Caribbean - Central America Weather

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
440 PM AST Tue Dec 26 2017

.SYNOPSIS...A mid to upper level ridge will build and hold across
the region for 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 Thursday...
Patches of low level moisture will 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 Thursday. However, due to
the rapid movement of the showers, not significant rainfall
accumulations are expected.

A mid to upper level ridge will continue to build and hold across
the region for the next several days. This feature will keep drier
air in the mid to upper level of the atmosphere maintaining an
overall good weather conditions across the local islands for most
of the week. East northeast trades will continue across the area
for the next several days. These winds will continue to bring
surges of moisture from the surrounding waters into the U.S.
Virgin Islands, Vieques, Culebra and Puerto Rico through at least
Thursday. 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...Friday through Tuesday (From previous AFD)...High
pressure will continue over the mid and upper levels through early
next week. At the surface the easterly trade wind flow with brief
passing showers will continue through Monday. A strong low and
trough will develop over the western Atlantic, causing winds to
become more southeasterly on Tuesday. Intermittent moisture surges
will continue this week and through the weekend then moisture is
expected to increase on Tuesday of next week as a cold front
begins to approach the area.

&&

.AVIATION...VFR conditions expected, but -SHRA/SHRA will move across
TJSJ/TIST/TJBQ/TNCM/TKPK at times. Some of them will produce SCT-BKN
ceilings at FL025-FL060. Limited convection expected across W-PR
with VCSH at TJMZ til 26/22z. After 26/22z, passing -SHRA/SHRA can
be expected across TJSJ/TIST/TISX/TNCM/TKPK, elsewhere fair wx
conds. Sfc winds will continue from the E-NE at 10 to 20 with higher
gusts, dropping around 10 kts overnight.

&&

.MARINE...As winds increase Small Craft Advisory conditions will
spread across most of the local waters. Wind driven seas of 7 to 8
feet are expected to propagate across most of the waters during
the next few days. High rip current risk is in effect for the
northwest to northeast beaches of Puerto Rico and for the northern
beaches of Saint Croix until at least Wednesday afternoon.

&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
456 AM AST Wed Dec 27 2017

.SYNOPSIS...Brief trade wind showers persist in moderate to strong
easterly flow. Afternoon showers will form in the southwest
portion of Puerto Rico through Monday and then shift to the
northwest portion Tuesday and Wednesday of next week.

&&

.SHORT TERM...Wednesday through Friday...
Partly cloudy skies prevailed across the forecast area overnight
and early this morning with passing showers observed across the
north and east coastal areas of Puerto Rico as well as the U.S.
Virgin Islands, Vieques and Culebra. The overnight minimum
temperatures were in the low to mid 70s at lower elevations and
winds were from the east northeast at around 10 knots. Continue to
expect a generally fair and mainly stable weather pattern during
the forecast period under a ridge pattern aloft. Although the
ridge pattern will remain as the dominant weather feature, still
expect passing showers embedded in the trades. The surface high
pressure across the central Atlantic will continue to yield a
moderate to fresh east northeast wind flow which will bring those
patches of low level moisture at times. In the afternoon hours,
limited shower activity across west Puerto Rico cant be ruled out.

.LONG TERM...Saturday through Wednesday...
The upper level jet across the area on Friday will lift to the
north over the weekend, leaving just the ridge that extends
northwest along the northeast coast of South America. As a trough
deepens over Florida and the northwest Caribbean, flow will
become southwest at upper levels and the ridge will build to our
east. At lower levels, patches and bands of moisture continue to
ride by in easterly flow carrying generally shallow trade wind
showers through early next week. As the upper level trough
approaches and a surface front moves toward the area through the
Atlantic north of the Bahama Islands, low level flow will become
more southeasterly, but bands of moisture will continue to move
through the area bringing showers to the northwest portion of
Puerto Rico during the afternoons and brief trade wind showers to
the eastern slopes during the overnight and early morning hours.
At this time the front is not expected to move through the
forecast area.

&&

.AVIATION...VFR conds are expected to continue at all TAF sites
through the forecast period with SHRA/-SHRA at the Leeward and USVI
terminals as well as JSJ/JBQ. Aft 27/16z, an isolated showers is
possible in and around JMZ. Continue to expect ENE winds 15 to 20
knots.

&&

.MARINE...Small craft advisories continue for all waters except
along the western and southern coast of Puerto Rico. Marine
conditions will begin to improve on Thursday and small craft
advisories should come down completely by late Friday for a short
time. The outer Atlantic waters will likely see 7 foot seas again
by Sunday.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 85 76 86 75 / 50 50 50 30
STT 86 77 87 77 / 50 50 50 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
400 PM AST Wed Dec 27 2017

.SYNOPSIS...Easterly wind flow expected to continue for the next
few days with near normal moisture across the local area causing
trade wind showers to continue over the local islands. Broad upper
ridge south of the local area will remain in place for the next
several days. Breezy conditions to continue through Thursday,
starting to diminish wind speed on Friday.

