Caribbean - Central America Weather

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
505 AM AST Thu Mar 12 2020

.SYNOPSIS...High pressure continues over the Atlantic waters and a
weakening front to the north continues to be a source of clouds
and scattered showers. On Friday low pressure will develop at
lower levels to the northeast of the area and will cause flow to
become northeasterly here. This will send patches of moisture
across the area through much of next week, with night and early
morning showers in the northeast portion of Puerto Rico and
afternoon showers in the south and southwest when sufficient
moisture exists. The islands to the east will generally see
seasonal temperatures and isolated showers.

&&

.SHORT TERM...Thursday through Saturday...
A mid to upper level trough will continue to hold over the
eastern Caribbean through the end of the workweek. On Thursday,
however, dry air is expected to filter in at the mid-levels. In
fact, the latest estimates from GOES- 16 Total Precipitable Water
satellite product shows an area of precipitable water as low as
1.0 to 1.1 inches just to the southeast of the forecast area,
while the guidance are suggesting values of about 1.2 to 1.3
inches. This will translate to a reduction in rain activity
across the area, although a few showers carried by the trade winds
could still move over portions of eastern Puerto Rico and the
U.S. Virgin Islands, especially in the morning hours. However, in
the afternoon, due to local effects, showers should develop over
the northwestern quadrant of Puerto Rico. Additionally,
temperatures at 500 mb are expected to be at around -10 degree
Celsius and since the trough will provide some instability aloft,
isolated thunderstorms cannot be ruled out.

Moving into Friday, moisture increase at the mid-levels once again,
with precipitable water values climbing back to 1.6 inches. Also,
with the axis of the trough at the mid to upper levels closer to
the area, conditions will become more favorable for enhance shower
activity over the area and isolated thunderstorms. The heaviest
activity is expected across the interior and western Puerto Rico
during the afternoon hours, but additional activity will also be
possible over eastern Puerto Rico, including the San Juan metro
area. Urban and small stream flooding will be possible as well.

On Saturday, the upper level trough will begin to move toward the
east, while at the surface and the induced trough at lower levels will
shift the winds from the northeast, with drier air anticipated.
However, small patches of moisture may bring passing showers over
the islands.

.LONG TERM...Sunday through Thursday...
The upper level trough that has been hanging around for several
days will pass through on Saturday and a second weaker trough
will move through on Tuesday. Although the flow aloft will turn
to the northwest after the trough passage on Saturday it will
quickly become westerly late Sunday and continue through Thursday.

The lingering trough aloft will be instrumental in the continuing
development of an area of low pressure to the northeast of the
area at low and mid levels. This low will also have a northeast
southwest oriented trough that will pass just to the southeast of
the area that will cause mid and lower level flow to become
northeasterly and remain so for the rest of the period.

Air to our northeast is cooler and the lower levels will have
patches of moisture that will drive showers across the area for
much of the period. The NBM and the GFS are at extreme odds with
each other as to the probabilities of precipitation during this
period with the NBM forecasting 70-90 percent chances of rain and
the GFS dipping even into the single digits. Drier air will
certainly enter into the forecast area at 700 mb and cause shower
activity to diminish in quantity and intensity, but low level
moisture should not completely disappear and fragments of moisture
are expected to break off of the showers around the low pressure
to the northeast and ride across the forecast area. Expect these
fragments to result in minor but persistent passing showers--
mainly over Puerto Rico. Moisture from the fragments will also
cause shower activity in the south and southwest around the
Cordillera Central to occur if moisture patches coincide with
afternoon heating. On Thursday 500 mb temperatures may again
return to minus 9 degrees, but moisture will be limited,
nevertheless an isolated thunderstorm cannot be ruled out then.

&&

.AVIATION...VFR conditions are expected to prevail through 12/16Z
across all terminals. After that, VCSH and VCTS could cause brief
reductions in VIS to MVFR conditions across TJMZ/TJBQ,
respectively, until 12/22Z. Winds at FL050 will be out of the ESE
at 10 to 16 knots. Maximum winds WSW 75-85 knots btwn FL330-470, .
diminishing after 12/15Z.

&&

.MARINE...Seas have now been mainly driven by winds. These winds
are now tapering off. The outer buoy was running 20 to 22 knots
earlier this morning, but is now generally below 20 knots. Seas
there have come down a foot from the 12 feet they were earlier. At
the inner buoy winds are considerably lower and seas have just
dropped below 7 feet. Models have been fairly consistent in
bringing all seas in the local forecast area to below 7 feet by 2
AM AST tomorrow, (Friday). A new set of northeasterly swell will
enter the area Saturday night, but seas will scarcely rise above
7 feet early next week.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 85 74 84 75 / 40 50 40 40
STT 84 74 83 73 / 20 30 30 40

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
501 AM AST Fri Mar 13 2020

.SYNOPSIS...A weak low forming northeast of the forecast area
induced by the passage of a long wave upper trough today will
cause north to northeast flow to persist through much of the next
week. This will bring some intermittent shower activity to the
islands with the best rainfall on the windward slopes and the
northern U.S. Virgin Islands. A second, though weaker upper level
trough will cause a similar enhancement of shower activity
Thursday and Friday of next week.

&&

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

A mid to upper level trough with its axis located just west of
the islands will continue to provide instability aloft on Friday.
At the surface, moisture associated with an inverted trough to the
northeast will begin to advance into the region. Groups of clouds
and showers are expected to move across portions of eastern
Puerto Rico and over the U.S. Virgin Islands during the morning
hours, with isolated thunderstorms possible over the waters. In
the afternoon, due to a combination of local effects, the
available moisture and the instability, showers are expected to
develop across the interior and western Puerto Rico, with
additional activity possible near the San Juan metro area.
Additionally, 500 mb temperatures will remain at -10 to -9
degrees, hence, expect isolated thunderstorms to develop as well.
And, in fact, thunderstorms have been active in the outer Atlantic
waters north of Isabela and Camuy early this morning. Afternoon
shower activity could be heavy at times and urban and small
stream flooding will be a possibility across western Puerto Rico
and in the Greater San Juan Metropolitan Area. As the inverted
trough begins to transition into a closed low northeast of the
islands late today, winds are expected to become more northeast.
The lingering shower activity could then shift southward, into
southwestern Puerto Rico later in the afternoon hours.

For the weekend, instability will decrease as the mid to upper level
trough moves toward the central North Atlantic. At the lower levels,
the northeast flow will persist, promoting a cool advective pattern
that will favor early shower generation, affecting the northern
sections of Puerto Rico and the U.S. Virgin Islands, while afternoon
convection should develop over the southwestern quadrant of the main
island. On Sunday, however, drier air is expected to filter in at
the lower levels, with precipitable water values forecast to drop
between 0.8 to 1.0 inches. As a result, expect mainly fair weather
conditions, with only occasional showers affecting the islands
during the overnight and early morning hours.

.LONG TERM...Monday through Saturday...
With the upper level trough now nearly dissipated and a long wave
trough well to our north, the low pressure that was well defined
to the northeast will open up and become an open wave that passes
through the area on Wednesday. By Friday another relatively
intense short wave will deepen as it moves through Hispaniola and
enhance shower formation and the possibility of thunderstorms.

High pressure at the surface Thursday and Friday will bring back
more northeasterly flow and the pattern of showers seen early in
the week. Currently the best moisture of the week is expected on
Thursday, but may also be repeated on the following Saturday.

&&

.AVIATION...Mainly VFR conditions are expected to prevail across all
terminals. VCSH are expected after 13/17Z at TJSJ and VCTS are
psbl aft 13/16Z, which could result in brief reduction in VIS and
MVFR conditions at these terminals. Winds will be out of the east
at 10 knots, shifting to the northeast by 14/00Z. Maximum winds
WSW 70-80 kts btwn FL380-470.

&&

.MARINE...Seas will continue to diminish today and Saturday, but seas
up to 7 feet are expected to reappear Saturday night in the outer
Atlantic waters as waves generated by winds around a developing
low to the northeast arrive in the local area.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 85 74 83 73 / 20 40 40 40
STT 83 73 84 72 / 30 30 30 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
519 AM AST Sat Mar 14 2020

.SYNOPSIS...A weak surface low-pressure developing northeast of
the area along with a surface high pressure along across the
southwestern Atlantic will promote a northeasterly wind flow
throughout the weekend. Low-level moisture embedded in the
northeasterly flow will affect the area from to time during the
weekend with areas of showers. The moisture remnants of the weak
surface low pressure will move southwestward and over the area
during the first half of the work week with an increase in shower
activity. Windier conditions are expected during the latter half
of next week as a broad surface high pressure moves across the
Atlantic basin.

