Caribbean - Central America Weather

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
504 AM AST Wed Apr 1 2020

.SYNOPSIS...
Overall dry and stable conditions with mostly sunny and fair weather
skies will prevail through Thursday with limited shower development
forecast over the islands. On Friday and into the weekend, a frontal
boundary and weak prefrontal trough is to approach and set up across
the region. By then, a short wave trough will cross the western
Atlantic and move just north of the region. This expected weather
pattern will increase low level moisture convergence and instability
aloft, and therefore result in better potential for shower development
across the islands and regional waters.

&&

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

High pressure will continue to prevail over the region today. Dry
and stable conditions associated to this weather feature will limit
the generation of showers this afternoon. Winds are expected to
slowly shift toward a more southerly component starting later this
morning through Thursday. Therefore, showers will develop over the
West and Northwest sections of the island during the afternoon
hours. This shift on the winds will generate warmer temperatures
across the area, with highs in the upper 80s across the northern and
eastern half of Puerto Rico. Across the U.S. Virgin Islands max
temps should range in the mid to upper 80s.

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

Low level convergence and pooling of moisture will return by
Saturday and continue through the weekend as the frontal boundary
and associated shearline is forecast to stall and drift southwards
across the area. This along with the proximity of the upper level
trough will increase the potential for shower development across
the islands and coastal waters each day. Some of the shower activity
may be enhanced as a subtropical jet segment is to cross the region
thereby destabilizing the upper levels. Urban and small stream
flooding will be possible in isolated areas over the weekend and
possibly into early next week especially during the afternoon
hours. Under this expected moist and unstable airmass, the best
potential for convective development still looks like it will be
on Saturday and Sunday. Conditions will gradually improve by
Monday as the upper trough is forecast weaken, and the low level
wind flow becomes more east to northeast. This is in response to a
surface high pressure ridge which will build and spread across
the west Atlantic.

By Tuesday and for the remainder of the period, expect some
moisture fragments from the depleted shearline to return with the
easterly trades. This will favor periods of passing early morning
showers over the coastal waters,and isolated to scattered showers
each afternoon over portions of the islands.

&&

.AVIATION...Mainly VFR conditions are expected to prevail across all
terminals during the next 24 hours. VCSH are possible this afternoon
for TJMZ/TJBQ, and no lightning is expected. Winds primarily out of
the east at 10-15 knots with sea breeze modifications, and turning
more from the ESE later this morning. for TIST/TISX/TNCM/TKPK.

&&

.MARINE...A light to gentle southeasterly wind flow will prevail
across the regional waters through Thursday with fairly tranquil
marine conditions. Marine conditions are however expected to
deteriorate by late Friday and into the upcoming weekend, as a
northerly swell will invade the Atlantic waters and local
passages. Winds will become light and variable with a more
northerly component over the weekend as a frontal boundary is
forecast to sink southwards across the regional waters. This in
turn will increase the chance for more shower development across
the local waters. Small Craft Advisories and precautionary
statements will also be likely by then, for portions of the local
waters.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 74 89 75 / 10 10 10 10
STT 84 74 83 74 / 10 20 20 20

[cycloneye]

Area Forecast Discussion...CORRECTED
National Weather Service San Juan PR
436 AM AST Thu Apr 2 2020


.SYNOPSIS...
Warm temperatures are expected to continue today under a
southeasterly wind flow across the islands. An increase in
moisture at the lower levels today should result in afternoon
convection mainly across northwestern Puerto Rico. A frontal
boundary will approach the area during the weekend, bringing an
increase in showers.


.SHORT TERM...Today through Saturday...
Moisture increases only at the lowest levels of the atmosphere
today as southeast to south flow from 1000-700 mb continues across
the forecast area. This will give rise to a few areas where
showers can develop over Puerto Rico, namely from the northwest
along the northern half of the island to almost Catano. High
pressure in the central Atlantic at the surface will drift
erratically, but inexorably to the east which will allow winds to
become more east southeast by the end of the period. A cold front
moving across Cuba at the moment will move across Hispaniola
Friday and Friday evening and into Puerto Rico Saturday. But
before it enters the forecast area, moisture already moving over
the area will become enhanced at the 850 mb level and form a pre-
frontal band ahead of the front which will be a factor in the
rainfall Friday and Saturday. The best showers should move into
the northern waters of the forecast area Saturday evening and
stall. Providing moisture into the long term period. This
moisture, being shallow, will provide only spotty areas of
significant rainfall.

.LONG TERM...Sunday through Friday...
A long-wave mid to upper level trough will continue to be the
dominant weather feature across the western Atlantic early in the
forecast period, while it will begin to move away, toward the
central Atlantic by mid-week. At the surface on Sunday and Monday,
a frontal boundary near the area and a surface high pressure over
the eastern Atlantic will result in an area of low level
convergence that will drag moisture into the islands. Precipitable
water values are expected to range between 1.3 to 1.5 inches
these days. Additionally, at the upper levels, a piece of the jet
stream will be located north of the islands, hence increasing
somewhat instability aloft. That said, conditions appear to be
more conducive for an increase in showers across the islands.
Under a light wind flow across the islands, this activity could be
slow-moving, and might result in urban and small stream flooding
across the area.

By the latter part of the long-term forecast period, as the long-
wave trough moves toward the Central Atlantic, conditions are
expected to become less favorable for any significant rainfall
activity to occur. However, at the lower levels, moisture and low
level convergence remains. Therefore, groups of showers may
affect the area early in the morning hours across the coastal
areas, while in the afternoon, supported by diurnal effects,
additional showers may develop as well.

&&

.AVIATION...VFR conditions are expected to prevail across all
terminals during the next 24 hours. Sct SHRA to dvlp in nwrn and
interior PR aft 02/16Z with mtn top obscurations. Winds primarily
out of the SE across the region at 5-15 knots with sea breeze
modifications. Max winds WSW-W 60-75 kt btwn FL350-470 strongest at
FL400.


&&

.MARINE...
Tranquil marine conditions are expected to prevail through today,
but becoming choppy on Friday and hazardous for the weekend. This
is due to a northerly swell invading the Atlantic and local
waters. Seas below 4 feet are expected for today with winds out of
the southeast up to 10 knots. For the beaches, the risk of rip
currents is moderate for the northern coasts of Puerto Rico, all
of Culebra, the northwestern beaches of Saint Thomas and the
eastern tip of Saint Croix. The risk will be low elsewhere today
and also tonight and Friday in the U.S. Virgin Islands.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 73 90 74 / 20 10 30 30
STT 85 74 84 74 / 20 10 20 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
455 AM AST Fri Apr 3 2020

.SYNOPSIS...
Another warm day is expected today under a southeasterly wind
flow. A cold front will approach the islands this weekend,
resulting in an increase in shower activity. This system will stay
close to the area through much of the next workweek. Hazardous
seas are also expected for the weekend due to a northerly swell,
starting tonight through Monday.

&&

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

High surface pressure across the central Atlantic will drift toward
the Canary Islands during the period. This will allow a cold front
associated with a moderately strong low in the western Atlantic to
advance from between the southern Bahama Islands and Hispaniola
today to the local area Sunday. Currently some moisture is noted
over the Caribbean and the south southeast flow has pressed showers
over the coastal plains and against the flanks of the mountains
there. This has produced areas of less than one quarter inch along
much of the southeast and eastern coasts and spots of over 1 inches
over Arroyo, Patillas, Maunabo, Naguabo, Ceiba and Fajardo
municipalities. That flow will continue for a little while this
morning until local sea breezes focus the activity in the interior.
The southeast flow will also provoke considerable warming over the
greater San Juan and Bayamon Metropolitan areas to the point that
San Juan may break its maximum record temperature for the date today
of 91 degrees.

Current GFS models forecast light flow ahead of the frontal passage
Saturday and that the actual front will weaken considerably and be
supplanted by better moisture and convergence just southeast of the
forecast area on Sunday. Winds are mostly influenced by
land and sea breeze circulations on Friday night and Saturday, but
become light northerly on Saturday night and Sunday. This will bring
relief to the north coast from the warm temperatures expected today
and Saturday, but even Sunday, highs in the mid and upper 80s may be
seen. Showers during the period are limited by the moisture that is
scarcely present above 8.5 kft or 750 mb. On Saturday they are
mainly seen in interior Puerto Rico and on Sunday mainly along the
coast and slopes of northern Puerto Rico. The U.S. Virgin Islands
will see little in the way of significant rain with this system. But
showers may appear down stream from the islands.

