unstable conditions aloft during the period. In the meantime, an
induced low level trough will continue to move westwards across the
region through Tuesday to maintain an east to northeast wind flow
and good low level moisture convergence across the northeastern
Caribbean. The lingering upper trough will aid in enhancing shower
development across the local waters during the overnight and early
morning hours. Some showers will be transported inland along the
north and east coastal areas from time to time, but no significant
rainfall accumulations are anticipated. During the afternoon hours
the available moisture and favorable conditions aloft along with
good daytime heating will favor enhanced afternoon convection today
especially over the central interior and southwest sections of
Puerto Rico. On Tuesday and Wednesday, the afternoon convection
should be focused over the west interior and northwest sections of
Puerto Rico as the steering winds are forecast to become more east
southeast. Brief afternoon showers cannot be ruled out east day
around the San Juan metro, but no widespread rainfall is expected at
this time. However, urban and small stream flooding will be likely
each day with the heaviest rains over the west sections of Puerto
Rico.

For the U.S. Virgin Islands, isolated to scattered showers will also
be possible in and around the islands, with a chance of isolated
thunderstorm mainly over the coastal waters during the overnight and
early morning hours. The shower activity is not expected to be
significant or widespread at this time but brief periods locally
heavy rains will be possible mainly on the west end of the islands
during the afternoon. In general, an overall moist and unstable
weather pattern is expected to prevail across the forecast area for
the short term period.

.LONG TERM...Thursday through Tuesday...
On Thursday, an upper level low will be located over Hispaniola, and
another one will be located to the northeast of the forecast area.
These features will maintain 500 mb temperatures around -7 degrees.
At the surface, moisture associated with a tropical wave will
affect the islands, with precipitable water values around 2.0
inches. This pattern looks favorable for the development of
widespread showers and thunderstorms. However, uncertainty, due to
variations in timing of arrival of the tropical wave and the
position of the upper level low exist, since these details will
determine how much rain the islands will receive during this time
period. By Friday and the weekend, moisture levels decrease in the
area, but low level patches of clouds will provide enough fuel
for passing showers affecting the eastern half of Puerto Rico and
the U.S. Virgin Islands through the day, followed by afternoon
convection over the interior and western Puerto Rico. By late
Sunday into Tuesday, a wetter pattern is favored once again as a
series of tropical waves advance into the Caribbean Sea, enhancing
the potential for showers and isolated thunderstorms over the
islands.


&&

.AVIATION...
Prevailing VFR at all terminal but VCSH psbl at TIST/TISX/TJSJ/TJBQ
til 29/14Z. SCT OCNL BKN cld lyrs nr FL025...FL050 with SCT SHRA en
route btw islands and ovr regional waters. Isold TSRA psbl at TJMZ
fm 29/17Z-22Z with VCSH at remaining terminals. SFC wnds calm to
lgt/vrb bcmg fm E to ENE at 10-20 kts aft 29/14z. L/lvl wnds fm NE-N
btw 10-20 kts and backing w/ht BLO FL250.

&&

.MARINE...
Relatively tranquil marine conditions are expected to prevail
through the next few days. However, afternoon thunderstorms over
the coastal waters of western and northern Puerto Rico could
result in locally hazardous seas due to winds and lightning. For
the beachgoers, there is a moderate rip current risk for some of
the local beaches.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 80 89 79 / 40 50 50 40
STT 89 79 88 80 / 40 60 50 50
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Re: Caribbean - Central America Weather

#20249 Postby cycloneye » Tue Jun 30, 2020 4:44 am

Area Forecast Discussion
National Weather Service San Juan PR
339 AM AST Tue Jun 30 2020

.SYNOPSIS...
Passing early showers will affect the islands due to a induced
surface trough crossing the area. A tropical wave will approach
the area by Wednesday and Thursday, increasing moisture and shower
activity over the islands. In general, an unsettled weather
pattern is expected to prevail through the next few days.

&&

.SHORT TERM...Today through Thursday...
Broad upper level trough will linger across the region through
Wednesday, then gradually weaken its hold by Thursday at it lifts
north and east of the area. This will maintain unstable conditions
aloft during the period. An induced low level trough will
continue to cross the forecast area today, with the low level
winds forecast to become more southeasterly during the afternoon
as the trough shifts farther west of the region.

The combination of the two aforementioned features will aid in
enhancing passing shower activity over the regional waters during
the rest of the early morning hours. Periods of moderate to locally
heavy rains of short duration will affect parts of the north and
east coastal areas of the islands from time to time. During the rest
of today, available moisture and the favorable conditions aloft,
along with daytime heating will again favor enhanced afternoon
convection over parts of the islands. However, most of the activity
should be focused over the central interior and northwest sections
of Puerto Rico and on the west-end of the U.S.Virgin Islands,as the
steering winds become more southeasterly. Periods of moderate to
locally heavy rains and isolated thunderstorms will be possible over
these areas, as well as around parts of the San Juan metro where
showers may develop later in the afternoon.

On Wednesday, lesser moisture convergence and instability aloft is
forecast as both the upper trough and low level trough will weakens.
However, brief early morning passing showers will still be possible
followed by locally and diurnally induced afternoon convection over
parts of the islands. By late Wednesday into Thursday , recent model
guidance was less bullish with moisture transport across the region,
but still suggest increasing moisture and instability accompanying a
tropical wave which is forecast to quickly cross the region on
Thursday. This along with the proximity of the upper trough just
north of the region should favor fairly active weather condtions
with better potential for shower and thunderstorm activity in and
around the islands. Urban and small stream flooding as well as
ponding of water on roadways and in poor drainage areas will
therefore remain possible in isolated area especially during the
afternoon hours. In general, an overall moist and unstable weather
pattern is expected to prevail across the forecast area for the
short term period.

.LONG TERM...Friday through Wednesday...
As the tropical wave depart from the islands, a drier air mass,
along with some Saharan dust is expected to filter in from the east
on Friday. At the upper levels, a low pressure system positioned
over Hispaniola will add some instability, with 500 mb temperatures
at around -7 degrees. Therefore, there will be a potential for
showers and thunderstorms, especially during the afternoon hours
over northwestern Puerto Rico. This activity is not expected to be
widespread, however.

