Caribbean - Central America Weather

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cycloneye
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Re: Caribbean - Central America Weather

#19141 Postby cycloneye » Fri Dec 15, 2017 3:57 pm

Area Forecast Discussion
National Weather Service San Juan PR
445 PM AST Fri Dec 15 2017

.SYNOPSIS...A mid to upper level ridge will hold across the forecast
area through the weekend and into early next week. Surface high pressure
ridge will continue to build and spread across the east central Atlantic
yielding moderate to strong east to northeast winds through the weekend.
Mostly fair weather skies and seasonal condtions expected to persist
for the next several days.

&&

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

The dominant high pressure ridge pattern, will continue to favor
a strong trade wind cap inversion across the region supporting
mostly fair weather skies across the islands. Model guidance,
satellite imagery and recent upper air sounding continued to suggest
a relatively dry and stable air mass to persist through Sunday.
In addition moisture advection will be limited except for that
brought in across the north and east coastal areas by the moderate
to strong east northeast trades. Expect plenty of sunshine and
few passing clouds with pleasant daytime and overnight temperatures
during the next few days. Occasional light passing showers will remain
possible during the overnight and early morning hours followed by
limited shower activity during the afternoons.

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

A mid to upper level ridge will hold across the forecast area through
at least Wednesday. The ridge pattern aloft is then expected to gradually
erode during the latter part of next week, as a polar trough will move
across the central Atlantic then sink southwards into the northeastern
Caribbean. The surface high pressure ridge pattern north of the region
is forecast to persist through the forecast period. This will result
in moderate to strong east northeast winds. Expect a fair and mainly
stable weather pattern across the islands and coastal waters through
most of next week, except for passing showers especially during the
early morning and late evening hours. Seasonable temperatures are
expected to continue. By the end of the period low level moisture
is forecast to gradually increase as the ridge aloft erodes in response
to an upper trough sinking southwards across the region. This will
result in a better chance for shower activity across the local islands.
Widespread and significant rainfall accumulations as not forecast
at this time.

&&

.AVIATION...VFR conditions will prevail across all terminals through
the forecast period. Afternoon SHRA over the SW quadrant of PR could
affect briefly TJPS/TJMZ. Winds will continue ENE at 10-15 kts with
higher gusts at times.

&&

.MARINE... A north swell between 4-6 feet will continue to affect
the Atlantic waters and passages overnight. This will result in a
high risk of rip currents across the Atlantic beaches of Puerto
Rico, Culebra and St. Thomas. Moderate to fresh east to northeast
winds will continue at 10-15 knots with higher gusts at times increasing
to 15 to 20 knots over the weekend. Small craft advisory will remain
in effect overnight through Saturday for the offshore Atlantic waters.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 76 85 77 84 / 20 20 30 30
STT 76 86 75 87 / 20 30 30 30
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Re: Caribbean - Central America Weather

#19142 Postby cycloneye » Sat Dec 16, 2017 7:00 am

Area Forecast Discussion
National Weather Service San Juan PR
529 AM AST Sat Dec 16 2017

.SYNOPSIS...
Under a ridge pattern aloft, another fair weather day is expected
across the islands. A surface high pressure across the Central
Atlantic will tighten the local pressure gradient increasing the
northeasterly wind flow through the weekend.

&&

.SHORT TERM...Tonight through Monday...
A persistent mid to upper level ridge will suppress wide spread
convection across Puerto Rico and the U.S. Virgin Islands through
the beginning of next week. San Juan Skew-T soundings shows drier
air from 800 mb to 200 mb this is also a reason why showers will
be limited across the region through Wednesday. Similar to the
previous days fair weather conditions will remain across the
forecast area with the possibility for a occasional shower during
the afternoon. Otherwise mostly sunny skies with daytime high
temperatures reaching the low to mid 80s with an easterly wind of
10 to 15 mph with higher gusts possible.

.LONG TERM...Tuesday through Saturday...
The ridge pattern aloft will hold across the islands through the
upcoming mid-week. Therefore, expect mostly mostly clear skies
with a few passing showers from time to time each day. The ridge
pattern is forecast to slowly erodes during the latter part of
next week, as a polar trough amplified from the Northeast into the
northeastern Caribbean. There is enough uncertainty about the
final solutions at this time. However, if weather guidance are in
the right track, this will result in a better chance for shower
activity across the local islands, as well as thunderstorm
development.

&&

.AVIATION...
VFR conditions are expected to prevail for the reminder
of the TAF period. This morning sfc winds 10 to 15 kts before
increasing to 15 to 20 kts with higher gusts by 16/14Z. Isolated
showers are possible during the afternoon but any showers that might
form will be short-lived.

&&

.MARINE...
A northerly swell will continue to slowly erodes across the
Atlantic waters through the morning hours. Mariners can expect
seas between 5 and 7 feet across the Atlantic Offshore waters.
Elsewhere, seas between 4 and 6 feet. Winds will blow from the
east to east-northeast at 10 to 20 knots. A small craft advisory
is in effect across the Atlantic Waters until at least 11 am AST
today. However, rough and hazardous seas will return across the
Offshore waters and Caribbean Waters later tonight.

For the beach goers, there is a high risk of rip currents along
the north facing beaches of Puerto Rico and Culebra and along the
north facing beaches of Saint Thomas and Saint John.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 84 77 84 77 / 10 20 30 30
STT 86 76 87 76 / 20 20 30 30
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Re: Caribbean - Central America Weather

#19143 Postby cycloneye » Sat Dec 16, 2017 4:54 pm

Area Forecast Discussion
National Weather Service San Juan PR
506 PM AST Sat Dec 16 2017

.SYNOPSIS...A mid to upper level ridge will continue to dominate
the local weather conditions for the next several days. A surface
high pressure building across the western Atlantic will promote
a moderate to fresh wind flow from the east-northeast. Fair
weather conditions and a trade wind shower pattern will prevail
across the forecast area.


&&

.SHORT TERM...Saturday through Monday...Ridge aloft and surface
high pressure across the western Atlantic will keep a trade wind
shower pattern across the forecast area through the short term
period. These showers should affect mainly the northern areas of
Puerto Rico and a few of them could reach the interior areas, as
the steering winds from the northeast are between 18-25 kts.
Across the USVI, expect trade wind showers at times. However, no
significant rainfall amounts are expected at the moment. Breezy
conditions will continue through Monday.


.LONG TERM...From previous discussion...Tuesday through
Saturday...The ridge pattern aloft will hold across the islands
through the upcoming mid-week. Therefore, expect mostly mostly
clear skies with a few passing showers from time to time each day.
The ridge pattern is forecast to slowly erodes during the latter
part of next week, as a polar trough amplified from the Northeast
into the northeastern Caribbean. There is enough uncertainty about
the final solutions at this time. However, if weather guidance
are in the right track, this will result in a better chance for
shower activity across the local islands, as well as thunderstorm
development.


&&

.AVIATION...SCT-BKN cld lyrs FL025...FL050...passing SHRA en route
btw islands and ovr coastal waters durg prd. Prevailing VFR at all
local terminals but VCSH AT TJSJ/TJBQ/TJMZ/TJPS til 16/23z. Sfc wnds
mainly fm NE 15-20 kts with higher gusts. low level winds fm NE 20-
25 kts blo FL300...then backing and incr w/ht.