At upper levels, a low pressure wobbles around in the western
Atlantic before most of its energy is siphoned off to general flow
across the north central Atlantic. An associated jet will be joined
by a strengthening sub-tropical jet that will remain mostly north of
Puerto Rico and the U.S. Virgin Islands, but whose tail will pass
overhead Sunday morning. Limited upward vertical motion associated
with the jet and the low relative humidities at mid and upper levels
will prevent convection due to anything other than locally driven
effects from occurring.

.LONG TERM...Monday through Saturday...
As the frontal boundary lingers near the islands, enhanced shower
activity is expected to continue due to low level convergence and
the moisture associated with this system. The latest guidance
shows that the front will meander near Puerto Rico and the U.S.
Virgin Islands through much of the workweek, with precipitable
waters values ranging between 1.4 to 1.6 through Wednesday. Then,
on Friday and Saturday, these values are expected to climb near
1.8 inches as the system is pushed back across the islands. At the
upper levels, a 50 to 60 knots jet will also provide some
instability aloft that should aid in the development of shower
activity across the region on Monday and Tuesday. However, this
jet will then move toward the east by the end of the week, hence
instability is expected to decrease. In general, under this
weather pattern, shower activity is favored, with urban and small
streaming flooding possible each day of the week.


&&

.AVIATION...VFR conditions are expected to prevail across all
terminals during the next 24 hours. Sct SHRA to dvlp in nwrn and
interior PR aft 02/17Z with mtn top obscurations. Winds primarily
SE-S across the region at 5-15 knots with local sea breeze
influences. Max winds WSW-W 56-66 kt btwn FL330-480 strongest at
FL405.


&&

.MARINE...
Seas up to 6 feet are expected across the offshore Atlantic waters
early today as a northerly swell begins to invade the waters. By
tonight, seas increase to 7 feet, and a small craft advisory will
be in effect. These conditions will spread across the coastal
waters and passages through the weekend. For the beaches, a high
rip currents exist for north-central PR, while the risk is
moderate across the northern coast of PR, and low everywhere else.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 91 74 90 74 / 30 10 40 40
STT 86 73 86 73 / 10 10 20 40

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
434 AM AST Sat Apr 4 2020

.SYNOPSIS...A cold front will drift into the area Saturday night
and Sunday bringing some additional shower activity and then dissolve
on Monday. A band of better moisture southeast of the area Sunday
will move toward Puerto Rico and the U.S. Virgin Islands, but
weaken. This band will reform over the area late Thursday and
Friday.

&&

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

Clear skies prevailed across the local islands during the overnight
hours with a few sprinkles noted over the Atlantic offshore waters.
The overnight low temperatures ranged from the upper 70s to around
80 degrees at the lower elevations. Winds were light and variable.

As a frontal boundary approaches the forecast area from the north-
northwest, low level moisture is expected to increase with
precipitable water values ranging between 1.40 and 1.60 through at
least Monday. At upper levels, a gradual intensification of the
subtropical jet maxima north of Puerto Rico is expected, which may
enhance shower development across the forecast area throughout the
day today. Nevertheless by Sunday, the convergent/subsident side of
the upper jet will dominate the region. Therefore, under available
moisture near the normal range, fair upper level dynamics and light
surface winds, expect shower development over central, north and
east Puerto Rico this afternoon. By the evening and early morning
hours on Sunday, shower activity will be then focus over the north
and east coastal areas as well as over the US Virgin Islands.
Locally induced afternoon showers are expected once again Sunday
afternoon, although intensity and areal coverage may decrease due
to the lack of upper level dynamics. Somewhat drier conditions are
expected on Monday.

Slow moving showers are expected under light winds today, therefore
there is an increasing potential for ponding of water on roadways
and urban and small stream flooding.

.LONG TERM...Tuesday through Monday...

On Tuesday the drier air behind the weakening frontal boundary
will filter into the forecast area. Nevertheless there will be
enough moisture for early morning showers along the windward coast
in the northeast of Puerto Rico during the overnight and early
morning period. This moisture will play into local effects and
also produce showers over southwest Puerto Rico Tuesday afternoon.
Moisture then increases Tuesday night through Thursday evening as
a band of moisture that was pulled out of South America Sunday
and formed southeast of the area, slowly moves over Puerto Rico
and the U.S. Virgin Islands. Since surface flow Tuesday through
Thursday will remain east northeast this moisture will help
generate showers for the eastern coasts of Puerto Rico with some
isolated showers over the U.S. Virgin Islands.

High pressure at the surface over the western tropical Atlantic
will move into the Caribbean over the next weekend and dissipate.
Surface winds become southeasterly Friday and saturday and the
northeast coastal portion of Puerto Rico will warm into the upper
80s to lower 90s again. The high pressure will be closely
followed by a trough in the lower levels that will drag some of
the best moisture in several weeks across the area late in that
weekend, Sunday and Monday.

&&

.AVIATION...VFR conds are expected to prevail at all TAF sites
through the forecast period. Aft 04/16z, however, shower development
is expected over central PR with VCSH/SHRA remaining possible in and
around JSJ. Mountain obscurations. Winds are expected to be light
and variable with sea breeze variations developing after 04/14z.
Max winds WSW 75-90 kts btwn FL330-465. Strongest winds at FL400.

&&

.MARINE...Northerly swell is increasing and will peak today. Seas
will subside only slightly before swell increase again on Monday
morning. The risk of rip currents will be high for coasts with a
northern exposure on the Atlantic side through at least Tuesday,
but seas should begin to subside after that through the end of the
week.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 77 84 75 / 50 40 40 40
STT 86 75 79 74 / 30 40 40 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
532 AM AST Sun Apr 5 2020

.SYNOPSIS...A frontal boundary just north of the area will weaken
as it moves across Puerto Rico and the northern U.S. Virgin
Islands today and tonight. Moisture from South America will be
siphoned up into the southeast portion of the forecast area early
next week, but it too will weaken. Then the old frontal boundary
will become a shearline and re-activate over Puerto Rico and the
U.S. Virgin Islands Thursday through Saturday.


&&

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

Clear skies prevailed across the local islands during the overnight
hours with some showers noted over the Atlantic waters. The
overnight low temperatures ranged from the upper 70s to around 80
degrees at the lower elevations. Winds were light and variable.

The chance for shower activity continues through the forecast cycle
as moisture associated with a frontal boundary remains in and around
the local islands. Model guidance continues to suggest maximum
values of precipitable water ranging between 1.40 and 1.60 inches
through at least Tuesday. The best moisture advection is likely to
be observed tonight with a second maximum on Monday night. At upper
levels, the lack of forcing continues. As a result, continue to
expect shower development over central Puerto Rico this afternoon.
By the evening and early morning hours showers will be then focused
over the north and east coastal areas of Puerto Rico and over the US
Virgin Islands.

Similar weather conditions are expected Monday and Tuesday with
passing showers along coastal areas of north and east Puerto Rico
and outlying islands as well as locally induced showers over central
Puerto Rico in the afternoon.

Slow moving showers are expected under light winds, therefore the
potential for ponding of water on roadways and urban and small
stream flooding continues.

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

High pressure at the surface will continue to shift eastward into
the central Atlantic ocean. At the same time the old cold front
will still be near the area in the form of a shear line. This will
provide a focal point--or line--for shower activity.

Low level flow will shift from east northeast on Wednesday to
southeast on Thursday. At least a modest southerly component in
the easterly flow will continue at lower levels during the weekend
and into the next week. The old boundary will finally lift north
on Saturday to complete a warming and drying trend begun on Friday
and peaking on Saturday.

Upper level flow will be mostly west northwest through much of
this week, but will become more northerly as a weak trough forms
southeast of the area and high pressure ridges in from the
southwest across the central Caribbean and into Puerto Rico.
Without a strong upper low nearby, 500 mb temperatures will remain
too warm for serious convection in an atmosphere that remains dry
at mid and upper levels for the entire period, so thunderstorms
are not expected.