For the weekend, moisture increases, as an easterly perturbation
advances over the islands. With the upper level low still in place
west of Puerto Rico, a similar pattern should be expected, but with
better moisture as the surface, more frequent passing showers should
be moving over the islands, followed by the usual afternoon activity
affecting the western half of Puerto Rico.

For the workweek, a mid level ridge will develop north of the
area, while the upper level low moves away. Even though this will
result in a reduction of instability aloft, with 500 mb temperatures
warming up to -5 to -3 degree Celsius, a series of tropical waves
will be advancing from the east, supplying low level moisture.
Therefore, the potential will still exist for the development of
shower activity over the area each day.


&&

.AVIATION...
Prevailing VFR durg prd but VCSH psbl at TIST/TISX/TJSJ/TJBQ til
29/14Z. SCT OCNL BKN cld lyrs nr FL025...FL050 w/WDLY SCT passing
SHRA ovr regional waters and en route btw islands. SHRA/Isold TSRA
psbl at TJMZ/TJBQ fm 30/17Z-30/22Z with VCSH psbl at remaining
terminals. SFC wnds calm to lgt/vrb bcmg fm E to SE at 10-20 kts aft
29/14z with sea breeze variations. L/lvl wnds fm E btw 10-15 kts BLO
FL200.

&&

.MARINE...
Generally tranquil marine conditions are expected today with seas
at 5 feet. However, by mid-week, seas will become choppy as a
tropical wave crosses the islands. This will increase the
potential of thunderstorms as well. For the beachgoers, a moderate
rip current risk exist for some of the local beaches.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 92 79 90 79 / 30 40 40 40
STT 91 80 90 80 / 40 50 50 60
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Re: Caribbean - Central America Weather

#20250 Postby cycloneye » Wed Jul 01, 2020 4:45 am

Area Forecast Discussion
National Weather Service San Juan PR
333 AM AST Wed Jul 1 2020

.SYNOPSIS...
Afternoon shower and thunderstorm activity is expected again,
mainly over northwestern Puerto Rico. A tropical wave will
approach the area by late today and tomorrow, enhancing the
rainfall potential over the islands. Temperatures will remain
warm, with highs around 90 degrees.

&&

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

The upper-level trough, which aided in the development of deep
convection across the interior and western Puerto Rico early this
week, will continue to weaken as it moves north away from the area.
Nevertheless, locally and diurnally induced showers and isolated
thunderstorms are expected to develop across the interior and the
western regions of Puerto Rico this afternoon, with isolated to
scattered showers over eastern Puerto Rico during the morning hours.
Tonight into Thursday, a tropical wave will move into the region and
increase rain chances as well as low-level moisture. Thursday, the
east to southeast wind flow, should put the strongest convection
over the interior and western Puerto Rico during the afternoon.

Current guidance has precipitable water peaking to 2.0 inches
Thursday morning, then slowly falling through the remainder of the
day. The tropical wave is expected to be west of Puerto Rico by
Friday morning; with a drier air mass and saharan dust filtering in
from the east. limit low-level moisture, upper-level instability as
well as drier air mass will inhibit the development of deep
convection during the afternoon on Friday. However, significant
surface heating and local effects will cause a few showers to
develop. Temperatures across the lower-elevations will range from
the upper 80s to the lower 90s.

.LONG TERM...Saturday through Thursday...
An upper level low will be positioned over Hispaniola through the
weekend. In the meantime, at the lower levels, patches of moisture
will be carried by the trade winds over the islands. As is usual
with this pattern, passing shower activity should be expected over
eastern Puerto Rico and the U.S. Virgin Islands early in the day,
followed by afternoon activity over the interior and western
portions of Puerto Rico. While thunderstorm activity will remain
possible due to some support aloft due to the upper level low, a
mid-level ridge will build over the Atlantic Ocean, causing 500 mb
temperatures to warm up to around -4 to -5 degree Celsius. As a
result, thunderstorm activity will remain possible each afternoon,
but widespread significant accumulation are not anticipated.

For the workweek, the ridge will hold north of the islands, but at
the surface, a series of tropical waves will make their way into
the area. Although conditions aloft won`t be particularly
favorable for a significant rainfall event, the moisture supplied
by the tropical wave should increase the potential for shower and
thunderstorm activity over the forecast area.

&&

.AVIATION...
Mainly VFR conditions are expected for all terminals through 01/15z,
then SHRA/TSRA are expected across terminals TJBQ and TJMZ. Brief
MVRF conds are possible due to the SHRA/TSRA with conds improving by
02/02z. A tropical wave will cause SHRA and possible ISO TSRA over
the Leeward Island terminals by 01/16Z, this activity will continue
through 02/06Z. Wind will be from the east to southeast at 10 to 15
kts with sea breeze variations after 01/14z.


&&

.MARINE...
Seas up to 5 feet are expected today, increasing to 6 feet by
tonight over the offshore Atlantic waters. A tropical wave will
advance into the area late today and tomorrow, resulting in
an increase in shower and thunderstorm activity over the local
waters. There is a moderate rip current risk for some of the local
beaches.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 79 91 79 / 40 50 50 50
STT 90 81 89 80 / 40 50 30 30
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Re: Caribbean - Central America Weather

#20251 Postby cycloneye » Thu Jul 02, 2020 4:43 am

Area Forecast Discussion
National Weather Service San Juan PR
332 AM AST Thu Jul 2 2020

.SYNOPSIS...

A tropical wave is causing unsettled weather across the local and
regional waters. This activity will continue through the rest of
the day, with showers and isolated thunderstorms developing across
the interior and the western areas of Puerto Rico. Friday through
the weekend, a dry Saharan air mass will encompass the region and
cause relatively dry conditions.


&&

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

A weak tropical wave moving over the islands will continue to
generate showers and thunderstorms through today. Early in the day,
the activity will be focus over the U.S. Virgin Islands and eastern
Puerto Rico. In the afternoon, convection is expected to develop
over the interior and western Puerto Rico, and some showers will be
possible over the San Juan metro area as well. Moderate to heavy
showers are expected with this afternoon activity, with the
potential for urban and small stream flooding. As the wave moves
away by late Thursday, drier air is expected to filter in, limiting
the potential for additional showers over the forecast area. Saharan
dust is embedded in this air mass, so hazy skies are expected for
the next several days. Additionally, a mid-level ridge is expected
to build in over the western Atlantic Ocean, which should result in
mainly fair weather conditions for the next few days. For Saturday,
an easterly disturbance will move over the area, with precipitable
water values forecast to increase to around 1.6 to 1.8 inches, which
should result in another round of shower. Rainfall accumulations are
not forecast to be significant due to unfavorable weather conditions
aloft.

