Caribbean - Central America Weather

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
445 AM AST Wed Apr 22 2020

.SYNOPSIS...
A mid to upper level ridge will continue to persist through much
of the forecast period. Although a mainly stable weather pattern
is expected, patches of moisture will continue to move in from
time to time across the islands. Stronger winds are expected for
Friday and for the weekend.

&&

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

Mid to upper level ridge will persist across the region through
Friday to promote fairly dry and stable conditions aloft. Surface
high pressure ridge across the north central Atlantic will maintain
the light to moderate east to southeast tradewind flow across the
forecast area through Thursday, then become more east northeast by
Friday while increasing in intensity. Therefore, expect the trade
wind cap inversion to persist across the forecast area and
consequently support mostly fair and sunny weather conditions. The
light to moderate east southeast tradewinds will continue to
transport shallow patches of low level moisture with occasional
embedded showers across the region from time to time.

The overall weather pattern and stable conditions aloft will
continue to limit moisture pooling and only favor periods of passing
showers each morning over the coastal waters and along some of the
coastal areas. Today, locally and diurnally induced afternoon
convection should be focused mainly across portions of the interior
and west to northwest sections of Puerto Rico, as well as around
parts of the San Juan metro. Some of the locally heavy rain-showers
may lead to ponding of water on roadways and in poor drainage areas
and possibly minor urban and small stream flooding in isolated
spots. Daytime high temperatures may again reach the high 80s to
near 90 degrees along portions of the north coastal areas of Puerto
Rico. Mostly sunny to partly cloudy skies and fair weather
conditions should prevail elsewhere and across the U.S. Virgin
Islands. However isolated showers will remain possible each day on
the west end or just downwind of the islands. By Friday a gradual
increase in the east to northeast winds is forecast as a surface
high pressure ridge is to build north of the region while moving
eastwards across the West and southwest Atlantic.

.LONG TERM...Saturday through Thursday

High pressure will continue to hold at all levels over the
central Atlantic Ocean. At the surface, this feature is tightening
the pressure gradient, resulting in moderate to locally strong
winds through the weekend. In general, the stable weather pattern
lingers for most of the long-term forecast period. However,
patches of moisture dragged by the trade winds may still move from
time to time, affecting portions of eastern PR & USVI. Afternoon
activity will be possible as well, mainly across western Puerto
Rico.

For the first half of the workweek, winds are expected to relax a
bit as the gradient loosen. In terms of rain, the same pattern
holds with only fragmented groups of clouds arriving to the
islands from the east. Due to a lack of upper level support and
moisture being confined to the lower levels of the atmosphere,
significant rainfall activity is not anticipated.


&&

.AVIATION...VFR durg prd. SCT ocnl BKN lyrs nr FL025...FL050...FL080
with SHRA en route btw islands and ovr regional waters. SFC Wnds
calm to lgt/vrb bcmg fm E-SE 10-15 kts with sea breeze variations
aft 22/14Z. Fm 22/16Z-22/23Z SHRA/+SHRA psbl with brief MVFR mainly
ovr ctrl mtn range of PR and west interior as well as VCTY TJBQ/TJMZ
and downwind from the USVI into E-PR.


&&

.MARINE...
Seas up to 5 feet are expected across the local waters today
with winds out of the east-southeast at 10 to 15 knots. A
northerly swell will continue to affect the Atlantic waters and
passages today, but seas will remain below small craft advisory
criteria. For the beaches, a moderate rip current risk continues
for the northern and eastern coast of Puerto Rico, Vieques,
Culebra, San Thomas and St. John.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 91 77 89 76 / 30 30 30 30
STT 88 76 88 76 / 40 40 40 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
449 AM AST Thu Apr 23 2020

.SYNOPSIS...
An weak easterly perturbation now crossing the region will bring a
slight increase in moisture across the forecast area. Therfore passing
showers can be expected to affect the coastal waters and some of the
coastal areas during the early morning hours. Locally and diurnally
induced afternoon shower activity is expected, but should be focused
over parts of the interior and west sections of Puerto Rico. A mid to
upper level ridge will continue to build across the region into the
weekend. This will limit convective development while strengthening
the trade wind cap inversion. Otherwise, mostly fair weather conditions
and sunny skies should prevail in most areas for the next several days.
The tradewinds will increase by Friday into the weekend as a surface
high pressure ridge will build north of the region.

&&

.SHORT TERM...Thursday through Saturday...

A fair weather pattern with a few clouds prevailed across the local
islands during the overnight hours. Isolated light showers were
observed over the regional waters. Rain-free conditions, however,
prevailed over the land areas. The overnight low temperatures were
generally in the 70s across the lower elevations and in the 60s
across the higher elevations. Winds were light and variable.

As a weak easterly perturbation reaches the local islands early this
morning, expect brief trade wind showers over the US Virgin Islands
and eastern Puerto Rico. This low level moisture is expected to
combine with local effects and diurnal heating to result in
afternoon showers over the interior and northwest sections of Puerto
Rico. With the heaviest showers, ponding of water and minor urban
flooding is possible.

A fair weather pattern is then expected to prevail Friday into the
upcoming weekend. Although locally induced afternoon showers cannot
be ruled out, the overall pattern remains stable under the influence
of a mid-level ridge and a drier airmass. Latest guidance suggests
precipitable water values below 1.20 inches - which is well below
normal - Friday and Saturday.

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

High pressure will continue strengthen and hold at all levels over
the forecast area. At the surface, This feature will maintain a
fairly tight local pressure gradient, resulting in moderate to
locally strong trade winds at least until Monday. Overall, a
fairly dry and stable pattern will persist for most of the forecast
period, except for brief intervals of shallow tradewind moisture
from time to time. This in turn will favor periods of quick
passing showers over the coastal waters and parts of the east
coastal areas from time to time. Locally and diurnally induced
afternoon shower development will remain possible each day, but
should be mainly across western Puerto Rico. Lesser activity and
mostly sunny skies should prevail in and around the U.S. Virgin
islands.

For the first half of the workweek, winds are forecast to relax
once again as the pressure gradient loosens in response to the
surface high lifting farther northwards. A similar weather pattern
should hold for the latter half of the period but with less frequent
passing clouds and shower activity each day. Due to a lack of upper
level support and limited moisture transport being confined to
the lower levels of the atmosphere, significant rainfall activity
is not anticipated for the forecast period, except for locally
and diurnally induced afternoon showers of short durations each
day.

&&

.AVIATION...Mostly VFR conds are expected to prevail at all TAF
sites through the forecast cycle. However, brief periods of MVFR
conds in SHRA will remain possible at JBQ and JMZ between 23/17z and
23/22z. Easterly winds 10 to 15 knots with higher wind gusts and sea
breeze variations today.

&&

.MARINE...A northerly swell will continue to slowly dissipate across
the Atlantic Waters and Caribbean Passages this morning. Seas will
be at 4 feet or less and winds from the east at 5 to 15 knots today.
Winds and seas are however forecast to slightly increase later tonight
and through the upcoming weekend.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 77 89 76 / 20 20 10 10
STT 88 77 88 77 / 30 20 20 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
506 AM AST Fri Apr 24 2020

.SYNOPSIS...
Satellite imagery and recent derived precipitable water products
suggests a drier airmass spreading across the region, as a mid to
upper level high pressure ridge will continue to strengthen across
the forecast area. Surface high pressure ridge over the western
Atlantic will also continue to shift eastwards and north of the
region into the weekend. This will result in a tightening of the
local pressure gradient and increasing trade winds. Consequently,
an overall dry and stable airmass should prevail for the next
several days, with shower activity limited to portions of the
coastal waters and mainly over western PR during the afternoon
hours.

&&

.SHORT TERM...Friday through Sunday...