&&

.SHORT TERM...Today through Friday...
Breezy easterly winds will continue through Thursday, the
decreasing slightly on Friday. The available moisture is expected
to be near normal with patches of higher moisture, to cause brief
showers across the windward side of the islands through the days.
So skies are expected to be partly to variably cloudy across much
of the local area with brief moments of showers, which are not
expected to cause significant flooding, but some ponding of water
is possible in poor drainage areas. This pattern is expected to
continue for the next several days. Near normal temperatures
expected, so highs in the low to mid 80s across the lower
elevations and in the 70s across the higher elevations, while the
overnight lows will be in the low to mid 70s across the lower
elevations and in the 60s across the higher elevations, with even
slightly cooler temps overnight across some isolated areas across
the highest valleys.

.LONG TERM...Saturday through Wednesday...
...From previous discussion...

The upper level jet across the area on Friday will lift to the
north over the weekend, leaving just the ridge that extends
northwest along the northeast coast of South America. As a trough
deepens over Florida and the northwest Caribbean, flow will become
southwest at upper levels and the ridge will build to our east.
At lower levels, patches and bands of moisture continue to ride by
in easterly flow carrying generally shallow trade wind showers
through early next week. As the upper level trough approaches and
a surface front moves toward the area through the Atlantic north
of the Bahama Islands, low level flow will become more
southeasterly, but bands of moisture will continue to move through
the area bringing showers to the northwest portion of Puerto Rico
during the afternoons and brief trade wind showers to the eastern
slopes during the overnight and early morning hours. At this time
the front is not expected to move through the forecast area.


&&

.AVIATION...VFR conditions expected, but -SHRA/SHRA will move across
TJSJ/TIST/TISX/TJBQ/TNCM/TKPK at times. Some of them will produce
SCT-BKN ceilings at FL025-FL060. Limited convection expected across
W-PR with VCSH at TJMZ til 27/22z. Sfc winds will continue from the
E-NE at 10 to 20 with higher gusts, then btwn 10 and 15 kt
overnight.


&&

.MARINE...Small craft advisory across the local waters due to seas
up to 8 feet, winds up to 20 knots. High risk of rip currents
across northern PR and eastern St. Croix. These marine and surf
zone conditions are expected through at least Thursday, gradually
improving thereafter.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 76 86 75 85 / 50 50 30 30
STT 77 87 77 86 / 50 50 30 30

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
511 AM AST Thu Dec 28 2017

.SYNOPSIS...Trade wind showers will continue over the area through
the next 7 to 10 days. Winds will shift to the southeast mid-week
next week as a long wave upper level trough approaches the area.

&&

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

Partly cloudy skies prevailed across the forecast area overnight and
early this morning with passing showers observed across the north
and east coastal areas of Puerto Rico as well as the U.S. Virgin
Islands, Vieques and Culebra. The overnight minimum temperatures
were in the low to mid 70s at lower elevations and winds were from
the east at 10 mph or less.

The ridge aloft will hold through the upcoming weekend while
weakening. At lower levels, brisk trade winds will continue to
prevail. Although the weakening ridge pattern with its associated
inversion will hold through the forecast period, still expect
patches of moisture moving in from time to time. Based on the
latest guidance, the highest PW values associated with these
patches of moisture are expected today and late Saturday.
Therefore, expect a mainly fair and generally stable weather
pattern with passing showers across the north and east coastal
areas of Puerto Rico as well as the U.S. Virgin Islands, Vieques
and Culebra every day but particularly today and Saturday night.
Since the associated inversion is quite elevated, afternoon
showers across west Puerto Rico can`t be ruled out each day.

.LONG TERM...Moisture Saturday night will decline through early
Monday morning, but a passing trough will bring that moisture back
beginning Monday with the advance of tropical moisture into the
area from the southeast. The moisture lingers through late week
next week as an upper level trough remains northwest of the area
and an upper level ridge builds east of the area to hold flow
aloft from the southwest beyond the end of next week. Thus there
may be a short break in the persistent rains on Sunday night and
again late next week, but otherwise the passing showers will be
the prevailing weather through the end of next week with the
heaviest rains expected on Wednesday and Thursday. Ordinarily this
southeast flow would bring warmer than normal temperatures to the
north coast and especially the Greater San Juan Metropolitan
area, but the addition of mid and high cloudiness should mute the
effect considerably.