&&

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

Current guidance depicts a rather tranquil period with patches of
moisture embedded in the easterly trades, weak tropical waves,
and Saharan dust. The GFS shows a wave moving across the region
during the afternoon on Monday, the wave moisture will aid in the
development of showers and isolated thunderstorms across eastern
Puerto Rico and the U.S Virgin Islands during the morning hours,
followed by showers and isolated thunderstorms during afternoon
over the interior and western areas of Puerto Rico. The tropical
wave and its associated moisture are expected to be west of
Puerto Rico by Tuesday morning.

Tuesday, The GFS shows a dry Saharan air mass filtering into the
region from the east. The Saharan dust and mid-level ridge will
inhibit the development of deep convection trough the middle of
the week, however, locally and diurnally induced showers are
expected to develop each day. The best potential for widespread
rainfall will depend on the strength of the tropical waves, mid-
level moisture and upper-level forcing. The GFS and EURO show weak
tropical waves transversing the region every 3 to 4 days; this
aligns with the calculated wave period of waves that move off of
Africa.

&&

.AVIATION...

Mainly VFR conditions are expected to prevail across
all terminals. VCSH are expected to affect all terminals, except
western Puerto Rico through the early morning hours. VCTS are
expected after 16Z for TJBQ, which could cause briefly MVFR
conditions due to reduced VIS and ceilings. Winds will be out of the
ESE at 10 to 15 knots.

&&

.MARINE...

Seas are choppy with wave heights up to 6 feet as a tropical wave
continues to move through the local and regional waters. The wave
will cause winds up 20 knots from the east- southeast. Late
tonight seas and winds should subside with calmer conditions
prevailing. A moderate risk of rip currents will remain for most
north, south, and east facing beaches.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 79 91 79 / 50 20 30 20
STT 88 80 90 79 / 30 20 20 30
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Re: Caribbean - Central America Weather

#20252 Postby cycloneye » Sat Jul 04, 2020 5:10 am

Area Forecast Discussion
National Weather Service San Juan PR
447 AM AST Sat Jul 4 2020

.SYNOPSIS...More shower activity is expected today and Sunday as
moisture increases and an upper-level low develops west of the
area. A weak tropical wave will move across the area on Monday
bringing additional rainfall activity followed by a potentially
stronger tropical wave by the middle of the week, with the
possibility of more significant rainfall activity. Drier weather
conditions with suspended Saharan Dust particulates will follow by
the latter half of the work week.

&&

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

A weak TUTT low will form over Hispaniola and persist through
Sunday. It will move northwest toward the Bahamas on Monday. High
pressure at upper levels will drift west to the local Atlantic
waters north of Puerto Rico. A weak southerly jet of less than 30
knots will drift westward across the area on Sunday. A mid level
ridge will remain just north of the area through the period.

The total precipitable water product shows a lobe of 1.8 inch
moisture entering the area from the east northeast. It will aid
some better convection--mostly over Puerto Rico today. At lower
levels a patch of moisture will move through on Sunday followed by
drier air early Monday. A weak tropical wave will move through
the area on Monday. Current timing in the GFS suggests that
moisture will improve after noon on Monday with showers lingering
overnight over eastern Puerto Rico. Thunderstorms are expected
each afternoon in western Puerto Rico and possibly in the El
Yunque streamer.

The NAAPS model indicates that the dust will lessen today, but will
come back on Sunday night. More moderately dense dust is pouring
into the eastern Tropical Atlantic at this time.

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

Latest model guidance is indicating that another tropical wave
will move across the eastern Caribbean and near the vicinity of
the forecast area later Tuesday evening through at least the first
half of Wednesday. However, there are differences in terms of
timing as well as positioning of this wave amongst the guidance.
The ECMWF model is the fastest as it brings the wave in late
Tuesday afternoon and exiting the forecast area by early Wednesday
morning. This model also shows the heaviest activity associated
with this wave remaining to the south, therefore, the rainfall
activity would not be that significant if this solution would to
verify. The GFS model on the other hand is slower with bringing
the wave in as it brings it in during the overnight hours of
Tuesday into Wednesday with the moisture not exiting the area
until Wednesday evening. This model is farther north with the
moisture axis, therefore, more significant rainfall activity would
be more likely under this solution. Given the varying solutions,
confidence on the timing and how much of an impact the wave will
have on the region is low at this time and we will need to wait
for additional model cycles during the next couple of days for a
better consensus.

After the wave passage, drier conditions as well as another
episode of suspended Saharan Dust particulates will follow by the
latter half of the work week. Therefore, fair weather conditions
along with hazy skies can be expected. Afternoon convection will
be possible across western Puerto Rico due to local and diurnal
effects.


&&

.AVIATION...Isold SHRA surround TIST and local waters N and S of
PR, but mainly VFR conditions are expected to prevail through the
forecast period. HZ due to Saharan dust is expected, but VIS is
expected to remain P6SM. After 17Z, VCTS could result in brief MVFR
conditions at TJBQ. Sfc winds will be out of the ESE at 10 to 15
knots. Maximum winds 20 knots or less BLO FL540.

&&

.MARINE...Seas of up to 5 feet and winds of up to 15 knots will
prevail across the regional waters for today. Seas will increase
slightly on Sunday through early next week as winds increase.
There is a moderate risk of rip currents for the northern beaches
of Puerto Rico as well as for some beaches of Culebra, Vieques and
Saint Croix for today.

&&

.FIRE WEATHER...Latest surface observations continue to indicate
very dry soils across the southern Coastal Plains of Puerto Rico
with KBDI values across Camp Santiago and Cabo Rojo at 770 and
681, respectively. Weather conditions for today are expected to
remain dry. Therefore, relative humidity values are forecast to
drop in the lower to middle 50s with some areas possibly dropping
as low as in the middle 40s. Sustained winds are expected to be
near 15 mph with frequent higher gusts. Therefore, an elevated
fire danger threat exists for the southern coastal plains and a
fire danger statement (RFDSJU) has been issued accordingly.