&&

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

Scattered showers affected much of the northern to eastern half of
Puerto Rico during the overnight hours. Moderate to brief heavy
showers were observed with this activity and rainfall accumulations
ranged between a quarter to three quarters of an inch, mainly over
northeastern PR. Elsewhere, partly cloudy skies prevailed and
minimum temperatures were between the mid 60s to low 70s.

A mid to upper level low northeast of the region is inducing a
surface trough across the northeastern Caribbean. This trough is
forecast to close into a weak surface low later this morning. The
weak low and a building surface high pressure over the southwestern
Atlantic, will promote moderate to strong northeasterly trade winds
across the islands through the weekend. This will also favor a cool
advective pattern, with passing trade wind showers moving at times
across the northern sections of PR and across the USVI during the
night/early morning hours. As the steering winds will be from the
northeast, expect afternoon showers to develop mainly along the
Cordillera Central and over southern PR. Although the area will
remain on the convergent side of the upper low, models suggest that
500MB temps will continue today between -7 to -9 degrees C and
gradually warming to around -5C on Sunday and Monday. Therefore,
isolated thunderstorms are possible this afternoon. The low is
forecast to open into a trough while sinking to the southwest later
on Monday, this will gradually increase low level moisture and
shower activity from the Atlantic waters and across the USVI and
northern sections of PR.

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

Low-level moisture associated with the remnants of the
aformentioned surface low pressure will move over the area on
Tuesday through early Wednesday in northerly flow. This will help
produce scattered shower activity across the northern and eastern
half of Puerto Rico as well as the USVI with additional activity
across southern Puerto Rico during the afternoon hours. Mid to
upper-levels are not expected to be particularly favorable for
any organized convective activity that will produce significant
rainfall accumulations as the area will be located on the
subsident side of a mid to upper-level ridge, which will be
located over the western Caribbean basin.

By Thursday, a broad surface high pressure will be moving off the
northeastern coast of the United States and into the Atlantic
basin. This feature will result in a tightening of the local
pressure gradient and as a result an increase in the winds from
the east northeast is expected through Saturday. These brisk east
northeast winds will also transport patches of low-level moisture
into the region. At upper-levels, a shortwave trough will be
located near Hispanola. Therefore, the combination of the
increased low-level moisture and the short-wave trough at upper-
levels could help to enhance somewhat the shower activity over the
area Thursday through Saturday.

&&

.AVIATION...Mainly VFR conditions are expected to prevail across all
terminals during the next 24 hours. However, tempo MVFR conds are
possible from 17z-23z at TJPS due to TSRA/SHRA. At TJSJ/TJBQ/TIST,
trade wind SHRA could cause brief MVFR cigs at times. ENE winds
expected at 10-15 kt, increasing this evening with higher gusts
across the northern PR terminals.

&&

.MARINE...Choppy seas of up to 6 feet are expected the Atlantic
waters and Mona Passage with 5 feet or less expected elsewhere
through this evening. Hazardous seas of up to 7 feet are expected
once again across the offshore Atlantic waters starting this
evening. This is due to the combination of a weak northeasterly
swell and increasing northerly winds from a developing surface
low pressure northeast of the area. For beachgoers, there is a
high risk of rip currents for the north-central to northwestern
beaches of Puerto Rico today with a low to moderate risk expected
elsewhere. The high risk of rip currents will extend to the rest
of the northern beaches of Puerto Rico by this evening and
continuing through at least the early part of next week.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 83 72 81 73 / 50 50 30 30
STT 83 74 81 73 / 50 30 20 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
405 AM AST Sun Mar 15 2020

.SYNOPSIS...Fair weather conditions are expected today as a drier
air mass moves overhead. An increase in shower activity is
expected during the first half of the work week as the moisture
remnants of a surface low-pressure, currently located northeast of
the region, moves across the area. Windier conditions with trade wind
showers are expected during the latter half of the work week as a broad
surface high pressure moves across the Atlantic basin.

&&

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

A surface low northeast of the region and a weak surface high over
the southwestern Atlantic will continue to promote breezy northeast
trades across the islands today. Gusty winds between 25-30 mph are
possible through the day, mainly across the northwestern coastal
areas of Puerto Rico. A mid level ridge over the Gulf of Mexico
extends into the western Caribbean, this ridge will gradually build
into the long term period and promote drier air intrusion and stable
conditions aloft. A mid to upper level low, currently northeast of
the Leeward Islands is forecast to open to a trough and move further
into the central Atlantic by Monday. As this weather pattern
evolves, the surface low is forecast to also open into a trough
while gradually sinking to the southwest and moving across the
islands from Monday through Tuesday. This will cause shower activity
to increase across the islands on both days. Lacking any upper level
support, thunderstorms are not expected, but periods of moderate to
locally heavy rainfall cannot be ruled out as the trough moves
across the area.

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

The moisture remnants associated with the aformentioned surface
low pressure will continue to produce scattered shower activity
across the area on Wednesday. Showers can be expected across
northern and eastern portions of Puerto Rico and the northern USVI
during the morning hours followed by additional development across
western Puerto Rico during the afternoon hours as the available
moisture combines with strong daytime heating and local effects.
However, given that the conditions aloft are expected to remain
hostile to any organized convective activity due to subsidence
from a ridge that will be located over the Western Caribbean,
significant rainfall accumulations are not expected.

By Thursday, a broad surface high pressure will move from the
northeastern United States into the Atlantic basin. This feature
will be tightening the local pressure gradient, resulting in an
increase in the low-level winds from the northeast. At the same
time, patches of low-level moisture will also be moving over the
area to result in passing trade wind showers. The same weather
pattern looks to repeat itself on Friday. A decrease in the
overall shower activity looks to be on tap by next weekend as a
drier air mass from the northeast advects over the region,
resulting in mainly fair weather conditions.

&&

.AVIATION...Mainly VFR conditions are expected to prevail across all
terminals during the next 24 hours. However, -SHRA is expected to
develop in and around TJPS btw 17z-23z, causing brief MVFR cigs.
Northeast winds will continue around 15 kts with higher gusts at
times, sea breeze variations are expected across southern PR after
14z.

&&

.MARINE...Choppy and rough seas can be expected across most of the
regional waters through the early portion of the work week. This
is due to the combination a short Dominant period northeasterly
swell and moderate to locally fresh northerly winds from a surface
low-pressure located northeast of the area. Seas of up to 7 feet
are expected across the Atlantic waters and Mona passage, where
small craft advisories are in effect. Seas of between 3 and 6
feet are expected elsewhere. For beachgoers, there is a high risk
of rip currents for the northern of beaches of Puerto Rico as
well as for Culebrita Beach in Culebra. A low to moderate risk of rip
currents is expected elsewhere.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 81 72 82 74 / 20 30 50 50
STT 84 73 84 76 / 10 30 50 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
448 AM AST Mon Mar 16 2020

.SYNOPSIS...Surface low to our northeast will open into a trough
and move across the region from late Monday through Tuesday.
Another pulse of low level moisture moves from the east on
Wednesday. At least through Friday, shower activity will focus
across the northeastern sections of PR and across the USVI during
the overnight/morning hours, followed by afternoon showers over
southwestern PR. Breezy conditions are expected to return during
the latter part of the week due to building surface high over the
western Atlantic.

&&

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

A surface low pressure located northeast of the area will
continue to generate a northerly wind flow for today. This
northerly flow will push low-level cloud fragments across the
area and generate isolated to scattered shower activity across
portions the area. These showers are expected to be brief with
only minor accumulations expected. The areas with the highest
probability of observing these showers will be across northern and
eastern portions of Puerto Rico and the USVI.

The surface low pressure is expected to degenerate into an open
trough later today and tonight while at the same time moving
southwestward through Tuesday, with the wind flow becoming more
northeasterly. This will continue to push low-level cloud
fragments with isolated to scattered shower activity expected
across the northern and eastern portions of Puerto Rico and the
USVI, extending into southwestern portions of Puerto Rico during
the afternoon. Once again, these showers are expected to be brief
with only light rainfall accumulations.

By Wednesday, the low-level moisture is expected to increase with
precipitable water values climbing to 1.5 inches. Therefore, an
increase in the shower activity is expected, with higher rainfall
accumulations possible. The activity will be concentrated across
northern and eastern Puerto Rico and the USVI during the morning
hours followed by additional development across southwestern Puerto
Rico during the afternoon hours.

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

A broad surface high pressure building over the western Atlantic
and into our area will promote a breezy northeasterly wind flow
from Thursday through Sunday. Embedded on this flow, fragmented
clouds and passing trade wind showers will move at times across
the islands, mainly on Thursday and Friday morning. A long wave
trough is forecast to move over the central Caribbean through the
long term period. However, lacking any low to mid-level support
and drier air intrusion from the north, mostly fair weather
conditions are expected to prevail during the weekend and into
early next week across the islands.