Clear skies and rain-free conditions prevailed across the local
islands overnight. The overnight low temperatures were generally in
the 70s across the lower elevations and in the 60s across the higher
elevations with easterly winds at 10 MPH or less.

A generally fair and mainly stable weather pattern is expected to
prevail across the local islands today and into the upcoming weekend
under ridge pattern and precipitable water values near or below the
normal range which is 1.50 inches. Best moisture advection will
continue to be associated with patches of low level moisture
embedded in the trades which are expected to move across the
local islands from time to time.

Therefore, continue to expect trade winds showers across the
US Virgin Islands and eastern sections of Puerto Rico as well as
some locally induced afternoon showers over western Puerto Rico each
day. Surface high pressure north of the area will tighten the local
pressure gradient to result in easterly winds at 15 to 20 mph.
Therefore, breezy conditions through the weekend. Light rainfall
amounts today since fast-moving showers will prevail.

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

High pressure ridge will continue to hold at all levels over the
forecast area at least through Monday, before gradually weakening
aloft. At the surface, the ridge will maintain a fairly tight local
pressure gradient, resulting in moderate to locally strong trade
winds until Monday. Thereafter, the ridge is to shift into the
north central Atlantic promoting an east to southeast wind flow
across the forecast area, with a gradual increase in moisture
advection during the latter part of the period.

Overall, a fairly dry and stable pattern will persist for the
first half of the period, except for brief intervals of shallow
trade wind moisture from time to time. This will favor periods of
quick passing showers over the coastal waters and parts of the
east coastal areas. Locally and diurnally induced afternoon
shower development will remain possible each day. The activity
should be mainly across western Puerto Rico, and in the form of
streamers in and around parts of the east interior and the San
Juan metro area. Lesser activity and mostly sunny skies should
prevail in and around the U.S. Virgin islands.

Present model guidance suggest a slight increase in moisture advection
by the latter half of the period as an easterly perturbation will
approach the forecast area. A gradual erosion of the ridge aloft and
weakening of the trade wind inversion, along with the approach of
the aforementioned feature, will increase the potential for shower
development across the regional waters during the overnight and
early morning hours, as well as daytime convection over the islands
on Friday and Saturday afternoon.

&&

.AVIATION...VFR conds are expected to prevail at all TAF sites
through the forecast cycle. However, brief periods of MVFR conds in
SHRA will remain possible at JMZ between 24/17z and 24/22z. Easterly
winds at around 15 knots with higher wind gusts and sea breeze
variations today.

&&

.MARINE...Seas will be becoming choppy today as winds and seas
increase up to 20 knots and 6 feet respectively. Small craft
operators should exercise caution.

There is a moderate risk of rip currents across most of the local
beaches of the forecast area, except for south and western PR.

&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
427 AM AST Sat Apr 25 2020

.SYNOPSIS...Although a fair weather pattern is expected to
prevail through early next week, patches of low-level moisture
embedded within the trade winds will support limited shower
activity through midweek, with no significant rainfall activity
expected. Surface high pressure moving across the north Atlantic
will maintain a moderate to fresh wind flow through early next
week. Enhanced shower activity under a generally southeasterly
surface wind flow can be expected by the end of the workweek into
the weekend with the arrival of a deep trough from the northwest.


&&

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

High pressure at lower levels will continue across the central and
east central Atlantic through the period, driving moderate to fresh
trade winds across the area. A weak pulse of moisture is moving into
Puerto Rico at the moment, and will push precipitable water values
just over 1.5 inches this morning, but otherwise precipitable water
values will bounce around between 0.9 and 1.25 inches through
Monday. Moisture will be almost entirely below 700 mb during the
period and will come in the form of bands and patches that will
bring light to moderate showers in our typical diurnal pattern. This
will bring showers to the windward coasts and slope in the late
nights and early mornings, then spread over to the western sections
of the island during the afternoons. Some clearing during the
afternoons is expected over eastern Puerto Rico.

This will be a relative dry time for the U.S. Virgin Islands with
only isolated showers occurring over land. Nevertheless some
downstream shallow convection is expected each day from late morning
to mid afternoon over the local waters.

Upper level winds will be light and variable as high pressure over
the Caribbean moves east and past the islands today through Monday.

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

A surface high pressure moving away from the local area will
maintain a moderate east to southeast wind flow through at least
Friday. Thereafter, a surface trough approaching the region from
the northwest will support a generally southeasterly surface wind
flow through the weekend. Under this flow, temperatures above-
normal can be expected.

In terms of shower activity, shower development will be driven by
fragments of low- level moisture embedded in the trade winds
through most of the period. A gradual erosion of the ridge aloft
and weakening of the trade wind inversion will enhance the
potential for shower activity by the latter part of the week.
Model guidance suggests that increased moisture advection and
favorable conditions due to divergence aloft, resulting from an
upper- level trough approaching the area from the northwest, will
support a higher potential for shower activity during the
weekend. In fact, the GFS-model guidance suggests that
precipitable water vapor will peak around 1.9 inches on Saturday
and Sunday, with surface temperatures reaching the low 90s.


&&

.AVIATION...Sct SHRA will cont over PR and downstream from the USVI
durg the morning hours and increase over the central and NW portions
of the island this afternoon. Mtn top obscurations psbl along the
Cordillera Central aft 25/15Z. Sfc winds ESE 5-15 kt with stronger
sea breezes aft 25/14Z. Max winds E-ESE 15-20 kt blo FL050.


&&

.MARINE...Small craft operators are urged to exercise caution
across the offshore Atlantic and Caribbean waters, as well as the
Anegada passage and coastal waters surrounding the USVI and
eastern Puerto Rico due to seas up to 6 feet and/or winds up to 20
knots. Elsewhere, relatively tranquil marine conditions with seas
up to 5 feet are expected. There is a moderate risk of rip
currents for beaches along the north and southeast coast of
Puerto Rico, most beaches in Culebra and Saint Thomas, as well as a
few beaches in Vieques and Saint Croix.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 77 90 76 / 40 20 20 20
STT 86 77 87 76 / 30 20 20 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
440 AM AST Sun Apr 26 2020

.SYNOPSIS...A surface high pressure will continue to maintain a
moderate to fresh easterly wind flow during the next few days,
resulting in choppy marine conditions. Although fair and stable
conditions are expected to prevail through midweek, patches of
low- level moisture streaming across the region will enhance
shower activity from time-to-time. Increased moisture content
coupled with favorable atmospheric conditions is expected to favor
a more active weather pattern by the latter part of the workweek
into the weekend.


&&

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

High pressure at lower levels will continue across the central and
east central Atlantic through the period, driving moderate to fresh
trade winds across the area. A weak band of moisture is moving into
the forecast area at the moment, and will nudge precipitable water
values to just over 1.3 inches this morning, but otherwise
precipitable water values will bounce around between 0.8 and 1.4
inches through Tuesday. Moisture will be almost entirely below 700
mb during the period and will come in the form of bands and patches
with weak low level forcing modeled in the time height section of
the GFS. This will bring brief light to moderate showers in our
typical diurnal pattern, that is, showers on the windward coasts and
slope in the late nights and early mornings, which then spread over
to the western sections of the island during the afternoons. Some
clearing during the afternoons is expected over eastern Puerto Rico.

This will be a relative dry time for the U.S. Virgin Islands with
only isolated showers occurring over land. Nevertheless some
downstream shallow convection is expected each day from late morning
to mid afternoon over the local waters.

Upper level winds will be light and variable as high pressure over
the Anegada Passage moves east and past the Leeward Islands on
Monday. A second weaker ridge will move through the area on Tuesday.