.PRELIMINARY POINT TEMPS/POPS...
SJU 90 79 90 80 / 30 30 20 20
STT 90 79 90 80 / 30 30 30 40
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Re: Caribbean - Central America Weather

#20253 Postby cycloneye » Sun Jul 05, 2020 4:55 am

Area Forecast Discussion
National Weather Service San Juan PR
453 AM AST Sun Jul 5 2020

.SYNOPSIS...A surge in low-level moisture and an upper-level low
located west of the area is expected to increase shower activity
across the area for today. A weak tropical wave will bring
additional shower activity late Monday. Thereafter, a stronger
tropical wave may bring more significant rainfall activity
Tuesday night into Wednesday. Conditions dry out by the latter
half of the work week as a Saharan Air Layer moves overhead.

&&

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

A weak TUTT low just north of Haiti will drift north of the
southeastern Bahama Islands by the end of the period. High pressure
at upper levels east of the Lesser Antilles will move into the
Atlantic waters just north of the forecast area overnight Monday and
over Hispaniola on Tuesday. At mid levels, high pressure north of
the area strengthens during the period.

The total precipitable water product shows a lobe of 1.8-1.9 inch
moisture over the U.S. Virgin Islands with good moisture over most
of the forecast area. At the moment a dry slot is moving west over
the Leeward Islands, but moisture from a tropical wave now at 53
degrees west longitude appears to be moving faster and is causing
the dry slot to lose breadth as it approaches. The dry slot will
arrive over eastern Puerto Rico late today and allow showers to
dissipate over eastern Puerto Rico except for a few stragglers.
Temperatures at 500 mb are rising from minus 6 degrees now to minus
3 degrees this evening so as to reduce instability at the same time.
With good moisture and heating, isolated thunderstorms are still
possible during the afternoon. Sufficient moisture will exist for
heavy showers and urban and small stream flooding over western and
interior Puerto Rico and downstream from the U.S. Virgin islands
during the afternoons each day. Showers will diminish considerably
with the dry slot passage tonight, although isolated to scattered
showers are still expected over and just ahead of the Luquillo range
in Puerto Rico. Moisture will increase Monday and peak around
midnight on Tuesday morning and showers are likely across much of
Puerto Rico then. The approach of a tropical wave will aid in
another increase of moisture during the day Tuesday and Tuesday
night.

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

The aformentioned tropical wave is expected to affect the area
into Wednesday with precipitable water values of around 2 inches.
Therefore, periods of shower and isolated thunderstorm activity
is expected across portions of the local area. There still
continues to be some timing differences amongst the model
guidance. The ECMWF model continues to be the faster with the
wave passage as it has the wave and the associated moisture field
exit the area in the morning hours. The GFS model on the hand is
slower, hanging the moisture around into the evening hours.

After the wave passage, a drier air mass due to a Saharan Air
Layer is expected through the end of the work week. Therefore,
fair weather conditions along with hazy skies are expected. Shower
activity that develops will be confined to the western half of
Puerto Rico due to local and diurnal effects. Another tropical
wave could affect the area late Saturday into Sunday, bringing
additional rainfall activity.

&&

.AVIATION...Sct SHRA surround PR/USVI with some intrusions over ern
and sern PR. VFR conds are expected to prevail til 05/16Z except
with hir mtns obscured. After 17Z, VCTS could result in brief MVFR
conditions at TJBQ/TJMZ with interior mtn obscured in +SHRA. Sfc
winds will be out of the E at 10 to 15 knots with hir gusts. Maximum
winds S 25-35 kt btwn FL345-465.

&&

.MARINE...Seas between 3 and 6 feet are expected across the
regional waters for today, with the highest seas expected across
the offshore Atlantic waters. Choppy seas are expected to continue
into early next week due to moderate to fresh easterly winds. A
moderate risk of rip currents is expected for the northern and
southeastern beaches of Puerto Rico, the eastern and southern
beaches of Culebra and Vieques, the southern beaches of Saint
Thomas and Saint John, and the eastern two-third beaches of Saint
Croix for today.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 80 90 79 / 50 20 40 60
STT 88 80 90 80 / 60 30 40 40
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Re: Caribbean - Central America Weather

#20254 Postby cycloneye » Mon Jul 06, 2020 5:41 am

Area Forecast Discussion
National Weather Service San Juan PR
508 AM AST Mon Jul 6 2020

.SYNOPSIS...Moist lower levels will have drier air from 850-300
mb only briefly interrupted by passing tropical waves this
afternoon, Tuesday night through Wednesday and again on Sunday.
Showers and isolated thunderstorms are expected to accompany the
waves with the wave of mid-week expected to be the best rain-
bearer. East to east southeast trade winds will continue through
the period.

&&

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

A narrow slot of drier air is expected to filter into the region
this morning, resulting in just a few showers. Then, by this
afternoon, a weak tropical wave is expected to move across the
region with low-level moisture increasing. This will result in
afternoon convection across western Puerto Rico, where some
localized urban and small stream flooding is possible with the
heaviest activity. Isolated to scattered passing showers associated
with the moisture from this wave are possible during the overnight
and morning hours of Tuesday across portions of eastern Puerto Rico
and in and around the USVI. Rainfall accumulations for the most part
should remain pretty light. Another round of afternoon convection is
likely across western Puerto Rico on Tuesday.

Attention, then, on Tuesday night into Wednesday, turns to a
strong tropical wave located a few hundred miles east of the
Windward Islands. This wave and its associated moisture field is
expected to arrive into the forecast area beginning later Tuesday
evening and lasting into at least the part of Wednesday. Latest
model guidance indicates precipitable water values of between 2
and 2.2 inches associated with this wave. Therefore, there is the
potential for some organized convective activity to affect
portions of the area, with the heaviest activity expected during
the overnight hours of Tuesday across the eastern third of Puerto
Rico as the low-level moisture convergence appears to be the
greatest across this area. The USVI are expected to see scattered
showers and isolated thunderstorms from time to time during this
period as well. Uncertainty in terms of how much rain is expected
during the day on Wednesday continues to be high as model
guidance continues to diverge on how long the moisture field hangs
around. The ECMWF model continues to show the high moisture
content leaving the area during the morning hours and as a result,
the activity across eastern Puerto Rico and the USVI would shut
off with afternoon convection only across northwestern Puerto
Rico. The GFS model, on the other hand, holds on to the high
moisture content through the late afternoon hours into eastern
Puerto Rico. This would result in eastern Puerto Rico continuing
to receive additional rainfall activity into the afternoon hours
with the USVI expected to dry out. We expect to have a better
consensus with the model guidance during the next 12 to 24 hours
as to the most likely outcome in terms of the rainfall coverage
during the day on Wednesday.