&&

.MARINE...Wind driven seas will result in choppy conditions across
most of the regional waters and passages through at least Monday.
Small craft advisories will be in effect starting overnight due to
7 ft seas. Moderate to fresh northeast trades will continue
between 15-20 knots. A moderate risk of rip currents will continue
across most of the local islands, especially along the north and
east facing beaches of the islands.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 77 84 76 83 / 20 30 30 50
STT 77 86 76 86 / 20 30 30 50
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Re: Caribbean - Central America Weather

#19144 Postby cycloneye » Sun Dec 17, 2017 7:10 am

Area Forecast Discussion
National Weather Service San Juan PR
545 AM AST Sun Dec 17 2017

.SYNOPSIS...
The weather conditions will be dominate by a mid-upper level
ridge through at least mid-week. A surge of moisture is forecast
to move across the islands latter this morning into the afternoon.
Under a northeasterly wind flow patches of moisture will bring
periods of clouds and showers at times each day.

&&

.SHORT TERM...Today through Wednesday...
A persistent mid to upper level ridge will keep a trade wind
shower pattern over Puerto Rico and the U.S. Virgin Islands
through Wednesday. Today a surge of moisture will move over the
U.S. Virgin Islands this morning and will continue to move east
into Puerto Rico later today. Scattered showers will be possible
during the morning hours across northern Puerto Rico and the U.S.
Virgin Islands. As surface winds convergence over Puerto Rico
later today the chance for shower activity will increase. Tuesday
the upper level ridge begins to weaken ahead of a cut-off low that
will dive southward into the forecast area.

.LONG TERM...Wednesday through Tuesday...
The ridge pattern is forecast to slowly erodes after mid-week, as
a polar trough amplified from the Northeast and sink into the
northeastern Caribbean. Also, weather guidance is suggesting a
transition to a wetter pattern as moisture increase across the
islands. If weather guidance are in the right track, this will
result in a better chance for shower activity across the local
islands, as well as thunderstorm development.

&&

.AVIATION...
VFR conditions are expected to prevail for the reminder of the
TAF period. Isolated SHRA are possible across terminals TJBQ and
TJSJ until 17/10Z. SHRA will remain possible for the reminder of
the TAF period due to moisture moving in from the east. SFC winds
out of the E to NE at 10 to 15 kts with higher gusts possible.

&&

.MARINE...
A fresh to strong northeasterly wind flow will result in choppy
and rough seas across the regional waters. Small craft advisories
are in effect for most of the local waters. Mariners can expect
seas at 5 to 7 feet with occasional seas up to 9 feet and winds up
to 20 knots.

For the beach goers, a high risk of rip currents is in effect
across the north facing beaches of northwest Puerto Rico and St
Croix, elsewhere a moderate to low risk of rip currents.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 84 76 83 77 / 30 20 30 30
STT 87 76 86 75 / 40 20 30 30
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Re: Caribbean - Central America Weather

#19145 Postby cycloneye » Mon Dec 18, 2017 5:40 am

Area Forecast Discussion
National Weather Service San Juan PR
532 AM AST Mon Dec 18 2017

.SYNOPSIS...
Puerto Rico and the U.S. Virgin Islands weather will be controlled by
a mid to upper level ridge through Friday. On thursday a trough
of low pressure will move into the Atlantic waters and cause the
mid to upper level high pressure in the Atlantic to weaken. This
will cause unsettled weather across Puerto Rico and the U.S.
Virgin Islands through the Sunday.

&&

.Short Term...Today through Wednesday...
A surface high pressure over the western Atlantic will tight the
local pressure gradient inducing a northeast wind flow across the
islands. The breezy northeasterly wind flow will bring patches of
clouds and showers mainly across the U.S. Virgin Islands and the
northern and eastern portions of Puerto Rico at times. A ridge
pattern aloft will limit vertical development. The upper to mid
level ridge will slowly erodes after Wednesday as a TUTT low sink
from the northeast over the Northeastern Caribbean.

&&

.LONG TERM...Friday through Thursday...
The mid to upper level ridge that has brought somewhat fair
weather with an occasional isolated shower will weaken ahead of a
cold front that will move into the north Atlantic waters. The
front will push an upper level trough near the forecast area on
Friday. Friday will be a transition day from quiet weather to a
more unsettled pattern due to an increase in tropical moisture
across Puerto Rico and the U.S. Virgin Islands. The GFS and ECMWF
models are indicating that this active pattern will remain through
Christmas due to an tutt low that might cut off near Puerto Rico
and the U.S. Virgin Islands. At this time it`s something to keep
an eye on over the next several days.

&&

.Aviation...
Trade wind showers will continue to affect TIST/TISX
TJSJ/TJBQ through 18/16z. As a result SCT-BKN cigs at FL025-FL060
are possible. All taf sites are expected to receive periods of -
SHRA/SHRA btwn 18/19-23z. Surface winds will continue at 10-15 kt
increasing at 15-20 kt with higher gusts aft 18/13z.

&&

.MARINE...
Northeasterly wind flow will continue over the next several days.
This will result in choppy and rough seas across most of the
local waters ways. Small craft advisories will remain in effect
until later this afternoon. Seas will be 5 to 7 feet with
occasional seas up to 8 feet with winds 10 to 15 kts with higher
gusts. High rip current risk remains for the northern facing
beaches while moderate to low risk for the other areas..


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 83 77 85 77 / 40 40 30 50
STT 86 79 86 76 / 50 30 30 50
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Re: Caribbean - Central America Weather

#19146 Postby cycloneye » Mon Dec 18, 2017 3:51 pm

Area Forecast Discussion
National Weather Service San Juan PR
344 PM AST Mon Dec 18 2017

.SYNOPSIS...Mid and upper level ridge will prevail over the local
area through the workweek. ENE to NE winds expected for the next
few days as a SFC high pressure remains to the NW of the local
area. Upper trough to approach the local area this weekend,
possibly causing unsettled weather.

&&

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

Seasonable temperatures are expected for the next few days as we
stay under an ENE to NE wind flow. Therefore expect high temps in
the low to mid 80s across the lower elevations and in the 70s
across the higher elevations. Near normal moisture is also
expected and the ridge in the mid and upper levels will promote
mainly fair weather with passing showers across the northern and
eastern sections of PR as well as around the USVI.

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

The mid to upper level ridge that has brought somewhat fair
weather with an occasional isolated shower will weaken ahead of a
cold front that will move into the north Atlantic waters. The
front will push an upper level trough near the forecast area on
Friday. Friday will be a transition day from quiet weather to a
more unsettled pattern due to an increase in tropical moisture
across Puerto Rico and the U.S. Virgin Islands. The GFS and ECMWF
models are indicating that this active pattern will remain through
Christmas due to an tutt low that might cut off near Puerto Rico
and the U.S. Virgin Islands. At this time it`s something to keep
an eye on over the next several days.

&&

.AVIATION...Mainly VFR conditions will prevail across all the
terminals through the forecast period. However, brief passing trade
wind showers could affect at times the northern and eastern PR
terminals as well as the USVI/Leeward terminals. Winds will continue
from the northeast at 10-15 kts.