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

A series of surface high pressure moving across north Atlantic
will maintain a generally moderate surface wind flow across the
region. As the first surface high continues to move farther away,
winds are expected to favor a more southeasterly direction by the
end of the workweek. By Saturday and continuing on Sunday, a
surface trough moving north of the local area is expected to
generate a more south-southeasterly wind flow, which is more
apparent at the 700 mbar layer. This flow will also result in
above normal high temperatures across the local islands. Once the
second surface high begins to influence the local wind flow,
winds will favor a more easterly direction while maintaining a
moderate intensity.

Generally fair and stable weather conditions are expected to
prevail through most of the long-term forecast period. However,
locally induced shower development will be driven by the timing
of fragments of low- level moisture streaming across the region
from time-to- time. A gradual erosion of the ridge aloft and
weakening of the trade wind inversion will enhance the potential
for shower activity by the latter part of the week. Model
guidance continues to suggests that increased moisture advection,
resulting from the southerly flow from the trough, will support a
higher potential for shower activity, particularly on Sunday. In
fact, the GFS- model guidance suggests that precipitable water
vapor will peak around 1.9 inches by Sunday afternoon (18Z). So
far, the lowest potential for shower activity is expected on
Saturday and Monday with the entrance of an extended area of drier
air. Nevertheless, afternoon convection is still expected each
day.


&&

.AVIATION...Isold -SHRA will cont over ern PR and and ovr the lcl
waters durg the morning hours and increase over the central and NW
portions of the island this afternoon. Mtn top obscurations psbl
along the Cordillera Central aft 25/15Z. Sfc winds E 5-15 kt with
stronger sea breezes of 10-20 kt aft 26/15Z. Max winds E-ESE 15-20
kt blo FL070.


&&

.MARINE...Small craft operators are urged to exercise caution
across most of the local waters due to seas up to 6 feet and/or
winds up to 20 knots. Also, a moderate risk of rip currents is in
place for most local beaches of Puerto Rico and the US Virgin
Islands, except for beaches along the western coast of Puerto
Rico and Saint Croix, as well as the northwestern coast of
Vieques.


&&

.FIRE WEATHER...Relatively drier air confined between patches of
low-level moisture streaming across the area is forecast to
cause relative humidity to drop into the los 40s by late morning
into the late afternoon hours, particularly across the
southeastern coastal plains of Puerto Rico. In the meantime,
surface winds are expected to peak between 15-20 mph with gusts up
to 30 mph and sea breeze variations. Given the expected weather
conditions and recent KBDI observations within fire danger
thresholds in the area, a Fire Danger Discussion has been issued
for elevated fire weather conditions expected today.


&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
425 AM AST Mon Apr 27 2020

.SYNOPSIS...Prevailing low level high pressure in the Atlantic,
will keep moderate easterly trade winds today and tomorrow. Winds
will tend to become more southeasterly at lower levels and
temperatures will warm somewhat Wednesday through Saturday with
bubbles of tropical moisture moving through. At this time better
moisture and shower activity is expected on Sunday, but not more
than that which would cause localized urban and small stream
flooding.

&&

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

A surface high pressure located across the central Atlantic will
continue to promote a moderate easterly wind flow across the area.
Within this flow, a weak patch of low-level moisture, now moving
over the northern Leeward Islands, will stream into the forecast
area today. This patch will bring brief light to moderate showers
and increased cloud cover to eastern Puerto Rico and the local
islands before it dissipates early this afternoon. Lingering
moisture, peaking around 1.3 inches by 18Z, combined with local
effects and diurnal heating will support shower development across
the interior and northwestern sectors of Puerto Rico. Streamer-
like showers downwind from El Yunque and the local islands cannot
be ruled out. Nevertheless, neither significant rainfall
accumulations nor flooding are expected since this activity will
be shallow and short- lived.

Following this area of moisture, an extended area of relatively
drier air will move in and dominate the local weather conditions
through at least late Tuesday night. During this period, GFS model
guidance suggests that precipitable water vapor will drop below an
inch. Although fair and stable weather conditions are expected, the
typical shower pattern can still be expected with a few overnight
and early morning showers moving over windward areas followed by
limited afternoon convection over the interior and northwestern
sections of Puerto Rico driven by local effects. By Wednesday,
increased moisture advection and slightly favorable conditions
aloft, resulting from a slight weakening of the trade wind cap,
will result in a higher potential for shower activity across the
area.

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

High pressure at the surface over the east central Atlantic and
just northeast of the forecast area at 700 mb will begin to cause
southeast flow during the period. Patches of modest moisture will
move through Wednesday night, Thursday night and Friday night, to
bring scattered showers punctuated by drier days, although locally
driven showers would still be expected. With southeast winds
temperatures begin to rise area-wide and over the northeast coast
especially. 1000-850 mb thicknesses rise about 5 meters during
the period and beyond. Warmest temperatures are expected on
Saturday however as mid-level columnar moisture increases to
almost 2 inches on Sunday afternoon. The additional cloudiness
should provide some relief from highs in the lower 90s, although
San Juan is still expected to see around 90 degrees Sunday.

Since Lifted Indices approach minus 7 to minus 8 degrees, have
added isolated thunderstorms to the forecast Sunday and beyond--
mainly over Puerto Rico and the Atlantic waters Sunday night.

At upper levels, High pressure continues over the southern
Caribbean and the adjoining portions of South America. Over the
weekend a short wave trough will move north of the area with an
accompanying 80-knot jet at about 23 north on Sunday. Although
winds at upper levels will increase to more than 50 knots over the
area, little additional support is offered beyond the better
moisture and instability.

&&

.AVIATION...Mainly VFR conditions expected during the next 24 hours.
Passing showers will result in VCSH at TJSJ, TIST and TNCM through
27/12Z. Afternoon convection will bring VCSH to TJSJ, TJMZ, and TJBQ
between 27/15-23Z. This could result in brief MVFR conditions with
SCT-BKN between FL025-050. Light and variable surface winds expected
through around 27/10Z, turning from the E at 10-20 knots with sea
breeze variations thereafter. Maximum winds 15 kt abv the sfc.

&&

.MARINE...As winds diminish below 15 knots, seas will fall back
below 6 feet, in most areas as early as tonight. Seas may touch 6
feet in the outer Atlantic waters next weekend, but small craft
advisories are not expected during the next 7 days.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 76 89 76 / 20 20 20 30
STT 88 76 87 76 / 30 20 20 30

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
529 AM AST Tue Apr 28 2020

.SYNOPSIS...

Easterly perturbation will increase clouds and passing showers
across the local region today and tomorrow. However, no
significant rainfall accumulations is anticipated. Afternoon
showers will develop downwind from the U.S. Virgin Islands and
into eastern Puerto Rico, as well as across the Cordillera
Central and western sections of Puerto Rico. A similar pattern
will persist though much of the week.

&&

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

High pressure continues to be the dominant feature at all levels
over the central and eastern Atlantic Ocean. This is resulting in
stable conditions across the islands. At the surface, the high is
promoting a moderate easterly wind flow that will drag fragmented
group of clouds from time to time. For today, a pocket of air with
precipitable water values around 1.0 inch will be moving over the
U.S. Virgin Islands and eastern Puerto Rico, followed by an area of
slightly higher moisture late on Tuesday and into Wednesday. As a
result, only passing showers are expected early in the day over the
eastern half of the forecast area, followed by convection developing
over western Puerto Rico. However, due to the lack of upper level
support or significant amount of moisture, only modest accumulations
are anticipated. For Thursday, the latest guidance are suggesting
that an area of better low level moisture may move over the area,
although precipitable water values only increase to about 1.5
inches. Nevertheless, expect an increase in showers across the
USVI/Western PR through the morning hours, followed by afternoon
activity over northwestern Puerto Rico.