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

The upper air pattern is chaotic during the period Thursday
through Saturday as minor low pressures form around Puerto Rico
and the U.S. Virgin Islands and flow remains variable up to 25
knots. Mid levels are more consistent with high pressure remaining
just north of the area in an east-west ridge. At lower levels
areas of drier air approach Puerto Rico from the east, but are
really only able to dominate between 850 and 300 mb with breaks on
Wednesday, (the day before) and on Sunday from passing tropical
waves. Lower levels, however, remain fairly moist.

Hence convection forms each day in east to east southeast flow in
the typical diurnal pattern for Puerto Rico and the U.S. Virgin
Islands; that is with isolated occasionally scattered showers
over the local waters and occasionally crossing over the USVI and
into eastern Puerto Rico during the night and morning hours and
afternoon showers and thunderstorms heavy enough to produce
ponding on roadways and low-lying areas and occasionally localized
urban and small stream flooding. Afternoon convection downstream
from the USVI is also likely. All of the convection will be
limited by the extensive dry layer above 5-7 kft each day. No
other significant features are seen impacting the area for the
next 10 days.

&&

.AVIATION...Mainly VFR conditions expected across the local area.
SHRA/TSRA expected across western PR between 06/16z and 06/23z,
resulting in VCTS across TJBQ and mtn obscurations in interior PR.
Winds light and variable through 06/12z, increasing to up to 15
knots from the E with higher gusts and sea breeze variations after
06/14z. Maximum winds S 30-40 kt btwn FL410-455.

&&

.MARINE...High pressure in the northeast central Atlantic and
passing tropical waves will keep moderate to fresh east to east
southeast tradewinds over the area through the next 10 days. Seas
may reach 7 feet in the outer Atlantic waters Tuesday and
Wednesday when a small craft advisory is in effect. Then Friday
through Sunday seas are again forecast to increase and become
hazardous in all the area`s outer waters.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 79 90 78 / 20 40 30 70
STT 91 82 90 82 / 30 30 50 60

&&
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Re: Caribbean - Central America Weather

#20255 Postby cycloneye » Wed Jul 08, 2020 4:51 am

Area Forecast Discussion
National Weather Service San Juan PR
523 AM AST Wed Jul 8 2020

.SYNOPSIS...The tropical wave that left good rainfall coverage
Wednesday will continue to move away from the area today. Some
showers and thunderstorms will trail the system today. Minimal
shower activity will occur on Friday and Saturday, until a more
vigorous waves crosses through the area Saturday night and
Sunday. Saharan dust will return on Friday, and again on Sunday
night or Monday after the next significant tropical wave.

&&

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

Despite precipitable water values of between 2.0 and 2.3 inches
across the area due to a tropical wave, not much in the way of
organized rainfall activity materialized during the overnight hours
as the best dynamics associated with the wave lifted to the north
away from the forecast area. Nevertheless, with the high moisture
content remaining over the area through the morning hours, areas
of showers are possible across the eastern and southern portions
of Puerto Rico. Significant rainfall accumulations, however, are
not expected. Across the USVI, a few showers may be observed.
Then, by late this morning into the afternoon hours, the moisture
content is expected to erode substantially as a dry air mass due
to a Saharan Air Layer moves in from the east. Therefore, rainfall
chances will diminish across the USVI and eastern PR with only
northwest Puerto Rico observing some convection.

By this evening and during the day on Thursday, the dry air due to
the aformentioned Saharan Air Layer will take hold across the entire
area. Therefore, mainly fair weather conditions along with hazy
skies are expected. Shower activity is expected to be very limited.
Some showers and a few thunderstorms may develop across western
Puerto Rico Thursday afternoon, however, urban and small stream flooding
is not expected. A weak easterly wave is expected to move over
the area late Thursday night into Friday, increasing the low-level
moisture slightly. This will result in an increase in passing
shower activity across portions of eastern Puerto Rico and in and
around the USVI into the morning hours of Friday. This will be
followed by some afternoon convection with isolated thunderstorms across
western and northwestern Puerto Rico.

.LONG TERM...Saturday through Wednesday...
At upper levels relatively strong high pressure east north east of
Puerto Rico and the U.S. Virgin Islands on Friday will pass to the
north of Puerto Rico on Monday. A TUTT low off the coast of Brazil
on Friday will pass through the southeastern Caribbean on Tuesday
south of Puerto Rico.

At mid levels, high pressure in the central sub-tropical Atlantic
will move west into the western Atlantic north of the area during
the period.

At lower levels, a weak disturbance is expected to cross through
on Friday. Another tropical wave crossing 50 degrees west
longitude around 12 degrees north on Friday is forecast by the GFS
to cross the U.S. Virgin Islands and Puerto Rico on Sunday, with
the strongest winds and convection of the system crossing directly
over the area. Winds in the GFS were seen to reach 40-45 knots
between 850 and 700 mb inclusive. The ECMWF agrees on timing but
does not show the intense winds at the surface or lower levels
that the GFS does. The GFS was no longer forecasting a closed
circulation with this system today. On Tuesday night and
Wednesday, high pressure at 700 mb just north of Hispaniola will
bring some moisture back across the area for increased shower
activity.

After the wave today, moisture remains very modest until the wave
approaches Saturday night and Sunday. The GFS continues to paint
this as a very vigorous system that will bring significant and
relatively certain rains the forecast area, with the most
significant rainfall in eastern Puerto Rico. The strength of the
system in the GFS is somewhat suspect and confidence is moderately
low, so most likely the GFS currently represents the most we
could reasonably expect from this wave and likely amounts and
winds will be somewhat less, perhaps only two thirds of what it is
forecasting. This would bring one to two inches of rain and 15 to
25 knots of winds. After the wave passage moisture diminishes
back down to the base level of around 1.5-1.6 inches of
precipitable water, but weak disturbances Tuesday afternoon
through Wednesday could enhance the showers over the local area.

