Caribbean - Central America Weather

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
412 PM AST Mon Feb 12 2018

.SYNOPSIS...

A mid to upper level ridge will cause a stable and fair weather
pattern through the end of the week. Although a stable weather
pattern will prevail there is a possibility for a few trade wind
showers with strong east northeast winds of 15 to 20 mph with
higher gusts.

&&

.SHORT TERM...Tonight through Thursday...

High pressure in the central Atlantic will shift into the western
Atlantic and sink south during the period losing almost 13 mb in the
process. This will allow winds to relax somewhat in the process.

A 500 mb trough extends into the tropical Atlantic near 50 west from
low pressure almost 600 miles north of the Cape Verde Islands. From
there it extends back across the Caribbean just south of Puerto
Rico. Convection with higher tops can be seen close to the
vorticity maximums in the trough which also coincide with a
temperature trough. Some tiny tops of 30 to 35 kft are also forming
over interior Puerto Rico as this is being written. Temperatures at
500 mb are seen to drop off to as little as minus 12 degrees at
13/12Z. This cooler air will enhance instability just as a maximum
in moisture just below 500 mb moves by. Since mid-level are already
relatively dry, this will enhance shower activity only slightly but
will keep showers likely during the next several nights in north and
northeast Puerto Rico and all the islands east of there. The GFS
shows showers likely through Thursday in eastern Puerto Rico.
Amounts should range from 0.10 to 0.20 inches, but higher amounts
may occur on the windward slopes. Winds will not diminish until
after Tuesday. Although winds will subside somewhat each night,
stronger winds will return during the mornings. A high wind advisory
may therefore be necessary Tuesday as well.

&&

.LONG TERM...

Two features will control the long term period the first is the
mid to upper level ridge that remains anchored across the region
and the other item is the low level moisture that will move in
periodically from the east. The ridge of high pressure will cause
fresh moderate east northeast winds of 15 to 20 mph also
occasionally trade wind showers will be possible mainly across
north and northeast Puerto Rico as well as Vieques, Culebra and
the U.S. Virgin Islands during the morning and afternoon.


&&

.AVIATION...

VFR conds will prevail, but brief MVFR is expected in
TNCM/TKPK thru 13/13Z. Gusty winds will cont thru 13/22Z, but gusts
will be less frequent btwn 13/02-10Z. Sfc winds E 15-25kt with gust
to 40 kt till nightfall when winds will be 10-20 kt. Then winds
resume aft 13/12Z. Sct brief SHRA mainly USVI/nrn PR. Max winds WNW-
NW 60 kt FL400-460 til 13/06Z.

&&

.MARINE...

Winds and seas will remain hazardous through Wednesday with winds
of 20 to 25 kts with gusts of 30 kts. A high risk of rip currents
still remains for north, southwest, and southeast facing beaches
of Puerto Rico along with Culebra, Vieques and St. Croix. A high
surf advisory will remain in effect through Tuesday.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 74 83 74 82 / 40 40 40 40
STT 73 84 73 84 / 30 30 20 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
520 AM AST Tue Feb 13 2018

.SYNOPSIS...Breezy to windy conditions throughout the day.
Continue to expect passing showers along the northern and
eastern sections of Puerto Rico as well as the US Virgin
islands. Hazardous seas will continue to prevail much of
the week.

&&

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

A mid level trough is extending from the northeast Atlantic all
the way to the Caribbean. There is also an upper trough that
extends from a low pressure in the NE Atlantic to the Caribbean.
However, instability associated with this trough should be minimal
as we would be in the convergent side of the trough. There is
also a strong surface high pressure the central Atlantic, causing
strong ENE winds across the local area today, decreasing slightly
on Wednesday. The strong winds today will likely be between 15 and
25 MPH with wind gusts that could reach 35 MPH briefly. There is
a wind advisory in effect until 6PM today. This strong wind will
cause the marine conditions to continue to be hazardous and also,
once combined with the dry air over the local area, it increased
the fire danger across the south coastal plains.

The local weather is expected to be generally a typical pattern
for the time of year, which mainly has brief showers embedded in
the trades with some showers developing over PR due to local
effects. However, given the lack of upper level instability and
limited moisture, the rainfall accumulations are not expected to
be significant widespread. The overall moisture is expected to be
relatively low today once again, with precipitable water values
expected to be just over 1 inch, which is still near the 25th
percentile for this time of year. Similar precipitable water
values expected on Wednesday and Thursday.

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

A mid level ridge will hold across the forecast area through the
forecast period. At lower levels, high pressure systems north of
the area will continue to yield a moderate to fresh east northeast
wind flow which will bring patches of low level moisture at times.
Therefore, continue to expect a generally fair and stable weather
pattern with some passing showers across north and east Puerto
Rico as well Vieques, Culebra, and the USVI particularly in the
late evening and early morning hours. Seasonable temperatures to
continue.

&&

.AVIATION...VFR conds expected across the local terminals with
VCSH expected in ISOLD/SCT SHRA for the next 24 hours. Winds from
the ENE at around 15 to 20KT with higher gusts, possibly reaching
30KT, expected. Winds at TJPS will be from the E to ESE during
the day. Winds decreasing slightly after 13/23Z.

&&

.MARINE...Hazardous seas between 8 and 12 feet and ENE winds
between 15-25 kt with possible gusts in the mid 30s to continue
today. There is a high surf advisory for the northern beaches of
Puerto Rico and St. Croix through this afternoon. Life threatening
rip currents will continue to prevail across most of the beaches
through the end of the work week. Marine conditions will slowly
improve by the end of the week.

&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
337 PM AST Tue Feb 13 2018

.SYNOPSIS...

Breezy conditions will start to decrease later this evening with
winds falling to 15 to 20 mph. Mid to upper level ridges will
maintain their foothold over the caribbean and local islands
during the long and short term periods thus creating seasonable
weather with a few trade wind showers mainly during the morning
and afternoon hours.

&&

.SHORT TERM...

At the surface a ridge of high pressure is currently over the
region and will remain over the area through Thursday thus the
low level flow will be east to northeast with winds ranging from
15 to 20 mph. Remaining at the low levels tropical moisture will
periodically move across Puerto Rico and the U.S. Virgin island
during the short term period.

At the mid to upper levels a trough is positioned in the far east
Atlantic waters and will not have an effect on our local weather
but several upper level ridges will build across the region thus
creating a seasonable weather pattern with a few showers embedded
in the trades.


.LONG TERM...

A mid to upper level ridge will maintain its hold over the
caribbean waters and local islands. At the lower levels a high
pressure system to the east of Florida will produce moderate to fresh
east northeast wind flow which will bring patches of low level
moisture at times. Therefore, continue to expect a generally fair
and stable weather pattern with some passing showers across north
and east Puerto Rico as well Vieques, Culebra, and the USVI
particularly in the late evening and early morning hours.
Seasonable temperatures to continue.


&&

.AVIATION...

Mainly VFR conditions will continue to prevail across
all TAF sites through the forecast period. VCSH can be expected
across TIST, TISX and TJSJ. Low level winds will be mainly east at
15 to 20 kts with higher gusts.

&&

.MARINE...

Hazardous seas between 8 and 12 feet with east to northeast winds
ranging from 15 to 22 kts. Life threatening rip currents will
continue to prevail across most of the beaches through the end of
the work week. Marine conditions will slowly improve by the end of
the week.