&&

.AVIATION...Mainly VFR conditions expected across the area. Iso-sct
brief SHRA may result in VCSH across the local terminals, however,
no significant impacts to operations expected. Winds from the N-NNE
less than 10 kts through 16/12z, increasing to 12 to 18 kts with
higher gusts and sea breeze variations after 16/14z.

&&

.MARINE...Small craft advisories remain in effect for the
Atlantic waters and for the Mona passage through Tuesday
afternoon. Seas between 5-7 feet and occasionally up to 9 feet are
expected across these waters. Elsewhere, seas should range between
3-6 feet. The surface low northeast of the region that is
generating the small swell and breezy(15-20 kts) northerly winds,
will gradually open into a trough and move across the region
between Tuesday and Wednesday.

Seas and winds will decrease briefly as the trough moves across
the regional waters, but a building surface high over the western
Atlantic will increase winds(20-25 kts) and seas once again from
Thursday night and through the weekend. A high rip current risk is
in effect through Tuesday for the northern beaches of Puerto
Rico.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 81 74 83 74 / 50 40 50 50
STT 84 75 84 74 / 50 40 40 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
407 AM AST Tue Mar 17 2020

.SYNOPSIS...A surface trough will move across the region later
today and through Wednesday. This will increase shower activity
in general across the islands. A broad surface high pressure will
promote breezy northeast winds during the second part of the
workweek and through the weekend. Drier air in the mid to upper
levels will also move over the region through at least early next
week. This should result in fair weather conditions across the
islands, with trade wind showers moving from time to time with
the breezy trades.


&&

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

A broad low-level trough located just northeast of the region will
continue to generate a northeasterly wind flow for today. This
northeasterly flow will advect low-level cloud fragments that will
generate isolated to scattered shower activity across portions of
the area. Much like yesterday, these showers are expected to be
brief with minor accumulations expected. For the morning hours,
these brief showers will be concentrated mainly across northern
and eastern portions of PR and the northern USVI. Then, during the
afternoon hours, some of these showers may extend into portions
western and southwestern Puerto Rico.

As the low-level trough axis approaches the area later tonight and
through Wednesday, the low-level moisture content is expected to
increase with precipitable water values climbing to 1.5-1.6 inches.
This will result in more frequent passing showers across portions of
northern and eastern PR and the northern USVI tonight through
Wednesday morning. Then, during the afternoon hours, more numerous
showers are expected across western and southwestern portions of
Puerto Rico. Rainfall accumulations are expected to be somewhat
higher on Wednesday compared to today so ponding of water on
roadways and in low-lying areas is likely. Minor urban and small
stream flooding cannot be ruled out in isolated areas.

On Thursday, the low-level flow is expected to increase as well as
remain from the northeast as a broad surface high pressure moves
across the Atlantic Basin. This northeasterly wind flow will advect
patches of low-level moisture into the area with passing showers
expected across northern and eastern portions of Puerto Rico and the
northern USVI during the morning hours followed by the development
of showers across the southwestern quadrant of Puerto Rico during
the afternoon hours.

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

A strong surface high pressure moving from the western Atlantic
into the central Atlantic will maintain fresh to strong
northeasterly winds across the region. Winds are forecast to peak
between 20-25 kts with higher gusts through the weekend. As the
surface high moves further into the eastern Atlantic, areas of low
level clouds and showers will move at times across the islands
from the Atlantic waters. Drier air aloft from a broad mid-level
ridge over the western Caribbean will erode the available moisture
across the region. A long wave trough will move over the region
later in the weekend into early next week, but as drier mid-level
air will prevail no significant rainfall accumulations are
anticipated at this moment.


&&

.AVIATION...Mainly VFR conditions expected. Iso-Sct brief SHRA
expected across portions of the area, which may result in VCSH
across the local terminals. However, significant impacts to
operations not expected. Winds will continue from the NNE-NE mainly
below 10 kts through 17/12z, increasing to 12 to 18 kts with higher
gusts and sea breeze variations after 17/14z.


&&

.MARINE...Small craft advisories will expire later this afternoon
as seas continue between 5-7 feet across the Atlantic waters and
Mona Passage. Northerly winds up to 20 knots will prevail across
the regional waters and small crafts should exercise caution
across the rest of the local waters. A high risk of rip currents
continues across the northern beaches of Puerto Rico due to the
combination of a fading northeasterly swell and the fresh
northerly winds. Marine conditions will improve briefly tonight
and on Wednesday, before a strong surface high over the western
Atlantic increase the winds and seas once again through the end of
the week.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 83 74 83 74 / 40 60 60 40
STT 84 74 84 74 / 40 50 20 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
436 AM AST Wed Mar 18 2020

.SYNOPSIS...A surface trough will move across the region today.
This will increase shower activity in general across Puerto Rico
and the U.S. Virgin Islands. A broad surface high pressure will
promote breezy east to northeast winds from Thursday through
Saturday. Drier air in the mid to upper levels will also move
over the region through at least early next week. This should
result in mostly fair weather conditions across the islands, with
trade wind showers moving from time to time with the breezy
trades.


&&

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

Moisture content will be on the increase today across the local area
as a low-level trough moves across. Precipitable water values are
expected to increase to 1.5 and 1.6 inches. Therefore, an increase
in the areal coverage and intensity of the shower activity is
expected for today compared to previous days. Scattered showers are
expected to be concentrated across the northern and eastern half of
Puerto Rico and portions of the USVI during the morning hours,
followed by the development of heavier showers across the
southwestern quadrant of Puerto Rico during the afternoon hours as
the available combines with daytime heating and local effects. Minor
urban and small stream flooding is possible with the heaviest
rainfall activity, especially across southwest Puerto Rico, for this
afternoon.

Winds will be on the increase from the northeast on Thursday and
Friday as a broad surface high pressure moves across the Atlantic
Basin, tightening the local pressure gradient. Patches of low-level
moisture riding in the northeasterly wind flow will bring low-level
cloud fragments to generate trade wind shower activity across the
area. Passing showers can be expected across portions of the
northern and eastern half of Puerto Rico and the USVI during the
morning hours followed by additional shower development across the
southwestern quadrant of Puerto Rico during the afternoon hours.
Given that the low-level flow will be strong, the shower activity is
expected to be fast moving. Therefore, the main hazard will be
ponding of water on roadways and in low-lying and poor-drainage
areas.

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

The surface high pressure will move further into the north-central
Atlantic while maintaining fresh to locally strong northeasterly
winds across the region through Saturday. Another surface high,
but weaker, is forecast to build just to our north by Sunday
and winds are expected to decrease from 20-25 kt to 15-20 kt
through early next week. Areas of low level clouds and showers
will move at times across the islands from the Atlantic waters
with the northeasterly trade winds through much of the long term
period. A long wave trough will move over the region later in the
weekend into early next week, with precipitable water content
peaking Sunday and on Wednesday at near 1.50 inches.


&&

.AVIATION...Sct SHRA expected across northern and eastern PR and
the USVI through at least 18/14z, resulting in VCSH across
TJBQ/TJSJ/TIST/TISX. Brief MVFR conditions cannot be ruled out due
to reduced visibilities and/or ceilings. SHRA expected across W
and SW PR between 18/16z and 18/23z, affecting the vicinity of
TJMZ/TJBQ. TEMPO MVFR conditions cannot be ruled out. Winds will
be from the ENE-NE at less than 10 kts through 18/12Z, increasing
to 12 to 18 kts with higher gusts and some sea breeze variations
after 18/14z.


&&

.MARINE...Seas will continue to range between 4-6 feet today and
ENE winds will prevail between 15-20 knots. Marine conditions are
expected to gradually deteriorate later tonight and through the
weekend, as a strong surface high pressure builds over the western
Atlantic. This will increase the trade winds to 20-25 kts by
THursday and seas will build from 5-7 feet tonight across the
offshore Atlantic waters to 8-10 feet by Friday. Hazardous marine
conditions are expected across the regional waters through the
weekend. As winds and seas increase, the risk of rip currents will
increase for most of the east and north facing beaches of the
islands.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 83 73 83 74 / 60 50 50 50
STT 84 73 85 74 / 50 40 50 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
517 AM AST Thu Mar 19 2020

.SYNOPSIS...

Increasing winds continue across the local islands, as well as the
local waters, today. These winds will continue to bring passing
showers to the local waters, and onshore in windward portions of
the islands, this morning. During the afternoon, showers are
likely, especially in southwestern portions of Puerto Rico.
Increasingly hazardous marine conditions are also expected for the
local waters into the weekend.