&&

.AVIATION...Mainly VFR conditions expected across all areas
terminals. Sct SHRA and iso TS may affect northwest PR btwn
08/16z and 08/22z, resulting in VCTS across TJBQ. Winds will be
ESE below 10 kts through 08/12z, increasing to up to 20 knots with
higher gusts and sea breeze variations after 08/14z. Maximum
winds SE 20-25 kt btwn FL010-125.

&&

.MARINE...Seas are generally running less than 7 feet in most
areas, and some small craft advisories have been lowered, and
advisories for the Caribbean sea and Anegada passage were
shortened. All small craft advisory conditions should be down by
this evening. The next wave is being forecast as stronger than
this wave, and 7 to 8 foot seas will likely spread across most of
the waters, except those sheltered by Puerto Rico from east to
southeast flow beginning Saturday afternoon.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 91 79 91 80 / 30 10 20 40
STT 89 80 90 80 / 20 10 20 20
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Re: Caribbean - Central America Weather

#20256 Postby cycloneye » Thu Jul 09, 2020 5:13 am

Area Forecast Discussion
National Weather Service San Juan PR
412 AM AST Thu Jul 9 2020

.SYNOPSIS...

A dry Saharan air mass will hold over the region through Friday.
The air mass will limit afternoon shower development;
nevertheless, a few showers will develop due to diurnal and local
effects. Late Saturday into Sunday, a tropical wave will move
into the area and increase rain chances for Puerto Rico and the
U.S. Virgin Islands.

&&

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

Drier air with Saharan dust will continue today across the region.
This will cause hazy skies and inhibit widespread shower activity
over the islands. Regardless, shallow low-level moisture embedded in
the trade winds will bring the occasional passing shower across the
U.S. Virgin Islands and eastern sections of Puerto Rico through the
morning hours and this will be followed by diurnally induced
afternoon showers over western PR.

On Friday, a weak easterly perturbation and an upper level trough
approaching from the Atlantic waters will increase scattered shower
activity between the USVI and eastern PR during the overnight/early
morning hours and the potential for isolated thunderstorms over
western PR during the afternoon hours. Streamers are expected to
develop off the islands each day as trade winds increase between 15-
20 knots. Another area of Saharan dust and dry mid-level air will
return once again early on Saturday, ahead of the next tropical
wave. This wave will increase shower and thunderstorms from Saturday
afternoon into Saturday night across the USVI and eastern PR.

&&

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

Currently, the best chance for the development of deep convection
in the long-term period will be Sunday, as a tropical wave pulls
a bulk of moisture over the U.S. Virgin Islands and Puerto Rico.
The low-level moisture, significant heating, and modest upper-
level divergence will will produce scattered to numerous showers
and thunderstorms across the region. Then moisture is expected to
decrease during the day on Monday, the GFS shows precipitable
water values falling to 1.35 inches by Monday evening. Although
moisture is forecast to decrease during the day, a few scattered
to isolated showers are possible during the afternoon due to local
and diurnal effects. By mid-week, the GFS pulls moisture from the
central Atlantic across Puerto Rico and the U.S. Virgin Islands.
Analysis of the 500, 700, and 250 mb RH values show the increase
is a result of E-NE winds advecting moisture over the area. RH
values will go from the upper 30s to the middle 60s to the lower
70s through late Wednesday night.

At the end of the workweek, a drier air mass will limit the
development of deep convection; however, a few showers and
possibly isolated thunderstorms are possible during the
afternoon. Temperatures during the period are forecast to be near
the upper 80s to the lower 90s in lower elevations, and the lower
to the middle 80s in higher elevations.

&&

.AVIATION...

Aviation...Mainly VFR conditions are expected to prevail across all
terminals during the next 24 hours. HZ due to Saharan dust expected
but vsby should remain P6SM. East winds will increase between 10-15
kt with higher gusts and sea breeze variations after 14z.

&&

.MARINE...

Choppy marine conditions will continue across most of the local
waters due to seas up to 6 feet and winds up to 20 kts. Due to
the above conditions, small craft operators are urged to
exercise caution. There is a moderate risk of rip currents for
the northern and southern beaches of Puerto Rico, and the northern
and southern beaches of Vieques and the U.S. Virgin Islands.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 91 80 90 78 / 20 40 40 10
STT 90 80 89 82 / 20 30 30 20
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Re: Caribbean - Central America Weather

#20257 Postby cycloneye » Fri Jul 10, 2020 5:34 am

Area Forecast Discussion
National Weather Service San Juan PR
421 AM AST Fri Jul 10 2020

.SYNOPSIS...

A dry Saharan air mass will encompass the region late this evening
through Saturday morning, and promote relatively fair weather
conditions across the area. A tropical wave is forecast to invade
the local waters late Saturday night into Sunday and bring an end
to the relatively stable weather conditions. Showers and
thunderstorms are forecast to develop across the local waters, and
Puerto Rico and the U.S. Virgin Islands. The incoming tropical
wave will be our best chance to see significant rainfall
accumulations for the next seven days. Early next week, a dry and
stable weather pattern will prevail through Wednesday, then, a
slight increase in moisture is expected Thursday and Friday.


&&

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

An upper level low a few hundred miles north of the region and an
easterly perturbation will continue to increase shower activity
between the U.S. Virgin Islands and eastern PR through the rest of
morning hours. Moderate rainfall amounts are possible with this
shower activity. Then during the afternoon hours, isolated
thunderstorms are expected to develop over portions of central and
west/northwest PR. Urban and small stream flooding is possible with
this activity. In addition, streamers are expected to develop off
the USVI and move west/northwest and from el Yunque into the San
Juan metro area around noon through the mid-afternoon hours.

Saharan dust and dry mid-level air returns once again early on
Saturday, ahead of the next tropical wave. This wave will increase
shower and thunderstorms from Saturday afternoon into Saturday night
across portions of the eastern waters of the islands and across the
USVI and eastern sections of PR. As the wave moves across the
islands, showers with isolated thunderstorms are expected to affect
the rest of PR and regional waters during the overnight hours into
Sunday morning. As the wave pulls away later on Sunday, winds turn
more from the east to southeast and another band of moisture
associated to the wave will cause showers and thunderstorms to
develop once again across mainland PR during the afternoon hours.