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

A surface high pressure system over the Atlantic basin will
induce an east-southeast wind flow during the long period.
Although a fair-weather pattern will dominate the conditions in
the northeast Caribbean, patches of moisture will move through
each day. Maximum temperatures across portions of the northern
sections of Puerto Rico and the northern U.S. Virgin Islands will
rise into the upper-80s and low-90s during the afternoon hours.

At upper levels, a short wave trough will move off to the north of
the islands, weakening the high pressure aloft during the
weekend. This system will induce a more zonal flow with an upper-
level jet by the weekend into next week.

&&

.AVIATION...

Aviation...Mainly VFR conditions are expected across all terminals
during the forecast period. VCSH are expected after 28/17Z at
TJMZ/TJBQ, which could cause very brief MVFR cigs. Conditions will
improve before 28/22Z. Winds will be out of the east to east-
southeast at 10 to 15 knots.

&&

.MARINE...

Seas are gradually improving, and now are expected to be up to 5
feet and winds up to 15 knots for the rest of the night into
Tuesday. A small northerly swell is forecast to reach the islands
by May 2 or 3. There is a moderate risk of rip currents today for
the beaches of northern Puerto Rico and eastern St Croix and
Vieques. Elsewhere, a low risk of rip currents is expected.

&&

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

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
412 AM AST Wed Apr 29 2020

.SYNOPSIS...A moderate easterly to east-south-easterly wind flow
will continue over the next few days as a surface high pressure
prevails in the central Atlantic and another surface high pressure
enters the southwester Atlantic this weekend. A surface low across
the NE-US will pull moisture from the south and over the local
area on Thursday, but drier air returns on Friday into Saturday.
Frontal boundary could be to the north of the local islands early
next week, causing higher than normal moisture over the local
area next week.


&&

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

A weakening mid-level ridge northeast of the region will continue to
promote overall fair weather conditions today. At lower levels, east
to southeast trades will continue to bring patches of low level
moisture across the local area. Therefore, passing showers with
minor rainfall amounts will move at times across the U.S. Virgin
Islands and the eastern coastal areas of Puerto Rico today. On
Thursday, a weak mid-level trough is forecast to move over the
region, enhancing afternoon shower development over the
western/northwestern sections of Puerto Rico as precipitable
water(PWAT) content peaks between 1.50-1.70 inches. Moderate
rainfall amounts can be expected. By Friday, moisture erodes quickly
as PWAT drops between 1.00-1.20 inches due to drier air filtering
from 850mb-500mb. A broad surface high is expected to move into the
central Atlantic and promote southeasterly winds across the islands.
This, in combination with a drier weather pattern will result in
normal to above normal temperatures across the islands.

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

Surface low pressure entering the NW-Atlantic will pull moisture
from the south cause the moisture to increase across the local
area. This sfc low will have an associated front, which will stall
to the north of the local area, causing the higher than normal
moisture to continue over the local area for most of next week.
However, the lack of mid to upper level dynamics means that the
shower activity will be mainly scattered and then locally induced
showers across sections of western PR. The long range models have
an area of higher amounts of rainfall across the local Atlantic
waters on Sunday into Monday, which may be due to an increase in
upper level winds causing some divergence. But otherwise, even
with the higher moisture content, we would expect mainly scattered
showers, perhaps locally numerous at times, then afternoon showers
across central to western PR. Cloudiness should increase as well.
Also, the forecast max temps are still forecast to be in the upper
80s to low 90s, but with the higher moisture, we can expect higher
apparent temperatures.

&&

.AVIATION...Mainly VFR conditions are expected to prevail across all
terminals during the next 24 hours. However, trade wind showers may
cause brief MVFR cigs across the USVI and northern PR terminals
through 29/12z. Diurnally induced afternoon showers could impact
TJMZ/TJBQ btw 29/16z-22z with tempo MVFR conds. East winds will
increase 10-15 kt aft 14z with sea breeze variations and higher
gusts.


&&

.MARINE...Tranquil marine conditions expected today and Thursday,
a small swell may affect the local waters on Friday, causing
choppy conditions. Winds will be generally up to 15 knots today
and Thursday, increasing up to 20 knots on Friday. That said,
there is a small area in the nearshore Atlantic waters of Puerto
Rico that will observe winds up to 20 knots today. The tranquil
marine conditions and moderate winds will cause a moderate risk of
rip currents only across a few beaches of northern PR, Culebrita
in Culebra and Cramer Park in Saint Croix.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 77 89 77 / 20 30 20 20
STT 85 76 86 77 / 40 30 40 10

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
424 AM AST Thu Apr 30 2020

.SYNOPSIS...The combination of a surface high pressure moving
across the central Atlantic and a frontal boundary moving off the
northeast United States will result in a southeasterly wind flow
through the upcoming weekend. Patches of low-level moisture
embedded within this southeasterly flow will result in areas of
showers through Saturday, however, due to unfavorable conditions
aloft, significant rainfall activity is not expected. Deeper
moisture is expected to move over the area Sunday and through the
first half of next week. This will result in more significant
showers across portions of the area.

&&

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

A weak mid-level trough is currently moving across the region from
the west. At lower levels, areas of scattered showers and low-level
clouds are moving with the trade winds from the Leeward Islands into
the local islands. Therefore, expect showers to continue through the
morning hours across the U.S. Virgin Islands and portions of eastern
and southern Puerto Rico. Then, diurnally induced afternoon showers
are expected to develop mainly over portions of the interior and the
northwestern quadrant of PR, as well over the San Juan metro area.
Moderate rainfall amounts are posible with these showers.

A drier air mass if forecast to move from the east quickly on
Friday, as an upper-level ridge holds over the eastern Caribbean.
Meanwhile, a broad low-level ridge will move northeast of the
region, while a polar trough and associated surface front enters the
western Atlantic. This will turn winds more from the southeast and
drier air will linger through at least Saturday, limiting shower
activity across the region. Warmer temperatures are expected across
the islands and locally induced afternoon showers are expected
mainly over the northwestern areas of PR.

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

A surface high pressure across the central Atlantic will continue
to maintain a southeasterly wind flow across the area through much
of the long term period. Meanwhile, between Sunday and Tuesday,
an axis of deeper moisture with precipitable water values ranging
between 1.7 and 2.0 inches will move over the area. This will
result in an increase in shower activity, especially across
interior and northern portions of Puerto Rico. The main driver for
the shower development will be in the form of diurnal heating and
sea breeze convergence as the mid to upper-level forcing looks to
be marginal. Additionally, the low-level flow is expected to
diminish to less than 10 knots as a frontal boundary stalls well
north of the area. As a result, the shower activity that develops
during the afternoon hours could be slow-moving, imposing a risk
of localized urban and small stream flooding. The deeper moisture
will also result in an increase in mid-level instability, especially
for Monday and Tuesday. Therefore, there is a higher potential
for some thunderstorms to materialize. Across the USVI, isolated
to scattered showers can be expected during this period, however,
given the lack of significant forcing aloft, significant rainfall
activity is not expected at this time.

Weather conditions are expected to improve by the middle to latter
half of next week as a weak ridge aloft settles in, eroding the
moisture content substantially. However, some locally and
diurnally induced showers can still be expected, mainly across
the northwestern quadrant of Puerto Rico during the afternoon
hours.

&&

.AVIATION...Mainly VFR conditions are expected to prevail across all
terminals. However, trade wind showers may cause tempo MVFR conds
across the USVI terminals and TJSJ through the morning hours.
Afternoon +SHRA expected over northwest PR, causing tempo MVFR conds
at TJBQ btw 30/17z-23z. East to southeast winds will increase
between 10-15 kt aft 14z with sea breeze variations and higher
gusts.