These conditions will, however, be favorable for late night and
early morning showers in eastern Puerto Rico, favoring the eastern
and southeastern slopes. During the afternoon flow will favor
shower generations along and north of the Cordillera Central.
Because flow at mid levels is westerly and reaches as low as 850
mb, showers will tend to favor central and east central Puerto
Rico during the afternoons, even though showers in west and
northwest Puerto Rico will occur from time to time. The best
showers should be seen Wednesday through Friday.

&&

.AVIATION...VFR conds are expected to prevail at all TAF sites
through the forecast period. Aft 05/16z, however, shower development
is expected over central PR with VCSH/SHRA remaining possible in and
PR TAF sites. Mountain obscurations. VCSH in and around the USVI
terminals aft 05/22. Winds are expected to be light and variable
with sea breeze variations developing after 05/14z. Maximum winds
WSW-W 65-75 kt btwn FL350-470.


&&

.MARINE...Marine conditions will continue to be hazardous in the
Atlantic waters today and increase slightly on Monday due to
northerly swell. Conditions improve Tuesday through Saturday and
currently all Small Craft Advisories will be down by Monday night.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 85 75 86 75 / 40 50 50 50
STT 84 75 82 74 / 20 50 50 50

[cycloneye]

Area Forecast Discussion...CORRECTED
National Weather Service San Juan PR
537 AM AST Mon Apr 6 2020

.SYNOPSIS...
Low-level moisture from a weak frontal boundary/shearline located
near the area will linger over the area. In the morning hours,
mainly fair weather conditions are expected, however, some passing
showers could affect eastern sections of Puerto Rico. Conditions change
in the afternoon hours when more shower activity is expected due
to the combination of low-level moisture from the
boundary/shearline and diurnal and local effects. Urban and small
stream flooding can be expected with the heaviest showers,
especially in the San Juan metro area and interior and eastern
interior of Puerto Rico. Hazardous marine conditions will
continue across the Atlantic waters with a High surf advisory
until 8 AM AST this morning and small craft advisories and high
risk of rip current in effect for the northen beaches of the
islands.

&&

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

A similar weather pattern compared to the last couple days is
expected to continue through the short-term period. A weak frontal
boundary/shearline is located just south of the area, providing
sufficient low-level moisture with precipitable water values
expected to range between 1.4 and 1.7 inches. The low-level moisture
combining with sea breeze convergence and diurnal heating is
expected to induce another round of showers across interior Puerto
Rico this afternoon. Just like this past weekend, the low-level flow
during the next couple of days will remain light and thus, the
showers that do develop are expected to be slow-moving once again.
Given that the soils are saturated across central and eastern
interior of Puerto Rico from the rounds of heavy rain this past
weekend, additional heavy rainfall activity is expected to result in
urban and small stream flooding. This same general weather pattern
is expected to repeat itself on Tuesday. Across the USVI, mostly dry
weather conditions are expected with just a slight chance of a few
showers.

The weak frontal boundary/shearline currently located just south of
the area is expected to retreat towards the area on Wednesday and
with it the low-level moisture is expected to increase with
precipitable water values peaking at around 1.8 inches. Therefore,
an increase in shower activity is expected across the area,
including the USVI. With the low-level flow expected to remain
light, the shower activity is expected to be slow-moving once again.
Therefore, urban and small stream flooding will continue to remain a
threat across areas that receive the heaviest rainfall activity.

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

The GFS model guidance suggest that the low-level moisture from
the frontal boundary lingers over the area on Thursday in
southeasterly flow. This increase in moisture in combination with
the local effects will result in shower activity across northern,
eastern and interior sections of Puerto Rico. This weather pattern
of southeasterly flow will continue for the next several days as
a frontal boundary builds over the northwestern Atlantic and moves
to the central Atlantic and a high pressure is located well over
the eastern Atlantic. This will result in warmer temperatures
over the local islands with shower activity in the afternoon
hours. On Sunday and Monday, a surface high pressure in the
Atlantic will change the wind flow coming from the east. For
those days and lasting into Tuesday, the GFS model guidance
suggest less low-level moisture across the region. This can
result in less shower activity across the region. However, morning
showers still possible across the eastern and northeastern
sections of Puerto Rico and the USVI, as well as some afternoon
showers due to the local effects.

&&

.AVIATION...
Mainly VFR conditions expected across all TAF sites. SCT
SHRA expected across interior PR between 06/16z and 07/23z. This
will result in VCSH across TJMZ and possibly TJSJ. Winds light and
variable, increasing to 10 to 15 kts with sea breeze variations
after 06/14z.

&&

.MARINE...

Hazardous marine conditions will continue across the Atlantic Waters
and Caribbean Passages through at least Tuesday due to a northerly
swell. Mariners can expect seas between 6 to 8 feet with
occasional seas up to 10 feet across the Atlantic waters, Mona and
Anegada Passages. For the Caribbean waters, tranquil marine
conditions are expected for the next several days with seas up to
5 feet with occasional seas up to 6 feet. Also, winds will
continue mainly light and variable. At the beaches, a high surf
advisory is in effect until 8 AM for the north and eastern beaches
of Puerto Rico. Also, a high rip current risk continues for the
north-facing beaches of the islands. Showers activity is expected
across the local waters.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 85 76 84 75 / 40 40 30 40
STT 87 75 86 73 / 20 20 20 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
506 AM AST Tue Apr 7 2020

.SYNOPSIS...
Mostly fair weather conditions are expected to continue for the
rest of the early morning hours. However, some brief passing
showers still possible across northeastern and eastern sections
of Puerto Rico, as well the U.S. Virgin Islands. In the afternoon
hours, isolated to scattered showers will develop across the
interior sector of Puerto Rico. Marine conditions will gradually
improve during the next several days.

&&

.SHORT TERM...today through Thursday...

A dissipating frontal boundary remains nearly stationary over the
area, enhancing the low-level moisture content as precipitable water
values will continue to range between 1.4 and 1.7 inches, which is
near normal for this time of the year. For the morning hours,
isolated showers are possible across the northern coast of Puerto
Rico. Then, during the afternoon hours, as the available moisture
combines with daytime heating and sea breeze convergence, another
round of showers is expected to develop across interior Puerto Rico.
The low-level flow remains light, and thus, any showers that develop
will be slow-moving once again. Ponding of water on roadways and in
low-lying areas as well as minor urban and small stream flooding
will be possible with the heaviest and most persistent rainfall
activity. Across the USVI, mainly dry weather conditions with just a
slight chance of a few showers are expected.

On Wednesday, shower activity may become more widespread across the
area as the low-level moisture content in association to the
aformentioned frontal boundary increases with precipitable water
values increasing to approximately 1.8-1.9 inches. With the low-
level flow changing to the east to east-southeast, shower activity
will be concentrated across western interior, northwestern, and
northern portions of Puerto Rico. Given that the low-level flow will
continue to remain light, shower activity will be slow-moving once
again and therefore, the threat for urban and small stream flooding
will remain. A better chance of showers is expected across the USVI,
however, significant rainfall accumulations are not expected.

Weather conditions change on Thursday with the boundary lifting
towards the north away from the area under a southerly wind flow
with a drier airmass moving in. This will result in more limited
shower activity across the area. Nevertheless, some showers are
still possible across the northern half of Puerto Rico during the
afternoon hours as a result of local and diurnal effects.

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

On Friday, a southeasterly wind flow will carry some low-level
moisture fragments across the region and will result in shower
activity in the afternoon hours, across western and north central
sectors of Puerto Rico. A different weather pattern is expected
on Saturday as a dry air mass moves across the region, limiting
the shower activity across the islands. However, some afternoon
convection still possible due to the local effects. Afternoon
development should be focused over the interior and northwest
sections of Puerto Rico. Also, the southeasterly wind flow is
expected to result in warmer temperatures across the coastal areas
of northern Puerto Rico.

On Monday, a building high pressure located in the northeastern
Atlantic will carry some low-level moisture across the region.
This moisture in combination with the local effects can result in
more shower activity across the main island, especially
in the afternoon hours due to the diurnal heating. For the U.S.
Virgin Islands, some passing showers still possible in the
morning hours.