&&

.MARINE...Seas will be up to 6 feet this evening and ENE to NE
winds up to 20 knots. There is a high risk of rip currents for the
northern beaches of PR until 6 AM Tuesday, and for Culebra island
until 6 PM this evening.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 77 85 77 83 / 40 40 50 30
STT 79 86 76 83 / 40 40 50 30
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Re: Caribbean - Central America Weather

#19147 Postby cycloneye » Tue Dec 19, 2017 5:40 am

Area Forecast Discussion
National Weather Service San Juan PR
517 AM AST Tue Dec 19 2017

.SYNOPSIS...

A mid and upper level ridge will prevail over the local area
through late Thursday. ENE to NE winds expected for the next few
days as a SFC high pressure remains over the region. A cold front
will move off the east coast of the U.S. this Thursday and cause
the high to weaken and become elongated north to south. There
won`t be a frontal passage with this system but it will create a
trough of low pressure just north of the Islands. This trough of
low pressure will shear out and create a weakness at the surface
which will enhance shower activity through the weekend. Monday
models indicate that a TUTT low will move close to the region and
possibly cause showers and thunderstorms on Christmas through
Wednesday of next week. If this pattern materializes the weather
could remain unsettled through next weekend.


&&

.Short Term...Today through Thursday...

A northeasterly wind flow will bring patches of clouds and showers
at time mainly across the U.S. Virgin Islands and the northern and
eastern sections of Puerto Rico. The islands weather conditions will
be dominated by a mid-upper level ridge through the work week.
Although, pleasant temperatures without significant rainfall
accumulations are expected, the region will observe breezy
conditions with trade wind showers at times. This showers will be
focused on the U.S. Virgin Islands and the windward portions of
Puerto Rico during the evening and morning hours followed by limited
induce afternoon showers across SW-PR each day. The ridge aloft will
slowly erodes after mid-week as a TUTT low sink from the northeast
over the NE-Caribbean.

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

Mid to upper level ridge will start to weaken ahead of a cold
front that will move off the east coast of U.S. on Thursday. This
front will continue to move to the northeast out into the Atlantic
waters. The only impact that we will see from this front is that
it will push an upper level trough near the forecast area on
Friday and pull tropical moisture over the Islands through Sunday.
Once the front washes out it will leave a weak shear line at the
surface and create confluence over the forecast area which will
cause scattered convection.

The GFS and ECMWF models still show an active pattern Saturday
through Christmas. Both models show a TUTT low moving south near
Puerto Rico and the U.S. Virgin Islands late Sunday and early
Monday. If the Islands remain on the east side of TUTT low there`s a
possibility for heavy rain early next week. Still the low will
bust the trade winds cap and bring deep tropical moisture over the
region.


&&

.AVIATION...

Mainly VFR conditions will prevail across all the
terminals through the forecast period. However, brief gusty winds
and passing trade wind showers could affect at times the northern
and eastern PR terminals as well as the USVI/Leeward terminals.
Winds will continue from the northeast at 10-15 kts with higher
gusts.



&&

.MARINE...

Seas up to 6 feet today with a ENE to NE winds up to 15 knots.
There is a moderate to low risk of rip currents for the northern
beaches today.




&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 83 75 84 76 / 30 30 30 50
STT 86 75 86 76 / 30 30 20 30
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Re: Caribbean - Central America Weather

#19148 Postby cycloneye » Tue Dec 19, 2017 3:36 pm

Area Forecast Discussion
National Weather Service San Juan PR
404 PM AST Tue Dec 19 2017

.SYNOPSIS...Upper level ridge is expected to prevail over the
local area through the rest of the workweek. ENE to NE winds
expected for the next few days as a SFC high pressure remains to
the NW of the local area. Upper trough to approach the local area
late this weekend, possibly causing inclement weather for the
early part of next week.

&&

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

Seasonable temperatures are will continue for the rest of the
workweek as we continue under the ENE to NE wind flow. Therefore
expect high temps in the low to mid 80s across the lower
elevations and in the 70s across the higher elevations with
overnight minimum temperatures in the low to mid 70s across the
lower elevations and in the 60s across the higher elevations.
Below normal moisture is also expected for the most part with a
few patches of higher moisture briefly affecting the area, with
the ridge in the mid and upper levels, this will promote mainly a
fair weather pattern with brief showers across the northern and
eastern sections of PR as well as around the USVI.

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

The GFS and ECMWF models still show an active pattern Saturday
through Christmas. Both models show a TUTT low moving south just
to the northeast of Puerto Rico and the U.S. Virgin Islands late
Sunday and early Monday. As of now, the TUTT is expected to remain
to our north and east which typically causes more activity across
the Leeward islands than the local islands, but if the TUTT moves
just a little further west than expected, there would be a
possibility for significant rain early next week. Regardless of
the final location of the TUTT, the available moisture is expected
to increase.

&&

.AVIATION...VFR conds will continue to prevail at all TAF sites
through the forecast period with VCSH in and around the Leeward and
USVI terminals as well as JSJ/JBQ. ENE winds 10-15 knots with some
sea breeze variation through 19/22z...becoming at around 10 knots
overnight.


&&

.MARINE...Seas will be choppy since they will be up to 6 feet
across the local waters with winds up to 20 knots this afternoon
and through tonight. There will be a high risk of rip currents
starting late this afternoon for the northern beaches of PR and
Culebra, low to moderate elsewhere.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 75 84 76 85 / 30 30 50 20
STT 75 86 76 86 / 30 20 30 20
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Re: Caribbean - Central America Weather

#19149 Postby cycloneye » Wed Dec 20, 2017 6:11 am

Area Forecast Discussion
National Weather Service San Juan PR
544 AM AST Wed Dec 20 2017

.SYNOPSIS...
A ridge aloft will slowly erodes through the weekend. Then, a
retrogressing TUTT Low is forecast to amplify across the Northeast
Caribbean. At the surface, a northeasterly wind flow will push
patches of clouds and showers from time to time each day. Maximum
temperatures will continue in the low and mid 80s along the
coastal areas and between the mid and high 70s in the higher
elevations.

&&

.SHORT TERM...Today through Friday...
High pressure ridge both at the surface and in the mid to upper
levels, will continue to support mainly a fair and stable weather
pattern across the region, except for the passing trade wind
showers across the north and east coastal sections of the islands
each day. Under the dominant northeast wind flow expect seasonable
temperatures with a mixture of sunshine and clouds for the rest
of the workweek. Periods of passing low level clouds and trade
wind showers can be expected especially during the late evening
and early morning hours. The shower activity will be brief and
mostly of light to moderate intensity. Near normal daytime high
temps in the low to mid 80s can be expected across the coastal
areas , and in the mid to high 70s in the higher elevations.
Minimum temperatures will be in the low to mid 70s across the
lower elevations and in the 60s across the higher elevations.
Winds between 10 to 15 mph can be expected along coastal areas
with occasionally higher gusts...and between 15-20 mph in higher
elevations during the daytime.

.LONG TERM...Saturday through Thursday...
Model guidance still shows a retrogressing TUTT low moving over
Northeast Caribbean Saturday through Christmas. Both GFS and ECMWF
show a TUTT low swinging by the leeward islands. If Puerto Rico
and the U.S. Virgin Islands remains on the subsidence side, there
is less chance for organize convection and heavy rains through
this period. However, frequent showers embedded in the trades
could affect the islands each day. As the TUTT meander and
dissipate a jet stream will move from the south over the local
region late Tuesday night into Thursday.