&&

.AVIATION...VFR conds are expected to continue at all TAF sites
through the forecast period with SHRA/-SHRA at the Leeward and USVI
terminals as well as JSJ/JBQ. Aft 28/16z, an isolated shower is
possible in and around JMZ. Low level winds from the east at 15 to
20 knots. Maximum winds 50 to 65 knots from FL330-450 diminishing
today and tonight.

&&

.MARINE...The GFS is now more decisive about dropping seas on
Friday. Small craft advisories are now no longer expected in the
local area through at least mid week next week.


&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
350 PM AST Thu Dec 28 2017

.SYNOPSIS...

Easterly trade winds are moving scattered showers across Puerto
Rico and the U.S. Virgin Islands with most of this activity
diminishing by sunset. These easterly trade wind showers will
persist through the weekend. Sunday, a polar trough will move
close to the islands and cause the upper level ridge to weaken.
This will cause an increase in low level moisture on Monday over
the area, but at this time the main upper level forcing which is
the trough will remain north of the Islands so wind driven showers
will once again be the weather maker.

&&

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

Fair weather conditions will prevail through early Sunday with the
only weather being easterly trade winds transporting patches of
low level moisture over Puerto Rico and the U.S. Virgin Islands.
Although, low level moisture will move over the region
periodically SJU skew-T sounding shows it will have a hard time
making it to the upper level of the atmosphere due to persistent
drier air that is in place from the high pressure ridge. So the
patches of moisture will only cause an occasional passing shower
typically during the morning and afternoon.

Sunday, will be a transition day for the area. The cold front
that has brought freezing temperatures to the Midwest and
northeast will move into the eastern Atlantic waters and impinge
on the upper level ridge thus weakening the ridge.

LONG TERM...From previous discussion...

Moisture Saturday night will decline through early Monday
morning, but a passing trough will bring that moisture back
beginning Monday with the advance of tropical moisture into the
area from the southeast. The moisture lingers through late week
next week as an upper level trough remains northwest of the area
and an upper level ridge builds east of the area to hold flow
aloft from the southwest beyond the end of next week. Thus there
may be a short break in the persistent rains on Sunday night and
again late next week, but otherwise the passing showers will be
the prevailing weather through the end of next week with the
heaviest rains expected on Wednesday and Thursday. Ordinarily this
southeast flow would bring warmer than normal temperatures to the
north coast and especially the Greater San Juan Metropolitan
area, but the addition of mid and high cloudiness should mute the
effect considerably.

&&

.Aviation...

VFR conds are expected to continue with scat SHRA/-SHRA
across the Leeward/USVI terminals as well as JSJ. VCSH or even brief
SHRA are expected at JMZ btwn thru 28/22z. This activity will result
in SCT or even brief BKN ceilings at FL022-FL050. Sfc winds from the
E-NE at 10 to 15 knots, diminishing at 10 knots or less overnight.

&&

.MARINE...

Small craft advisory across the local waters due to seas
up to 7 feet with occasional seas up to 9 feet, and easterly
winds 10 to 15 kts. High rip currents risk across northern PR
while other areas have a low to medium risk for rip currents.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 75 84 74 84 / 30 30 50 50
STT 74 85 74 84 / 30 30 50 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
455 AM AST Fri Dec 29 2017

.SYNOPSIS...A mid to upper level ridge pattern will continue to
prevail through the weekend while weakening. Trade winds will
continue to bring patches of low level moisture to result in
passing showers at times, particularly the eastern half of Puerto
Rico, as well as the U.S. Virgin Islands, Vieques and Culebra.
Shower activity across west Puerto Rico cant be ruled out each
afternoon. The chance for shower and thunderstorm will increase
by mid week next week.

&&

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

A sub equatorial jet around the broad high pressure over the
eastern Caribbean will continue through the period as will the
easterly trade winds generated by the surface high pressure in the
east central Atlantic that weakly links to the North American
continental high pressure. This leaves only patches of moisture
migrating through the easterly flow and the weak troughs
generating them embedded in that flow to explain any variations in
the shower pattern for the next 3 days that we have been
experiencing for the past week. Currently models suggest that
maximums in moisture will occur this morning in eastern Puerto
Rico and this afternoon in western Puerto Rico , and Saturday
afternoon through Sunday evening. Although 850 and 700 mb flow
vary somewhat between east northeast and east southeast the main
effects will be on the windward sides of Puerto Rico in the
overnight and early morning hours and the western sections and
interior during the afternoons each day. The U.S. Virgin Islands
will see brief passing showers with less variations.

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

Moisture advection is expected to increase across the local isles
early next week as a weak surface front stalls west of the area.
However, a sharp increase in the available moisture/precipitable
water is expected by Wednesday as a deep polar trough develops
across the western Atlantic. This feature and its associated
surface front will promote a moist southeasterly wind flow through
Thursday. As the surface front moves closer to the forecast area,
winds will become more northeasterly. At this time, PW maximum is
expected Thu-Fri which in fact may exceed 2SD.