&&

.MARINE...A surface high pressure moving across the central
Atlantic will result in a moderate to fresh southeasterly flow
across the local waters today and Friday. This will result in some
choppy seas of between 5 and 6 feet, mainly across portions of
the Atlantic waters. Across the rest of the regional waters, seas
of less than 5 feet are expected. There is a moderate risk of rip
currents across most of the northern beaches of Puerto Rico as
well as across the east-facing beaches of Culebra, Vieques, and
Saint Croix.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 77 90 77 / 40 30 30 30
STT 84 76 87 77 / 50 40 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
437 AM AST Sat May 2 2020

.SYNOPSIS...A mid-level ridge is expected to weaken under pressure
from a polar trough on Sunday. This will cause trade winds to
decrease and low-level moisture will gradually pool over the
region through early next week. A surface high over the central
Atlantic will tighten the pressure gradient once again by midweek
and moderate to fresh trades will carry areas of low-level clouds
and passing showers through the long term period. Warmer
temperatures will continue due to southeasterly winds


&&

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

A relatively stable weather pattern will continue across the area
for today as a mid-level ridge prevails. This will continue to limit
the coverage of shower activity. However, patches of low-level
moisture embedded within the southeasterly wind flow will be moving
over the area. This will result in some showers during the morning
hours across portions of southern and southeastern PR as well as
across portions of the USVI. Then, during the afternoon hours,
showers are expected across the northwestern quadrant of Puerto
Rico. Showers in the form of streamers may also develop downwind of
the USVI and also downwind of Vieques, affecting portions of
northeast Puerto Rico. However, given the relatively stable
conditions aloft, significant rainfall accumulations are not
expected. Therefore, the flooding potential should continue to
remain low.

On Sunday, the aformentioned mid-level ridge is forecast to weaken
as a polar trough moves across the western Atlantic. At low-levels,
a frontal boundary is expected to be located well north of the area.
What this feature will do is weaken the low-level steering flow to
less than 10 kts. One major difference compared to previous runs is
that model guidance is significantly drier. Therefore, less shower
activity is now anticipated than previously forecasted.
Nevertheless, sufficient moisture will still be available to combine
with diurnal heating and sea breeze convergence to generate
scattered showers across interior and northern portions of Puerto
Rico during the afternoon hours. Across the USVI, only a few showers
are expected.

Better moisture is still on tap to pool over the area on Monday with
precipitable water values increasing to over 1.7 inches. This
moisture as it combines with diurnal heating and sea breeze
convergence will result in the development of scattered to numerous
showers across portions of interior and northern Puerto Rico. With
the steering flow expected to remain very light, the showers that do
develop will move slowly. Therefore, there will be a greater threat
for urban and small stream flooding to materialize. In addition,
isolated thunderstorms are also possible as the mid-level
instability increases. Across the USVI, isolated to scattered
showers are possible, however, significant rainfall activity is not
expected at this time.

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

A weak surface high pressure over the western Atlantic will move
north of the region and into the central Atlantic between Tuesday
and Wednesday, while strengthening and holding across much of the
Atlantic throught the long term period. This will increase once
again the trade winds across the region from the east to
southeast. Lacking any significant upper level support and low-
level feature, the weather conditions will be dominated by the
local effects and from moisture embedded on the trade winds.
Therefore, diurnally induced afternoon showers can be expected
each afternoon over portions of the interior and western PR, as
well as streamers developing off the USVI and from el Yunque area
into the SJU metro area through the long term period. Normal to
above normal temperatures will continue across the islands.


&&

.AVIATION...Mainly VFR conditions expected. SHRA expected across
interior and northwest PR between 02/16z and 02/23z, affecting the
vicinity of TJBQ and TJMZ. TEMPO MVFR conditions possible,
especially across TJBQ. Winds will be less than 10 kts from the ESE
through 02/12z, increasing to 10 to 15 kts with sea breeze
variations after 02/14z.


&&

.MARINE...A 4 to 5 feet long period northerly swell will move
later today across the Atlantic waters. The swell will continue to
fill on Sunday and spread across the local passages. Moderate to
locally fresh east to southeasterly winds will prevail today,
causing choppy seas up to 6 feet across the offshore Atlantic
waters and the Anegada Passage. Winds will gradually decrease on
Sunday and through early next week.

There is a high rip current risk in effect for some of the
northern beaches of Puerto Rico. Please refer to the latest Surf
Zone Forecast(SRFSJU) and Coastal Hazard Message(CFWSJU) for more
information.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 77 90 76 / 20 10 20 20
STT 87 78 86 77 / 20 20 10 10

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
445 AM AST Sun May 3 2020

.SYNOPSIS...Diurnally induced afternoon showers are expected each
day across portions of the interior and western Puerto Rico. A
250 mb jet will pass mainly north of the region through early next
week. At lower levels, light to moderate trades are expected to
continue through midweek, before a sfc to 700 mb ridge builds
east-northeast of the area. This will increase winds and turn
winds more from the southeast through the end of the week.


&&

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

The combination of a surface high pressure over the central Atlantic
and a frontal boundary well north of the area will result a very
light east southeast flow for today. Mainly fair weather conditions
are expected during the morning hours as a drier than normal airmass
prevails over the area. However, a few showers cannot be ruled out
across portions of eastern and southeastern Puerto Rico. Then,
during the afternoon hours, the low-level moisture is expected to
increase slightly. This moisture as it combines with strong daytime
heating and sea breeze convergence will result in the development of
showers across portions of interior, western, and northern Puerto
Rico. Given that the steering flow will be very light, these showers
are expected to be slow-moving. However, the intensity and duration
of the shower activity will be limited as there will be very dry air
above 700 mb. Therefore, the flooding potential will continue to
remain low for today. Across the USVI, mainly fair weather
conditions are expected.

The potential for more significant showers increase Monday and
Tuesday as moisture will be somewhat deeper, with precipitable water
values climbing to above 1.7 inches. As this deeper moisture
combines with strong daytime and sea breeze convergence, expect
afternoon shower development across portions of interior, western,
and northern portions of Puerto Rico. With the low-level steering
flow remaining light, below 10 knots, the showers will be slow-
moving. Therefore, there is a higher potential for urban and small
stream flooding to materialize in areas that receive a prolonged
period of heavy rainfall activity. Across the USVI, isolated to
locally scattered showers are expected, however, rainfall
accumulations will remain quite limited.

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

Building low to mid level ridge across the central Atlantic into
the eastern Caribbean will provide drier air intrusion and
increase the trade wind cap. This will decrease the aereal
coverage and intensity of the afternoon showers, and promote fair
weather conditions across the islands. No significant changes in
the long term period are expected at this moment, as another
surface high rolls from the western Atlantic into the central
Atlantic during the weekend. Having said that, the weather
conditions will be driven by the typical diurnally induced
afternoon showers due to the combination of the sea breeze
convergence and day time heating. The overall precipitable water
content will gradually decrease from Wednesday onwards.


&&

.AVIATION...Mainly VFR conditions expected. SHRA expected across
portions of interior, northern, and western PR between 03/16z and
03/23z, resulting in VCSH across TJMZ/TJBQ/TJSJ. Winds light and
variable through 03/12z, increasing to 10 to 15 kts from the ESE
with sea breeze variations after 03/14z.

&&

.MARINE...A long period northerly swell will maintain seas up to
6 feet across the offshore Atlantic waters today, and small crafts
should exercise caution. The swell will continue to fill across
the northern coastal waters and passages of the islands today,
while subsiding gradually tonight into Monday. There is a High
Rip Current Risk in effect for the northern beaches of mainland
Puerto Rico today. Easterly winds up to 15 knots are expected
across the regional waters.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 77 89 77 / 40 20 30 20
STT 86 77 86 77 / 10 20 10 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
522 AM AST Tue May 5 2020

.SYNOPSIS...