&&

.AVIATION...
VFR conds will prevail at all TAF sites through the
forecast period. Isold SHRA steered by moderate NE trade winds btw
15-25 kts blo FL200 en route btw islands and ovr coastal waters.
Wnds backing and bcmg fm N and incr w/ht abv FL250. VCSH at
TJSJ/TJBQ/TISX/TIST and at the terminals the Leeward Islands
TNCM.TJPJ TIL 20/15Z. Sfc wnd fm ENE 5-10 KTS...bcmg fm NE 10-15 kts
aft 20/14z with ocnl higher gusts and sea breeze variations.

&&

.MARINE...
Mariners can expect winds at 10 to 20 knots and seas up to 6 feet
across the Atlantic and Caribbean Passages. As a result, small
craft operator are urge to exercise caution across these waters.
Elsewhere expect seas at 5 feet or less and winds around 15 knots.

For the beach goers, there is a high risk of rip current for the
northwest to northeast facing beaches of Puerto Rico and for
Culebra island.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 85 76 85 76 / 30 40 20 30
STT 85 77 85 77 / 20 40 20 30
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Re: Caribbean - Central America Weather

#19150 Postby cycloneye » Wed Dec 20, 2017 4:16 pm

Area Forecast Discussion
National Weather Service San Juan PR
410 PM AST Wed Dec 20 2017

.SYNOPSIS...Upper ridge will continue over the area for the next
few days, eroding in the weekend as a TUTT Low moves into the
eastern Caribbean. SFC high pressure will continue to promote a
NE to ENE wind flow which will bring some passing clouds and brief
showers.

&&

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

Continued seasonable temperatures are expected for the rest of
the workweek as the wind flow continues from the NE to ENE and the
available moisture continues to be slightly below normal.
Daytime high temps are expected to be in the low to mid 80s
across the lower elevations and in the 70s across the higher
elevations with overnight minimum temperatures in the low to mid
70s across the lower elevations and in the 60s across the higher
elevations with slightly lower temperatures in some areas. Even
though below normal moisture is expected for the next few days,
there will be a few patches of higher moisture moving in, briefly
affecting the local area, mainly promoting a fair weather pattern
with brief showers across the northern and eastern sections of PR
as well as around the USVI.

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

...From previous discussion...
Model guidance still shows a retrogressing TUTT low moving over
Northeast Caribbean Saturday through Christmas. Both GFS and ECMWF
show a TUTT low swinging by the leeward islands. If Puerto Rico
and the U.S. Virgin Islands remains on the subsident side, there
is less chance for organize convection and heavy rains through
this period. However, frequent showers embedded in the trades
could affect the islands each day. As the TUTT meander and
dissipate a jet stream will move from the south over the local
region late Tuesday night into Thursday.

&&

.AVIATION...VFR conds will continue to prevail at all TAF sites
through the forecast period with VCSH in and around the Leeward and
USVI terminals as well as JSJ/JBQ. ENE winds 10-15 knots with some
sea breeze variation through 20/22z...becoming at around 10 knots
overnight.

&&

.MARINE...Small craft should exercise caution due to winds at 10
to 20 knots and seas up to 6 feet across the Atlantic and
Caribbean Passages. Elsewhere expect seas at 5 feet or less and
winds around 15 knots. There is a high risk of rip currents until
6 PM for northern PR and Culebra, moderate risk for tonight.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 76 85 76 85 / 40 20 30 20
STT 77 85 77 85 / 40 20 30 20

&&
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Re: Caribbean - Central America Weather

#19151 Postby cycloneye » Thu Dec 21, 2017 6:21 am

Area Forecast Discussion
National Weather Service San Juan PR
449 AM AST Thu Dec 21 2017

.SYNOPSIS...Broad mid-upper level high extending eastward across the
region from the northwest Caribbean, will maintain a strong trade wind
cap inversion over the forecast area during the next several days.
Surface high across the northeast Atlantic and weak frontal trough
across the north central Atlantic will maintain east- northeast trade
winds across the northeastern Caribbean. The dominant east-northeast
wind flow will continue to transport periods of shallow moisture and
intervals of trade wind showers across the islands and coastal waters.
Expect this pattern to hold through most of the upcoming weekend.

&&

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

Ridge aloft will continue to promote fair weather conditions during
the next few days. Normal to below normal PWAT content and upper ridge
will only allow for light to moderate brief afternoon showers today
and they will gradually decrease through Saturday as drier air aloft
is expected. East to northeast trade winds will continue to carry some
low level clouds and passing showers through the short term period.
No significant rainfall accumulations are expected at the moment across
the islands.

Day time temperatures will range from the mid to high 80s across coastal
areas to the low/mid 70s across the higher elevations. Overnight temperatures
will range from the high 50s across the higher elevations of PR to the
low/mid 70s across the coastal areas of the islands. East to northeast
winds will continue between 10-15 mph with lighter land breeze variations
during the night time.

.LONG TERM...Sunday through next week Friday...

Model guidance continued to suggest an amplifying Tutt to sink southwards
across the northern Leewards into the southeastern Caribbean by Sunday
and during the early parts of next week. However, the forecast area
should still remain on the subsident/convergent side of the trough at
least until midweek/Christmas day. As the migratory high shift eastward,
another ridge will build and spread eastwards across the western Atlantic.
This will bring a return of the moderate to strong east northeast trade
winds during the latter part of next week. Thereafter, the Tutt is to
retrogress and gradually lift northward across the region while weakening
the trade wind cap inversion. This scenario should support a better
chance for low level moisture pooling and convergence thereby increasing
the chance for passing trade wind showers especially during the late
evening and early morning hours. At this time however, do not foresee
any significant amounts of moisture accumulation across the region during
the latter part of the period, as the Tutt is to quickly weaken and
high pressure is to build aloft, as well as over the west Atlantic
by Friday of next week once again increasing the northeasterly trade
winds bring breezy conditions to the region.

&&

.AVIATION...VFR conditions today. But passing -SHRA/SHRA at times
possible at TJSJ/TIST til around 02/15z. Elsewhere FEW-SCT ceiling
at FL025-FL045. Mount obsc with SHRA/+SHRA are expected to develop
across the interior and west PR btwn 02/17z-23z. Some of these
SHRA/+SHRA will possibly move near/over TJMZ. NE winds at less
than 8 kt increasing at around 10-13 knots and shifting more from
the east with sea breezes variations aft 02/13z.

&&

.MARINE...Marine conditions will continue below the small craft
advisory thresholds through the upcoming weekend. Winds of up to
15 knots with occasionally higher gusts, and seas of 6 feet or
less can be expected at least through Friday. Rip current risk
for the next several days should remain low to moderate for the
local beaches.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 84 75 85 75 / 30 30 30 30
STT 85 76 85 74 / 30 30 30 20
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Re: Caribbean - Central America Weather

#19152 Postby cycloneye » Thu Dec 21, 2017 3:46 pm

Area Forecast Discussion
National Weather Service San Juan PR
342 PM AST Thu Dec 21 2017

.SYNOPSIS...Broad upper high pressure will continue just over the
local area until Saturday as it continues to move west and a TUTT
develops and approaches the northeastern Caribbean. The TUTT is
expected to stay NE of the Leewards, not causing instability over
the local islands. Moderate ENE winds to continue for the next
several days. Near normal to below normal moisture, mainly limited
to the lower levels, will continue for the next several days with
a few patches of higher moisture moving through occasionally,
causing brief showers. Overall, seasonable weather conditions are
expected for the next several days.