Therefore, based on latest guidance, expect a seasonal weather
pattern with passing showers at times Mon-Tue. The chance for
showers and thunderstorms will increase by midweek through the
end of the forecast period as the upper trough and associated
surface front moves closer.

&&

.AVIATION...VFR conditions will prevail through 30/06Z except that
brief MVFR conds are psbl at TJMZ due to CIGS in SHRA. SHRA will
increase over PR aft 29/15Z mainly over interior and western
sections. Hir trrn will be obscured till aft 29/22Z. Sfc winds
easterly 10 to 15 kt with sea breeze influences diminishing to less
than 10 kt overnight. Max winds west 70-80 kt from FL350-430 thru
30/12Z.

&&

.MARINE...Hazardous seas will continue to prevail particularly
across the offshore Atlantic waters with seas up to 7 feet and a
moderate to locally fresh easterly wind flow. Seas will continue
to subside across the local waters but remain choppy.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 84 73 84 73 / 40 30 40 40
STT 85 73 84 73 / 60 30 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
343 PM AST Fri Dec 29 2017

.SYNOPSIS...

The mid to upper level ridge will continue to hold until the
weekend but will begin to weaken on Saturday. This weekends
weather will be similar to the previous few days with wind driven
showers occasionally moving over Puerto Rico and the U.S. Virgin
Islands with light accumulation amounts. The chance for showers
and thunderstorms will increase by mid next week.

&&

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

Mostly cloudy to partly cloudy conditions occured across the
region today. Low level moisture out of the east moved over the
U.S. Virgin Islands and Puerto Rico today thus triggering showers
with a few embedded thunderstorms. These showers should continue
to diminish from east to west across Puerto Rico by sunset, but
isolated showers are still possible over the north Atlantic
waters. This weekends weather will be controlled by easterly
trades that may bring showers over Puerto Rico and the U.S. Virgin
Islands.

&&

LONG TERM...Monday through Saturday (From previous discussion)...

Moisture advection is expected to increase across the local isles
early next week as a weak surface front stalls west of the area.
However, a sharp increase in the available moisture/precipitable
water is expected by Wednesday as a deep polar trough develops
across the western Atlantic. This feature and its associated
surface front will promote a moist southeasterly wind flow through
Thursday. As the surface front moves closer to the forecast area,
winds will become more northeasterly. At this time, PW maximum is
expected Thu-Fri which in fact may exceed 2SD.

Therefore, based on latest guidance, expect a seasonal weather
pattern with passing showers at times Mon-Tue. The chance for
showers and thunderstorms will increase by midweek through the
end of the forecast period as the upper trough and associated
surface front moves closer.

&&

.AVIATION...

Brief periods of MVFR conditions will continue across
the Leeward, USVI and TJSJ taf sites until at least 29/22Z. SHRA
with mountain obscuration will continue until 29/22 over interior
and western sections of Puerto Rico. Surface winds will remain from
the east to east-northeast at 10 to 15 kt with sea breeze influences
until 29/22, diminishing to less than 10 kt overnight.

&&

.MARINE...

Seas up to 6 feet but seas should continue to subside over the
next several days. Winds 10 to 15 kts with moderate risk for rip
currents across the north facing beaches of Puerto Rico, northern
beaches of Vieques, St. Thomas and St. John. Otherwise other areas
will have a low rip currents risk.

&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
435 AM AST Sat Dec 30 2017

.SYNOPSIS...A seasonal weather pattern will continue to prevail
across the local isles through early the next week with trade
wind showers across windward areas and a few locally induced
afternoon showers across the interior and west portions of Puerto
Rico. The chance for shower and thunderstorm activity will
increase by mid week next week as an upper trough establishes
across the western Atlantic and its associated surface front
stalls close to our forecast area.

&&

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

Partly cloudy skies prevailed across the forecast area overnight
with passing showers observed across the north and east coastal
areas of Puerto Rico as well as the U.S. Virgin Islands, Vieques and
Culebra. The overnight minimum temperatures were in the low to mid
70s at lower elevations and winds were from the east at 10 mph or
less.

Patches of low level moisture embedded in the trade winds will
continue to affect the local islands from time to time today and the
rest of the weekend. Expect passing showers to affect mainly the
east and northeast sections of Puerto Rico this morning, with some
cloudiness and showers affecting most of the area this afternoon, as
a patch of moisture moves through the area. Surface high pressure
system will continue to dominates the local region through at least
Monday. A much drier air mass is expected to move across the region
Monday afternoon.