&&

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

A plume of moisture advecting toward the islands will bring passing
showers and clouds mainly across the windward sections of Puerto
Rico and the U.S. Virgin Islands today. The northeasterly flow will
aid in the development of showers across the interior and southwest
quadrant late this morning into the afternoon hours. This passing
showers will create periods of moderate to locally heavy rains.
However, given the winds are relatively strong, the main hazard
expected is ponding of water in roads and poorly drained areas.

A broad surface high pressure over the Atlantic Ocean will maintain
the islands under a northeasterly wind flow, which will result in
additional moisture advection on Friday. Precipitable water values
are forecast to range around 1.5 inches. Therefore, showers will
continue with scattered showers concentrated across the northern and
eastern half of Puerto Rico and portions of the USVI during the
overnight and morning hours. Once again this activity will make its
way into the interior and western sections during the afternoon
hours.

A trough aloft will amplify over the islands by Saturday. However,
although this feature will promote an upper level jet, the lack of
moisture at mid levels will limit the vertical development.

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

On Sunday, increasing moisture will push into the area from the
east, embedded in the trade winds. Meanwhile, a mid-level low
will persist over the area, allowing for higher levels of
instability. The combination of these influences will lead to the
potential for passing showers during the overnight and morning,
with afternoon showers due to local effects and diurnal heating
likely. This pattern continues on Tuesday, as well. Additionally,
an upper-level trough will approach, lingering to the west of the
local islands into midweek. Being on the east-side of the trough
suggests divergence aloft, which will support more instability
aloft, and therefore a higher potential for shower activity,
especially from afternoon showers.

On Wednesday, the pattern is forecast to shift. During the day, the
mid-level low will pull away to the north as it weakens. In the
upper-levels, the trough will make its way across the area during
the morning; this is likely to result in the local islands being on
the subsidence side of the feature by the afternoon. As such, there
will be less support for instability. This relatively dry air,
combined with increasing stability aloft, will act to inhibit shower
activity, though will likely not eliminate it.

Thursday brings gradually increasing moisture levels, as patches of
moisture are carried across the area, embedded in the trade winds.
Conditions aloft, however, will be generally stable. As such, there
will likely be a slight uptick in shower activity, but widespread
significant shower activity is not anticipated at this time.

&&

.AVIATION...

SHRA are expected to move across the local flying area today. This
activity will affect northern and eastern PR and the USVI through at
least 19/16z, resulting in VCSH across TJBQ/TJSJ/TIST/TISX. Brief
MVFR conditions cannot be ruled out due to reduced visibilities
and/or ceilings. SHRA activity will spread into the interior and
western PR btwn 19/16-20/00z, affecting the vicinity of TJMZ/TJBQ.
Winds will be from the NE at 10 kt, increasing 15-20kt with gusts
and sea breeze variations aft 19/13z.

&&

.MARINE...

Enhanced trade winds due to a building surface ridge to the north
will persist today through at least the end of the week. Wind speeds
up to around 15 to 25 mph are expected across the bulk of the local
waters. This will cause building seas across the area. Hazardous
conditions will spread today through the end of the week, and are
expected to continue into early next week. Seas up to around 7 to 10
feet are possible by this weekend, especially in the outer
Atlantic waters.

For the beachgoers, there is a high risk of rip currents at beaches
from northwestern Puerto Rico to San Juan and vicinity. Elsewhere,
the risk will largely be moderate, with the exception of
southwestern Puerto Rico, where the risk of rip currents is low.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 83 74 83 74 / 50 50 40 50
STT 84 73 85 73 / 50 50 40 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
521 AM AST Fri Mar 20 2020

.SYNOPSIS...

Showers continue across the area, though somewhat diminished as
dry air makes its way into the region. Relatively strong winds
persist out of the northeast today as well, with speeds up to 25
knots anticipated. Local effects and diurnal heating will combine
with the available moisture to cause shower activity this
afternoon. Similar conditions are expected again tomorrow.

&&

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

Moisture advection will continue early this morning due to breezy
northeasterly winds. This activity will create ponding of water in
roads and poorly drained areas across north and northeast Puerto
Rico as well as across portions of the U.S. Virgin Islands.

A somewhat drier air mass will make its way across the islands
limiting shower activity. Meanwhile, expect northeast between 15 and
25 mph with gusts around 30 mph or higher. The combination of this
winds, the available moisture and local effects will aid in the
development of showers across the interior and southwest quadrant
late this morning into the afternoon hours. Once again, given the
winds are relatively strong, the main hazard expected is ponding of
water in roads and poorly drained areas.

A broad surface high pressure over the Atlantic Ocean will keep the
islands under a northeasterly wind flow through the weekend. Expect
a mixtures of clouds and sunshine each day. But, under this flow,
patches of clouds and showers will reach the island at times,
especially over northern PR and the USVI. Followed by locally induce
showers over the interior and southwestern sections as well as
downwind from the islands. Although a trough aloft will amplify over
the islands, moisture should be confined to the lower levels,
limiting the intensity and coverage on Saturday. At this time, model
guidance are suggesting moisture and mid-level instability
increasing somewhat on Sunday.

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

On Monday, there will remain enhanced moisture over the area,
especially in the south. Additionally, a trough will persist in the
mid-levels over the region; in the upper-levels, the trough will
press westward, remaining to the west on Monday. Because of this,
instability aloft is expected, which will act to support the
development of shower activity, especially with afternoon showers
due to local effects and diurnal heating.Passing showers are likely
during the overnight and morning hours across the local waters and
onshore in windward areas. In the afternoon, the peak of the
activity will likely be in southwestern and interior Puerto Rico.

Tuesday will be a bit of a transition day. Moisture levels will
decrease, as will the vertical extent of the moisture. Stability
increases aloft as the mid-level trough weakens and begins to pull
away to the northeast, and the upper-level trough will progress
eastward over the area. Both features aloft are forecast to be past
the area to the east/northeast by Wednesday; behind them, ridges
will slowly shift eastward and build into the area from the west,
leading to further increases in stability. Beyond Tuesday, moisture
will generally be capped below 700 hPa. Patches of moisture will
continue to be carried into the area, embedded on the trade winds,
but with a general drying trend for Friday. There will remain
sufficient moisture to sustain shower activity, but decreasing
activity is expected after the early week.

&&

.AVIATION...

SHRA/-SHRA are expected to move across the local flying area from
time to time. Northern and eastern PR, the USVI and the Leeward
Islands will be affected through at least 20/16z, resulting in VCSH
across the terminals. Brief MVFR conditions cannot be ruled out due
to reduced visibilities and/or ceilings. A drier air mass will
reduce SHRA activity after 20/13z, but local effects will aid in the
development of clouds/SHRA over the interior/SW-PR btwn 20/16-
21/00z. Winds will be from the NE at 10-20 kt and gusty.

&&

.MARINE...

Seas are continuing to build across the local waters, and hazardous
seas will persist through the weekend and into early next week. Seas
up to 10 feet are possible in the offshore Atlantic waters, with up
to 8 feet elsewhere. There are Small Craft Advisories currently in
effect associated with these hazardous seas across most of the local
waters, with the exception of nearshore waters of southwestern
Puerto Rico.

At the beaches, there is a high risk of rip currents at northwestern
to northeastern Puerto Rico, as well as Culebra, St. Thomas, and St.
Croix. Elsewhere, there is a moderate risk of rip currents, except
low at some beaches of southwestern Puerto Rico.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 81 74 82 74 / 60 60 30 10
STT 85 73 83 74 / 60 60 10 10

[cycloneye]

Area Forecast Discussion...CORRECTED
National Weather Service San Juan PR
530 AM AST Sat Mar 21 2020

.SYNOPSIS...

Breezy northeasterly winds will bring a surge of moisture across
the islands early this morning. An upper-level trough lingering
across the region will increase instability through the weekend.
Hazardous marine conditions will prevailed through the weekend.

&&

.SHORT TERM...Today through Monday

Northeasterly wind flow will continue to push low-level moisture
across the region though the morning hours. This activity will
create ponding of water in roads and poorly drained areas across
north and northeast Puerto Rico as well as across portions of the
U.S. Virgin Islands.

A strong high pressure located well north of the region will
continue to generate a breezy northeasterly winds through at
least Sunday afternoon. This wind flow will continue to push
fragments of low-level moisture across the region. The combination
of this moisture with the local effects will aid in the
development of showers across northern and eastern sections of
Puerto Rico in the morning and evening hours. Then, across the
western and interior sections of Puerto Rico during the afternoon. On
Monday, the model guidance GFS shows a broad area of low-level
moisture reaching the region. Additionally, a trough will persist
in the mid-levels over the region. Because of this, instability
aloft is expected, which will act to support the development of
shower activity, most with afternoon showers especially over the
southwestern and interior sections of Puerto Rico.