&&

.AVIATION...
Mainly VFR conditions expected. SHRA expected across
interior PR between 07/16Z and 07/23Z, resulting in VCSH across
TJPS/TJMZ/TJSJ. Winds light and variable through 07/12z, increasing
to 10 to 15 kts from the E-NE with sea breeze variations after
07/14z.

&&

.MARINE...
Marine conditions will gradually improve today as the northerly
swell diminishes across the region. Seas up to 6 feet are expected
across the Atlantic waters and Mona Passage. Therefore, small
craft operators should exercise caution across these waters. In
the Caribbean waters, seas between 2 to 5 feet are expected. Some
passing showers are expected across the regional waters for
today.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 84 75 86 75 / 30 40 50 40
STT 87 75 85 76 / 20 40 40 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
453 AM AST Wed Apr 8 2020

.SYNOPSIS...
Moisture associated with a weak frontal boundary continue across
the area. This will result in passing showers across the area
in the morning hours specially across northern and eastern
sections of Puerto Rico. Them in the afternoon hours, scattered
to numerous showers will affect the interior and northwestern
sections of Puerto Rico. Urban and small stream flooding still
possibles with the heaviest showers. Drier weather is anticipated
for Friday and continue for the rest of the weekend. Across the
regional waters, seas up to 6 feet across the Atlantic waters,
therefore small craft operators should exercise caution.



&&

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

Abundant low-level moisture associated with an old frontal boundary
continues situated over the area. This has resulted in scattered to
numerous showers across the northern and eastern portions of Puerto
Rico during the overnight hours. Showers will continue to affect
these areas through the morning hours. Then, during the afternoon
hours, as the available moisture combines with diurnal heating and
sea breeze convergence, scattered to numerous showers are expected
across portions of interior, western, and the northern half of
Puerto Rico. Once again, the low-level flow remains very light and
thus, slow-moving showers are expected. Therefore, the potential is
there for urban and small stream flooding to materialize in areas in
areas that a prolonged period of heavy rainfall activity. Across the
USVI, scattered showers are expected from time to time, especially
across Saint Thomas and Saint John. The activity across these areas
may result in ponding of water on roadways and in poor-drainage
areas.

Weather conditions are expected to improve for both Thursday and
Friday as the old frontal boundary and its associated moisture lifts
to the northeast and drier air moves over the area under a southerly
flow. Therefore, more limited shower activity is expected. However,
some afternoon showers are still expected to develop across interior
and northern portions of Puerto Rico due to local and diurnal
effects. Due to the southerly flow, high temperatures along the
urbanized areas of northern Puerto Rico may top out in the lower 90s
both days

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

On Saturday, a drier mas mass is expected to move across the
region limiting the afternoon convection. However, some passing
showers could develop across across western and interior sectors
of Puerto Rico. These southeasterly wind flow is expected to
result in warmer temperatures across the coastal areas of northern
Puerto Rico. On Monday, the wind flow change from east to
northeast pushing fragments of low-level moisture across the
region. . Afternoon development should be focused over the
interior and western sections of Puerto Rico.

On Tuesday to Wednesday, a building high pressure located in the
northeastern Atlantic will carry some low-level moisture across
the region. This moisture in combination with the local effects
can result in more shower activity across the main island,
especially in the afternoon hours due to the diurnal heating. For
the U.S. Virgin Islands, some passing showers still possible in
the morning hours. For Thursday, GFS model guidance suggest
a little less moisture across the region, that said, less chance
of shower activity could be possible.


&&

.AVIATION...
Sct SHRA expected across eastern PR and the northern
USVI through at least 08/14z, resulting in VCSH mainly across
TJSJ/TIST. SHRA expected across interior and northern PR as well as
across the northern USVI from 07/16z through 08/23Z. This will
result in VCSH across TJMZ/TJBQ/TJSJ/TIST. MVFR conditions will be
possible if SHRA affect the terminal sites. Winds will be from the E-
ENE below 10 kts through 08/12z, increasing to 12 to 18 kts with sea
breeze variations after 08/14z.


&&

.MARINE...
Across the regional waters, seas between 4 to 6 feet across the
Atlantic waters. Therefore, small craft operators should
exercise caution especially over the Atlantic waters and Mona
passage. Over the Caribbean waters, seas between 2 to 5 feet are
expected. A slowly weakening frontal boundary will aid in
maintaining showers mainly across portions of the nearshore
Atlantic waters and local passages.


expected to
continue for the next few days with winds up to 10 knots or less.
There is a moderate risk of rip currents at north- facing beaches,
with generally low risk elsewhere.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 85 76 90 76 / 50 50 40 20
STT 86 76 84 77 / 50 40 20 10

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
402 AM AST Thu Apr 9 2020

.SYNOPSIS...Residual moisture from a weakening frontal boundary
lifting northward away from the area will result in a few showers
during the morning hours across portions of northeast and eastern
Puerto Rico and the northern USVI followed by afternoon
convection across interior and northern portions of Puerto Rico. A
benign weather pattern is then expected on Friday and through the
upcoming weekend as a ridge aloft builds overhead and the low-
level moisture erodes, resulting in mainly fair weather conditions
with very limited shower activity.

&&

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

Lingering low-level moisture associated with a departing frontal
boundary will remain over the area for today. In the morning
hours, a few showers are possible across northeastern and eastern
sections of Puerto Rico as well as the northern USVI. For the
afternoon hours, convection along the interior and northern
sections of Puerto Rico could result in ponding of water on
roadways and in poor drainage areas. Also, once again the
afternoon convection will be slow moving due to very light low-
level wind flow. Therefore, the potential exists for urban and
small stream flooding during the afternoon hours in isolated areas
with the heaviest showers.

On Friday and Saturday, conditions are expected to improve due to
a drier mass moving over the region. This will result in less
shower activity. However, some afternoon convection still
possible across northern and western sections of Puerto Rico due
to local effects. The winds will be from the south-southeast, and
thus, an increase in temperatures is anticipated in urban areas
of northern Puerto Rico with highs in the lower 90s.

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

The long term period will be characterized by a mid to upper-
level ridge that is expected to influence our local weather
pattern. Therefore, deep organized convective activity is not
expected through the period. At lower levels, a surface high
pressure is expected to move across the western Atlantic on
Sunday, switching the low-level flow to the east to east
northeast. Therefore, temperatures are expected to return to more
seasonable levels with highs in the 80s. Model guidance is
suggesting that the moisture content will be quite limited across
the area Sunday and Monday and thus, mainly fair weather
conditions can be expected with showers limited to western Puerto
Rico each afternoon due to local and diurnal effects.

Low-level moisture is expected to increase somewhat Tuesday into
early Wednesday as the aformentioned surface high pressure pushes
the remnants of a frontal boundary across the area. This may
increase the shower activity somewhat. However, given unfavorable
upper-level dynamics due to the aformentioned ridge, significant
rainfall activity appears unlikely. After the remnants of the
frontal boundary moves southwestward away from the area later
Wednesday, a drier air mass will move overhead to result in mainly
fair weather conditions once again through the rest of the work
week.

&&

.AVIATION...Isolated to scattered showers are expected for some
portions of interior and northern PR between 09/16z and 09/22z,
for that reason, VCSH are possible mainly across the TJMZ, TJSJ
and TJBQ terminal sites. Light and variable winds expected through
09/12Z, increasing to 10-15 kt from the S-SE with sea breeze
variations after 09/14z.

&&

.MARINE...Tranquil marine conditions with seas of between 2 and 5
feet are expected across the regional waters through at least the
upcoming weekend. A weakening frontal boundary will result in
areas of showers across the Atlantic waters for today. A moderate
risk of rip currents is in effect for most of the north-facing
beaches of the islands.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 76 92 77 / 40 30 20 0
STT 85 77 85 77 / 20 20 10 10

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
356 AM AST Fri Apr 10 2020

.SYNOPSIS...Mainly fair weather conditions expected across the
area today through the upcoming weekend due to limited low-level
moisture and a building ridge aloft. This ridge aloft pattern is
expected to hold through much of next week, therefore, significant
rainfall activity is unlikely. However, patches of low-level
moisture embedded in the easterly flow will result in occasional
passing showers.