&&

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

Mostly fair weather is expected for the next few days with near
normal to slightly below normal moisture for the time of year.
There is also the upper high pressure that will keep a stable
atmosphere through early Saturday, but then a TUTT will approach
the northern Leewards, but staying to the NE, which will keep us
in the subsident side of the TUTT, which means that convection is
suppressed and therefore mainly light and brief showers are
expected. Winds for the next few days will remain from the ENE and
the temperatures will be near normal to the time of year, which
is daytime max temps in the low to mid 80s across the lower
elevations and in the 70s across the higher elevations, while the
overnight low temps will be in the low to mid 70s across the lower
elevations and in the 60s across the higher elevations with some
areas that could be slightly cooler. However, the higher
elevations of the USVI are expected to be in the upper 60s to low
70s as their overnight low.

Bottom line, seasonable weather pattern is expected with near
normal temperatures and brief showers at night and early in the
morning, mostly fair weather.

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

...From previous discussion...

Model guidance continued to suggest an amplifying Tutt to sink southwards
near the northern Leewards by Sunday and during the early parts
of next week. However, the forecast area should still remain on
the subsident/convergent side of the trough at least until
midweek/Christmas day. As the migratory high shift eastward,
another ridge will build and spread eastwards across the western
Atlantic. This will bring a return of the moderate to strong east
northeast trade winds during the latter part of next week.
Thereafter, the Tutt is to retrogress and gradually lift northward
across the region while weakening the trade wind cap inversion.
This scenario should support a better chance for low level
moisture pooling and convergence thereby increasing the chance for
passing trade wind showers especially during the late evening and
early morning hours. At this time however, do not foresee any
significant amounts of moisture accumulation across the region
during the latter part of the period, as the Tutt is to quickly
weaken and high pressure is to build aloft, as well as over the
west Atlantic by Friday of next week once again increasing the
northeasterly trade winds bring breezy conditions to the region.

&&

.AVIATION...VFR conds will continue to prevail at all TAF sites
through the forecast period with -SHRA possible at JMZ through
21/22z. VCSH at the Leeward and USVI terminals as well as JSJ/JBQ
overnight. Easterly winds 10-15 knots with some sea breeze variation
through 21/22z...becoming at around 10 knots overnight.


&&

.MARINE...Seas up to 5 feet and winds 15 to 20 knots, mainly
across the local offshore waters and local passages. There is a
moderate risk of rip currents along the north and east facing
beaches of Puerto Rico as well as many beaches in Vieques and
Culebra. The northeast beaches of Saint Thomas and the north and
eastern beaches of Saint Croix also has moderate risk.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 75 85 75 84 / 30 30 30 30
STT 76 85 74 86 / 30 30 20 40
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Re: Caribbean - Central America Weather

#19153 Postby cycloneye » Fri Dec 22, 2017 5:40 am

Area Forecast Discussion
National Weather Service San Juan PR
426 AM AST Fri Dec 22 2017

.SYNOPSIS...Upper level ridge and dry air aloft will continue
through Saturday. A tutt will form over the Atlantic waters and
remain to the northeast of the forecast area through Monday. Trade
wind showers will continue across the forecast area for the next
several days under a northeast wind flow. Winds will increase by
mid week next week.


&&

.SHORT TERM...Today through Sunday... Forecast on track for the
next several days with seasonable weather pattern expected and near
normal temperatures along with passing trade wind showers mainly
overnight and during the early morning hours. This will be followed
by mostly fair weather during the day.

Based on latest model guidance and overall synoptic pattern...The
broad mid to upper level high pressure ridge should hold through
today and maintain an overall stable and dry airmass at least
through Saturday. By Sunday the ridge is to erode in response to a
TUTT which is now forecast to retrogress across the northern
Leewards, then linger just NE of the region while weakening. This
should however continue to keep the area in the subsident side of
the TUTT, resulting in limited and suppressed convective activity
across the islands and coastal waters. Consequently,mostly brief
light to moderate showers are expected through Saturday with a
slight increase in moisture advection and potential for morning and
afternoon showers on Sunday. Mostly fair weather conditions and
pleasant near normal temperatures should however prevail during the
period.

.LONG TERM...Monday through Friday...As the tutt weakens an upper
level ridge will build north and over the area and hold through
much of next week. However, an induced perturbation associated to
the tutt is forecast to move by mid week across the forecast area.
This will result in a better chance for showers over the islands
between Tuesday and Wednesday. Drier mid level air will return
quickly and a fair weather pattern should prevail through the end
of the week. In general, under northeast steering winds, best
chance for showers is across the northern and eastern portions of
the island followed by iso-sct showers over the southwest
quadrant of PR during the afternoon hours. Across the USVI,
showers embedded on the trades will continue at times through the
long term period. Seasonable temperatures will continue across
the islands.


&&

.AVIATION...VFR conds at all local TAF sites thru fcst prd. VCSH
at the Leeward and USVI terminals as well as TJSJ/TJBQ til 22/14z.
SHRA en route btw islands and ovr coastal waters w/SCT ocnl Bkn
lyrs...nr FL025..FL050...Mostly SKC abv. Sfc wnd calm to
lgt/vrb... bcmg fm NE 10-15 kts aft 22/14z with some sea breeze
variation through 22/22z. L/lvl wnds fm NE 10-15 kts blo FL250...
then backing and incr w/ht abv. No sig AVN wx impacts anticipated
durg prd.


&&

.MARINE...Seas between 3-5 feet are expected today across most of
the local waters and passages. Small crafts should exercise
caution across the offshore Caribbean waters due to winds up to 20
knots. Elsewhere, winds should range between 10-15 knots from the
east-northeast. There is a moderate risk of rip currents for the
north facing beaches of the islands. Seas will be hazardous by
mid week next week in response to a wind surge from the east.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 84 75 85 75 / 40 30 30 50
STT 85 75 85 75 / 30 30 40 50
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Re: Caribbean - Central America Weather

#19154 Postby cycloneye » Fri Dec 22, 2017 3:21 pm

Area Forecast Discussion
National Weather Service San Juan PR
339 PM AST Fri Dec 22 2017

.SYNOPSIS...Upper level ridge and dry air aloft will continue
as the main weather feature across the region through Saturday.
The upper ridge is expected to erode as A TUTT forms over the
Atlantic waters and remain to the northeast of the forecast area
through Monday. Trade wind showers will continue across the
forecast area for the next several days under a northeast wind
flow. Winds will increase by mid week next week.

&&

.SHORT TERM...Tonight through Sunday...Doppler radar indicated
isolated to scattered showers embedded in the east-northeast
trades moving rapidly southwestward across the surrounding waters
with few of them affecting the U.S. Virgin Islands, Vieques,
Culebra as well as the eastern and northern sections of Puerto
Rico so far this afternoon. Elsewhere across the local islands,
not significant shower activity was observed.

For the next several days expect the continuation of seasonable
weather pattern and near normal temperatures along with passing
trade wind showers mainly overnight and during the early morning
hours. This will be followed by mostly fair weather during the
rest of the day. The persistent upper level ridge over the region
for the past several days will maintain an overall stable and dry
airmass at least through Saturday. The upper ridge is expected to
erode by Sunday as a TUTT retrogress across the northern
Leewards. This feature is then expected to linger just NE of the
region while weakening. As this happens the local area is expected
to remain in the subsident side of the TUTT, resulting in limited
and suppressed convective activity across the islands and coastal
waters. Consequently, mostly brief light to moderate showers are
expected through Saturday with a slight increase in moisture
advection and potential for morning and afternoon showers on
Sunday. Mostly fair weather conditions and pleasant near normal
temperatures should however prevail during the period.