&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
423 AM AST Wed Feb 14 2018

.SYNOPSIS...Surface high pressure north of the region will
maintain breezy conditions across the area today. Winds are
expected to slowly decrease later this evening through Thursday
as the local high pressure gradient relaxes and allows the prevailing
winds to decrease to 15 to 20 mph. Mid to upper level ridge will
continue to hold over the northeastern Caribbean during the entire
period,supporting a seasonable weather pattern with mostly fair
weather skies and pleasant temperatures except for the occasional
passing early morning and late evening showers.

&&

.SHORT TERM...TODAY THROUGH FRIDAY...
A mid level trough is extending from the northeast and central
Atlantic all the way to the Caribbean. An upper trough also extends
from a low pressure across the northeast Atlantic to the Caribbean.
However, the effects of these features over the forecast areas are
minimal. A surface high pressure across the central Atlantic will
continue to induce a strong east northeast wind flow across the
local area today, decreasing slightly tonight and Thursday. The
winds today will likely be between 15 and 25 MPH with wind gusts
that could reach 30 mph briefly. This strong trade winds will
continue to cause hazardous marine conditions across most of the
coastal waters. The local wind in combination with the dry air over
the region is expected to increase the fire danger across the south
coastal plains of Puerto Rico Today.

Brief passing showers embedded in the trades will move from time to
time across the local islands today and during the next several
days, affecting mainly the northern and eastern sections of Puerto
Rico during the night and morning hours with some showers expected
to develop across western Puerto Rico each afternoon. However, given
the lack of upper level instability and limited moisture, the
rainfall accumulations are not expected to be significant
widespread.

.LONG TERM...Saturday through Thursday of next week...
A mid to upper level ridge will remain anchored over the Caribbean
waters and extend across the local region. The low level high
pressure system spread across the Atlantic and extending across
the region will maintain moderate to fairly strong east northeast
trade winds. This will continue to aid in bringing occasional patches
of low level moisture across the islands and coastal waters. Therefore,
expect an overall fair and stable weather pattern with periods of passing
showers mainly across the north and east coastal sections of Puerto
Rico as well Vieques, Culebra, and the USVI particularly during the
late evening and early morning hours. Mostly fair weather skies and
breezy conditions will prevail during the daytime hours. Seasonable
temperatures con be expected during the entire period.

&&

.AVIATION...Mainly VFR conditions expected to prevail through the
forecast period. Trade wind showers in an ENE wind flow will continue
at times to move across the Leeward/USVI/Northern PR terminals. Previous
14/00z TJSJ sounding indicated ENE winds of 12-30 knots below FL150
and between 25-46 knots up to FL300. Sfc wnds between 5-15 kts will
incr to 15-20 kts aft 14/14z with ocnl higher gusts during til 14/22z.

&&

.MARINE...Hazardous seas between 8 and 12 feet will persist with east
to northeast winds ranging from 15 to 22 kts. Marine conditions will
slowly improve by Thursday and Friday. However, Small craft advisories
will continue in effect across most of the regional waters.

Life threatening rip current risks will also prevail across most of
the local beaches of PR, adjacent islands and the USVI through the
end of the work week. Please refer to the latest Surf Zone Forecast
issued by WFO San Juan PR.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 82 73 84 74 / 50 40 40 30
STT 84 72 84 73 / 30 10 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
456 AM AST Thu Feb 15 2018

.SYNOPSIS...Surface high pressure north of the region spread across
the central Atlantic, will continue to promote moderate to strong
east northeast winds across the local area. Patches of shallow moisture
will bring brief showers across the local area from time to time for
the next several days. Mostly fair weather conditions are expected
to prevail, especially during the daytime hours. Marine and surf zone
conditions will remain hazardous for portions of the local waters,
passages and beaches during the next several days.

&&

.SHORT TERM...Today through Saturday...
A surface high pressure across the central Atlantic will continue to
dominate the local weather conditions today through at least Saturday.
Winds are expected to slowly decrease Today and Friday, where winds
between 10-20 mph winds can be expected. Overall available moisture
will be normal to below normal. The local wind in combination with
the overall dry airmass over the region is expected to elevate the
risk of fire danger across the south coastal plains of Puerto Rico
Today.

There will be patches of moisture moving in, causing brief passing
showers across the area. These showers will mainly affect the local
waters, USVI, Vieques and Culebra, and the north and eastern sections
of PR, particularly in the morning, evening and overnight hours. During
the daytime hours, some cloudiness could occur over PR due to local
effects and some showers are expected to develop across the interior
into the southwestern sections of PR. There is no upper level forcing
in support, so the showers that do affect any one area are not expected
to produce very significant amounts of rain, in most cases less than
a quarter of an inch of rain is to be expected. This pattern is expected
for the rest of the workweek and until the upcoming weekend. Seasonable
temperatures will prevail each day

.LONG TERM...Sunday through Friday...
The mid to upper level ridge will remain anchored over the northeastern
Caribbean through most of the period. The persistent low level high
pressure system spread across the Atlantic and extending across the
region, will maintain moderate to strong east northeast trade winds.
This will continue to transport occasional patches of low level moisture
across the region from time to time. Expect an overall fair and
stable weather pattern with periods of passing showers mainly
across the north and east coastal sections of Puerto Rico as well
Vieques, Culebra, and the USVI during the late evening and early
morning hours. Mostly fair weather skies and overall breezy
conditions will prevail during the daytime hours. By Monday and
through Tuesday of next week recent model guidance suggests east
to north east winds to increase once again. This will result in
windy conditions (winds 20 to 25 mph+) across the region. Near
seasonable temperatures and overall cool advective pattern is
forecast during the entire period.

&&

.AVIATION...Mainly VFR conditions expected to prevail through the
forecast period. Trade wind showers will continue at times to move
across the Leeward/USVI/Northern PR terminals. Latest TJSJ sounding
indicated an ENE winds at 10-32 kts all the way from the surface to
around 25k feet, becoming WNW and stronger above 25k feet.

&&

.MARINE...Choppy and hazardous seas between 6 and 10 feet will
continue across the regional waters. Seas are expected to slowly
diminish through Friday, but small craft advisories will remain in
effect through at least Friday due to the moderate to locally fresh
winds and choppy seas.

Life threatening rip currents will continue across most of the
beaches in Puerto Rico and the U.S. Virgin Islands where there is
a moderate to high risk of rip currents, except for some beaches
in the west and south coasts of Puerto Rico. Please refer to the
latest Surf Zone forecast issued by WFO San Juan PR.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 82 73 83 73 / 50 30 30 30
STT 83 72 83 72 / 50 30 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
423 PM AST Thu Feb 15 2018

.SYNOPSIS...Pressure gradient over the local area is relaxing a
little, which is causing the winds to diminish slightly and will
hold steady through the weekend. Patches of moisture will continue
passing over the area, bringing scattered to locally numerous,
but brief showers, especially during the evening into the
following mornings for the next few days.