&&

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

Model guidance suggest less low-level moisture across the region.
Therefore, dry and stable conditions are expected across the
region, limiting the generation of afternoon shower activity.
Southerly winds will prevail through at least Saturday. This
will generate above-normal temperatures, especially across the
urban areas of northern Puerto Rico with highs in the lower 90s
possible. Across the U.S. Virgin Islands max temps should range
in the mid to upper 80s. On Sunday, the winds shift more easterly
due to a building high pressure over the western Atlantic. Mostly
fair weather conditions are expected during the morning hours for
Puerto Rico and the U.S. Virgin islands. However, some low-level
moisture fragments can reach the region embedded in the wind
flow. Therefore, showers will develop over the western and
interior sections of the Puerto Rico during the afternoon hours.
Elsewhere, isolated showers will be possible. Rainfall
accumulations, however, should remain on the light side.

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

The ridge aloft pattern is expected to hold through much of next
week and thus, deep organized convective activity appears
unlikely. At lower-levels, a broad surface high pressure is
expected to move across the western Atlantic through early next
week. This will increase the low-level flow somewhat. This surface
high pressure will also push the remnants of a frontal boundary
across the area late Monday through Tuesday, increasing the low-
level moisture. This will result in an increase shower activity.

By mid-week, a mid to upper-level trough is expected to amplify
across the western tropical Atlantic. This feature will induce
low-level easterly perturbations, which will move westward with
the easterly trade wind flow and affect the area during the latter
half of the work week into the following weekend. This will
result in occasional passing showers with activity to be
concentrated across eastern portions of Puerto Rico and the USVI
during the overnight and morning hours followed by additional
activity across western Puerto Rico during the afternoon hours due
to diurnal heating and local effects. However, given the
unfavorable dynamics aloft, significant rainfall activity appears
unlikely.

&&

.AVIATION...VFR conds expected today with fair weather conditions.
Winds light and variable through 10/13Z, increasing to up to 10
kts from the S-SSE, with sea breeze variations developing after
10/14Z.

&&

.MARINE...Tranquil marine conditions are expected to prevail
across the regional waters through the upcoming weekend with seas
of up to 4 feet. There is a moderate risk of rip currents for the
north-facing beaches of Puerto Rico and Culebra as well as for the
northwestern beaches of Saint Thomas and the eastern beaches of
Saint Croix.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 77 91 77 / 20 0 10 20
STT 86 79 86 77 / 20 10 10 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
350 AM AST Sat Apr 11 2020

.SYNOPSIS...
Fair weather conditions are expected to prevail across the islands
for the weekend. Moisture increase by Monday with a chance of
passing showers. This pattern is expected to continue for much of
the workweek. However, no significant rainfall is expected.

&&

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

Clear skies and rain-free conditions prevailed across the local
islands during the overnight hours. The overnight low temperatures
ranged from the upper 70s at the lower elevations to the upper 60s
at the higher elevations. Winds were light and variable.

A generally fair and mainly stable weather pattern is expected to
prevail during the weekend as limited low level moisture and a
relatively flat mid level ridge prevail across the forecast area.
Model guidance suggests precipitable water between 1.00 and 1.20
inches Sat-Sun, increasing somewhat on Monday under east northeast
winds. Meanwhile, light east southeast winds will continue to
prevail across the local islands.

As a result, continue to expect locally induced afternoon showers
across the interior and west section of Puerto Rico due to sea
breeze convergence. Elsewhere, rain-free conditions to continue.The
light southerly wind flow will also promote maximum temperature in
the upper 80s along the north coast of Puerto Rico today.

The chance of passing showers will increase on Monday as low level
moisture associated with the remnants of an old frontal boundary
reaches the local islands under the east northeast wind flow.

.LONG TERM...Tuesday through Sunday...
A surface high pressure over the western Atlantic will push
fragments of clouds associated with the remnants of a cold front
over the area on Tuesday. This will result in passing showers
affecting mainly portions of the northern and eastern half of Puerto
Rico and the U.S. Virgin Islands through the day. In the afternoon,
as is usual with this pattern, the activity should be focused across
the southwestern quadrant of Puerto Rico. In the meantime, an upper
level trough will be located to the northeast of the Lesser Antilles
through much of the workweek. Although the area of best upper level
dynamics will stay well to the east of the forecast area,
perturbations at the lower levels associated with this system will
move in the area from time to time. Therefore, through much of the
long-term period, a pattern of passing showers across eastern
PR/USVI, followed by afternoon convection across western Puerto Rico
is favored. However, due to the lack of upper level support,
significant rainfall accumulations are not expected at this time.


&&

.AVIATION...VFR conds are expected to prevail at all TAF sites
during the forecast cycle. Shower development over central Puerto
Rico between 11/16z and 11/22z. Light southerly winds will continue
to prevail today with sea breezes developing aft 11/15z.


&&

.MARINE...
Tranquil marine conditions are expected to continue for the rest
of the weekend with seas below 5 feet. A northerly swell will
arrive on Monday, but seas should remain below small craft
advisory criteria. There is a moderate risk of rip currents for
the northern coast of Puerto Rico, Culebra, northwestern St.
Thomas and the eastern tip of St. Croix.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 75 89 76 / 20 20 10 40
STT 83 77 84 77 / 20 20 10 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
354 AM AST Sun Apr 12 2020

.SYNOPSIS...
Fair weather conditions are expected to prevail today, but
moisture associated with the remnants of a cold front will begin
to enter the islands during the first half of the workweek. A
pattern with patches of clouds moving in from time to time will
continue through the rest of the week.

&&

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

Fair weather conditions will prevailed through the short term
period. A surface high pressure moving eastward across the Atlantic
Ocean will promote E to ENE winds between 10 and 20 mph. Although
moisture will increase somewhat compared to yesterday`s, a few
passing showers will affect the windward sections at times. For the
afternoon, showers will develop along and to the west of the
Cordillera Central during the afternoon, as well as downwind from
the US Virgin Islands.

The remnants of a frontal boundary is forecast to stall over the
Atlantic Ocean and sink southward near the islands bringing
additional moisture and increasing the frequency of the scattered
showers Monday and Tuesday.

.LONG TERM...Wednesday through Monday...
As a mid to upper level trough continues to the east of the Lesser
Antilles, a mid to upper level ridge begins to build just over the
western Caribbean. At the surface, high pressure continues to hold
over the western Atlantic. This feature will continue to drag
fragments of moisture associated with the remnants of a cold
front over the area. In addition, the upper level trough will aid
in the development of additional patches of moisture that will be
drag by the trade winds to the local islands. This will result in
passing showers across eastern Puerto Rico and over the U.S.
Virgin Islands through the day, while additional activity should
develop across western Puerto Rico each afternoon. However, as the
mid to upper level ridge continues to take control, the dynamics
will not favor significant rainfall activity over the area.
Nevertheless, ponding of water on roadways and low-lying areas
will be possible with these expected showers.


&&

.AVIATION...VFR conditions are expected to prevail through the
forecast period. SHRA and clouds will develop along and to the west
of the Cordillera Central between 12/16-13/01z. Winds are expected
calm to light and variable until 12/13z, then will return until from
the E-ENE at 10 to 20 kt with higher gusts and sea breeze
variations.


&&

.MARINE...
Tranquil marine conditions are expected to continue today with
seas at 4 feet or less. However, a northerly swell will cause seas
to become choppy starting tonight and into Monday, increasing up
to 6 feet. Conditions will improve once again on Tuesday. There is
a moderate rip current risk for the northern coast of Puerto Rico,
Culebra, and the eastern tip of St. Croix.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 76 86 75 / 10 20 30 50
STT 87 77 86 75 / 10 20 30 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
502 AM AST Mon Apr 13 2020

.SYNOPSIS...
The trade winds will push moisture associated with an old frontal
boundary across the islands. Therefore, showers will increase in
frequency and coverage during the morning hours, followed by
locally induce convection during the afternoon hours. A jet aloft
is forecast to swing by the islands during the maximum heating
today.