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

On Tuesday, a surface low pressure will move into the Eastern
Seaboard weakening pressure gradient and local winds across the
islands. The lingering moisture will result in passing showers
during the overnight and morning hours across the local waters
and onshore in windward areas. In the afternoon, a dry air mass is
forecast to reach the islands from the central Atlantic limiting
the activity to the western and interior sections of Puerto Rico.
This somewhat drier air mass will last through at least mid-week.

At this time, model guidance are suggesting a short wave trough
aloft by Thursday into the weekend. This trough is forecasted to
progress eastward over the eastern Caribbean and behind it, a
ridge will build over the western Caribbean. At this time,
moisture will be confined to the low-levels and will continue to
reach the islands embedded in the trade winds.

&&

Aviation...

VFR conds across the local terminals. Winds from the E-NE at 15-20KT
gusting to around 25-25KT possible for most of the forecast period.
TJPS could observe winds gust, at around 10KT gusting to 15KT or so
due to the passing showers. Brief VCSH possible this afternoon but
increasing SHRA over the local area will cause more persistent VCSH
or even TEMPO SHRA across TJSJ and TIST this evening and tonight.


&&

.MARINE...

Hazardous marine conditions are observe across the local waters.
Mariners can expect seas between 6 and 10 feet and northeast winds
between 15 and 25 kt with gusts around 30 kt. Small craft
advisories are in effect through at least early next week.

For the beachgoers, a high rip current risk continues for the
beaches from northwestern to northeastern Puerto Rico, Vieques,
Culebra, St. Thomas and St. Croix.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 79 71 83 74 / 30 30 50 50
STT 84 73 84 72 / 10 30 50 40

[cycloneye]

Area Forecast Discussion...CORRECTED
National Weather Service San Juan PR
516 AM AST Sun Mar 22 2020

.SYNOPSIS...

Breezy east to northeast winds will continue in response to a
surface high pressure situated across the Atlantic Ocean through
at least late Monday night. Plenty of moisture and a mid-upper-
level trough will promote rainy conditions through at least
Tuesday afternoon. A drier air mass will limit shower activity by
mid-week.

&&

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

A strong surface high pressure located off to the north over the
Atlantic waters will result in an east to northeast wind flow
over the region. This wind flow will continue to push low-level
moisture and cloudiness over the region at least through Monday.
Low-level moisture in combination with a mid-level trough will
aid in the development of showers over sectors of Puerto Rico at
times.

For today, passing showers are forecast across and north sections
of Puerto Rico. In the afternoon, showers will spread into the
interior an western sections of Puerto Rico. Period of moderate to
heavy showers will result in ponding of water in roadways and
poor drainage areas.

For Monday, the presence of low-level moisture, a jet aloft and
cold temperatures at 500 mb will promote the development of
thunderstorms, especially over western Puerto Rico during the
afternoon hours. Persistent downpours could result in urban and
small stream flooding.

On Tuesday, a drier air mass will filter from the east limiting
shower activity across the islands. However, passing showers could
be expected in the morning and evening hours over the eastern and
northeastern section of Puerto Rico and the u.S. Virgin Islands.

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

Model guidance are suggesting an upper level perturbation
maintaining a jet stream aloft. However, at low- and mid-levels,
the available moisture will be restricted, which could limit the
formation of rain across the islands. Lack of moisture should
persist through at least early Friday. The typical passing showers
should not be ruled out.

As the trough moves eastward over the northeast Caribbean/Atlantic
Ocean a ridge aloft will build over the central Caribbean and
into the local islands. At the surface, another high pressure is
forecast to build over the western Atlantic, migrating to central
Atlantic, increasing the pressure gradient by the weekend. Winds
will increase as well as moisture transport and the frequency of
showers.

&&

.AVIATION...

Mainly VFR conditions expected to prevail across all terminals.
However, -SHRA may cause tempo MVFR conditions across TIST/TISX
btw 22/06z-12z. Winds from the E-NE at 15-20KT gusting to around
25-23KT possible for most of the forecast period.

&&

.MARINE...

Hazardous marine conditions with seas up to 10 feet will continue
through at least Monday due to the combination of a short period
northeasterly swell and fresh to strong east to northeast winds
(15-25 knots with higher gusts). Small craft advisories are in
effect for the Atlantic waters, Caribbean passages and offshore
Caribbean waters. Elsewhere, mariners should exercise caution. A
high rip current risk is also in effect for most of the north and
east facing beaches of the islands.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 82 75 81 73 / 50 50 50 30
STT 84 73 82 72 / 50 60 40 20

[cycloneye]

 https://twitter.com/268Weather/status/1241742761092689921

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
518 AM AST Mon Mar 23 2020

.SYNOPSIS...
Periods of moderate to heavy showers prevailed across most of the
eastern and northern sections of Puerto Rico overnight. These
weather pattern is expected to continue today with scattered to
numerous showers across eastern and north sections of Puerto Rico
in the morning hours. Them, in the afternoon hours showers will
develop over portions of central, and western Puerto Rico. Urban
and small stream flooding can be expected across these areas.
Hazardous marine conditions will continue today.

&&

.SHORT TERM...Today through Wednesday

Higher than normal moisture continues over the local area. This
moisture, combined with the mid to upper level troughs to our
west is causing numerous showers across the local waters, eastern
PR and the USVI. The numerous shower activity is expected to
continue this morning, continuing to affect the aforementioned
areas. The deeper moisture will linger through today, but drier
air is expected to start filtering in, perhaps causing the shower
activity to reduce slightly as the day progresses. This is one
reason why the Hi-Res models show significant rainfall this
afternoon, but limited to the southwestern quadrant of PR, while
much lighter and isolated to scattered showers elsewhere. The
timing of the drier air moving in will be crucial on how much rain
is observed today, but the latest guidance indicates that by this
evening significantly drier air will be moving in, and the shower
activity should be greatly reduced. For Tuesday and Wednesday,
the drier air should limit the shower activity over the local
area, and therefore the forecast is for no more than isolated to
scattered showers with minimal accumulations of rain. The local
winds will remain from the ENE at about 15 mph during the day and
the daytime high temps will be in the low to mid 80s across the
USVI and the lower elevations of PR, and in the 70s across the
higher elevations of PR.

.LONG TERM...Thursday through Monday

On Thursday, in the mid and upper levels a trough is expected to
move eastward over the eastern Caribbean. Model guidance GFS and
ECMWF suggest lack of moisture through at least early Friday.
However, the typical passing showers should not be ruled out in
the afternoon hours due to local effects.

For Friday, model guidance GFS suggest another high pressure
building over the western Atlantic. This ridge are expected to move
to central Atlantic, increasing the pressure gradient by the weekend
and Monday. The building high pressure will result in stable
conditions and a drier air mass across the area. This pattern will
prevail through at least Monday. However, fragments of moisture will
reach the region dragged by the prevailing moderate to strong trade
winds and increasing the potential for shower development and
cloudiness.


&&

.AVIATION...SHRA across the local area will affect the TJSJ and
TIST terminals through at least 23/13Z. Wx conds are expected to
gradually improve thereafter, but VCSH can be expected across
most of the local terminals. Winds will remain from the ENE at
10-15KT with occasional gusts today. CIGs could be at around
FL030-040 today.


&&

.MARINE...
A strong east to northeasterly wind flow will create hazardous
marine conditions with seas up to 8 feet wand winds between 15-25
knots with higher gusts. Small craft advisories are in effect for
most of the local waters. Elsewhere, mariners should exercise
caution. A high rip current risk is also in effect for most of the
north and east facing beaches of the islands at least through
today.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 82 73 82 73 / 60 30 20 30
STT 84 73 83 72 / 40 20 10 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
441 AM AST Tue Mar 24 2020

.SYNOPSIS...Weather conditions will continue to improve today with
the entrance of relatively drier air. Nevertheless, fragments of
low-level moisture embedded in the trade winds will enhance
shower activity from time-to- time with overnight and early
morning showers moving over windward areas, followed by afternoon
convection across the interior and western sections of the
islands. A generally east to northeast wind flow will dominate
the region. This flow is expected to diminish by the end of the
workweek, but a developing surface high pressure will enhance a
stronger flow by the end of the weekend into early next week.