&&

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

East to east northeast winds are still expected across the local
area for the next several days. It will be somewhat breezy for the
rest of today with winds at 15-20mph with occasional gusts, winds
decreasing to 5-15mph starting tonight and continuing into this
weekend. This is due to a slight relaxing of the local pressure
gradient from a surface high pressure to the north of the local
area. Overall available moisture will continue to be below normal,
but patches of moisture are moving in, causing scattered to
numerous, but brief showers across the area. These showers will
affect the local waters, USVI, Vieques and Culebra, and the north
and eastern sections of PR, particularly in the evening and early
morning hours. During the daytime hours, most of the cloud
and shower development is expected across the interior into
western PR, especially in the afternoon. The upper levels are not
particularly unstable over the local area, so the showers that do
affect any one area are not expected to produce very significant
amounts of rain, the same forecast remains, less than a quarter
of an inch of rain is to be expected at any given day through this
weekend.

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

.From previous discussion...

The mid to upper level ridge will remain anchored over the
northeastern Caribbean through most of the period. The persistent
low level high pressure system spread across the Atlantic and
extending across the region, will maintain moderate to strong east
northeast trade winds. This will continue to transport occasional
patches of low level moisture across the region from time to
time. Expect an overall fair and stable weather pattern with
periods of passing showers mainly across the north and east
coastal sections of Puerto Rico as well Vieques, Culebra, and the
USVI during the late evening and early morning hours. Mostly fair
weather skies and overall breezy conditions will prevail during
the daytime hours. By Monday and through Tuesday of next week
recent model guidance suggests east to north east winds to
increase once again. This will result in windy conditions (winds
20 to 25 mph+) across the region. Near seasonable temperatures and
overall cool advective pattern is forecast during the entire
period.


&&

.AVIATION...The easterly winds continues at 15 to 20 knots with
higher gusts. Winds are fcst to drop around 10 kt aft 15/23z,
increasing once again around 15 kt aft 16/13z. SHRA/-SHRA will move
from time to time across TJSJ/TIST/TJBQ. TJMZ can expect VCSH
between 15/18-22z. Clouds embedded in the trades will produce BKN-
OVC ceilings btwn FL020-FL080 at TJSJ/TIST/TKPK/TNCM thru the
overnight hrs.


&&

.MARINE...Seas and surf zones continue to be hazardous. Seas are
still up to 8 feet and there is a moderate to high risk of rip
currents across many of the beaches in PR and the USVI. Small
craft advisories continue until Friday, then seas subside a
little. However, seas will once again become hazardous by Sunday.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 73 83 73 83 / 60 30 30 30
STT 72 83 72 83 / 60 30 30 30

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
336 AM AST Fri Feb 16 2018

.SYNOPSIS...Pressure gradient over the local area is relaxing a
little, which is causing the winds to diminish slightly and will
hold steady through the weekend. Patches of moisture will continue
passing over the area, bringing scattered to locally numerous,
but brief showers, especially during the evening and morning
hours.

&&

.SHORT TERM...Today through Sunday...
Recent FAA radar and satellite images showed a large cluster of low
level clouds with embedded showers moving across the region during
the overnight hours. Rainfall amounts were generally around a
quarter of an inch of rain with the heaviest showers. Minor ponding
of waters on roadways and in low lying areas is expected to continue
through the early morning hours. Expect conditions to gradually
improve by late morning with decreasing cloudiness and mostly fair
weather skies through the rest of the day. The exception will be
over parts of the interior and west to southwest sections of PR
where locally and diurnally induced showers may form and stream
westward.

On Saturday and Sunday...East to northeast winds will persist across
the local area for the next several days. Breezy conditions expected
once again by late Saturday through Sunday, as the surface high will
strengthen north of the region leading to increasing trade winds
between 15-25 mph with occasional gusts. Patches of low level
moisture with associated showers in the easterly trades will
continue to move across the region but is expected to become more
frequent by Sunday as the winds increase. These showers will affect
the local waters, USVI, Vieques and Culebra, and the north and
eastern sections of PR, particularly in the evening and early
morning hours. During the daytime hours, most of the cloud and
shower development is expected across the interior into western PR,
especially during the afternoon.

.LONG TERM...Monday through Saturday...
A mid to upper level ridge will remain anchored over the region
until at least Wednesday, limiting the development of deep
convection across the forecast area. By late Wednesday through the
end of the forecast period, an upper level trough associated with
an upper low across the central Atlantic is expected to amplify
across the northeast Caribbean. A cold front will move across the
northwest Atlantic Saturday and Sunday. A strong surface high
pressure is expected to move across the northwest Atlantic behind
the cold front on Monday and eventually across the Central
Atlantic by mid week. Recent model guidance suggests east to
north east winds to increase once again in association with this
strong surface high pressure. This will result in windy conditions
(winds 20 to 25 mph+) across the region. Near seasonable
temperatures and overall cool advective pattern is forecast during
the entire period.

Occasional patches of low level moisture embedded in the east
northeast trades will move across the region from time to time.
Expect an overall fair and stable weather pattern with periods of
passing showers mainly across the north and east coastal sections
of Puerto Rico as well across Vieques, Culebra, and the USVI
during the late evening and early morning hours. Some shower
activity is also expected across interior and southwest Puerto
Rico each afternoon.

&&

.AVIATION...SCT-BKN cld lyrs nr FL022...FL050...FL080. -SHRA/SHRA en
route btw islands and over coastal waters...and Tempo MVFR at
TJSJ/TJBQ/TIST/TISX/TNCM TIL 16/10Z. Sfc wnds nr 10kts incr 15 to 20
kts with occasionally higher gusts aft 16/14z.Low level wnds fm NE
15-25 KTS. VCSH at TJMZ 16/18-16/22z.

&&

.MARINE...Choppy and hazardous seas between 6 and 8 feet will continue
across the regional waters today. Seas will continue to gradually
decrease through Saturday but increase once again through early
next week. Life threatening rip currents will continue across most
of the northern beaches in Puerto Rico and St. Croix.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 83 74 82 74 / 30 30 30 30
STT 83 73 83 73 / 30 30 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
331 AM AST Sat Feb 17 2018

.SYNOPSIS...Surface high pressure continues to the north of the
local islands, causing moderate east to east northeast winds
across the local area. The local pressure gradient will tighten
early in the workweek as a stronger surface high pressure
develops across the northwestern Atlantic. This will cause the
local winds to increase and the marine conditions to become
hazardous once again. Overall available moisture will remain
below normal, but patches of low level moisture will pass through
occasionally, causing brief showers across the islands. An upper
low pressure could approach the local area late in the upcoming
workweek but it is not expected to have a significant impact in
the local weather, therefore no major change in the weather
conditions is anticipated for the next several days.

&&

.SHORT TERM...Today through Monday...
Moderate east northeast trade winds winds will persist across the
local area through the weekend and into early next week. Breezy
conditions are therefore expected today through Monday, as the
surface high pressure ridge across the Atlantic will strengthen
north of the region leading to increasing trade winds between
15-25 mph with more frequent gusty winds.

Patches of low level moisture and associated trade wind showers will
continue to make their way and increase in frequency across the
region by Sunday, as the pressure gradient tightens and trade winds
increase. These showers and clouds will affect the local waters,
U.S. Virgin Islands, Vieques and Culebra, and the north and eastern
sections of PR, especially during the evening and early morning
hours. During the day, most of the cloud and shower development is
then expected to form and stream across the interior into west
sections of PR during the afternoons. Elsewhere and over the USVI,
mostly sunny fair weather skies and breezy to windy conditions will
prevail during the period with no significant rainfall or weather
feature anticipated at this time.