.LONG TERM...Monday through Friday (From Previous AFD)...
As the tutt weakens an upper level ridge will build north and
over the area and hold through much of next week. However, an
induced perturbation associated to the tutt is forecast to move by
mid week across the forecast area. This will result in a better
chance for showers over the islands between Tuesday and Wednesday.
Drier mid level air will return quickly and a fair weather
pattern should prevail through the end of the week. In general,
under northeast steering winds, best chance for showers is across
the northern and eastern portions of the island followed by iso-
sct showers over the southwest quadrant of PR during the afternoon
hours. Across the USVI, showers embedded on the trades will
continue at times through the long term period. Seasonable
temperatures will continue across the islands.

&&

.AVIATION...VFR conds will continue to prevail at all TAF sites
through the forecast period with -SHRA possible at JMZ through
22/22z. VCSH at the Leeward and USVI terminals as well as JSJ/JBQ
overnight. Easterly winds 10-15 knots with some sea breeze variation
through 22/22z...becoming at around 10 knots overnight.

&&

.MARINE...Relatively quiet marine conditions will continue at the
local waters for this time of the year. Seas between 3-5 feet are
expected tonight across most of the local waters and passages.
Seas will slightly increase up to 6 across the offshore Atlantic
waters on Saturday. Winds will range between 10-15 knots from the
east-northeast. There is a moderate risk of rip currents for the
north facing beaches of the islands. Seas will be hazardous by mid
week next week in response to a wind surge from the east.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 75 85 75 84 / 30 30 50 50
STT 75 85 75 85 / 30 40 50 50
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Re: Caribbean - Central America Weather

#19155 Postby cycloneye » Sat Dec 23, 2017 2:36 pm

/issued 341 AM AST Sat Dec 23 2017/

SYNOPSIS...Mid to upper level ridging and dry and stable conditions
aloft will remain the dominant weather feature across the region, as
a tutt is forecast to remain just north and east of the area. The upper
ridge is however to slightly erode as the Tutt lifts just farther northeast
of the forecast area through Monday.Persistent northeast trade winds
will continue for the next several days with winds increasing by the
middle of next week in response to the tightening of the local pressure
gradient.

SHORT TERM...Today through Monday...Surface high pressure across the
North Central Atlantic will continue to produce a moderate to fresh
trade wind flow across the local area throughout the forecast period.
Patches of low level moisture embedded in the northeast trade wind
flow will affect the local islands from time to time.

A slot of drier air is anticipated later today into Sunday which will
limit the chances for showers across the region. However, for Sunday
morning, another patch of low level moisture is forecast to affect Puerto
Rico and the U.S. Virgin Islands. Therefore, a slight increase in shower
activity is expected. No overall changes in this weather pattern is
expected through at least Monday.

LONG TERM...Tuesday through Saturday...As the Tutt gradually fills
and lifts northeast of the region, a mid to upper level ridge will
build across the western Atlantic and spread eastwards across the
area. The upper ridge is to then hold across the area through
much of next week. Strong surface high pressure ridge across the
central and northeast Atlantic will remain the dominant weather
feature during the forecast period.

However, the combination of the strong high pressure ridge extending
from across the northeast Atlantic, and a weak frontal trough northwest
of the area will induce a weak low level trough across the northeastern
Caribbean TuesdaY through Wednesday. This will increase the chance of
low level moisture transport, and consequently a better change for passing
showers in the moderate to strong northeast trade winds. During the
afternoons, isolated to scattered showers some of moderate intensity
will be possible mainly over the central interior and southwest sections
of Puerto Rico. No significant rainfall accumulations are so far expected.

By the end of the week and into the weekend...overall dry and stable
conditions aloft and lesser low level moisture, will promote a mostly
fair weather pattern across the forecast area with a return of near
seasonable weather conditions and local temperatures. The best chance
for the shower activity will continue to be over the coastal waters
and along parts of the north and east coastal sections of the islands
each morning. This will be followed by mostly isolated afternoon showers,
focused mainly over the southwest quadrant of Puerto Rico. Across the
U.S.Virgin Islands, occasionally passing trade wind showers will
remain possible across the surrounding coastal waters and some
coastal areas each morning, with limited shower activity mainly
downwind of the islands during the afternoon hours.

AVIATION...VFR conditions will prevail across all TAF sites through
23/22Z. Some light to moderate passing showers can be expected across
most terminals from time to time. Low level winds will be mainly northeast
at 10 to 15 knots with higher gusts.

MARINE...Maritime conditions will gradually deteriorate as 15 to
20 kt winds and 6 foot wind driven seas spread across the regional
waters during the weekend and into next week. Small craft advisories
will likely be required by Tuesday night in Atlantic and Caribbean
outer waters as well as some of the local passages.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 85 75 84 74 / 40 50 40 50
STT 85 75 85 74 / 40 40 30 50
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Re: Caribbean - Central America Weather

#19156 Postby cycloneye » Sat Dec 23, 2017 3:29 pm

Area Forecast Discussion
National Weather Service San Juan PR
347 PM AST Sat Dec 23 2017

.SYNOPSIS...Mid to upper level ridge is expected to erode rapidly
tonight and Sunday as a TUTT develops to the northeast of the
forecast area. East northeast trade winds will continue across the
region for the next several days with winds increasing by the
middle of next week in response to the tightening of the local
pressure gradient.

&&

.SHORT TERM...Tonight through Monday...
Doppler radar indicated isolated to scattered showers embedded in
the east-northeast trades moving west southwestward across the
surrounding waters with few of them affecting the U.S. Virgin
Islands, Vieques, Culebra as well as the eastern and northern
sections of Puerto Rico so far this afternoon. Elsewhere across
the local islands, no significant shower activity was observed.

For the next few days expect the continuation of seasonable
weather pattern and near normal temperatures along with passing
trade wind showers mainly overnight and during the early morning
hours. The mid to upper level ridge over the region for the past
several days is expected to rapidly erode tonight and Sunday as a
TUTT amplify across the northern Leewards islands. This feature
is then expected to linger just NE of the region while weakening
until early next week. As this happens the local area is expected
to remain in the subsident side of the TUTT, resulting in limited
and suppressed convective activity across the islands and coastal
waters. Consequently, mostly brief light to moderate showers are
expected tonight with a slight increase in moisture advection and
potential for morning and afternoon showers Sunday and Monday.

A developing surface high pressure across the northwestern
Atlantic will maintain a moderate to fresh trade wind flow across
the local area for the next several days.

.LONG TERM...Tuesday through Saturday (from previous discussion)...
As the Tutt gradually fills and lifts northeast of the region, a
mid to upper level ridge will build across the western Atlantic
and spread eastwards across the area. The upper ridge is to then
hold across the area through much of next week. Strong surface
high pressure ridge across the central and northeast Atlantic will
remain the dominant weather feature during the forecast period.