&&

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

East to northeasterly winds will prevail today as a strong SFC high
pressure across the central Atlantic continues to dominate. However,
on Wednesday, a SFC low pressure will move into the western
Atlantic, causing the local winds to diminish and have a slight SE
component, which will continue into Thursday. The available moisture
will increase slightly today, but the deeper moisture will remain
over the Caribbean waters, causing scattered showers over the waters
and perhaps across the USVI, especially St Croix. That said, when the
increase in moisture combines with the local effects in Puerto Rico,
scattered to numerous locally induced showers can be expected this
afternoon across the interior and western sections, but the
accumulations are expected to be limited because the moisture,
although slightly higher, it is still fairly limited to the lower
levels and precipitable water could remain below 1.3 inches. Even
drier air is expected for Wednesday and Thursday, and therefore
mostly fair weather is expected with brief periods of isolated to
scattered showers, that could cause minimal rain accumulations. With
the gradual shift in winds from ENE today to E-ESE on Thursday and
the drier air moving in, the daytime high temps will be in the low
to mid 80s today, in the mid 80s on Wednesday, and in the mid to
upper 80s on Thursday.


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

Global models guidance continues to suggest a relatively quiet
weather pattern during the long-term forecast period. The feature
of interest is a surface high pressure that is expected to move
off the southeast coast of the United States by Saturday. This
system is then expected to strengthen as it meanders over the
western Atlantic, increasing the local pressure gradient while
generating a fresh to strong flow through early next week. In
terms of shower activity, patches of low- level moisture embedded
in the trade winds will increase the chance for showers from
time- to- time. This will result in overnight and early morning
showers moving into windward areas, followed by afternoon
convection developing along the interior and western sections of
Puerto Rico, as well as downwind from El Yunque and the local
islands. So far, drier air in the mid- levels, lack of upper level
support and a relatively strong steering flow will limit the
intensity, coverage and effects of any shower affecting the area.
Thus, the flood threat remains low through the long- term
forecast period.


&&

.AVIATION...VFR conditions expected to prevail across the local
terminals. SCT SHRA over the area may cause VCSH across TISX, TIST
and TJSJ in the morning. Skies will be SCT most of the time but
brief CIGs are possible at FL030-060. Winds from the E-NE at 15-20KT
gusting to around 25KT possible today, especially for TJSJ, TJBQ,
TIST, and TISX.


&&

.MARINE...Although marine conditions will continue to improve
today, hazardous seas up to 7 feet are expected still expected in
some areas throughout the day. As a result, Small Craft
Advisories are in place for the Atlantic waters and Mona Passage
through this morning, while Advisories are in effect through this
afternoon for the Caribbean waters and Anegada Passage.
Nevertheless, small craft operators are urged to exercise caution
elsewhere due to seas up to 6 feet. There is a high risk of rip
currents for beaches along the north coast of Puerto Rico, Culebra
and Saint Croix.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 83 73 85 72 / 30 20 20 20
STT 84 73 84 73 / 30 20 20 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
419 AM AST Wed Mar 25 2020

.SYNOPSIS...Except for fragments of low-level moisture streaming
across the forecast area from time-to-time, a generally fair and
dry weather pattern is expected to prevail during the next few
days. Nevertheless, overnight and early morning showers moving
over windward areas nor limited afternoon convection across the
interior and western sections cannot be ruled out. Winds will
remain generally light to moderate, but a developing surface high
pressure will generate a stronger wind flow during the weekend
into early next week.


&&

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

The overall available moisture will continue to decrease today and
Thursday. Therefore the shower activity is expected to be
increasingly limited. That said, brief and light isolated to
scattered showers are still expected across the local waters,
eastern PR and the USVI. Locally induced showers in the afternoon
are possible across central and western PR, but the chances of
that happening are higher today than they are on Thursday. As
moisture increases slightly on Friday, the shower activity will
also become more scattered to numerous across central and western
PR on Friday afternoon. A SFC low pressure will move into the
western Atlantic today, gradually causing the local winds to shift
from ENE early this morning, to Easterly today, to ESE in some
parts of our forecast area and much lighter from Thursday. In
fact, the local winds may be light and variable late on Thursday
into Friday.


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

Global models guidance continue to suggest that relatively fair
weather conditions will prevail through the long term forecast
period. A developing surface high pressure moving into the western
Atlantic and north of the Bahamas will begin to generate an east
to northeast wind flow across the area by Saturday. As the high
continues to develop as it moves eastward and north of the
forecast area, the local pressure gradient will strengthen causing
winds to increase while favoring a more northeasterly component
between Sunday and Monday. Then, winds are expected to diminish
and favor a more east to southeast direction as the high pressure
moves away from the area and the local pressure gradient relaxes
by Tuesday. Lack of upper level support due to a strong mid to
upper level ridge will not support deep convective development
through the entire period. However, under a fresh to locally
strong steering flow, fragments of low- level moisture, associated
to an old surface induced trough and plume of moisture, will
quickly move in on Sunday. These fragments will bring overnight
and early morning showers across windward areas, while lingering
moisture and local effects will support shallow afternoon
convection across the interior and western portions of Puerto
Rico. Streamer-like showers downwind from El Yunque and the local
islands cannot be ruled out. A drier air mass is forecast to move
in by late Sunday night and dominate the local weather conditions
through midweek. Although a few patches of low-level moisture
embedded in the trades may move in from time- to-time, significant
shower activity is not anticipated during this period.


&&

.AVIATION...VFR conditions expected to prevail across the local
terminals. ISOL SHRA over the area may cause VCSH across TISX, TIST
and TJSJ in the morning. SHRA developing across W-PR after 25/17Z
could cause VCSH at TJPS, TJBQ, and TJMZ. FEW/SCT skies expected
most of the forecast period, but brief CIGs are possible at FL030-
060, especially early in the morning. Winds from the East with sea
breeze variations at 10-15KT gusting to around 20KT during the
daytime hours, becoming lighter after 25/23Z.


&&

.MARINE...Marine and coastal conditions will continue to improve
today. Nevertheless, small craft operators are urged to exercise
caution due to seas up to 6 feet and/or winds up to 20 knots. This
applies to the offshore Atlantic waters, nearshore and offshore
Caribbean waters, as well as the local passages. Elsewhere, seas
up to 5 feet and winds up to 15 knots are expected. There is a
moderate risk of rip currents along most of the local beaches,
except for beaches of Ponce and Vicinity westard along the coast
to Anasco in the west coast of Puerto Rico.

A northerly swell and increasing winds resulting from a developing
surface high pressure will deteriorate both marine and coastal
conditions during the weekend.


.FIRE WEATHER...The entrance of drier air could represent a threat
for fire-prone areas across the southern coastal plains of Puerto
Rico, causing relative humidity values to drop into the upper 40s
to low 50s. Although recent KBDI observations remain below fire
danger criteria with a value of 234 in Cabo Rojo and 547 in Camp
Santiago, lack of wetting rains could bring the latter close to
elevated fire danger criteria during the next few days. The
forecast calls for a light to moderate wind flow, but local
effects and sea breeze convergence could easily result in winds
to peak around 15 mph with higher gusts by late morning into the
early afternoon hours. Overall, a low fire danger threat remains
in place for today, but these conditions can quickly elevate
during the next few days.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 83 73 86 74 / 20 20 20 40
STT 84 72 84 73 / 20 10 20 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
405 AM AST Thu Mar 26 2020

.SYNOPSIS...A generally light to moderate wind flow is expected
through most of the forecast period. However, a developing surface
high moving across the western Atlantic will support a fresh to
locally strong northeasterly flow during the weekend into early
next week. This will also cause marine conditions to deteriorate.
Although mostly fair weather conditions are expected, fragments
of low-level moisture will enhance shower activity from time-to-
time. A peak in shower activity is expected on Saturday with the
development of a weak upper level trough west of the area.


&&

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

The overall available moisture will continue to decrease today but
increase slightly on Friday and Saturday. Given the much drier than
normal air mass for today, the shower activity is expected to be
limited. That said, brief and light isolated showers are still
expected across the local waters and the USVI. Locally induced
showers in the afternoon are possible across the higher elevations
of Puerto Rico due to a light SE wind flow, but the chances of more
significant afternoon showers increase on Friday and Saturday since
there will be more moisture. Also, a weak upper trough could develop
just west of the local islands on Saturday, which could provide some
instability and cause more significant afternoon showers over the
local area, especially over Puerto Rico. A SFC low pressure will
move NE across the western Atlantic today, gradually causing the
local winds to become SE as they weaken. By Friday, a SFC high
pressure will move into the western Atlantic, keeping a relatively
loose pressure gradient locally, and therefore causing weak winds,
and relatively variable across the local area. That said, stronger
winds from the ENE are expected to make a return on Saturday.

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

No major changes expected during the long-term forecast period.
Still, global models guidance continues to suggest that
relatively fair and drier weather conditions will prevail across
the region. On Sunday and Monday, a fresh to locally strong east
to northeast wind flow will persist over the region as a
developing surface high pressure moves north of the local islands.
By Tuesday, this feature is expected to weaken as it is slowly
moves east-southeastward into the western Atlantic. This will
cause winds to diminish and gradually turn from the east on
Wednesday and then from the southeast by Thursday.