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

Patches of moisture will pass through at times, causing brief
showers over the local area. These showers will mainly be observed
across the local waters, USVI, Vieques and Culebra as well as
northern and eastern PR, especially during the nighttime and early
morning hours. A strong SFC high pressure across the northwestern
Atlantic will cause the local pressure gradient to tighten early
in the workweek, which will cause windy conditions locally. These
winds will likely inhibit the usual sea breeze convergence in the
afternoon hours across western PR, which means that the areas that
could be affected by rain will probably be the local islands and
north and eastern PR, even during the daytime hours. Wednesday
looks to be the day with the best moisture so it is the day, in
the long term range of the forecast, that will likely observe the
best rainfall coverage, however, it is still expected to be
somewhat windy so the showers observe should be very brief. No
major change in the overall pattern is expected other than maybe
the wind speeds decreasing by Thursday.

&&

.AVIATION...SCT-BKN cld lyrs nr FL025...FL050...FL080. -SHRA/SHRA en
route btw islands and over coastal waters. VCSH with ocnl -RA at
TJSJ/TJBQ/TIST/TISX/TNCM TIL 17/14Z. Sfc wnds 10kts or less,
increasing 15 to 25 kts with occasionally higher gusts aft 16/14z.
Low level wnds fm NE 15-25 KTS. VCSH and BKN nr FL040-FL080 at TJMZ
and ctrl mtn range of PR 16/18-16/22z.

&&

.MARINE...Small craft operators are urged to exercise caution
across the local waters since seas will be up to 6 feet and the
local winds will be up to 20 knots, with the exception of the
coastal waters of southwestern Puerto Rico where the winds will be
up to 15 knots and the seas up to 4 feet. There is a moderate to
high risk of rip currents across most of the local beaches, please
refer to the local surf zone forecast for the details in your
area.



&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 82 74 83 74 / 50 30 30 30
STT 83 73 84 73 / 40 30 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
438 PM AST Sat Feb 17 2018

.SYNOPSIS...Surface high pressure continues to the north of the
local islands, causing moderate east to east northeast winds
across the local area. The local pressure gradient will tighten
early in the workweek as a stronger surface high pressure
develops across the northwestern Atlantic.

&&

.SHORT TERM...Tonight through Monday...Partly cloudy skies
prevailed across Puerto Rico and the U.S. Virgin Islands today. An
area of cloudiness moved across the area, with little
precipitation observed. Latest satelite images depicted a dry air
mass encompassing the region from the east. This dry air mass will
result in less shower activity. Partly cloudy to clear skies are
expected tonight into Sunday morning. A patch of low level
moisture embedded in the trade winds is expected to reach the
local area Sunday morning. Strong high pressure will build across
the region late sunday into Monday, maintaining relatively dry
weather conditions across the islands.

.LONG TERM....LONG TERM...Tuesday through Sunday...(previous
discussion)

Patches of moisture will pass through at times, causing brief
showers over the local area. These showers will mainly be observed
across the local waters, USVI, Vieques and Culebra as well as
northern and eastern PR, especially during the nighttime and early
morning hours. A strong SFC high pressure across the northwestern
Atlantic will cause the local pressure gradient to tighten early
in the workweek, which will cause windy conditions locally. These
winds will likely inhibit the usual sea breeze convergence in the
afternoon hours across western PR, which means that the areas that
could be affected by rain will probably be the local islands and
north and eastern PR, even during the daytime hours. Wednesday
looks to be the day with the best moisture so it is the day, in
the long term range of the forecast, that will likely observe the
best rainfall coverage, however, it is still expected to be
somewhat windy so the showers observe should be very brief. No
major change in the overall pattern is expected other than maybe
the wind speeds decreasing by Thursday.

&&

.AVIATION...A dry air mass will limit SHRA across the islands, but
Winds btwn 10 and 20 kt will push clouds and trade wind showers at
times mainly across TIST/TJSJ. SHRAs due to diurnal effects are
expected across the SW quadrant of PR resulting in VCSH at
TJMZ/TJPS. SCT-BKN cld lyrs nr FL025...FL050...FL080. Expect
easterly winds at 10-20 kt with gusts in/near SHRA. Winds are
expected to drop around 10 kt overnight.

&&

.MARINE...Seas have diminshed to around 6 feet across the local
waters.However, hazardous marine conditions are expected to
continue through at least mid next week. Seas will increase once
again late Sunday night. As a result, small craft advisories will
be in effect. Winds up to 20 knots are also expected.


&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
352 AM AST Sun Feb 18 2018

.SYNOPSIS...Surface high pressure across the Atlantic to the
north of the local islands will produce moderate east to east
northeast winds across the local area today. The local pressure
gradient will tighten early in the workweek as a stronger surface
high pressure develops across the northwestern Atlantic.

&&

.SHORT TERM...Today through Tuesday...
Prevailing easterly trade winds will continue to increase today
through Tuesday, as the surface high pressure ridge will build
north of the region and tighten the local pressure gradient.

As a result, expect frequent passing low level clouds with
occasional showers to affect the forecast area, especially during
the evening and early morning hours. This will be followed by mostly
sunny skies and fair weather under breezy conditions each day. As
pressure gradient continues to tighten, expect windy conditions (20-
25 MPH) with stronger and more frequent gusts by Monday and Tuesday.

Apart from the cool advective pattern of shallow moisture and quick
passing trade wind showers, an overall dry and stable airmass will
dominate the region, as the mid to upper level ridge will remain in
place for the next several days. As previously mentioned, expect to
see an increase in the early morning shower activity along portions
of the north and east coastal sections of the islands, as the trade
winds increase. These showers will be of short duration with no
significant weather impacts at this time. The exception will be the
deterioration of the marine conditions which is forecast to begin
later tonight and continue through Tuesday. Surf Zone Conditions are
also forecast to deteriorate creating dangerous rip currents along
most of the local beaches. Stay tuned and remain alert to the local
weather and marine conditions.

.LONG TERM...Wednesday through Monday...
An upper level trough is expected to amplify across the northeast
Caribbean Wednesday through Saturday. This feature will result in
an increase of moisture transport across the local islands and
surrounding waters. Strong surface high pressure is expected to
persist across the Atlantic waters, just to north of the local
islands until at least Friday. This surface high pressure will be
replaced by another strong high pressure Saturday through Monday.
Patches of moisture embedded in the east northeast trades will
continue to move over the forecast area at times, causing brief
showers over the local islands. These showers will affect mostly
the local waters, USVI, Vieques, Culebra as well as the northern
and eastern PR, especially during the nighttime and early morning
hours. The strong surface high pressure systems across the
Atlantic will cause the local pressure gradient to tighten early
in the workweek, which will cause windy conditions locally. These
winds will likely inhibit the usual sea breeze convergence in the
afternoon hours across western PR, which means that the areas that
could be affected by rain will probably be the USVI , Vieques,
Culebra and north and eastern PR, even during the daytime hours.
Wednesday through Saturday, looks to be the days with the best
moisture due to the presence of an upper level trough close to
the region. However, it is still expected to be somewhat windy so
the showers observe should be heavy but brief.

&&

.AVIATION...VFR conds durg entire prd at all terminals. SCT-BKN cld
lyrs nr FL025...FL050...FL080...SKC ABV. L/LVL WNDS fm ENE 15-20 kts
blo FL250. -SHRA/SHRA en route btw islands and ovr regional waters.
Few Tops btw FL100-FL120. Sfc wnds lgt/vrb bcmg 15-20 kts and gusty
aft 18/14z. No sig wx impacts at terminals or ovr local flying
area.