Weather conditions will continue unstable during the short term
period as deeper moisture combines with diurnal effects and
better dynamics aloft to promote shower activity. Temperatures
are expected to be above normal due to the influence of a
southeasterly wind flow through Friday. An improvement in the
overall weather pattern is expected next week as a surface high
pressure builds over the central Atlantic. Tranquil marine
conditions with seas less than 5 feet are expected through most
of the forecast period.

&&


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

A wet and unstable pattern will continue across the local islands
under a southerly wind flow. Moisture content will range between 1.8
and 2.0 inches, which is above normal. The steering wind flow will
increase somewhat but should be light and from the east-southeast.
CAPE will range around 1500 J/kg once again today. Under this
weather pattern, local effects, diurnal heating and sea breeze
variations will likely enhance the potential for thunderstorm
activity during the afternoon hours. This activity will have the
potential to create urban and small stream flooding mainly across
the eastern and the northwest quadrant of Puerto Rico. The U.S.
Virgin Islands can expect isolated to locally scattered showers,
without ruling out ponding of water in roads and low-lying areas.

Although TPW will range around 1.5 inches on Wednesday, a ridge
building aloft will decrease the potential for organized convection
across the islands. However, the formation of streamers downwind
from the Virgin Isles and El Yunque, as well as afternoon convection
over the northwest quadrant of PR are possible each day. A drying
trend with Saharan Dust Particles will being after Wednesday
afternoon into the long-term.


.LONG TERM...Friday through Tuesday

A surface high pressure and a ridge at 700 mb will be located
over the Central Atlantic. This will result in gentle to moderate
southeasterly wind flow across the forecast area through Friday.
Hence, temperatures above normal are forecast across northern
Puerto Rico, where high temperatures in the lower 90s are likely,
especially across the urban areas. A more easterly wind flow will
then be expected during the weekend as another surface high
pressure moves across the western Atlantic. This pattern will
result in relatively pleasant temperatures. Moreover, satellite
imagery and the NASA GEOS-5 Aerosol Model indicate the presence
of Saharan Dust in an air mass under the influence of the
aforementioned southeasterly wind flow. This will result in hazy
skies through early in the weekend.

Model guidance suggest a mid to upper-level building overhead and
prevailing through the rest of the long term period. Therefore,
fair weather conditions are expected across the area. Locally
induced shower activity will be limited and will not produce
significant rainfall accumulations.

&&


.AVIATION...

Mainly VFR conditions expected during the morning hrs.
SHRA are expected to increase in coverage and intensity across
portions of interior, north, east, and west PR between 05/15-23z,
resulting in SHRA/TSRA especially near/over TJMZ/TJBQ/TJSJ. Winds
light and variable through 05/12z, increasing btwn 10-15 kts from
the ESE with sea breeze variations after 05/14z.

&&


.MARINE...

A surface high pressure across the across the north-central Atlantic
will continue to produce a gentle to moderate east southeast
wind flow across the region. Therefore, mariners can expect
tranquil marine conditions through at least Wednesday. By midweek,
winds will increase to create choppy seas across the regional
waters. The moderate risk of rip currents wild hold on for the
next several days along most of the local beaches.

&&


.PRELIMINARY POINT TEMPS/POPS...
SJU 89 78 90 77 / 30 30 20 30
STT 87 78 85 79 / 20 20 40 40

[cycloneye]

 https://twitter.com/OnCaribWatch/status/1257686918692843523

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
523 AM AST Wed May 6 2020

.SYNOPSIS...

A showery weather is expected to prevail across the short term
period as patches of moisture reaches the islands. However, the
overall weather pattern is expected to be mostly fair with
temperatures reaching above normal highs and hazy skies. The long-
term forecast calls for mostly stable conditions due to the
presence of a strong surface high pressure. Marine conditions are
choppy due to increasing winds with seas up to 6 feet for most of
the local waters.

&&


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

The islands can expect a transition day, with a mixture of clouds
and sunshine throughout the day. However, passing showers will reach
the windward sections of Puerto Rico and the U.S. Virgin Islands at
times. Cloud cover and the potential for shower formation will
increase over the interior and northwest quadrant of Puerto Rico
this afternoon. Also, downwind from the U.S. Virgin Islands and El
Yunque affecting the San Juan Metropolitan area. Under east-
southeast winds, maximum temperatures will range from the upper-80s
to the low-90s over portions of the islands.

Surface high pressure over the central Atlantic will tighten the
local pressure gradient increasing surface winds. A ridge building
aloft, the strengthening of a trade wind cap, and a drier air mass
with Saharan dust particles will limit rain formation through the
short-term. However, the typical formation of streamers downwind
from the Virgin Isles and El Yunque, as well as afternoon
convection over the northwest quadrant of PR are possible each
day.


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

A surface high pressure and a ridge at mid levels will continue
over the central Atlantic and will hold for the duration of the
long-term period. This will result in a moderate southeasterly
wind flow across the region. Therefore, above normal temperatures
are forecast across the northern coast and urban areas of Puerto
Rico. Also, a dense cloud of Saharan Dust particles is expected
to result in hazy skies through the weekend. Overall,mostly fair
weather conditions are expected to prevail across the region for
much of the forecast period. However, low level moisture could
combine with local and diurnal effects to produce showers mainly
over parts of northwestern Puerto Rico in the afternoons. Rainfall
accumulations are not expected to be significant and could only
cause ponding of water on roadways and low laying areas with the
most persistent rains.

&&


.AVIATION...

Mainly VFR conditions expected during the morning hrs.
Passing showers will move from time to time across the local flying
area, but no significant impact is expected. Clouds and showers will
increase across the interior and northwest sections of Puerto Rico
between 06/16-23z, and could impact TJBQ. Winds light and variable
through 06/12z, increasing btwn 10-20 kts from the ESE with sea
breeze variations after 06/14z.

&&


.MARINE...

A slight increase in wind speeds across the region will result in
seas up to 6 feet for the next several days. Therefore marine
conditions will be choppy across the local waters. A moderate
risk of rip currents will continue for most of the north and east-
facing beaches of the islands.

&&


.PRELIMINARY POINT TEMPS/POPS...
SJU 91 77 92 78 / 10 30 30 10
STT 87 78 86 79 / 20 30 30 20

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
450 AM AST Thu May 7 2020

.SYNOPSIS...

Dry air and a trade wind inversion will limit shower activity
across the region. However, breezy trade winds will promote
limited shower advection across the windward sections at times. In
general, expect hazy skies and little or no rain today. A mid-
level high will set over the eastern Caribbean Friday into much of
next week, limiting upper-level dynamic.

&&

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

For today, mostly stable weather conditions with hazy skies due
to a Saharan air layer is expected across the region for the next
few days. However, due to the presence of low level moisture
embedded in an east to southeasterly wind flow, passing showers
remain possible for parts of southeastern Puerto Rico and the
U.S. Virgin Islands during the morning hours. Diurnal and local
effects will promote convection for sectors of the northwestern
quadrant of Puerto Rico in the afternoon. Thus, resulting in
brief shower activity. However, this activity is expected to be
minimal and no significant rainfall accumulation is anticipated.
Above normal temperatures are forecast for parts of northern
Puerto Rico and the U.S. Virgin Islands.

For the rest of the forecast period, a similar weather pattern is
anticipated as the surface high pressure over the central Atlantic
continues to promote an east-southeast wind flow. The ESE to SE
wind flow across the area will continue to result in warmer
temperatures with highs above normal values mainly for the north
and west coasts of Puerto Rico. This high pressure has also
enhanced pressure gradients over the region, resulting in breezy
conditions into next week. Overall, isolated to scattered showers
are expected mainly in the afternoons across northwestern Puerto
Rico due to shallow moisture combining with diurnal and local
effects.