&&

.SHORT TERM...Today through Wednesday....
A surface high pressure over the central Atlantic will push
fragments of clouds associated with a cold front across the islands,
as well as resulting in a moderate wind flow through the short-term
forecast period. The latest guidance indicates precipitable water
values increasing between 1.4 to 1.7 inches and that is being
confirmed by imagery from GOES-16 Total Precipitable Water product.
Under an east to east-northeast wind flow, passing showers are
expected to affect mainly portions of the U.S. Virgin Islands as
well as eastern and northern Puerto Rico through the day.
Additionally, showers are expected to develop across western Puerto
Rico in the afternoon due to a combination of available moisture and
local effects. Also, as an upper level trough digs just east of the
islands, 500 mb temperatures are expected to range between -7 to
-8 degree Celsius. This could contribute in the development of
afternoon isolated thunderstorms across western PR. Within the areas
of heaviest showers, ponding of water and minor urban and small
stream flooding will be possible.

For Tuesday and Wednesday, mid to upper level ridge will hold across
the Caribbean, resulting in less instability aloft. However, at the
lower levels, groups of clouds and showers will continue to be
carried by the trade winds across the islands, which once again will
result in nighttime and early morning passing showers across eastern
PR/USVI and afternoon convection developing across western PR. Due
to the lack of upper level support, significant rainfall activity is
not anticipated these days.

.LONG TERM...Thursday through Tuesday...
As the mid- to upper-level trough exit the Caribbean Basin, a mid-
to upper-level ridge is forecasted to build over the islands. A
mid-level high pressure will linger over the northeast Caribbean
through at least the first part of next week. At the surface,
high pressure continues to hold over the western Atlantic. This
feature will promote the advection of fragments of moisture over
the area from time to time. The aforementioned upper-level trough
will promote the development of patches of moisture that will be
drag by the trade winds to the northeast-Caribbean. Model
guidance is indicating the arrival of a drier air mass by the
first part of next week, which could bring Saharan dust particles.

&&

.AVIATION...
Mainly VFR conditions are expected to prevail across the
terminals. VCSH are expected to affect TJSJ/TIST/TISX after 12Z and
after 17Z, VCTS will be possible at TJMZ. This could result in brief
MVFR conditions due to reduced VIS. Conditions are expected to
improve after 21Z. FL050 winds will be out of the ENE at 10 to 18
knots with stronger gusts.

&&

.MARINE...
A northerly swell and moderate to locally fresh northeasterly
winds will result in choppy seas between 4 and 6 feet through at
least Tuesday. Therefore, small craft operators are urge to
exercise caution. Seas are forecast to drop below 6 feet after
Tuesday across most of the local waters.

There is a high risk of rip currents along the north-facing
beaches of Puerto Rico and Culebra. The northern beaches of the
U.S. Virgin Islands can expect a moderate risk of rip currents.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 76 87 77 / 30 40 30 40
STT 88 77 87 76 / 30 40 10 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
415 AM AST Tue Apr 14 2020

.SYNOPSIS...

Under a northeasterly wind flow, additional moisture will
continue to reach the islands through at least mid-week. A mid- to
upper- level ridge building aloft will hold throughout the week.
A dry air mass will filter from the east eroding moisture Friday
into the weekend.

&&

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

A surface high pressure located across the central Atlantic will
continue to escort patches of moisture associated with a cold front
near the islands. This system is also tightening the gradient a bit,
thus moderate to locally strong will continue through tomorrow,
especially over the waters and coastal areas. In the meantime, at
the mid-and upper levels, a trough is located to the northeast of
the lesser antilles, while a ridge extends across most of the
Caribbean Sea. This weather pattern will result in passing showers
across the eastern and northern half of Puerto Rico and U.S. Virgin
Islands during the overnight and early morning hours, followed by
afternoon convection, aided by local effects, across western Puerto
Rico. Ponding of water in roads and poorly drained areas will be
possible with the afternoon activity.

By Wednesday and Thursday, precipitable water values are expected to
range between 1.1 to 1.4 inches. Additionally, the mid to upper
level ridge will migrate toward the east, limiting the support aloft
for showers development. Nevertheless, shower activity is expected
to continue across the islands, with a similar pattern of early
showers moving over eastern and northern PR and across USVI and
afternoon convection over western PR. However, significant
rainfall accumulation is not anticipated at this time.

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

Mid-level high pressure will hold over the Caribbean Basin
through the long-term period. The migratory surface high-
pressures moving eastward over the Atlantic Ocean will induce
trade winds across the Northeast Caribbean. These feature will
promote the advection of fragments of moisture over the area from
time to time. A dry air mass with possible suspended Saharan dust
particles could arrive by the first part of next week.

&&

.AVIATION...

Mainly VFR conditions are expected to prevail across all terminals
through the forecast period. VCSH are expected after 17Z at
TJPS/TJBQ/TJMZ. These could result in brief periods of MVFR
conditions due to reduced VIS. Winds will be out of the ENE at 10
to 18 knots with stronger gusts.

&&

.MARINE...

A northerly swell will move over the Atlantic Waters and
Caribbean Passages today. Mariners can expect seas between 4 and
7 feet and east to northeast winds at 15 to 20 knots across these
waters. A small craft advisory is in effect for the Atlantic
Coastal and Offshore waters. Elsewhere, small craft operators
should exercise caution.

Seas will slowly improve Wednesday into the rest of the week.
Therefore, mariners can expect seas between 3 and 5 feet, but
local effects could increase seas up to 6 feet in some locations.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 77 88 77 / 30 40 40 40
STT 88 77 87 76 / 10 30 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
435 AM AST Wed Apr 15 2020

.SYNOPSIS...

A surge of moisture will bring showers across the windward
sections followed by afternoon convection over the southwest
quadrant of Puerto Rico and downwind from the U.S. Virgin Islands
today. A ridge system aloft and eroding moisture will result in a
fair-weather pattern the second half of the week into next week.
However, fragments of low-level moisture with clouds and showers
will reach the islands at times.

&&

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

A surface high pressure located across the central Atlantic will
continue to bring patches of moisture for the next few days. The SFC
high pressure will keep a moderate easterly wind flow across the
local area, turning slightly ENE on Friday. Meanwhile, a strong high
pressure is present in the mid levels, and in the upper levels, the
local islands are under a ridge, but an upper trough will be to our
east. That said, we should be in the subsident side of the upper
trough. This weather pattern will result in passing showers across
the eastern and northern sections of Puerto Rico and across the U.S.
Virgin Islands in the overnight and early morning hours each day,
followed by locally induced afternoon convection across western and
central PR due to local effects. Minor urban and small stream
flooding is possible with the afternoon activity, especially this
afternoon and Thursday afternoon. Some patches of moisture are also
expected on Friday, but not as deep as expected today and Thursday.

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

Mid-level high pressure will hold over the Caribbean Basin
sustaining a trade wind inversion through the long term period.
Trade winds will bring fragments of moisture across the Northeast
Caribbean from time to time through at least Saturday.

A surface low pressure with an associated cold front will move
into the western Atlantic on Saturday, weakening the local
pressure gradient and inducing a southerly wind flow across the
islands by the end of the weekend. Maximum temperature will
increase mainly across the northern sections of the islands. Model
guidances continues to indicate a dry air mass with suspended
Saharan dust particles arriving Monday through Thursday of next
week. However, the advection of fragments of moisture will result
in occasional periods of clouds and showers over the islands.

&&

.AVIATION...
Mainly VFR conditions are expected to prevail across
all terminals through the forecast period. However, VCSH are
expected for the USVI, TJSJ, and TJPS in the morning, but then in
the afternoon the SHRA activity may be around TJMZ and TJPS. SHRA
could affect the TJMZ terminal, causing brief MVFR conds. Winds will
be from the east at around 10-15 knots with occasional gusts and
sea breeze variations.

&&

.MARINE...

Mariners can expect seas up to 6 feet across the Atlantic and
Caribbean Offshore waters and the Anegada Passage. Small craft
operators should exercise caution across these waters. Elsewhere,
seas will slowly improve today into the rest of the week.
Therefore, mariners can expect seas between 2 and 5 feet and
easterly winds around 15 knots, but local effects could increase
seas and winds up to 6 feet and 20 knots, respectively, in some
locations.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 77 88 77 / 30 40 40 30
STT 88 77 87 76 / 10 30 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
437 AM AST Thu Apr 16 2020

.SYNOPSIS...Fair weather conditions under a generally moderate to
locally fresh easterly wind flow will prevail across the region
through most of the forecast period. However, fragments of low-
level moisture embedded in the trades will enhance shower activity
from time-to- time. The best chance for shower activity is
expected this afternoon, and then on Saturday and the second part
of next week. In the meantime, elevated to critical fire danger
conditions can be expected across the southern coastal plains of
Puerto Rico.