&&

.MARINE...Seas have diminished to around 6 feet across the local
waters, but will increase again tonight and Monday. Thus,
hazardous marine conditions are expected to continue through at
least mid week. As a result, small craft advisories will be in
effect. Winds up to 25 knots with higher gusts are expected.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 82 74 83 75 / 30 30 30 30
STT 84 72 85 73 / 30 30 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
414 PM AST Sun Feb 18 2018

.SYNOPSIS...Surface high pressure across the Atlantic to the
north of the local islands will produce moderate east to east
northeast winds across the local area today. The local pressure
gradient will tighten early in the workweek as a stronger surface
high pressure develops across the northwestern Atlantic.

&&

.SHORT TERM...Today through Tuesday...Pleasant weather condtions
prevailed across Puerto Rico and the U.S. Virgin Islands today.
Dry weather conditions prevailed, with isolated isolated passing
showers affecting the region sporadically. Even drier weather
conditions are expected to prevail tonight through Tuesday as
a strong high pressure across the Atlantic north of the islands
continues to produce good weather conditions. Winds will increase
too, which will result in breezy conditions across the local area.
In addition, this wind will transport patches of low level
moisture from time to time through the region.

.LONG TERM...Wednesday through Monday...Strong surface high
pressure will remain anchored across the western Atlantic through
the forecast period. However, for Wednesday through Saturday an
upper level trough is expected to amplify across the northeast
Caribbean Wednesday through Saturday. This feature will result in
an increase of moisture transport across the local islands and
surrounding waters.

&&

.AVIATION...VFR conds durg the fcst prd. SFC WNDS fm the E at 15-22 kts with
higher gusts will prevail through the evening. VCSH and BKN ceiling
at FL030-FL050 expected around TJMZ btwn 18/18-22z. Winds are
forecast to drop around 10 kts overnight increasing once again at 15
to 20 knots aft 19/13z. No sig wx impacts at terminals or ovr local
flying area.

&&

.MARINE...Marine conditions are expected to deteriorate rapidly
tonight into Monday with building seas of 6 to 8 feet and winds up
to 25 kts. Small Craft advisories will be in effect for all
coastal waters, except across the coastal waters of southwestern
Puerto Rico were seas below 5 feet are expected.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 74 83 75 82 / 30 30 30 30
STT 72 85 73 83 / 20 30 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
516 AM AST Mon Feb 19 2018

.SYNOPSIS...High pressure building in the western Atlantic will
sink slowly south during the week while weakening only slowly
generating fresh to strong breezes across the area. High pressure
at upper levels will build over the waters north of Cuba. A short
wave upper level trough will ride over the ridge today and
strengthen and stall east of the local area by Wednesday. Lower
level winds will carry shallow showers across the area from time
to time that will be enhanced by a weak frontal passage
Wednesday.

&&

.SHORT TERM...Today through Wednesday...
A few showers were observed overnight mostly across the surrounding
waters with few of them affecting the U.S. Virgin Islands as well as
the eastern and northern sections of Puerto Rico, leaving minimal
rainfall accumulations if any. Fairly dry and pleasant weather
conditions are expected to prevail today and the latest forecast is
in agreement with the observations and guidance.

An upper level ridge will hold over the region for the next few
days, limiting the development of deep convection across the local
islands. A strong surface high pressure is expected to move across
the northwest Atlantic behind a surface low and the associated cold
front across the north central Atlantic. This surface high pressure
system will produce an east to east northeast low level wind flow
across the local area for the next several days. As this high
pressure ridge strengthens north of the region, local pressure
gradient is expected to tightens, increasing the trades across the
region. This will result in breezy conditions across the local area
for the next few days. Winds of 20-25 MPH with frequent gusts of 30
MPH or greater are expected Today through Wednesday. Small patches
of shallow low level moisture embedded in the trades are expected to
move quickly across the region from time to time with little
rainfall accumulation. Generally there is little to no sea breeze
convergence with stronger winds, so the afternoon convection across
western PR is expected to be very limited. The exception will be the
deterioration of the marine conditions which is forecast to begin
today and continue through at least Wednesday. Surf Zone Conditions
will continue to also deteriorate creating dangerous rip currents
along most of the local beaches. Drier weather should commence
after a weak frontal passage Wednesday.

Due to the dry and breezy conditions expected today, an elevated
fire danger is expected across the southern coastal plains of Puerto
Rico and a Red Flag Warning will be in effect from 8 AM this morning
through 6 PM this evening for that area.

.LONG TERM...Thursday through Monday...
Pronounced northeast to east northeast low level flow will begin
to subside by mid week but will still be moderate to fresh by
Sunday. A weak cold front will usher in cooler and relatively
drier air Wednesday night through Thursday night. Patches of
moisture and weak, rumpled remnants of fronts will pass through
for the rest of the period insuring that brief scattered showers
keep windward slopes damp Friday through next Monday. A weak upper
level low will pinch off the trough extending toward the area at
250 mb on Thursday to enhance some of the showers that will
occur. When it lifts north it will bring an 85 knot jet of
southwest winds across the area, but generally flow will be
subsident on this side of the low until late in the weekend.

&&

.AVIATION...Mainly VFR conditions expected across the local
flying area for the next 24 hours. Winds will remain from the ENE at
10-15 knots until 19/12Z, increasing to 15-20 knots with occasional
gusts to 30 knots after that. SHRA activity is expected to be very
brief, VCSH possible.


&&

.MARINE...Winds and sea will increase today and tonight. Seas will
continue to increase through Thursday with up to 12 feet likely
in the northeast corner of our outer Atlantic waters Wednesday
night. Small craft advisories are likely to remain up across most
of the waters exposed to northeast swell through the end of the
week.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 83 72 81 73 / 30 20 30 30
STT 84 71 85 71 / 20 20 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
440 PM AST Mon Feb 19 2018

.SYNOPSIS...High pressure building in the western Atlantic will
sink slowly south during the week while weakening only slowly
generating fresh to strong breezes across the area.

&&

.SHORT TERM...Tonight through Wednesday. Partly sunny skies with
breeze conditions prevailed across Puerto Rico and the U.S. Virgin
Islands today. Very light passing showers were observed. Winds
between 20 to 25 mph were observed across some localized area,
mainly in higher elevations. Strong surface high pressure is the
responsible for these weather conditions. A very dry air mass has
encompassed the region. As a result, limited shower activity is
expected through at least Wednesday. An increase in low level
moisture is expected on Wednesday.

.LONG TERM...Thursday through Monday...(Previous discussion)

Pronounced northeast to east northeast low level flow will begin
to subside by mid week but will still be moderate to fresh by
Sunday. A weak cold front will usher in cooler and relatively
drier air Wednesday night through Thursday night. Patches of
moisture and weak, rumpled remnants of fronts will pass through
for the rest of the period insuring that brief scattered showers
keep windward slopes damp Friday through next Monday. A weak upper
level low will pinch off the trough extending toward the area at
250 mb on Thursday to enhance some of the showers that will occur.
When it lifts north it will bring an 85 knot jet of southwest
winds across the area, but generally flow will be subsident on
this side of the low until late in the weekend.