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

A mid-level high will set over the eastern Caribbean Friday into
much of next week, limiting upper-level dynamic. However, model
guidances are indicating the advection of a surge of moisture
Sunday through Monday. Then, moisture should erodes ahead of an
easterly perturbation, which is forecast to arrive Tuesday or
Wednesday. On the absence of any atmospheric trigger, expect the
typical advective pattern with light to locally moderate periods
of showers, with some isolated to locally scattered showers over
the western sections during the afternoon.

The aforementioned weather pattern will prevailed through much of
the long term period. That said, expect mainly stable and
tranquil weather conditions with the sporadic advection of patches
of moisture at times.

&&

.AVIATION...

Mostly fair weather with VFR conds are expected across the local
terminals during the 24 hour period. However, Saharan dust
particles will cause HZ conditions but, VIS at the terminals
should be mainly around 6SM or more. ESE winds at around 15kt
with occasional higher gusts and sea breeze variations are
expected after 07/13z. Lighter winds are expected after 07/22Z.

&&

.MARINE...

A surface high pressure across the Atlantic Ocean will maintain a
fresh to locally strong east to east-southeast wind flow through
the next few days. This will create choppy seas across portions of
the local waters through the rest of this week. Mariners can
expect seas up to 6 feet and winds between 15 and 20 knots. Small
craft operators should exercise caution.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 93 78 92 77 / 20 20 20 20
STT 86 80 87 79 / 20 20 20 20

[cycloneye]

[Div][

Area Forecast Discussion
National Weather Service San Juan PR
438 AM AST Fri May 8 2020

.SYNOPSIS...

Stable and hazy weather conditions will continue through the
weekend. A dry air mass and an east-southeast wind flow will
result in near or above normal temperatures especially over the
northern portions of Puerto Rico and the U.S. Virgin Islands.
Surface high pressure across the Central Atlantic and a mid to
upper-level ridge overhead are the main weather features that will
hold through much of the forecast period.

&&

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

A mid to upper-level ridge combined with a surface high pressure
over the central Atlantic will continue to promote fairly stable
conditions over the region through the end of the weekend.
However, moisture at the low levels will combine with local and
diurnal effects to generate shower activity over northwestern
Puerto Rico during the afternoons. This activity is expected to
result minimal rainfall accumulations as these showers will be
brief and minimal. Hazy conditions and above normal temperatures
will remain as the major features through this weekend. Satellite
imagery and aerosol dispersion models continue suggesting a layer
of Saharan dust over the forecast area for the next few days.
Temperatures are expected to reach in the low to mid 90s along
the northern coasts of the islands. An increase in wind speeds and
a change in direction more to the east by Saturday will promote
breezy conditions over the local waters and coastal areas.

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

The ridge pattern aloft will hold through much of the forecast
period. Moisture embedded in the trades will reach the islands
each day, but drier conditions should dominate the weather
pattern. On the absence of any atmospheric trigger, expect the
typical advective pattern with light to locally moderate periods
of showers, with some isolated to locally scattered showers over
the western sections during the afternoons. Now, the models are
suggesting the erosion/weakening of the ridge pattern by the end
of the next work-week.

&&

.AVIATION...

Mostly fair weather with VFR conds are expected across the local
terminals during the 24 hour period. However, Saharan dust
particles will cause HZ conditions. SE winds at 5-15kt with
occasional higher gusts are expected mainly in the afternoon.
Lighter winds are expected after 08/22Z.

&&

.MARINE...

Surface high pressure across the Atlantic Ocean will maintain a
moderate to fresh east to east-southeast wind flow through the
next few days. This will create choppy seas across portions of the
local waters through the forecast period. Mariners can expect
seas up to 6 feet and winds between 15 and 20 knots. Small craft
operators should exercise caution.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 93 78 90 77 / 10 20 10 30
STT 87 79 87 77 / 10 20 20 30
/Div]

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
329 AM AST Sat May 9 2020

.SYNOPSIS...

With the mid level ridge overhead and the surface high pressure
over the central Atlantic, mostly fair weather is expected across
the forecast area for the next several days. A shift in wind
direction more to the east will promote relatively pleasant
temperatures beginning Sunday. Due to moisture embedded in this
easterly trade winds low, the forecast call for brief passing
showers from time to time across the islands. Marine conditions
remain choppy for the next several days due to increasing winds.

&&


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

Dry and stable conditions are expected to continue today. Isolated
showers are possible over the western portions of Puerto Rico mainly
during the afternoon hours. Hazy conditions will continue to affect
the local region through at least the incoming work week.

Similar weather pattern is expected to persist through Sunday
afternoon generating fair weather across the region. a slight
increase on moisture is forecast to reach our local forecast area on
Sunday night, slightly increasing the shower coverage for the
eastern portion Puerto Rico and adjacent islands on Monday morning
and across the western portions of PR on Monday afternoon.

Winds are expected to become more easterly therefore generating
slightly lower temperatures this afternoon and Sunday.


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

The long term period points out to be mostly stable aloft with
fair weather conditions across the islands. This is due to the
fact that the ridge pattern aloft will hold through much of the
forecast period. However, brief periods of showers could be
expected as low level moisture embedded in the trades will reach
the islands each day. Thus, with the absence of any atmospheric
trigger, shower activity will be mostly advective with light to
locally moderate rain over the western sections during the
afternoons. Latest model guidance is now suggesting the erosion
of the ridge by the end of the next work-week. Therefore, a more
typical weather pattern could be expected.

&&


.AVIATION...

VFR conditions are expected to continue through 10/02Z
although visibilities will, at times, be limited to only 8-10 miles
in Saharan dust. Winds will be ESE at less than 10 kt, but increase
again to 10-15 kt by 09/14Z with some sea breeze influences
developing aft 09/15Z.

&&


.MARINE...

Moderate to fresh winds between 15 and 20 knots will result in
choppy marine conditions with seas of up to 6 feet across
most of the local waters during the next several days. Therefore,
small craft operators should exercise caution. There is a moderate
risk of rip currents for most of the local waters of Puerto Rico
ans U.S. Virgin Islands.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 77 88 77 / 10 30 30 30
STT 87 77 87 76 / 10 30 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
449 AM AST Sun May 10 2020

.SYNOPSIS...
A surface high pressure will continue to promote an east southeast
wind flow across the region. The GFS model guidance suggests
precipitable values between 1 to 1.5 inches today. Therefore,
fair weather conditions are expected with a low chance of rainfall
activity over the region. Daytime temperatures are expected to be
slightly cooler than previous days, nevertheless, the maximum
temperatures will range in the upper 80s to 90 degrees. Fragments
of low level moisture will move over the region on Monday,
resulting in some afternoon convection in the western and
interior sections of Puerto Rico. Marine conditions will continue
choppy with seas up to 6 feet and winds up to 20 knots.

&&

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

Clear skies and rain-free conditions prevailed overnight. Winds were
from the east southeast at 10 mph or less. The overnight minimum
temperatures were in the upper 70s at the lower elevations.

Ridge aloft will continue to prevail through the forecast cycle
although weakening somewhat Mon-Tue. At lower levels, east southeast
winds between 15 and 20 knots to continue. Under a weakening ridge
and a moderate to fresh wind flow, patches of low level moisture are
expected to move across the forecast area Mon-Tue increasing the
chances for locally induced afternoon showers across west Puerto
Rico as well as passing showers across the outlying islands.
Meanwhile continue to expect a dry and stable weather pattern today.
Showers if any, will be focused across northwest Puerto Rico due to
local effects and diurnal heating. Temperatures will range in the
upper 80s to 90 degrees along the coastal areas. Haziness will
continue to slowly decrease.

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

A building surface high pressure across the western Atlantic will
promote an easterly wind flow which will push fragments of low-level
moisture over the region. The moisture in combination with the
local effects will enhance the development of shower activity in
the afternoon hours over western and northwestern PR Wednesday.
In the morning and evening hours, the chance of showers remains
for eastern sections of Puerto Rico and the U.S. Virgin Islands.