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

Trade wind showers are expected to prevail across the forecast
area on Tuesday. However, a sharp increase in the available
moisture/precipitable water is still expected by mid week as a
broad polar trough develops across the western Atlantic. This
feature and its associated surface front will promote a moist
southeasterly wind flow much of the forecast period. At this time,
best moisture advection is expected to occur Thu-Fri with
precipitable water near or exceeding 2 inches. Therefore, based on
the latest guidance, the chance for showers and thunderstorms
will increase Wednesday and onwards as the upper trough prevails
across the western Atlantic and its associated surface front
stalls near or over the forecast area.

&&

.AVIATION...VFR conditions are expected to continue at all TAF sites
through the forecast period with SHRA/-SHRA at the Leeward and USVI
terminals as well as TJSJ/TJBQ. After 30/16z, an isolated shower is
possible in and around TJMZ. Low level winds from the east at 15 to
20 knots.

&&

.MARINE...Small craft should exercise caution as seas will be
choppy and up to 6 feet. Moderate risk of rip currents across
many beaches in PR except some beaches in the southern and
western coasts, also moderate risk of rip currents across most
of the beaches in Saint Croix.

&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
352 PM AST Sat Dec 30 2017

.SYNOPSIS...

Pleasant weather will continue to prevail through the middle of
next week with an occasional shower from time to time due to wind
driven trade winds that will stream low level moisture across
Puerto Rico and the U.S. Virgin Islands. Tuesday will be a
transition day due to an upper level trough moving near the
forecast area by Wednesday, winds will be out of the east
southeast and then southeast which will increase the low level
moisture across the region. The upper level trough overhead there
might be enough upper level forcing for thunderstorms Wednesday
through Friday.

&&

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

The ridge of high pressure over the area will weaken ahead of a
polar trough to the north thus creating an elevated trade wind cap
through Tuesday. Patches of low level moisture embedded in the
trade winds will move into the region periodically which could
lead to showers across the northern areas of Puerto Rico. Once
again convection will be limited due the persistent drier air in
the mid to upper levels of the atmosphere. San Juan TSJU skew-T
sounding shows drier air at 500 to 300 mb remaining through
Tuesday thus causing the local weather to be driven by easterly
trade winds.


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

Trade wind showers are expected to prevail across the forecast
area on Tuesday. However, a sharp increase in the available
moisture/precipitable water is still expected by mid week as a
broad polar trough develops across the western Atlantic. This
feature and its associated surface front will promote a moist
southeasterly wind flow much of the forecast period. At this time,
best moisture advection is expected to occur Thu-Fri with
precipitable water near or exceeding 2 inches. Therefore, based on
the latest guidance, the chance for showers and thunderstorms
will increase Wednesday and onwards as the upper trough prevails
across the western Atlantic and its associated surface front
stalls near or over the forecast area.

&&

.AVIATION...

Mostly VFR conditions are expected across the local
flying area with only VCSH across the Leewards, USVI and TJSJ taf
sites until at least 30/22z. An area of low level moisture to the
east of PR is expected to produce brief periods of MVFR conditions
across the Leewards, USVI and eastern PR taf sites after 30/22Z. Low
level winds will continue from the east at 10 to 15 knots
diminishing at around 10 knots after 30/22Z, but gusty near SHRA.

&&

.MARINE...

Small craft should exercise caution as seas will be near 6 feet
with winds 10 to 15 kts. Moderate risk of rip currents across
northern Puerto Rico beaches while southern and western coast will
have a low rip currents risk. Moderate risk of rip currents
across most of the beaches in St. Thomas and adjacent Islands and
moderate risk for rip currents along the southern coast of Saint
Croix.



&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
455 AM AST Sun Dec 31 2017

.SYNOPSIS...A seasonal weather pattern will continue to prevail
across the local isles through early Wednesday. The chance for
passing showers and a few isolated thunderstorms will increase
late Wednesday and onwards as an upper trough amplifies across
the western Atlantic and its associated surface front stalls
close to our forecast area.

&&

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

Patches of low level moisture embedded in the trade winds were
observed across the local area overnight. Most of the shower
activity was observed across the Atlantic coastal waters. In
addition, high level cloudiness streamed across the local area.
For the rest of this morning and throughout the day, expect
passing showers to affect mainly the east and northeast sections
of Puerto Rico.

Surface high pressure system will continue to dominates the local
region. This will result in easterly trade winds transporting
patches of low level moisture across the local area from time to
time through at least Monday. A much drier air mass is expected
to move across the region Tuesday morning.