However, the combination of the strong high pressure ridge extending
from across the northeast Atlantic, and a weak frontal trough northwest
of the area will induce a weak low level trough across the northeastern
Caribbean TuesdaY through Wednesday. This will increase the chance of
low level moisture transport, and consequently a better change for passing
showers in the moderate to strong northeast trade winds. During the
afternoons, isolated to scattered showers some of moderate intensity
will be possible mainly over the central interior and southwest sections
of Puerto Rico. No significant rainfall accumulations are so far expected.

By the end of the week and into the weekend...overall dry and stable
conditions aloft and lesser low level moisture, will promote a mostly
fair weather pattern across the forecast area with a return of near
seasonable weather conditions and local temperatures. The best chance
for the shower activity will continue to be over the coastal waters
and along parts of the north and east coastal sections of the islands
each morning. This will be followed by mostly isolated afternoon showers,
focused mainly over the southwest quadrant of Puerto Rico. Across the
U.S.Virgin Islands, occasionally passing trade wind showers will
remain possible across the surrounding coastal waters and some
coastal areas each morning, with limited shower activity mainly
downwind of the islands during the afternoon hours.

&&

.AVIATION...In general, VFR conds will continue through the forecast
period. But SHRA are expected at TJMZ/TNCM/TKPK btwn 23/18z-22z.
Then, SHRA/-SHRA are expected at TNCM/TKPK/TIST/TJSJ/TJBQ/TISX
overnight. Easterly winds 10-20 knots with some gusts through
23/22z...becoming at around 10-15 knots overnight.

&&

.MARINE...Seas up to 6 feet and winds up to 20 knots are expected
across the regional waters tonight and through the rest of the
weekend. Marine conditions are expected to gradually deteriorate
Monday night and Tuesday with wind driven seas increasing up to 7
or 8 feet. Small craft advisories will likely be required by
Tuesday night in Atlantic and Caribbean outer waters as well as
some of the local passages.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 75 84 74 84 / 50 40 50 50
STT 75 85 74 86 / 40 30 50 50
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Re: Caribbean - Central America Weather

#19157 Postby cycloneye » Sun Dec 24, 2017 6:04 am

Area Forecast Discussion
National Weather Service San Juan PR
400 AM AST Sun Dec 24 2017

.SYNOPSIS...Elongated mid to upper level ridge will hold just west
of the region as a Tutt will continue to extend southwest across
the northern Leeward islands into the eastern Caribbean through
Monday. The tutt is to then gradually fill and lift northwards
into the tropical Atlantic by Wednesday allowing the upper ridge
to reestablish overhead once again during the latter part of the
upcoming week. In the meantime...overall dry and stable conditions
will prevail aloft as we should remain of the subsident side of
the upper trough. East northeast trade winds will continue across
the area for the next several days with winds forecast to increase
through midweek in response to the tightening of the local
pressure gradient.

&&

.SHORT TERM...Today through Tuesday...Patches of low level moisture
embedded in the trade winds will continue to affect the local islands
today. Most of the activity will occur across the east and northeast
sections of Puerto Rico and across the U.S. Virgin Islands.

Overall, good weather conditions are expected to continue next couple
of days as local area remains under the influence of a high pressure
system which is located across the Atlantic. An upper level trough
will remain east of the island without having any impact on the local
weather conditions.

.LONG TERM...WEDNESDAY THROUGH NEXT WEEKEND...
As the Tutt gradually fills and lifts farther northeast of the region,
a mid to upper level ridge will build aloft then remain in place across
the region through the end of the week. This will maintain overall
stable conditions aloft.

The combination of a strong high pressure ridge across the northeast Atlantic,
and a frontal trough north of the area will induce a weak low level
trough across the northeastern Caribbean through Wednesday. This will
induce localized convergence and support a slight increase in low level
moisture advection across the area. Consequently, a better change for
passing showers in the moderate northeast trade winds can be expected
especially during the early morning with isolated to scattered afternoon
showers, mainly over the central interior and southwest sections of
Puerto Rico.

By Thursday and through the weekend, overall dry and stable conditions
aloft and lesser low level moisture to the strong surface high pressure
ridge north of the region will promote a mostly fair weather pattern
across the forecast area. Therefore seasonable weather conditions and
pleasant daytime temperatures can be expected during most of the week.
The best chance for the shower activity will be over the coastal waters
and along parts of the north and east coastal sections of the islands
each morning, followed by mostly isolated afternoon convection over
the southwest quadrant of Puerto Rico. Occasional passing trade wind
showers will remain possible across the coastal waters and some coastal
areas of the U.S. Virgin islands, with shower activity mainly downwind
of the islands each afternoon.

&&

.AVIATION...VFR conditions will prevail across all TAF sites through
24/22Z. Some light to moderate passing showers can be expected across
most terminals from time to time. Low level winds will be mainly east
to east northeast at 10 to 15 knots with higher gusts.

&&

.MARINE...Local and offshore buoys continue to indicate seas between
3-5 feet and ENE winds up to 15 knots. Small crafts should continue
to exercise caution across the offshore waters and passages due to
seas up to 6 feet and/or winds up to 20 knots. A moderate risk of
rip currents will continue today for most of the north and south
beaches of the islands.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 84 75 85 75 / 40 50 50 30
STT 85 74 86 75 / 30 50 50 40
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Re: Caribbean - Central America Weather

#19158 Postby cycloneye » Sun Dec 24, 2017 3:40 pm

Area Forecast Discussion
National Weather Service San Juan PR
402 PM AST Sun Dec 24 2017

.SYNOPSIS...Elongated mid to upper level ridge will hold mostly
north of the region as a tutt will continue to extend southwest
across the northern Leeward islands and northeastern Caribbean
through Monday. The tutt is expected to gradually fill by Tuesday
allowing an upper ridge to reestablish overhead once again by
mid-week. East northeast trade winds are forecast to increase
through midweek in response to the tightening of the local
pressure gradient.

&&

.SHORT TERM...Tonight through Tuesday...
Doppler radar indicated small patches of low level moisture
embedded in the northeast trades moving west southwestward from
the surrounding waters across the U.S. Virgin Islands, Vieques,
Culebra as well as across the eastern and northern sections of
Puerto Rico. However not significant rainfall accumulations were
observed. Overall, good weather conditions are expected to
continue next couple of days as local area remains under the
influence of a high pressure system which is located across the
Atlantic. An upper level trough will remain to the east northeast
of the region. However, the local islands will remain on the
subsident side of the upper trough without having any significant
impact on the local weather conditions. East northeast trades
will continue across the area for the next several days with winds
forecast to increase through midweek in response to the
tightening of the local pressure gradient.

.LONG TERM...Wednesday through Sunday...(From previous
Discussion) As the Tutt gradually fills and lifts farther
northeast of the region, a mid to upper level ridge will build
aloft then remain in place across the region through the end of
the week. This will maintain overall stable conditions aloft.

The combination of a strong high pressure ridge across the northeast Atlantic,
and a frontal trough north of the area will induce a weak low level
trough across the northeastern Caribbean through Wednesday. This will
induce localized convergence and support a slight increase in low level
moisture advection across the area. Consequently, a better change for
passing showers in the moderate northeast trade winds can be expected
especially during the early morning with isolated to scattered afternoon
showers, mainly over the central interior and southwest sections of
Puerto Rico.