On Thursday and into Friday, the GFS model guidance suggests an
increase in the precipitable water with values ranging between
1.3 to 1.8 inches. On Saturday, a building low pressure northwest
of the area will result in southeasterly winds and moisture
advection over the region. In general, a seasonable weather pattern
is expected with the typical afternoon showers due to the local
effects.

&&

.AVIATION...VFR conditions will continue to prevail at all TAF
sites through the forecast cycle. Isolated SHRA cannot be ruled
out in and around JMZ and JBQ between 10/17z and 10/21z. ESE winds
to continue at around 15 knots with some sea breezes variations.

&&

.MARINE...A surface high pressure will continue to generate a
east southeasterly wind flow between 15 to 20 knots. Choppy marine
conditions are expected to continue for the next several days
with seas up to 6 feet. Therefore, small craft operators should
exercise caution. There is a moderate risk of rip currents for
most of the local waters of Puerto Rico ans U.S. Virgin Islands.

&

.FIRE WEATHER...Latest surface observations continue to indicate
very dry soils across the southeast coastal plains of Puerto Rico.
Therefore, there is an elevated fire weather risk today. Please
refer to the Fire Danger Statement (RFDSJU) for details.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 77 89 77 / 10 20 20 20
STT 89 79 87 79 / 20 40 20 40

[cycloneye]

FXCA62 TJSJ 110929 CCA
AFDSJU

Area Forecast Discussion...CORRECTED
National Weather Service San Juan PR
529 AM AST Mon May 11 2020

.SYNOPSIS...Surface high pressure over the central Atlantic will
continue promoting an east to east southeast wind for the next
several days. With the exception of this morning, near or below
normal moisture is expected this week. Mid and upper level ridge
is expected to prevail for the next several days as well.
Essentially, mostly stable conditions are expected this week,
but brief isolated to scattered showers in the mornings and
overnight hours can be expected across the local waters, eastern
Puerto Rico and the USVI. Locally induced afternoon showers can be
expected across western to northwestern Puerto Rico. Temperatures
are expected to be slightly above normal, in the upper 80s to low
90s across the lower elevations for the next several days.

&&

.SHORT TERM...Today through Wednesday.

Surface high pressure located across the north central Atlantic
will continue weakening as it moves to the western Atlantic today
into Tuesday. An east southeasterly wind flow between 15 to 20
mph will continue over the region at least until Tuesday,
thereafter it will become more easterly. Satellite imagery shows
patches of low level moisture with precipitable water values
between 1.8 to 2.3 inches moving into the forecast area and are
expected to increase the chances for shower activity this morning
across the USVI and eastern Puerto Rico. Afternoon convection is
likely to develop across the interior and western sections of
Puerto Rico this afternoon. The heaviest rainfalls could result in
ponding of water on roadways and in poor-drainage areas across
northwest and interior Puerto Rico this afternoon and Tuesday.
Passing showers are expected for the morning and evening hours
across eastern tip of Puerto Rico and the U.S. Virgin Islands. On
Wednesday, dry and stable weather pattern is expected with some
locally induced showers in the afternoon across western Puerto
Rico. Daytime temperatures will range in the upper 80s to low 90s
across the coastal areas.

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

Near or below normal moisture is expected in the long term. The
long range guidance insists that mainly stable conditions will
continue. That said, brief isolated to scattered showers are
expected across the local waters, eastern Puerto Rico and the
USVI, with locally induced showers developing across western
Puerto Rico in the afternoons. The days with higher moisture are
expected to be on Friday into Saturday, which only brings the
precipitable water values to near normal, but it may be enough to
help cause higher shower activity across the local area, but the
mid and upper level ridge will likely continue to suppress
significant convection. The drier than normal conditions and the
east to southeast winds will cause the high temperatures to also
be above normal, reaching the upper 80s to low 90s across the
lower elevations.

&&

.AVIATION...VFR conditions will continue to prevail at all TAF sites.
Isolated SHRA cannot be ruled out in and around TJMZ and TJBQ
between 11/14z and 11/20z. ESE winds to continue at around 15 knots
with some wind gust up to 25kt and sea breezes variations.


&&

.MARINE...Small craft advisory is in effect for the offshore
Atlantic waters due to seas of up to 7 feet. Elsewhere, seas up to
6 feet are expected. The local winds will be at 10-20 knots from
the east to southeast. There is also a moderate risk of rip
currents across most of the local beaches.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 91 76 90 76 / 20 20 30 40
STT 86 79 87 78 / 20 20 10 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
414 AM AST Tue May 12 2020

.SYNOPSIS...Surface high pressure over the Atlantic will continue
to promote an east to southeast wind flow for the next several
days. Near or below normal moisture is expected for the next
several days, but brief patches of moisture will move in
occasionally. Mid and upper level ridge is expected to prevail
through the rest of the workweek as well. Mostly stable
conditions are expected for the rest of this week, but brief
isolated to scattered showers in the mornings and overnight hours
can be expected across the local waters, eastern Puerto Rico and
the USVI. Locally induced afternoon showers can be expected across
western to northwestern Puerto Rico. Temperatures are expected to
be slightly above normal, in the upper 80s to low 90s across the
lower elevations for the next several days.


&&

.SHORT TERM...Today through Thursday.

Surface high pressure to the northeast of the local area will
continue to cause east to southeasterly winds over the region. As
a result, warm temperatures are expected today and Wednesday over
the lower elevations of the local islands. Also, passing showers
will move into the eastern sections of Puerto Rico and over the
U.S. Virgin Islands from time to time this morning. Afternoon
convection will be focused over the northwestern and interior
sections of Puerto Rico. On Wednesday, drier air is expected to
filter over the region, providing fair weather conditions,
especially in the nighttime hours. A slight increase in moisture
is expected once again on Thursday, increasing the probability of
shower activity in the morning and evening hours over the local
waters, eastern sections of Puerto Rico and the U.S. Virgin
Islands. Also, locally induced afternoon shower activity over the
western sections of Puerto Rico is expected.

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

Near or below normal moisture is expected in the long term. The
long range guidance has been consistent in showing that mainly
stable conditions will continue through the weekend. However, the
latest model run is showing an upper level low to the north of the
local area on Monday, moving south and causing divergence and
increasing instability for the first half of next week, which
would translate to more significant shower activity, especially
across the northern sectors of our local area. That said,
confidence is low and more consistency between the different model
runs should be achieved before confidence increases.
Nevertheless, brief isolated to scattered showers are expected
across the local waters, eastern Puerto Rico and the USVI, with
locally induced showers developing across western Puerto Rico in
the afternoons. The days with higher moisture are expected to be
on Friday, but the mid to upper levels are not conducive for
widespread heavy showers. Therefore, any significant showers
should be somewhat limited with moderate showers having more
coverage. The drier than normal conditions and the east to
southeast winds will cause the high temperatures to also be above
normal, reaching the upper 80s to low 90s across the lower
elevations.


&&

.AVIATION...VFR conditions will continue to prevail at all TAF sites.
Some Brief -SHRA to Isolated SHRA are possible in and around
TJSJ, TJMZ and TJBQ between 12/14z and 12/20z. ESE winds to
continue at around 15 knots with some wind gusts up to 25kt and
sea breeze variations.

&&

.MARINE...Small craft operators are urged to exercise caution
today due to choppy seas up to 6 feet and winds up to 20 knots.
The local seas are expected to improve slightly on Wednesday, with
seas up to 5 feet, but the local winds will still be up to 20
knots. There is a moderate risk of rip currents for most of the
local beaches today.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 76 89 75 / 30 20 30 40
STT 87 77 87 76 / 10 20 30 30