In terms of shower activity, under a strong northeasterly flow
cool advection will result in showers streaming across the waters
into coastal areas of northern and eastern Puerto rico, as well
as the US Virgin Islands on Sunday into early next week.
Lingering moisture supported by local effects and diurnal heating
may aid in the development of afternoon convection across the
interior and western sectors of Puerto Rico. Streamer- like
showers downwind from the El Yunque and the local islands cannot
be ruled out. By Tuesday and Wednesday, shower activity is
expected to diminish with the entrance of drier air, but a
southeasterly flow is expected to enhance low-level moisture
convergence and shower activity by Thursday. Nevertheless, lack
of favorable conditions aloft will not support deep convective
development through the entire period, reducing the chances for
significant rainfall accumulations and the potential for flooding.


&&

.AVIATION...VFR conditions expected to prevail across the local
terminals. SHRA developing across central PR after 26/17Z could
cause VCSH at TJPS, TJBQ, and TJMZ. Winds from the E-SE with sea
breeze variations at 10-15KT, becoming light and variable after
26/23Z.


&&

.MARINE...Tranquil marine conditions with seas of 5 feet or below
and east to southeast winds around 10-15 knots will prevail through
at least late Friday night. By Saturday, the arrival of a
northerly swell and increasing winds up to 20 knots will result in
choppy to hazardous seas across most of the local waters. As a
result, Small Craft Advisories may be needed then. A moderate risk
of rip currents will continue for a few beaches along the north
coast of Puerto Rico and the U.S. Virgin Islands. However, the
risk is forecast to elevate to high as marine conditions
deteriorate by Saturday morning.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 85 73 83 76 / 20 20 20 40
STT 84 72 84 74 / 20 30 40 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
402 AM AST Fri Mar 27 2020

.SYNOPSIS...Relatively fair weather conditions are expected across
the region. A slight increase in moisture will enhance shower
activity today. Except for fragments of low-level moisture
embedded in the trades, weather conditions are forecast to remain
generally dry through most of the forecast period. Marine
conditions are expected to deteriorate during the weekend with the
arrival of a northerly swell and increasing trade winds.


&&

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

The available moisture will increase slightly today as a SFC low
across the NW Atlantic brings moisture up from a sfc perturbation to
the east and SE of the local area today, but it will also cause the
local winds to be light and from varying directions across the
forecast area. This increase in moisture will be more pronounced in
the eastern portions of the forecast area, which includes the USVI,
Vieques, Culebra and eastern PR, causing scattered showers across
the area, especially in the morning. That said, by this afternoon, a
SFC high pressure moves to the north of the local islands, causing
NNE winds across the western half of the forecast area. The light
wind speeds and the difference in wind direction could cause
convergence over the higher elevations of PR this afternoon, which
will combine with the increase in moisture and diurnal heating to
cause shower development. Therefore, scattered to numerous showers
are forecast this afternoon. The SFC perturbation will continue to
move west on Saturday, continuing to increase the moisture to near
normal values for the time of year, while an upper trough develops
to the west of the local islands and the prevailing wind becomes E-
ENE across the forecast area. This will cause isolated to scattered
showers in the morning on Saturday, and then scattered to numerous
showers across the interior into the southwestern quadrant of Puerto
Rico in the afternoon hours, while the USVI remains observing
isolated to scattered brief showers during the day. Stronger ENE
winds return on Sunday and moisture will decrease once again.
However, with the breezy winds we could observe isolated to
scattered showers across the local waters, USVI and the north and
eastern sections of PR in the morning hours, while a few locally
induced showers could develop across southwestern PR on Sunday
afternoon.

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

The projection of the long-term forecast has not changed. Global
models guidance continues to support a relatively fair weather
pattern across the region. The feature of interest is a developing
surface high pressure streaming across the western Atlantic
during the weekend into early next week. This system will is
expected to generate fresh to locally strong northeast flow on
Sunday and Monday. As the system continues to move eastward into
the central Atlantic and weakens, winds are to diminish and
gradually turn from the east on Wednesday and then to the
southeast by the end of the work week. Under a southeasterly flow,
warm temperatures can be expected, with daytime high temperatures
peaking in the mid to upper 80s and even in the lower 90s in
isolated areas.

Although relatively dry conditions are expected, fragments of
low-level moisture will continue to move in from time-to-time,
particularly on Sunday and Monday under a strong northeasterly steering
flow. The expected shower activity will be overnight and early
morning passing showers moving over windward areas of Puerto Rico
and the U.S. Virgin Islands from the waters, followed by locally
induced showers developing across the interior and western
sectors of Puerto Rico each afternoon. Streamer-like showers
downwind from El Yunque and the local islands cannot be ruled out.
Nevertheless, unfavorable conditions aloft will not support deep
convection, resulting in limited rainfall accumulations and a low
flood threat across the region.


&&

.AVIATION...VFR conditions expected to prevail across the local
terminals. SCT SHRA in the morning could cause VCSH at TIST and TJSJ
after 27/10Z. Developing SHRA after 27/17Z in PR could cause VCSH at
TJMZ and maintain it at TJSJ. Winds will be light, generally at 10KT
or less and variable, but with a strong sea breeze influence for the
terminals in PR staring after 27/13Z.


&&

.MARINE...Tranquil marine conditions with seas at 6 feet or below
and east winds up to 15 knots are expected across the local
waters today. There is a moderate risk of rip currents for beaches
along the northwest to northeast coast of Puerto Rico and most
beaches of Culebra, as well as Botany beach in Saint Thomas and
Cramer Park beach in Saint Croix. These conditions will last
through at least Saturday morning, before the arrival of a
northerly swell and increasing trade winds generate choppy to
hazardous seas across the region. As a result, Small Craft
Advisories and High Risk of Rip Current may be required by
Saturday afternoon.


&&

.FIRE WEATHER...KBDI values have remain within fire danger
thresholds, particularly around the Camp Santiago area where a
KBDI value of 557 was reported on Thursday. However, the overall
weather pattern expected will not support elevated nor critical
fire weather conditions today. Although the forecast calls for
relative humidity to drop into the upper 40s to low 50s due to the
entrance of drier air and lack of wetting rains, winds are
expected to remain light even at peak afternoon hours.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 83 75 85 74 / 30 40 40 40
STT 84 74 85 75 / 40 30 30 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
436 AM AST Sat Mar 28 2020

.SYNOPSIS...Enough moisture and instability remains over the local
area today to support another round of showers today. The shower
activity will be focused over the central interior, west interior
and west portions of Puerto Rico this afternoon. In contrast, much
drier and stable conditions are forecast most of next week.

&&

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

A low level trough now crossing Puerto Rico will continue to exit
the region this morning with associated trailing moisture. As a
result, variably cloudy skies with embedded shower activity will
continue to affect the forecast area bringing periods of moderate to
locally heavy rainfall to the coastal waters and parts of the north
and east coastal sections of Puerto Rico and the adjacent islands.
By late morning the shower activity should gradually diminish, as
the trough exits the region. This in turn will lead to partly cloudy
to mostly sunny skies in most areas, as drier air will gradually
filter in from the east.

For the rest of today...a surface high pressure ridge will continue
to build and spread eastward across the western Atlantic. This will
aid in tightening the local pressure gradient, resulting in
increasing northeasterly trade winds during the afternoon and
through the weekend into Monday. In the upper levels, a high
pressure ridge will spread eastwards from the southwest Atlantic,
resulting in subsidence aloft and the strengthening of the trade
wind cap inversion. However, lingering moisture along with local
effects and daytime heating will give way to afternoon shower
development over parts of the islands. Afternoon convection should
be focused over the central interior and western Puerto Rico, and
mainly on the west-end or just downwind of the U.S.Virgin Islands,
where lesser shower activity is expected. Urban and small stream
flooding and or ponding of water on roadways and in poor drainage
areas will remain possible over parts of western Puerto Rico during
the afternoon hours.

On Sunday and through Monday, an overall drying trend is forecast,
as conditions become stable aloft and low level moisture gradually
erodes. Still however expected periods of late evening and early
morning passing showers, which may be more frequent at times as the
northeast trade wind are forecast to increase. Significant rainfall
accumulations are not anticipated as the activity will be fast
moving. For both Sunday and Monday, afternoon convection will be
focused mainly over parts of the west interior and southwest
sections of Puerto Rico. Mostly fair weather skies and limited
shower activity is forecast for the remainder of the islands
including the U.S. Virgin Islands.