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

A sharp increase in the available moisture/precipitable water is
still expected late Wednesday and into Thursday as a broad polar
trough amplifies across the western Atlantic. This feature and
its associated surface front will promote a moist southeasterly
wind flow through at least Saturday. At this time, best moisture
advection is expect to occur Thu-Fri with precipitable water near
or exceeding 2 inches. A drier air mass will then encompass the
local isles Sunday into Monday as a mid level ridge strengthens
across the area. Therefore, based on the latest guidance, the
chance for passing showers and a few isolated thunderstorms will
increase late Wednesday and onwards as the upper trough prevails
across the western Atlantic and associated surface front stalls
near or over the forecast area. A seasonal weather pattern will
then return to the forecast area late the upcoming weekend and
into next week under trade winds.

&&

.AVIATION...VFR conditions are expected to continue at all TAF sites
through the forecast period with SHRA/-SHRA at the Leeward and USVI
terminals as well as TJSJ/TJBQ. Low level winds from the east at 10
to 15 knots.

&&

.MARINE...Small craft operators are urged to exercise caution due
to seas up to 6 feet across the local offshore Atlantic waters and
Anegada passage. Elsewhere, seas are expected to be up to 5 feet.
Winds will be easterly at 10-15KT.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 85 75 84 75 / 40 40 40 10
STT 84 74 83 74 / 30 30 20 10

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
410 PM AST Sun Dec 31 2017

.SYNOPSIS...
Fair weather conditions during the New Year`s Eve. Although
mostly clear to partly cloudy skies are expected, a few brief
trade wind showers could move across the windward sections of the
islands. Minimum temperatures ranging from the low to mid 70s
across coastal sections to the low to mid 60s across mountain
areas with isolated cooler areas in the high 50s.

&&

.SHORT TERM...Tonight through Tuesday...
A mid to upper level ridge will promote a fair weather pattern
the first days of 2018. But, a surface high pressure will continue
to advect trade wind showers at times. Therefore, seasonably
passing showers are forecast to move mainly across the U.S. Virgin
Islands and the windward sections of Puerto Rico during the
night-time and morning hours. During the afternoon, a mixture of
clouds and sunshine will prevailed across the local area with
limited convection across the western portions of Puerto Rico.

.LONG TERM...Wednesday through Monday...Previous Discussion...
A sharp increase in the available moisture/precipitable water is
still expected late Wednesday and into Thursday as a broad polar
trough amplifies across the western Atlantic. This feature and its
associated surface front will promote a moist southeasterly wind
flow through at least Saturday. At this time, best moisture
advection is expect to occur Thu-Fri with precipitable water near
or exceeding 2 inches. A drier air mass will then encompass the
local isles Sunday into Monday as a mid level ridge strengthens
across the area. Therefore, based on the latest guidance, the
chance for passing showers and a few isolated thunderstorms will
increase late Wednesday and onwards as the upper trough prevails
across the western Atlantic and associated surface front stalls
near or over the forecast area. A seasonal weather pattern will
then return to the forecast area late the upcoming weekend and
into next week under trade winds.

&&

.AVIATION...
Mostly VFR conditions are expected across the local flying area
with VCSH across the Leewards, USVI and TJSJ taf sites during the
forecast period. Small areas of moisture embedded in the trades
will continue to produce brief -SHRA/SHRA across the Leewards,
USVI and eastern PR taf sites overnight. Low level winds will
continue from the east at 10 to 15 knots diminishing at around 10
knots after 31/22Z. No significant flying hazard expected.

&&

.MARINE...
Tranquil marine conditions expected across most of the local
waters, except across the Atlantic Waters and Caribbean Passages
where seas up to 6 feet are expected. As a result, small craft
operators are urged to exercise caution across these waters.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 75 84 75 84 / 30 20 10 40
STT 74 83 74 83 / 20 20 10 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
519 AM AST Mon Jan 1 2018

.SYNOPSIS...High pressure across the Central Atlantic will
continue to produce a moderate trade wind dlow across the region.
Patches of low level moisture embedded in the trade winds will
continue to affect the local regino from time to time. Strong
surface low and associated frontal boundary will emerge across
the eastern United States seaboard by Friday, inducing a southeast
wind flow at the surface.

&&

.SHORT TERM...Today through Wednesday... A persistent surface high
will maintain a weak bridge of high pressure across the Atlantic
north of the area and moderately strong trade winds over Puerto Rico
and the U.S. Virgin Islands. Strong high pressure over the United
States will move east and cause the bridge to shift north. Low
pressure will then form in the western Atlantic just north of the
Bahama Islands and develop quickly as it moves north northeast along
the gulf stream. The front that develops behind it will not affect
Puerto Rico until after Wednesday.

Patchy moisture will pass through the area this morning followed by
drier air that will remain until Wednesday morning, when lower level
winds shift to the southeast. This will occur ahead of a weak
westward-moving low level trough and will bring up moisture from the
southeast that will affect the U.S. Virgin Islands more than Puerto
Rico this time. The southeast flow will last for a little more than
24 hours or until Thursday evening.