&&

.AVIATION...VFR conds are expected to prevail through the forecast
cycle with brief -SHRA/SHRA possible at the Leeward and USVI
terminals as well as JSJ/JBQ. ENE winds 15-25 knots with higher
gusts, becoming at around 12-15 knots overnight.

&&

.MARINE...Local buoy were showing an increase in seas with buoy
41053 located around 170 nautical miles northeast of San Juan
indicating near 7 feet. Seas are expected to remain hazardous for
the rest of the week. Small Craft advisories continue in effect.

&&

.FIRE WEATHER...Latest surface observations indicated relative
humidity values at Camp Santiago drop to 39% late this afternoon.
Although relative humidity values will remain near threshold level
tonight, winds are expected to decrease across the southern
plains.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 72 81 73 81 / 30 30 30 40
STT 71 85 71 83 / 30 30 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
517 AM AST Tue Feb 20 2018

.SYNOPSIS...High pressure in the western Atlantic will move
southwest while weakening during the week. This will produce fresh
to strong winds that will slowly decrease after mid week. Areas of
moisture will move through bringing episodes of showers to the
smaller islands and windward sides of Puerto Rico. Little change
is expected in the weather pattern for the next 5 to 7 days.


&&

.SHORT TERM...Today through Thursday...
Strong surface high pressure over the W Atlantic will continue to
sink into the SW North Atlantic. Fresh to locally strong east to
northeast trade winds will prevail across the region as the
pressure gradient tightens. Trade wind showers will continue to
move at times from the Atlantic waters into the region, affecting
mainly the northern USVI and the northern and eastern sections of
PR. On Wednesday, the remnants of an old front and windy
conditions will increase the frequency of showers across the
islands. Drier air will fill in briefly on Thursday morning but
shower activity will increase once again during the evening hours
as an upper level short wave trof moves just to the east-
northeast of the region.

A wind advisory was issued for the USVI and Vieques due to expected
sustained winds around 25 mph. Breezy conditions are expected across
the rest of the region with gusts in the low to mid 30 mph. As winds
are forecast to gradually increase and peak on Wednesday another
wind advisory will be required for at least the northern and eastern
municipalities of PR.

.LONG TERM...Friday through Wednesday...
Fading high pressure in the western Atlantic will continue to
drive moderate to fresh east northeast trade winds across the
area. Patches of moisture will form in the low level flow and
become progressively wetter with strong fluctuations in moisture
through the period generating increasing showers that will remain
brief and shallow but become more frequent and affect more of the
island of Puerto Rico during the period. An upper level jet
around a high building over the western tropical Atlantic will
grow over the area and translate to the northwest maintaining
subsidence at mid and upper levels through the period. Friday
should be the coolest day of the period with the GFS 1000-850 mb
thicknesses increasing afterward. Otherwise little change in the
overall pattern will be noted.

&&

.AVIATION...Mainly VFR conditions are expected to prevail through
forecast period. However, SHRA will continue to move at times early
this morning across TJSJ/TIST creating possible MVFR cigs. SHRA
expected to increase once again after 21/00z across the northern PR
terminals and TIST. East-northeast winds will prevail at 15-25 knots
with higher gusts after 20/14z. Sea breeze variations are possible
across the southwestern quadrant of PR. Winds back from NE to NW
and increase from 25 to 40 knots btwn FL170-350.

&&

.MARINE...Winds will be raising seas and short period swell during
the next 48 hours. Only sheltered areas on the western side of
Puerto Rico will escape small craft advisories and small craft
should still exercise caution there for winds. Winds will slowly
subside later in the week, but seas are expected to remain
hazardous in all but the waters least exposed to northeast swell and
seas through the weekend.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 81 75 82 73 / 60 60 60 60
STT 85 73 84 72 / 60 60 60 60

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
457 PM AST Tue Feb 20 2018

.SYNOPSIS...High pressure in the western Atlantic will move
southwest while weakening during the week. This will produce fresh
to strong winds that will slowly decrease after mid week. Areas of
moisture will move through bringing episodes of showers to the
smaller islands and windward sides of Puerto Rico. Little change
is expected in the weather pattern for the next 5 to 7 days.

&&

.SHORT TERM...Very dry and pleasant weather conditions prevailed
across Puerto Rico and the U.S. Virgin Islands today. Very little
shower activity was experienced across the region. Local area
remains under the influence of a high pressure system which
continue to produce fresh to strong winds across the region. This
weather pattern will continue through tonight. An old frontal
boundary will move across the region Wednesday, increasing the
cloudiness and chances for showers across the local islands. Very
dry air mass will encompass the region Thursday.

.LONG TERM...Friday through Wednesday...(no changes from previous
discussion)Fading high pressure in the western Atlantic will
continue to drive moderate to fresh east northeast trade winds
across the area. Patches of moisture will form in the low level
flow and become progressively wetter with strong fluctuations in
moisture through the period generating increasing showers that
will remain brief and shallow but become more frequent and affect
more of the island of Puerto Rico during the period. An upper
level jet around a high building over the western tropical
Atlantic will grow over the area and translate to the northwest
maintaining subsidence at mid and upper levels through the period.
Friday should be the coolest day of the period with the GFS
1000-850 mb thicknesses increasing afterward. Otherwise little
change in the overall pattern will be noted.


&&

.AVIATION...VFR conds are expected to prevail through the forecast
cycle with brief -SHRA/SHRA at the Leeward and USVI terminals as
well as JSJ/JBQ aft 21/10z. ENE winds 15-20 knots with higher gusts,
becoming at around 10-12 knots overnight.

&&

.MARINE...Local buoy are indicating hazardous seas up to 7 feet
in the nearshore waters of northern Puerto Rico, and up to 10
feet in the Atlantic offshore waters. Elsewhere except the coastal
waters SW of PR where seas will be up to 5 feet. Seas will
increase tomorrow as winds increase even more. There is a high
risk of rip currents across most of the local beaches of PR and
the USVI, except for western PR.


&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
549 AM AST Wed Feb 21 2018

.SYNOPSIS...Strong surface high pressure will continue across the
western Atlantic through early next week. Fresh to strong east to
northeast trades will persist through Thursday, decreasing
by the end of the week. Trade wind shower pattern will continue to
bring areas of showers across the USVI and the eastern sections of
PR each day. Retrogressing upper level trof and jet maxima pattern
will increase the development of showers across the region through
early next week.

&&

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

A few showers were seen north of the central mountains. A band of
better convection is just outside of the northeast corner of the
forecast area and is moving at 32 knots from the east northeast. It
should arrive in Saint Thomas and northeast Puerto Rico between
21/12-14Z. It will bring brief showers to much of the area as it
moves across and is likely to affect the area for most of the the
rest of the day. The main driver is high pressure at the surface
pressing a cooler air mass into the area. The GFS shows a weak cold
front acting as an area of convergence passing through today and
early this evening, followed by considerably drier air at 700 mb.
Nevertheless, moisture at 850 mb lingers through at least 22/18Z and
will generate showers across the area with pretty good certainty-
-especially along the windward slopes.