&&

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

A surface high pressure located across the central Atlantic will
continue causing a moderate easterly wind flow for the next few
days. Patches of moisture will continue to move in for the next few
days, but it looks like less moisture will be affecting the local
area on Friday, though moisture increases once again for Saturday. A
strong high pressure is present in the mid levels, and in the upper
levels, the local islands are under a ridge, but an upper trough
will be to our east through Friday, flattening by Saturday. This
weather pattern will result in passing showers across the eastern
and northern sections of Puerto Rico and across the U.S. Virgin
Islands in the overnight and early morning hours each day, followed
by locally induced afternoon convection across western and central
PR due to local effects, with Friday having the less activity than
today or Saturday. Minor urban and small stream flooding is possible
with the shower activity expected in the afternoon hours, especially
this afternoon and Saturday afternoon.



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

A surface high pressure lingering across the north Atlantic will
maintain a generally moderate to locally fresh east-southeast
wind flow across the region through at least midweek. Then, winds
are forecast to turn more from the east-northeast as a pre-frontal
trough approaches the region by the end of the workweek. Overall,
a mid-level ridge and unfavorable conditions aloft will not
support widespread nor deep convective development during the
long-term forecast period. However, fragments of low-level
moisture embedded in the trades will enhance shower activity from
time-to-time. This activity will be in the form of overnight and
early morning showers moving across the US Virgin Islands and
eastern Puerto Rico, followed by locally induced showers
developing across the interior and western portions of the islands
each afternoon. Streamer-like showers downwind from the local
islands and El Yunque cannot be ruled out each afternoon. So far,
models suggest that the best chance for showers can be expected by
the end of the workweek with arrival of the pre-frontal trough,
enhanced moisture content with the remnants of an old frontal
boundary, and somewhat improved conditions aloft.


&&

.AVIATION...Mainly VFR conditions are expected to prevail across
all terminals through the forecast period. However, VCSH are
possible across the USVI, and TJSJ in the morning, but then in the
afternoon the SHRA activity may be around TJMZ and TJPS. SHRA could
affect the TJMZ terminal, causing brief MVFR conds. Winds will be
from the east at around 10-15 knots with occasional gusts and sea
breeze variations.


&&

.MARINE...Tranquil marine conditions with seas at 5 feet or below
and generally easterly winds up to 15 knots are expected to
prevail across the local waters during the next few days. A
moderate risk of rip currents will continue for beaches along the
north coast of Puerto Rico, Culebra, Saint Thomas and Saint Croix.


&&

.FIRE WEATHER...Recent KBDI observations continue to support a
drying trend across fire-prone areas of southern Puerto Rico,
particularly around the Camp Santiago area with a value of 656.
Under a moderate to locally fresh east-northeasterly wind flow
forecast to peak around 15-18 mph with higher gusts, relative
humidity is expected to drop into the low to mid 40s by late
morning into the early afternoon hours. Given the expected
weather pattern and recent soil/vegetation observations, a Fire
Danger Statement has been issued due to elevated fire danger
conditions expected for today.


&&

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

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
433 AM AST Fri Apr 17 2020

.SYNOPSIS...

Atmospheric conditions will continue to produce fairly calm weather
across the region. Though no major weather systems such as fronts or
tropical waves are expected, occasional patches of moisture will
move in and induce scattered showers. These showers are mostly not
expected to be very impactful, though Saturday does have the
potential for water ponding on roadways and even some localized
flooding. Marine conditions will be quite tranquil, with wave
heights generally below 5 feet.


&&


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

A surface high pressure located across the central Atlantic will
persist over the area, while another SFC high pressure moves into
the western Atlantic. This will cause a moderate easterly wind flow
for the next few days. Near normal moisture is expected today, but a
patch of deeper moisture will move in on Saturday, while near normal
moisture returns on Sunday. A strong high pressure is present in the
mid levels, and the local islands are under an upper level ridge,
which is keeping the weather conditions relatively stable, but the
low level moisture will cause scattered showers across the eastern
and northern sections of Puerto Rico and across the U.S. Virgin
Islands in the overnight and early morning hours each day, followed
by locally induced afternoon convection across western and central
PR, as well as some areas in the San Juan metro due to local
effects, with less shower activity expected today and Sunday than on
Saturday. Ponding of water on roadways and poor drainage areas are
possible this afternoon and on Sunday, but for Saturday afternoon,
urban flooding is possible as more moisture and rainfall is
expected.


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

A fairly typical weather pattern for this time of year will
continue into this next workweek, with high surface pressure
dominating the central and eastern Atlantic for essentially the
full week. This will result in moderate to fresh easterly winds
across the region. At mid- to upper- atmospheric levels, a ridge
of high pressure will reside to our west all next week, which will
create subsiding and warming air over us. This leads to stable
and dry conditions aloft, with an inversion plainly manifest in
model soundings all next week. Given the above atmospheric
conditions, not much in the way of impactful weather is expected.
Patches of moisture will ride in on the easterly winds, giving
rise to occasional periods of scattered showers, and the timing of
those patches in near impossible to predict at this point. Some
impactful weather is possible if one of these patches arrives
during the optimal time of peak heating, which could create
showers that may lead to water ponding on roadways and in poor
drainage areas. Though it is tough to say at this point, it does
appear that Monday looks drier than later in the week. A decent
patch of moisture is projected to move in sometime Tuesday. Then
a cold front will pass to our north on Thursday and Friday, and it
may help increase the prevalence of moisture across the region.

&&


.AVIATION...

Mainly VFR conditions are expected to prevail across
all terminals through the forecast period. However, VCSH are
expected across the USVI and TJSJ in the morning, but then in the
afternoon the SHRA activity may be around TJMZ, TJBQ and TJPS. SHRA
could affect the TJMZ terminal, causing brief MVFR conds. Winds will
be from the east at around 10-15 knots with occasional gusts and sea
breeze variations.

&&


.MARINE...

Marine conditions are forecasted to be quite calm during the next
several days with seas of up to 5 feet and winds up to 15 knots. No
significant swell and/or wind event is expected during the next week
that would meet small craft advisory criteria. A moderate risk of
rip currents will continue for most of the north and east-facing
beaches of the islands through Friday.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 75 88 76 / 20 20 40 40
STT 88 76 86 77 / 20 30 30 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
431 AM AST Sat Apr 18 2020

.SYNOPSIS...Surface high pressure is expected to prevail across
the Atlantic waters through the weekend, but a surface low will
move into the western Atlantic, causing the local winds to become
east southeast by tonight and prevailing into Sunday, becoming
mainly easterly on Monday once again. High pressure in the mid
levels will maintain a sable atmosphere, but patches of higher low
level moisture will move in and combine with the local effects to
cause afternoon hours over portions of Puerto Rico, while the
USVI should observe mainly fair weather with brief isolated to
scattered showers. This particular weather pattern is expected for
the next several days.


&&

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

Today is expected to be more active compared to the past few days. A
surface high pressure is currently located across the central
Atlantic and headed eastward, while another surface high is moving
into the western Atlantic. This will cause a moderate easterly wind
flow for the next few days. Though no major weather systems such as
fronts or tropical waves are expected in the short term, a decent
patch of moisture will move in today, arriving right in time for the
hours of peak solar heating. This optimal timing will help to drive
scattered to numerous showers across the region for today. Showers
are forecast to move into the USVI and eastern Puerto Rico this
morning. Then as this moisture continues westward, showers will
develop over west to northwest Puerto Rico, and also in the metro
area of San Juan in the afternoon hours. Atmospheric conditions are
not expected to be overly favorable for lightning given the large
inversion at mid-levels and plenty of dry air in place, though a few
lightning strikes cannot be ruled out. The biggest threat is the
potential for localized flooding in the aforementioned areas in the
afternoon under persistent showers. These showers will slow down
into the evening hours.