Upper level flow is mainly convergent aloft and will not feed
convection. Mid levels do not moisten up until after the period, but
lower level moisture is expected to increase shower activity by
Wednesday afternoon. Until then only scattered showers are expected
across the area, mainly in western Puerto Rico each afternoon.

.LONG TERM...Thursday through Tuesday...A surface high pressure
across the central Atlantic is expected to maintain a generally
easterly trade wind flow across the region through late in the
weekend. This surface high is expected to drift rapidly eastward
while weakening as a strong surface low and associated frontal
boundary emerge across the eastern United States seaboard by
Friday. This feature will induce a southeast low level wind flow
across the northeast Caribbean through Friday. An increase in low
level moisture is then expected. however, upper level dynamic
will not favor widespread shower activity for now.

Another surface high will develop across the central Atlantic by
the weekend. This will induce a tight pressure gradient over the
region increasing the winds speed across the local islands. Patches
of moisture embedded in the trades will continue to affect the
local area through the forecast period.

&&

.AVIATION...VFR conditions will prevail through 02/06Z except
for brief MVFR conds psbl at TJMZ due to CIGS in SHRA. SHRA will
increase over PR aft 01/16Z mainly over interior and western
sections. Hir trrn will be obscured till aft 01/22Z. Sfc winds
easterly 10 to 15 kt with sea breeze influences from 01/14-21Z bcmg
less than 10 kt overnight with land breezes. Max winds west 40-45 kt
from FL360-490 thru 02/12Z.

&&

.MARINE...Winds up to 15 knots and seas up to 6 feet are expected
across the Atlantic outer waters and around Culebra and Vieques
and local passages. Elsewhere, seas between 3 to 5 feet are
expected to prevail through mid week.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 85 74 85 75 / 0 0 10 10
STT 83 73 84 74 / 10 0 10 20

&&

[Gustywind]

HAPPY NEW YEAR to you cycloneye and all the others neighbours from the islands ! All the very best to all!
Best regards.
Gustywind.

[cycloneye]

HAPPY NEW YEAR to you cycloneye and all the others neighbours from the islands ! All the very best to all!
Best regards.
Gustywind.

Happy New Year to you and family.

[Gustywind]

HAPPY NEW YEAR to you cycloneye and all the others neighbours from the islands ! All the very best to all!
Best regards.
Gustywind.

Happy New Year to you and family.

THANKS hope that PR is in better shape since Maria?

[msbee]

HAPPY NEW YEAR to you cycloneye and all the others neighbours from the islands ! All the very best to all!
Best regards.
Gustywind.

Happy New Year to you, Gustywind and Cycloneye, and all our other Caribbean neighbors.
May 2018 be a good recovery for those islands hit by hurricanes this year, and may 2018 keep us safe from future storms.
All the best to everyone!
Barbara

[cycloneye]

HAPPY NEW YEAR to you cycloneye and all the others neighbours from the islands ! All the very best to all!
Best regards.
Gustywind.

Happy New Year to you, Gustywind and Cycloneye, and all our other Caribbean neighbors.
May 2018 be a good recovery for those islands hit by hurricanes this year, and may 2018 keep us safe from future storms.
All the best to everyone!
Barbara

Same to you Barbara and no storms for us in 2018.

[Gustywind]

HAPPY NEW YEAR to you cycloneye and all the others neighbours from the islands ! All the very best to all!
Best regards.
Gustywind.

Happy New Year to you, Gustywind and Cycloneye, and all our other Caribbean neighbors.
May 2018 be a good recovery for those islands hit by hurricanes this year, and may 2018 keep us safe from future storms.
All the best to everyone!
Barbara

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
442 PM AST Mon Jan 1 2018

.SYNOPSIS...
The islands will continue under an easterly wind flow due to a
surface high pressure across western Atlantic. A relative stable
atmosphere will be in place until late Wednesday, when a polar
trough is forecast to amplify from the west over the region.

&&

.SHORT TERM...
The rest of this afternoon through early Tuesday morning...
Showers are expected to continue across the western interior and
western sections of Puerto Rico. Until now...rainfall
accumulations ranged around half an inch, if this activity
continues minor flooding will possibly affect these sections the
next hour or so. Showers are expected to diminish around sunset,
leaving mostly clear to partly cloudy skies with pleasant minimum
temperatures in the low and mid 70s along the coastal sections an
in the low 60s in the mountain areas. Under an easterly wind flow
some showers still possible mainly across the windward sections of
Puerto Rico and across the U.S. Virgin Islands overnight into
early Tuesday morning.