Winds are increasing today and will remain higher than yesterday
through tomorrow, Thursday. On Friday an upper level trough will
extend toward the west north of the area and will pull a 90 knot jet
from the southwest over the area. This will allow lower layers to
remain moist or actually regain moisture that will provoke another
round of showers across the area. Although no heavy amounts will be
able to fall for an extended period of time due to the granular
nature of the cells in the frontal band and its orientation, those
cells will likely be able to produce amounts of one half to one inch
on windward slopes and up to one quarter inch on windward coasts
during the next 24 hours. Amounts will diminish Thursday and Friday.
slightly cooler temperatures will be seen overnight, but daytime
temperatures will likely remain in the lower 80s for the lower
elevations due to some increase in sun Thursday and Friday for all
but the highest terrain.

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

High pressure north of the region will hold through Tuesday
maintaining a moderate to fresh east to northeast trade wind flow
across the area. Trade wind showers will continue to move and
increase in frequency during the weekend across the region.
Meanwhile, an upper level trough and jet maxima pattern over the
region will aid in the development of more showers and a wetter
pattern by next week. Afternoon shower development is expected
along the mountain ranges of PR through the long term period.
Urban and small stream flooding in isolated areas will be
possible with the heaviest showers on Tuesday and Wednesday.

&&

.AVIATION...Moisture gathered by a weak cold front will increase
across the area til 21/23Z. Hence expect mtn obscurations and lcl
MVFR in brief SHRA due to CIGs aft 21/13Z for TIST TNCM and TKPK.
MVFR in PR will be confined to interior non-TAF sites aft 21/15Z
with same mtn obscurations. Sfc winds incrg up to 20G33KT along nrn
coast of PR and most of USVI. Highest gusts nr SHRA. Max winds WNW
39 kt btwn FL400-460 backing overnight to WSW 55 to 65 kt by 22/12Z.

&&

.MARINE...Choppy and hazardous seas will continue through the rest
of the week across all local waters with the exception of the SW
coastal waters of PR. Wind driven seas are forecast to build up
to 12 this afternoon across the offshore Atlantic waters and the
Anegada passage. Although the dominant period will be around 8-10
seconds, large breaking waves between 8-12 feet are expected along
the northern beaches of the islands later this afternoon and are
expected to continue through Friday. Therefore, a high surf
advisory was issued for the northern coastal areas of the islands.
Life threatening rip currents will continue through the weekend
across most of the north, east and south facing beaches of the
islands. Please refer to latest coastal hazard message(CFWSJU)
and the surf zone forecast (SRFSJU) for detailed information.

Windy conditions will prevail across the regional waters through
at least Thursday with sustained east to northeast winds between
20-25 kt.

&&

.FIRE WEATHER...Low RH`s and windy conditions will result in an
elevated fire danger across the southern coast of PR today.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 82 73 81 74 / 70 60 20 60
STT 84 72 83 71 / 50 40 10 60

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
439 PM AST Wed Feb 21 2018

.SYNOPSIS...Strong surface high pressure will continue across the
western Atlantic through early next week. Fresh to strong east to
northeast trades will persist through Thursday, decreasing
by the end of the week.

&&

.SHORT TERM...Tonight through Friday...Cloudiness with showers
affected the local islands today. This was the result of an old
frontal boundary which is bringing periods of cloudiness with
showers at times. This weather pattern is expected to continue
through tonight, before a drier air mass encompass the region from
the north. For thursday, dry weather conditions are expected with
less shower activity. Next round of cloudiness and showers is
expected by Friday.

LONG TERM...Saturday through Thursday...(no changes from previous
discussion).

High pressure north of the region will hold through Tuesday
maintaining a moderate to fresh east to northeast trade wind flow
across the area. Trade wind showers will continue to move and
increase in frequency during the weekend across the region.
Meanwhile, an upper level trough and jet maxima pattern over the
region will aid in the development of more showers and a wetter
pattern by next week. Afternoon shower development is expected
along the mountain ranges of PR through the long term period.
Urban and small stream flooding in isolated areas will be
possible with the heaviest showers on Tuesday and Wednesday.

&&

.AVIATION...VFR conds are expected to prevail through the forecast
cycle with brief -SHRA/SHRA at the Leeward and USVI terminals as
well as JSJ/JBQ. ENE winds 15-25 knots with higher gusts, becoming
at around 15 knots overnight.

&&

.MARINE... buoy 41053 located near 170 miles northeast of San Juan
was showing seas up to 9 feet and buoy 41043 up to 12 feet in
the Atlantic offshore waters. Elsewhere except the coastal waters
SW of PR where seas will be up to 5 feet. Seas will increase
tomorrow as winds increase even more. There is a high risk of rip
currents across most of the local beaches of PR and the USVI,
except for western PR.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 73 81 74 82 / 30 20 60 60
STT 72 83 71 84 / 40 10 60 60

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
539 AM AST Thu Feb 22 2018

.SYNOPSIS...Strong surface high pressure over the western
Atlantic will continue to result in breezy conditions across the
region through at least Friday. Trade wind shower pattern will
continue to bring areas of showers across the USVI and the
northern sections of PR each day. Upper level trough and
associated jet maxima will move over the region on Fri-Sat. This
will increase the chances for heavier showers.

&&

.SHORT TERM...Today through Saturday...
A few showers still transit the local Atlantic waters and have
run up against the Luquillo range in Puerto Rico. Showers were
also seen just west of Saint Croix. After 10 PM overnight amounts
have been minimal if any. The weak frontal boundary has pretty
much cleared the forecast as it moves south. An area of closed
cell convection is now crossing into the northeast corner of the
forecast area and will contribute to the showers expected to re-
develop this afternoon and evening after a brief respite and
mostly sunny skies in the morning. High pressure will continue in
the western Atlantic through at least Monday as the pressure fades
from 1036 mb to 1024 mb and the center draws nearer from its
current position 970 miles north to around 730 miles north. An
upper level trough extends southwest several hundred miles to our
north and is accompanied on its souther periphery by a
strengthening jet. This moderate southwest jet will cross the area
from the southeast overnight Friday into Saturday morning
bringing 100 knots winds at 250 mb. As moist flow from the central
Atlantic continues at lower levels, its approach will allow
shower activity to increase. The 500 mb temperature will drop to
around minus 13 C and the lifted index will fall to minus 7
according to the GFS. There is a possibility of thunderstorms
developing over Puerto Rico Friday and Saturday. Will review the
situation again early Friday morning before adding them into the
grids. Although the showers in the thunderstorms could be heavy
flooding is not expected due to the rapid movement of said cells
across the area. so in summary, showers will return to the
windward slopes of Puerto Rico and at least the northern U.S.
Virgin Islands later tonight and increase through Friday night
aided by the trough and jet just mentioned. Showers should also be
forced across most of Puerto Rico north of the Cordillera Central
in the moderate to fresh trade winds that will persist through at
least Saturday.

.LONG TERM...Sunday through Thursday... High pressure north of
the region will hold through Tuesday maintaining a moderate to
locally fresh east to northeast trade wind flow across the area.
Trade wind showers will continue to move and increase in frequency
during the first part of next week. Meanwhile, upper level trough
over the central Caribbean will continue to aid in the
development of showers with possible thunderstorm development
through Tuesday. Urban and small stream flooding in isolated areas
will be possible with the heaviest showers during the long term
period.