Sunday and Monday appear less favorable for impactful showers. Less
moisture will be in place, and there will still be lots of dry air
aloft as well as the mid-level inversion. Showers are still likely
again Sunday and Monday for the San Juan metro area and western
Puerto Rico in the afternoon hours. A tropical wave will pass to our
south on Monday with no impact to our region.

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

Mainly stable weather is expected in the long term forecast. There
will be a high pressure in the mid and upper levels through the
period and most of the moisture will be limited to the lower
levels. At the surface, a high pressure will dominate the local
wind pattern, so mainly moderate easterly winds are expected.
Therefore we can expect near normal temperatures with isolated to
scattered showers across the local waters, USVI, and eastern PR
during the night time and early morning hours, while locally
induced showers can be expected across western PR and other areas
of sea breeze convergence or downstream the local islands or the
Luquillo Mountain Range.


&&

.AVIATION...Mainly VFR conditions are expected to prevail across
all terminals through the forecast period. However, VCSH are
expected across the USVI and TJSJ in the morning, and then in the
afternoon the SHRA activity is possible around TJMZ, TJBQ and TJSJ.
Brief MVFR conds are possible with these showers. Winds will be from
the east at around 10-15 knots with occasional gusts and sea breeze
variations.

&&

.MARINE...Tranquil marine conditions, perhaps slightly choppy
seas of 5 feet or less expected today. Seas could be choppy and
up to 6 feet on Sunday. The local winds will be mainly at around
10-15 knots with occasional gusts from the east to ESE by tonight.
For today, there is a moderate risk of rip currents for northern
PR, Culebra and eastern Vieques, as well as the beaches of
northern and eastern Saint Croix. There is a low risk of rip
currents elsewhere.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 75 90 78 / 30 20 20 20
STT 87 77 87 78 / 20 20 20 30

[cycloneye]

Area Forecast Discussion...CORRECTED
National Weather Service San Juan PR
629 AM AST Sun Apr 19 2020

.SYNOPSIS...Surface high pressure is expected to prevail across
the western Atlantic waters today, but a surface low will move
into the western Atlantic on Monday. However, a surface high
pressure will spread through the central Atlantic once again on
Tuesday. Easterly wnds are expected to prevail across the local
area for the next several days. High pressure in the mid levels
will maintain a stable atmosphere, but patches of low level
moisture will move in at times and combine with the local effects
to cause afternoon hours over portions of Puerto Rico, especially
western Puerto Rico; whereas the USVI should observe mainly fair
weather with brief isolated to scattered showers. This weather
pattern is expected for the next several days.

&&

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

After a fairly active day of shower activity yesterday, drier air is
moving into the region that will help to calm things down for today.
A ridge of high pressure currently resides at mid to upper levels
over the Caribbean. This ridge will contribute to warm and dry air
aloft, which is plainly seen in model soundings. A mid-level
inversion will remain in place for the short term forecast, that
will suppress chances for strong showers.

Despite these conditions, there will still be shower activity over
the next few days as patches of moisture move in on the easterly
trade winds. Today looks fairly quiet, with only a chance for
showers over western Puerto Rico in the afternoon. These showers
will be weaker and more isolated than what was observed
yesterday. Tomorrow and Tuesday, two separate patches of moisture
are expected to arrive around mid-day for both days. With the
combination of moisture moving in during the hours of peak solar
heating, more showers are expected for those days compared to
today. Dry and warm air aloft will keep these showers from being
very impactful, but it is possible that persistent showers lead to
some ponding of water over roadways and in areas of poor
drainage.

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

Mainly stable weather continues to be expected in the long term
forecast. There will be a high pressure in the mid and upper
levels through the period and most of the moisture will be limited
to the lower levels. At the surface, high pressure systems will
dominate the local wind pattern, although a few surface low
pressure systems will move into the western Atlantic, and slightly
shift the local winds to a more ESE direction, mainly moderate
easterly winds are expected. Therefore expect near normal temperatures
with isolated to scattered showers across the local waters, USVI,
and eastern PR during the night time and early morning hours,
while locally induced showers can be expected across western PR
and other areas of sea breeze convergence or downstream the local
islands or the Luquillo Mountain Range, which would affect
portions of the San Juan Metropolitan area.


&&

.AVIATION...Drier conditions will prevail today, so VFR conditions
are expected at all terminals during the forecast period. One
exception is TJMZ where VCSH is possible in the afternoon. Winds are
expected primarily out of the east at 5 to 15 kts with sea breeze
variations.


&&

.MARINE...Tranquil to slightly choppy marine conditions are
expected for the next several days with wave heights of 3 to 5
feet in the forecast. The local winds will be mainly from the
east at 10 to 20 knots for the next few days. There is a moderate
risk of rip currents for northern PR, most of Culebra and eastern
Vieques, as well as the beaches of northern and eastern Saint
Croix, northwestern Saint Thomas and southern Saint John. There is
a low risk of rip currents elsewhere.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 77 89 77 / 30 30 20 20
STT 88 78 85 77 / 20 20 30 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
313 AM AST Tue Apr 21 2020

.SYNOPSIS...
A mid to upper level ridge will continue to hold across the
region, promoting a mainly fair weather pattern across the
islands. However, patches of moisture embedded in the trade winds
will cause brief showers interruptions from time to time. This
pattern is expected to continue through early next week, although
with stronger winds for the end of the workweek into the weekend.

&&

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

Mid to upper level ridge will hold across the region through the
most of the period to maintain fairly dry and stable conditions
aloft. Surface high pressure ridge across the north central Atlantic
will maintain an east to southeast tradewind flow across the
forecast area. Expect a moderate trade wind cap inversion to persist
across the forecast area and consequently promote mostly fair
weather conditions. Light to moderate east southeast tradewinds will
persist through the short term period. This will continue to bring
shallow patches of low level moisture with a few embedded showers
across the region from time to time. The overall weather pattern
will therefore limit moisture pooling and only favor brief periods
of passing showers, mostly of light to moderate intensity each
morning along some of the coastal areas. This will be followed by
locally and diurnally induced afternoon showers. The shower activity
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 where a brief showers cannot be ruled out. Some of
the heavier rain-showers may lead to ponding of water on roadways
and in poor drainage area in isolated areas. Mostly sunny to partly
cloudy skies and fair weather conditions should prevail elsewhere
and across the U.S. Virgin Islands.

Significant and persistent rainfall is not anticipated over the
islands during the period, except for the passing morning showers,
followed by the diurnally induced afternoon showers in isolated
areas. However, the best potential for afternoon convection will be
on Wednesday and Thursday when a weak easterly perturbation and
a surge of shallow moisture will cross the region.

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

High pressure at all levels will continue to hold over the
Atlantic ocean through much of the long-term forecast period. The
surface feature will tighten the pressure gradient over the
eastern Caribbean resulting in increasing winds through the
weekend. Otherwise, a mainly tranquil weather pattern is expected
to prevail, with precipitable water values forecast to remain at
0.9 to 1.2 inches through Monday. However, patches of moisture
embedded in the trade winds will continue to arrive to the area,
causing passing showers across eastern Puerto Rico and the U.S.
Virgin Islands. In the afternoon hours, as is usual with this
pattern, additional activity is expected to develop over western
Puerto Rico. Since moisture is expected to be trapped at the lower
levels due to the mid-level high, significant rainfall activity
is not anticipated. By Tuesday and Wednesday, the latest guidance
are showing an increase in moisture as an easterly disturbance
reaches the area, that should increase the chance of showers over
the islands.

&&

.AVIATION... VFR durg prd. SCT ocnl BKN lyrs nr FL028...FL050
en route btw islands and ovr regional waters with Isold SHRA til
21/14Z. VCSH at TJBQ/TJMZ/TJSJ btw 21/17Z-21/22Z. SFC wnds lgt/vrb
AT 5 kts or less, bcmg 10-15 kts with sea breeze variations aft
21/14Z.

&&

.MARINE...
Seas up to 5 feet with winds mostly at around 15 knots are
expected across the local waters. A northerly swell will arrive
later today, but seas should remain below small craft advisory
criteria. A moderate rip current risk continues for the northern
coast of Puerto Rico and Culebra, and for a few beaches at Vieques
and the U.S. Virgin Islands.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 76 90 77 / 30 30 40 30
STT 81 77 82 78 / 30 40 40 40