By Thursday and through the weekend, overall dry and stable conditions
aloft and lesser low level moisture to the strong surface high pressure
ridge north of the region will promote a mostly fair weather pattern
across the forecast area. Therefore seasonable weather conditions and
pleasant daytime temperatures can be expected during most of the week.
The best chance for the shower activity will be over the coastal waters
and along parts of the north and east coastal sections of the islands
each morning, followed by mostly isolated afternoon convection over
the southwest quadrant of Puerto Rico. Occasional passing trade wind
showers will remain possible across the coastal waters and some coastal
areas of the U.S. Virgin islands, with shower activity mainly downwind
of the islands each afternoon.

&&

.AVIATION...A northeasterly wind flow at 10 to 20 knots with higher
gusts will bring passing -SHRA/SHRA at TJSJ/TIST/TJBQ/TISX/TNCM/TKPK
thru the fcst period. Afternoon convection in the VCTY of TJMZ/TJPS
btwn 24/18z-23z. Winds will diminish around 10 knots after 24/23z.

&&

.MARINE...Seas up to 6 feet and winds up to 20 knots are expected
across the regional waters tonight and Monday. Marine conditions
are expected to gradually deteriorate on Tuesday with wind driven
seas increasing up to 7 or 8 feet. A moderate risk of rip
currents will continue tonight and Monday for most of the beaches
of the local islands.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 75 85 75 85 / 50 30 20 30
STT 75 86 75 86 / 40 30 20 30
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Re: Caribbean - Central America Weather

#19159 Postby cycloneye » Mon Dec 25, 2017 5:52 am

Area Forecast Discussion
National Weather Service San Juan PR
435 AM AST Mon Dec 25 2017

.SYNOPSIS...As a mid to upper level trough across the Lesser
Antilles weakens, a mid to upper level ridge will strengthen
across the forecast area and hold much of the week. Brisk trade
winds to continue across the forecast area. A fair and mainly
stable weather pattern will continue to prevail with mainly
passing showers across windward areas.

&&

.SHORT TERM...Christmas day through Wednesday...

Passing clouds and occasional trade wind showers will continue to
move across the regional waters and reach the coastal areas of the
islands during the rest of the morning hours. So far, no significant
rainfall accumulations were observed or reported over the land
areas. Early morning temperatures were in the mid to low 70s along
the coastal areas.

Expect gradual clearing and lesser showers by late morning leaving
partly cloudy to mostly sunny skies the rest of the day. However,
with the moderate northeast trade winds, expect some brief afternoon
showers mainly over the interior and southwest sections of Puerto
Rico and downwind of the other islands including the USVI.

Similar weather pattern expected through Wednesday with a slight
increase in the northeasterly trade winds leading to breezy
conditions across most of the region. This will increase the early
morning onshore flow leading to more frequent passing showers and
brief gusty winds each day. This will be followed by a few afternoon
showers of short duration. Pleasant temperatures and overall fair
weather conditions expected to dominate the region.

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

A mid to upper level ridge will hold across the local isles much
of the forecast period. At lower levels, continue to expect a
moderate to fresh east northeast wind flow through the upcoming
weekend, becoming more easterly early next week. Under ridge
pattern aloft and brisk trade winds, expect a seasonal weather
pattern with passing showers across the north and east coastal
areas of Puerto Rico as well as Vieques, Culebra and the US Virgin
Islands. Locally induced afternoon showers cannot be ruled out
each afternoon particularly by the end of the forecast period when
winds are expected to slightly decrease and stronger sea breezes
will develop.

&&

.AVIATION...Prevailing NE wnd 20-25 kts blo FL150...incr ABV
bcmg fm N-NW w/ Max wnd around 50 kts nr FL300. Sfc wnd lgt/vrb
w/ocnl gust due to passing -SHRA...bcmg fm NE 10-15 kts w/ocnl gusts
aft 25/14z. SCT ocnl BKN cld lyrs nr FL022...FL040...mstly SKC abv.
Few tops nr FL100. -SHRA/SHRA at TJSJ/TIST/TJBQ/TISX/TNCM/TKPK til
25/14z and en route btw islands and ovr coastal waters.

&&

.MARINE...Seas up to 6 feet with east northeast winds 15 to 20
knots to continue through tonight. Marine conditions are expected
to gradually deteriorate on Tuesday with wind driven seas near 7
feet expected to prevail across most of the local waters. A
moderate risk of rip currents will continue across most of local
beaches throughout the day.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 85 75 85 75 / 40 30 30 30
STT 85 75 85 75 / 50 30 30 50
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Re: Caribbean - Central America Weather

#19160 Postby cycloneye » Mon Dec 25, 2017 4:03 pm

Area Forecast Discussion...CORRECTED
National Weather Service San Juan PR
406 PM AST Mon Dec 25 2017

.SYNOPSIS...A mid to upper level trough northeast of the region
is expected to weakens as a mid to upper level ridge strengthens
across the forecast area and hold much of the week. Brisk trade
winds expected to continue across the forecast area. A fair and
mainly stable weather pattern with only occasional passing trade
wind showers will continue to prevail across the region.

&&

.SHORT TERM...Tonight through Wednesday...
Small patches of low level moisture embedded in the northeast
trades will continue to move west southwestward from the
surrounding waters across the U.S. Virgin Islands, Vieques,
Culebra as well as across the eastern and northern sections of
Puerto Rico tonight and through at least Wednesday. However, due
to the rapid movement of the showers, not significant rainfall
accumulations are expected.

An upper level trough northeast of the region is expected to
weakens tonight. A mid to upper level ridge is then expected to
build across the region for the next several days. This feature
will maintain an overall good weather conditions for most of the
week. East northeast trades will continue across the area for the
next several days with winds forecast to increase through midweek
in response to the tightening of the local pressure gradient. This
will increase the early morning passing showers and brief gusty
winds each day. Some afternoon showers of short duration are
expected across southwest sections of Puerto Rico. Temperatures
will remain pleasant for the next several days.

.LONG TERM...Thursday through Tuesday (from previous AFD)...
A mid to upper level ridge will hold across the local isles much
of the forecast period. At lower levels, continue to expect a
moderate to fresh east northeast wind flow through the upcoming
weekend, becoming more easterly early next week. Under ridge
pattern aloft and brisk trade winds, expect a seasonal weather
pattern with passing showers across the north and east coastal
areas of Puerto Rico as well as Vieques, Culebra and the US Virgin
Islands. Locally induced afternoon showers cannot be ruled out
each afternoon particularly by the end of the forecast period when
winds are expected to slightly decrease and stronger sea breezes
will develop.

&&

.AVIATION...An east to northeast wind flow between 12 and 20 knots
with higher gusts will persist across the islands. The VCTY of TJMZ
can expect -SHRA/SHRA til 26/22z. Elsewhere, trade wind showers
will move at times near/across TJSJ/TIST/TISX/TNCM/TKPK/TJBQ thru
the fcst prd. Winds will diminish around 12 knots after 25/23z.

&&

.MARINE...Marine conditions are expected to gradually deteriorate
tonight and Tuesday with wind driven seas increasing to 7 feet
tonight and up to 8 feet on Tuesday. Small Craft Advisory is in
effect for the offshore Atlantic waters tonight and will be
expanded across other marine zone Tuesday morning. A moderate
risk of rip currents will continue across most of local beaches
tonight.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 75 85 75 84 / 30 30 30 20
STT 75 85 75 85 / 30 30 50 30
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