&&

.AVIATION...A weak cold front has moved south of the area.
Although some low level moisture follows, morning hours will be
much drier with only isolated SHRA affecting PR/USVI. SHRA will
incr across nrn PR/USVI aft 22/18Z with mtn obscurations and brief
MVFR mainly interior. The Leeward islands will experience the
drier air aft 22/12Z. SHRA to return to TNCM/TKPK aft 23/03Z.
Winds will abate slowly from ENE 10 to 20 kt with gusts TJBQ/TJSJ
up to 33 kt. Max winds W at 50 kt increasing to WSW 70-80kt btwn
FL340-440 by 23/12Z as upper level jet advanced over area.

&&

.MARINE...Rough seas continue across the regional waters except
in the coastal southwestern waters of PR. Seas will range between
8-12 feet and east to northeast trades at 15-25 knots will
continue across the region. Winds will gradually decrease through
the weekend as well as the seas. However, SCA are in effect
through the weekend due to seas still reaching 7-8 feet.

High surf advisory continues for the northern beaches of PR and
the USVI through Friday afternoon. High risk of rip currents will
continue through the weekend across the northern beaches of the
islands.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 81 74 82 73 / 20 70 70 60
STT 83 72 82 72 / 20 60 50 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
411 PM AST Thu Feb 22 2018

.SYNOPSIS...Strong surface high pressure over the western
Atlantic just north of the region will continue to result in
breezy conditions across the region through at least Friday.
Trade wind shower pattern will continue to bring areas of showers
across the USVI and the northern sections of PR each day. Upper
level trough and associated jet maxima will move over the region
Friday through Saturday. This will increase the chances of showers
across the region.

&&

.SHORT TERM...Tonight through Saturday...
Terminal Doppler radar indicated isolated to scattered passing
showers moving southwestward from the Atlantic waters, affecting
mostly the U.S. Virgin Islands, Vieques, Culebra as well the
northern and eastern sections of Puerto Rico. This activity is
expected to continue tonight. However, rainfall amounts have been
minimal if any. The remnants of a weak frontal boundary will
continue to dissipate across the Caribbean waters just south of
the region. Strong surface high pressure will hold across the
western Atlantic through at least Tuesday, next week. An upper
level trough extends southwest from an upper level low across the
central Atlantic, several hundred miles to our north and is
accompanied on its southern periphery by a strengthening jet. This
jet will cross the area from the southeast Friday into Saturday
morning bringing strong upper winds over the region. The strong
surface high pressure across the western Atlantic will continue to
bring patches of low level moisture across the local islands for
the nest several days. This moisture will combine with the strong
upper level winds and upper trough to allow shower activity to
increase Friday and Saturday. There is also a possibility of
thunderstorms developing over Puerto Rico Friday and Saturday.
Although the showers in the thunderstorms could be heavy flooding
is not expected due to the rapid movement the showers. In summary,
showers will continue across the windward slopes of Puerto Rico
and at least the northern U.S. Virgin Islands tonight and increase
through Friday night aided by the trough and jet just mentioned.
Showers should also be forced across most of Puerto Rico north of
the Cordillera Central in the moderate to fresh trade winds that
will persist through at least Saturday.

.LONG TERM...Sunday through Thursday...from previous discussion...
High pressure north of the region will hold through Tuesday
maintaining a moderate to locally fresh east to northeast trade
wind flow across the area. Trade wind showers will continue to
move and increase in frequency during the first part of next week.
Meanwhile, upper level trough over the central Caribbean will
continue to aid in the development of showers with possible
thunderstorm development through Tuesday. Urban and small stream
flooding in isolated areas will be possible with the heaviest
showers during the long term period.

&&

.AVIATION...VFR conds are expected to prevail through the forecast
cycle with VCSH at the Leeward and USVI terminals as well as
JSJ/JBQ. ENE winds 15-20 knots with higher gusts, becoming at around
10-12 knots overnight.

&&

.MARINE...Rough seas continue across the regional waters except
in the coastal southwestern waters of PR. Seas will range between
8-12 feet and east to northeast trades at 15-25 knots will
continue across the region. Winds will gradually decrease through
the weekend as well as the seas. However, SCA are in effect
through the weekend due to seas still reaching 7-8 feet. High
surf advisory continues for the northern beaches of PR and the
USVI through Friday afternoon. High risk of rip currents will
continue through the weekend across the northern beaches of the
islands.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 74 82 73 81 / 70 70 60 60
STT 72 82 72 83 / 60 50 40 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
551 AM AST Fri Feb 23 2018

.SYNOPSIS...High pressure will fade in the western Atlantic just
north of the local area over the weekend and into early next
week allowing winds to diminish and hazardous marine conditions
to subside. Moisture will peak on Sunday with increasing showers
until then. A gradual drying trend will then continue through next
Thursday.

&&

.SHORT TERM...Today through Sunday...
Satellite imagery detected patches of clouds approaching the islands
from the northeast. As these clouds approached, the Terminal Doppler
radar indicated showers with periods of moderate to locally heavy
rain. Through the morning hours, most of the activity is expected to
affect the local Atlantic Waters, the U.S. Virgin Islands, Vieques,
Culebra as well the northern and eastern sections of Puerto Rico.
Although rainfall amount are expected to be minimal, brief periods
of heavy showers could produce hazardous driving conditions. Showers
are forecast to develop across the interior and western sections
around noon, but some brief trade wind showers will remain possible
across the St Thomas, Culebra, the north and east Puerto Rico.

A strong but fading surface high pressure over the western
Atlantic will continue to dominate the local weather conditions
through at least the upcoming week. An upper level trough will
extend southwest over Hispanola through the weekend. Although the
surface moisture is not significant, the surface high pressure
will continue to push patches of moisture across the local
islands, which will result in scattered to numerous showers mostly
during the overnight and early morning hours. Then during the
afternoon hours, this moisture will combine with the upper level
dynamic to result in showers over the western portions of Puerto
Rico as well as downwind from the U.S. Virgin Islands each
afternoon.

.LONG TERM...Monday through Saturday...
Surface high pressure will fade in the western Atlantic just
north of the local area early next week, but will be replaced by a
second high moving out of the eastern United States Wednesday
through Friday. The rumpled remains of a cold front will pass
through the area Monday through Tuesday next week with continued
shower activity, even while precipitable water values trend
downward from Sunday`s peak. This will be due to drying at the top
of the lower levels of the atmosphere. A drier and much more
stable air mass will be ushered in behind the remnants of the cold
front passage on Tuesday. This will limit shower activity area-
wide. Moist air behind a second front on Friday of next week will
prepare the area for possibly more shower activity and a more
vigorous pre-frontal trough early in the week after next.

&&

.AVIATION...SHRA will continue to move across TJSJ/TIST/TNCM/TKPK
through the morning hours. Some of these SHRA will produce brief BKN
ceilings btwn FL020-FL050 at these sites. VFR conds are expected
elsewhere. SHRA will develop near TJMZ and in the VCTY of TJPS
during the afternoon (btwn 23/16-23z). ENE winds 10-15 kt
increasing at 15-20 knots with higher gusts aft 23/12z.

&&

.MARINE...Seas are expected to subside slowly this evening through
Sunday, such that by Sunday night all small craft advisories
should be down. Swell from a strong low in the northern Atlantic
mid week next week will send another surge of swell into the area
Wednesday night and Thursday when small craft advisories will
again be needed for the Atlantic waters and passages.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 81 73 82 73 / 60 60 60 60
STT 83 72 83 72 / 60 60 60 60