&&

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

The GFS and EURO remain in agreement that the long-term period will
remain reasonably dry. Nevertheless, easterly trade winds will
produce a few isolated to scattered showers across eastern Puerto
Rico and the U.S. Virgin Islands during the overnight and morning
hours. Then showers during the afternoon over the interior and
western areas of Puerto Rico as a result of local and diurnal
effects. Showers that develop during the afternoon will be short-
lived due to drier air in the mid-level of the atmosphere
suppressing the vertical development of the afternoon activity. The
GFS cross-section shows drier air remaining over the region through
the middle of the week. Precipitable water values are expected to
range from 1.4 to 1.7 inches through early Thursday.

An increase in moisture will cause precipitable water to increase
and peak to 2.0 inches late Thursday into Friday, as a result of E-
NE winds pulling patches of moisture from the central Atlantic over
the Puerto Rico and the U.S. Virgin Islands.

Temperatures during the period are forecast to be near the upper 80s
to the lower 90s in lower elevations, and the lower to the middle
80s in higher elevations.


&&

.AVIATION...

Mainly VFR conditions are expected to prevail across all
terminals during the next 24 hours. However, SHRA/TSRA over western
PR could cause tempo MVFR conds at TJBQ. East winds will increase
between 10-20 kt with higher gusts and sea breeze variations after
14z.

&&

.MARINE...

Choppy marine conditions will continue across most of the local
waters due to seas up to 6 feet and winds up to 20 kts. As a result,
small craft operators are urged to exercise caution. A moderate risk
of rip current for most of the local beaches. Seas are forecast to
increase during the weekend as a tropical wave approaches the
area.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 78 90 79 / 40 20 60 70
STT 89 82 91 80 / 30 20 60 70
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Re: Caribbean - Central America Weather

#20258 Postby cycloneye » Sat Jul 11, 2020 5:11 am

Area Forecast Discussion
National Weather Service San Juan PR
520 AM AST Sat Jul 11 2020

.SYNOPSIS...A tropical wave will move across the region later
tonight through Sunday. This will increase the potential for urban
and small stream flooding across the islands. Increasing winds
with the wave will cause choppy seas across portions of the local
waters. Drier air and Saharan dust will return early in the week. A
TUTT induced perturbation is forecast to increase shower activity
by the end of the workweek.


&&

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

Showers are forecast to continue to develop over the local waters
and eastern Puerto Rico this morning. Later this afternoon, showers
and isolated thunderstorms will develop over portions of the
interior and western Puerto Rico.

A once healthy tropical wave currently east of the Windward Islands
has succumbed to a drier air mass head of it. However, the wave will
still increase rain chances across the region late tonight through
Sunday evening. Winds will turn to the southeast as the wave
approaches the area this evening.

The GFS has precipitable water peaking to 2.2 inches on Sunday, due
to the tropical wave. The GFS model has consistently shown the best
low-level convergence and upper-level divergence on Sunday morning
and late Sunday afternoon. The GFS splits the tropical wave axis in
half and brings the northern portion of the wave over eastern Puerto
Rico and the U.S. Virgin Islands Sunday morning, and pushes the
energy through western Puerto Rico by Sunday afternoon. The southern
portion of the wave is forecast to lift from the Caribbean waters
and pool over the U.S. Virgin Islands and Puerto Rico by mid-day on
Sunday. The wave and its associated moisture should clear the region
by Monday morning, with a drier air mass filtering into the area
behind the wave. The lingering moisture will combine with local and
diurnal effects to induce afternoon showers on Monday.

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

Drier air with suspended Saharan dust will return next early next
week and linger through Wednesday. A northeast wind flow will
prevail as a broad surface high pressure holds across the central
Atlantic. However, shallow moisture will move at times with the
trade winds to cause passing light showers across the USVI and
eastern sections of PR during the overnight and early morning
hours. Followed by diurnal afternoon convection over
west/southwest PR. Moisture increases during the second half of
the week as a retrogressing TUTT and an induced low-level
perturbation enters the eastern Caribbean and moves across the
region. Therefore, shower and thunderstorm activity is expected to
increase, mainly in diurnal activity over central and western PR.


&&

.AVIATION...Mainly VFR conditions are expected to prevail across all
terminals until 11/15Z. Then SHRA/VCTS are expected to develop
across TJBQ and TJMZ until 12/03Z. SHRA/VCTS will develop across PR
and the leeward/windward island terminals by 11/22z. SHRA/TSRA could
cause brief MVRF conds over the above terminal sites today. Winds
will be from the east at 15 to 20 kts with higher gusts and sea
breeze variations after 14z.


&&

.MARINE...Choppy seas due to increasing winds will continue
through the weekend. A tropical wave will deteriorate the marine
and weather conditions overnight into Sunday. A moderate risk of
rip currents is expected across most of the beaches of PR. There
is a high risk of rip currents for the east facing beaches of St.
Croix.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 78 90 79 / 40 50 50 30
STT 91 80 89 82 / 40 40 30 30
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Re: Caribbean - Central America Weather

#20259 Postby cycloneye » Sun Jul 12, 2020 5:12 am

Area Forecast Discussion
National Weather Service San Juan PR
432 AM AST Sun Jul 12 2020

.SYNOPSIS...A tropical wave will continue to move across the
region through this afternoon. Urban and small stream flooding is
expected with the heaviest showers across the islands. Drier air
and Saharan dust will return early in the week. A TUTT induced
perturbation is forecast to increase shower and thunderstorm
activity during the second part of the workweek.


&&

.SHORT TERM...Today through Tuesday...
The axis of the tropical wave has moved across eastern Puerto Rico
early this morning. As a result, moderate to heavy rainfall and
isolated thunderstorms formed over E PR and the U.S. Virgin Islands.
The moderate to heavy rain is causing urban and small stream
flooding and ponding of water on roadways over portions of E PR and
the metro areas. This activity could cause similar problems for
other areas this morning, as the showers and thunderstorms moves
westward. TJUA dual pol instant precipitation rate shows rainfall
rates ranging from 2 to 3.5 inches/hour in some areas. Currently,
two inches of rain has fallen across E PR, additional one to two
inches is possible later this morning.