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

A high pressure at 700mb located north of Hispanola on Tuesday
morning will produce a very stable environment over Puerto Rico
and the U.S. Virgin Islands. With the subsidence side of the high
pressure over the local islands, precipitable water values are
forecast to drop near an inch. Further drying is expected on
Wednesday when the inversion cap strengthen. By that time,
moisture levels are forecast to reach two standard below normal.
Therefore, shower activity between Tuesday and Thursday will be
minimal...with only isolated showers, if any, developing over
western Puerto Rico during the afternoon hours. Surface winds
will shift to the southeast by midweek in response to the surface
high pressure moving eastward just north of Puerto Rico. This
will likely bring warmer than normal temperatures across the local
islands the second part of the week. Also on Friday, the probability
of precipitation remains low as moisture and stability remains
unfavorable for organized shower activity. It is not until the
weekend, when the surface high pressure relocates east northeast
of the Lesser Antilles that moisture increases somewhat across the
local islands. Then, scattered showers could be a possibility at
times.

&&

.AVIATION...VFR conds durg prd. SCT-BKN ovr cld lyrs nr FL025...
FL050...FL080 ovr regional waters btw Ern PR and the northern
Leeward islands. BKN-OVC btw W PR and the Mona Passage. SHRA ovr
local waters and en route btw islands. Few tops btw FL120-FL140 with
SHRA. Mtn top obscr ovr Ern PR in -SHRA/low cld lyrs til 28/12Z.
Winds light and variable...bcmg fm E-NE 10-15 kts aft 2814Z with sea
breeze variations.

&&

.MARINE...Wave models now are forecasting slightly lower wave
heights during the weekend as surface high pressure north of the
region is weaker than previously forecasted. Therefore, the Small
Craft Advisory for tonight and Sunday was cancelled early this
morning. However...small craft operators should exercise caution
mainly across the Atlantic Waters due to seas up to 6 feet. Elsewhere...
seas of 3-5 feet are anticipated over the next several days.

&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
444 AM AST Sun Mar 29 2020

.SYNOPSIS...Drier and more stable airmass will continue to spread
over the region. As a result, minimal shower activity is forecast
across Puerto Rico and the U.S. Virgin Islands through at least
midweek. Moisture and instability will surge again between Friday
and Saturday as a frontal boundary approaches from the north. This
will likely increase the shower activity across the local islands
late in the week.

&&

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

A surface high pressure ridge will continue to build and spread
eastward across the western Atlantic today through Tuesday to
maintain a moderate to relatively strong northeast wind flow across
the forecast area. A fairly strong mid level ridging is to also hold
during the period, while an upper level trough will linger just east
of the region, and therefore keep the area on the subsident side of
the trough axis during the entire period.

While an overall drying trend is forecast for the most part, still
expect the increasing northeasterly winds to bring periods of
shallow moisture across the region, especially during the overnight
and early morning hours. This advective pattern will continue and
therefore expect periods of mainly light to moderate showers across
the local waters and inland across parts of the north and east
coastal sections of the islands. Moisture transport will however
continue to diminish and erode during the next several days, as the
trade wind cap inversion strengthens across the region. The layered
precipitable water values which was around 1.40 inches, will
continue to decrease as recent forecast model guidance suggested
values to be an inch or less by Monday and Tuesday over the region.
That said, expect only short periods of overnight and early morning
showers over portion of the north and east coastal areas of the
islands, followed by some locally and diurnally induced afternoon
convection mainly in isolated areas each day. Afternoon shower
activity should be mainly focused over parts of the interior and
west sections of Puerto Rico, and on the west-end of just downwind
of the U.S. Virgin Islands. No significant rainfall accumulations or
flood problems are anticipated at this time, as mostly fair weather
and sunny skies is forecast for the entire period.

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

The relatively dry and stable pattern will hold Wednesday and
Thursday as a high pressure a few kilometers above the surface
(700mb) will inhibit the vertical development of shower across the
northeast Caribbean region. By that time, operational models
are suggesting precipitable water values around one inch. The
moisture content will limit the shower activity across most of
the area. However, short-lived showers can not ruled out each
afternoon over northwest Puerto Rico due to local effects. Also,
second part of the week will be characterized by warmer that
normal temperatures as a deep layer southeasterly flow establishes
across the local area.

Moisture rebounds Friday and Saturday when a frontal boundary and
its associated shearline approaches the region from the north. In
addition, a weak mid level perturbation will stream over the area
enhancing the instability across the local islands. Under this
fairly wet and unstable environment expect a few round of showers
starting on Friday and continue during the weekend. Moisture will
gradually decrease on Monday resulting in less shower activity.

&&

.AVIATION...VFR durg prd. SCT Ocnly Bkn lyrs nr FL025...FL050...
Mostly SKC ABV. Isold SHRA ovr regional waters and en route btw
islands. VCSH mainly at TJSJ/TIST/TISX til 29/13Z. SFC wnds fm
E-NE 10 kts or less...bcmg NE at 15-20 knots with ocnly hir gusts
aft 29/14z. Aftn convection btw 29/17-29/23z but limited to ovr
the interior and west sections of PR, and down-wind from the USVI.

&&

.MARINE...A northerly swell combined with wind-driven seas will
produce choppy seas across most of the local waters. The highest
seas are forecast for the offshore Atlantic waters where seas of
6-7 feet are likely through tonight. Elsewhere, seas of 4-6 feet
except the nearshore waters of southwest Puerto Rico where seas
are generally between 2-4 feet. Marine conditions improve through
at least mid-week as winds and seas gradually diminish across the
regional waters. Later in the week, a small northerly swell will
reach the local waters late Thursday into Friday.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 85 74 84 73 / 20 30 30 20
STT 86 73 85 73 / 20 20 20 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
505 AM AST Mon Mar 30 2020

.SYNOPSIS...
A continued drying trend and stable airmass will prevail across
the region through at least the middle of the work week. As a result,
minimal shower activity and convective development is forecast across
Puerto Rico and the U.S. Virgin Islands. Moisture and instability is
forecast to surge once again by Friday and into the upcoming weekend,
as a frontal boundary and upper level trough will approach the region
from the north and west respectively. This will likely increase
instability aloft and moisture convergence resulting in better
potential for shower development across the forecast area.

&&

.SHORT TERM...Tonight through Wednesday...
A surface high pressure will prevail over the local area through at
least Wednesday, generating a more stable and drier conditions.
Although this feature will limit the shower coverage across the
region through this period,quick passing showers are possible mainly
over along the northeast portions of Puerto Rico and adjacent
islands during the overnight and morning hours. A similar fair
weather pattern is expected for Tuesday and Wednesday, but with the
main difference being that winds will begin to shift more from the
east to southeast, hence the afternoon convection will focus on
western PR, but again, significant accumulation are not forecast.
Warmer daytime high temperatures will also be likely along the
north coastal areas Tuesday through Wednesday.


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

The relatively dry and stable pattern will through Thursday as a
strong high pressure ridging both in the upper level and at the
surface will continue to inhibit the vertical development of showers
across the region. Recent model guidance continued to suggest layered
precipitable water values around one inch or less. The dry air aloft
and lack of significant low level moisture advection under a more
east southeast wind flow, will limit the shower development across
most of the forecast area through at least Thursday. However, some
short- lived showers can not ruled out during the early morning
hours, and each afternoon over parts of the islands due to local
effects. On Friday and Saturday, the slightly warmer than normal
high temperatures is also forecast to continue for the north coastal
areas due to the more southeasterly wind flow.

Moisture also returns Friday and though the weekend, when the frontal
boundary and its associated shearline approaches and converges across
the region from the north. In addition, a mid to upper level trough
will stream over the area thereby enhancing the instability across
the forecast area. Under this expected fairly wetter and unstable
environment best potential for convective development starting on
Friday and continuing through the weekend. Moisture and instability
aloft will gradually decrease on late Monday and into Tuesday resulting
in less shower activity across the islands. Winds will also become
more northerly once again as the high pressure ridge will build
north of the region.

&&

.AVIATION...VFR conds are expected to prevail at all stations. Lcl
MVFR conds may occur in SW PR durg the aftn with mtn obscurations
over the Cordillera Central til 30/23Z. ENE sfc winds of 10 to 20
kts, these will be strongest alg the coasts with sea breeze variations.
Land breeze influences should be seen aft 30/23Z till 31/14Z . Winds
NE- ENE to prevail up to FL180.

&&

.MARINE...Across the regional waters today, seas will be mainly
between 3 to 6 feet, with east to northeast winds between 10 to
20 kt and higher gusts. Small craft operators should exercise
caution due to choppy seas, except for the coastal waters of
southwest Puerto Rico.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 84 73 85 73 / 30 20 10 10
STT 85 73 85 72 / 20 10 10 10