Tuesday through Wednesday...A drier air mass is forecast to move
in from the east, limiting rains even more. However, shower
advection can not be ruled out across the windward sections of the
islands during the overnight and morning hours, as well as
afternoon convection across the interior and west portions of
Puerto Rico. By late Wednesday, model guidance suggest a strong
surface low pressure moving along the eastern U.S. inducing a
southerly wind flow across the islands, which is forecast to pool
tropical moisture from the south. Also, atmospheric instability is
forecast to increase as a polar trough amplifies across the
western Atlantic.

.LONG TERM...Thursday through Tuesday...
A strong surface low and associated frontal boundary emerge
across the eastern United States seaboard by late Wednesday night
into early Thursday. This feature will induce a southeast low
level wind flow across the northeast Caribbean through the end of
the work-week. Under this southerly wind flow moisture pooling is
forecast through this period. Also a polar trough is forecast to
amplify from the west into the region. The final position of this
feature will determine the coverage and intensity of showers and
thunderstorms across the region.

Another surface high will develop across the central Atlantic by
the weekend. This will induce a tight pressure gradient over the
region increasing the winds speed across the local islands. Patches
of moisture embedded in the trades will continue to affect the
local area through the forecast period.

&&

.AVIATION...
Mostly VFR conditions are expected across the local flying area
with VCSH possible at terminals TJMZ, TJPS AND TJBQ later this
afternoon. Showers should diminish across the terminal sites by
02/00Z with SIGS of 3kft. SFC winds out of the east to east
northeast at 5 - 15 kts with no significant flying hazard
expected.

&&

.MARINE...
Mariner should exercise caution across the Atlantic Offshore
waters and Anegada Passage due to seas up to 6 feet. Elsewhere,
expect seas of 5 feet or less and winds between 10 and 15 knots.
A northerly swell is forecast to affect the Atlantic Waters and
Caribbean Passages by the end of the work week into the upcoming
weekend.

&&

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 74 85 75 86 / 30 30 10 10
STT 73 84 74 83 / 10 10 20 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
436 AM AST Tue Jan 2 2018

.SYNOPSIS...A relative stable atmosphere will be in place until
late Wednesday, when a polar trough is forecast to amplify from
the west over the region. Low level winds will shift from east to
southeast in response to the aformentioned polar trough.

&&

.SHORT TERM...Today through Thursday... Low pressure at the surface
will begin to form just north of the Windward Passage tonight, then
spread north along the gulf stream, deepening rapidly. This will
break the ridge to our north and cause our winds to turn to the
southeast on Wednesday. Better moisture will also move across the
area behind a trough that crosses through Tuesday and Tuesday night.
This will enhance the shower activity beginning Wednesday afternoon
across most of the forecast area. Shower activity during the
afternoon will also shift away from the southwest quadrant of Puerto
Rico. Moisture values will peak midday Thursday although the best
moisture will not arrive until Friday. Flow aloft shifts to the
southwest today as the ridge over the area moves east of us.
Although some significant bands of divergence aloft pass through the
area they appear to do so during the parts of the day that
convection is not favored and hence most precipitation amounts will
remain limited and thunderstorms will remain improbable. The
southeast winds on Wednesday will allow some warming on the north
coast and in the Greater San Juan Metropolitan area. MOS guidance
seems to handle this well.

.LONG TERM...Friday through Wednesday...Computer models indicated
a frontal boundary and associated frontal trough will remain
across the southeastern Bahamas and northern Hispaniola Friday and
Saturday. However the proximity of these systems will induce a
moist southeast wind flow across the region. As a result, periods
of showers will be affecting the local region both days. For
Sunday through Wednesday next week, upper level ridge is forecast
to build north of the area. This will result in relatively fair
weather conditions across the northeast Caribbean throughout this
period.

&&

.AVIATION...VFR conditions will prevail through 03/06Z except for
brief MVFR conds psbl in wrn PR due to CIGS in SHRA. SHRA will
increase over PR aft 02/16Z--mainly over interior and western
sections. Hir trrn will be obscured till aft 03/02Z. Sfc winds will
be easterly 10 to 15 kt with sea breeze influences from 01/14-21Z
bcmg less than 10 kt overnight with land breezes. Max winds west 40-
50 kt from FL400-480 thru 03/06Z.

&&

.MARINE...Seas between 3 to 5 feet and winds up to 15 kts are
expected across the local waters, except across the Mona Passage,
where seas up to 6 feet can be expected. There is a moderate risk
of rip currents for the north coast of Puerto Rico, Culebra and
the eastern third of Vieques and some beaches on Saint Croix and
Saint Thomas.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 85 74 86 75 / 10 10 30 30
STT 84 74 84 74 / 20 20 30 30