Satellite imagery from GOES 16 shows a patch of drier air behind the
current activity, the drier air is expected to arrive after sunrise
across E PR and adjacent Islands, and end the moderate to heavy
rainfall over E PR and the U.S. Virgin Islands. However, GOES-16
shows a plume of moisture on the hills of the drier air, the second
wave of moisture is expected to arrive across Puerto Rico and the
U.S. Virgin Islands this afternoon during the peak heating.
Therefore, expect showers and isolated thunderstorms to develop
across the metro, interior and western areas of Puerto Rico. Also,
additional rainfall that falls during the afternoon, could cause
flashy river basins and urban and small stream flooding. The wave is
forecast to be west of Puerto Rico late this evening, with a
relatively drier air filtering in over much over the area.

Monday and Tuesday, drier conditions are expected once again.
Nevertheless, locally and diurnally induced showers are possible
during the afternoon.

.LONG TERM...Wednesday through Sunday...
Drier air with suspended Saharan dust will continue on Wednesday
across the region, but moisture will continue at lower levels. A
surface high pressure north of the region will cause northeast
winds and this will favor showers over west/southwest Puerto
Rico on Wednesday afternoon. Moisture increases during the second
half of the workweek as a retrogressing TUTT and an induced low-
level perturbation enters the eastern Caribbean and moves across
the region. This will also cause winds to turn more from the east
to southeast, to favor afternoon convection on Thursday and Friday
over northwestern PR and from streamers developing off the USVI
and over eastern PR. Another weak easterly perturbation is
expected to move during the weekend.


&&

.AVIATION...VFR/MVFR conds are expected through the daytime hours
across the local terminals through 12/12Z. Brif MVRF conds could
occur over terminals TNCM/TKPK/TISX/TIST/TJSJ/TJPS due to SHRA/TSRA.
SHRA/TSRA are expected to develop across terminals TJBQ and TJMZ by
12/15Z and continue through 13/02Z. Over E PR and USVI VCSH/SRHA are
possible through 12/20Z. Sfc winds ESE 15 to 20 kt with higher
gust.


&&

.MARINE...A tropical wave will continue to cause squally weather
conditions today across the regional waters, as well as locally
higher seas and winds due to thunderstorm activity. Seas should
range overall between 4 to 6 feet with east winds up to 20 knots.
Small crafts should exercise caution across most of the regional
waters today. There is a moderate risk of rip currents across
most of the beaches of Puerto Rico, including Vieques and Culebra.
There is a high risk of rip currents for the eastern tip of St.
Croix.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 79 91 80 / 50 30 30 30
STT 89 82 90 80 / 40 20 30 20
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Re: Caribbean - Central America Weather

#20260 Postby cycloneye » Mon Jul 13, 2020 4:57 am

Area Forecast Discussion
National Weather Service San Juan PR
519 AM AST Mon Jul 13 2020

.SYNOPSIS...Drier air along with Saharan dust will maintain
support fair weather conditions with limited shower activity
today and Tuesday. By Wednesday and continuing through the end of
the workweek, expect a gradual increase in moisture and somewhat
favorable conditions aloft with the passage of TUTT and induced
low-level perturbation. This will enhance the potential for shower
and isolated thunderstorm development. An easterly perturbation
is expected to generate similar conditions by Saturday into early
next week.


&&

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

High-pressure aloft across the Atlantic Ocean and near the islands
will limit vertical development through at least Tuesday.
Accompanying the lack of dynamic forcing is the arrival of a drier
air mass with African dust particles. This airmass will linger
across the islands through at least Tuesday. Rainfall activity, if
any, will be wind-driven during the morning, and limited afternoon
convection over the western sections of the islands. Expect hazy
skies, and maximum temperatures in the low 90s with heat indices
between 1002 and 107 degrees Fahrenheit, especially in the coastal
and urban areas.

A surge of moisture will replace the dry air mass on Wednesday. This
surge of moisture will reach the islands at the same time that a
TUTT-low, increasing the potential for showery weather by that time.
Although the TUTT-low seems not to be in the most favorable
position, it will erode the mid-level high pressure.

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

A gradual increase in low-level moisture and somewhat favorable
conditions aloft are expected as a retrogressive TUTT and induced
surface perturbation streams across the northeastern Caribbean
through the second half of the workweek. This will enhance the
potential for showers and possible isolated thunderstorms across
the region, while briefly favoring a more southeasterly steering
flow. Under this flow, afternoon convection is expected to favor
portions of the northwestern Puerto Rico, as well as streamer-like
showers off El Yunque and the local islands into the San Juan
metropolitan area and eastern Puerto Rico. Model guidance suggests
that a narrow area of drier air will quickly follow late Friday
night into Saturday morning, but another weak easterly disturbance
is expected to approach the area on Saturday with the associated
moisture lingering into early next week. Overall, a relatively wet
environment is expected through most of the long-term forecast
period with an enhanced typical seasonal shower pattern.


&&

.AVIATION...VFR conds expected across the local terminals.
Although mostly clear and hazy skies will prevail, there is a
possibility to observe isold- SHRA over JSJ/IST/NCM/KPK at times.
SHRA/isol-TSRA will develop over the interior of PR btwn
13/17-22z. Winds will continue from the east at less than 10 kt
but will increase at 15-20 kt with higher gusts and sea breeze
variations after 13/13z.


&&

.MARINE...A surface high pressure north of the region will
maintain moderate to locally fresh easterly winds. Therefore,
choppy marine conditions with seas up to 6 feet and winds up to 20
knots are expected across portions of the local waters through at
least Tuesday. Thereafter, tranquil marine conditions are
expected. Isolated shower activity possible across the local
waters from time- to- time. A moderate risk of rip currents
continues for most of the local beaches, except for the west coast
of Puerto Rico and the northern USVI.

&&

.FIRE...Recent KBDI and 10-Hour fuel moisture continue to support
critical drying conditions across the southern coastal plains of
Puerto Rico with values between 650-750 and 9-10%, respectively.
Drier air along with Saharan dust will continue to support mainly
fair weather condition with relative humidity expected to drop
into the low 40s to low 50s between the late morning and early
afternoon hours. Since wetting rains are not expected and winds
are forecast to peak at 15-20 mph with higher gusts across these
areas, a Fire Danger Statement has been issued for elevated fire
danger conditions today.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 78 89 78 / 20 20 30 30
STT 90 79 90 78 / 10 30 30 30
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