Caribbean - Central America Weather

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
523 AM AST Sun Jan 14 2018

.SYNOPSIS...
A surface high pressure across the Atlantic Ocean will continue to
induce breezy trade winds through late this afternoon. This trade
winds will push clouds and showers across the U.S. Virgin Islands
and the northern and eastern portions of Puerto Rico during the
morning hours. Shower activity is expected across the western and
southwestern areas of Puerto Rico during the afternoon. Winds are
forecast to diminish somewhat this evening.

&&

.SHORT TERM...
Today through Tuesday...Scattered showers over the
Atlantic waters moved at times across the northern and eastern
portions of the islands during the overnight hours. This trade wind
shower pattern will continue through the day with minor rainfall
accumulations. Winds will gradually decrease and sea breezes will
aid in the development of afternoon showers across the west and
southwest portions of PR. Showers developing off streamers are
expected across the rest of the islands and in eastern PR. TUTT to
the northeast of the region will continue to induce showers just
east of the Leewards islands and under easterly winds will move at
times across the forecast area for the next few days.

A broad surface high pressure will continue across the Atlantic
ocean and a front will remain across the western Atlantic waters. A
tutt induced surface trough is forecast to develop and move north of
the region later on Monday and Tuesday. This will turn winds more
from the east to southeast and both GFS and ECMWF suggest better low
level moisture content on Tuesday across the region. However, a
ridge aloft will continue to build from the west and limit the
vertical development of showers through the short term period.

.LONG TERM...Wednesday through Saturday...
Mid to upper level ridge will remain over the region through
Saturday. This will cause seasonal weather with occasional trade
wind showers across the eastern half portion Puerto Rico and the
U.S Virgin Islands during the overnight and morning hours. Then
convection will spread across the western portions of Puerto Rico
during the afternoon hours each day. A frontal boundary will move
off the east coast of CONUS on Wednesday and will continue to
progress to the east which could help pull tropical low-level
moisture across Puerto Rico and the U.S. Virgin Islands Wednesday
through late Thursday. Then moisture is expected to erode across
the islands as model guidance suggest the arrival of cool
advection Friday or Saturday.

&&

.AVIATION...
Mainly VFR conditions will prevail across all terminals through
the forecast period. However, trade wind showers will move across
the Leeward/USVI/eastern PR terminals through the forecast period.
Afternoon SHRA is expected to develop mainly over the
west/southwestern interior portions of PR and to the south of
TJSJ. Surface winds will be east at 10-15 kt with higher gusts and
sea breeze variations after 14z.

&&

.MARINE...
Hazardous marine conditions will persist through the day as a
northeasterly swell and breezy conditions continues across the
islands. Seas are expected between 6 and 8 feet across the
Atlantic Ocean and at 5 to 7 feet across the Caribbean Waters.
Therefore small craft advisories continues in effect across the
local waters. Seas will improve somewhat late this afternoon, but
the outer Atlantic waters and Anegada Passage may see 7 foot
seas.

For the beach goers...the risk of rip currents is high along the
beaches of the Puerto Rican coastline, Culebra and St Croix.

&&

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

&&

[cycloneye]

issued 557 PM AST Sun Jan 14 2018/

SYNOPSIS...Brief passing trade wind showers will prevail through
most of the week with increasing moisture and a relatively deep
moist layer below the weak mid level inversion. After Wednesday,
moisture will decline into the next weekend. Northwest flow
continues aloft until Friday when the ridge of high pressure
crosses the area from the west.

SHORT TERM...Tonight through Wednesday...
There will be a slight increase in moisture behind a trough now over
Saint Martin that is oriented northeast/southwest. This trough will
arrive Monday morning in the U.S. Virgin Islands and Puerto Rico.
The increase in moisture is expected to continue through Tuesday
16/18Z. In response surface winds will veer a little arnd 15/18Z to
become east to east southeast, but will return to a more east
northeast orientation afterward. Hence the pattern of scattered
brief trade wind showers we have had over the weekend will increase
somewhat through the first several days of the week. At 700 mb a
ridge will form northeast of the area and generate a weak high
almost 400 miles northeast of the area Wednesday. At first it will
lessen moisture overnight Tuesday but then as it approaches with
more northeasterly flow, moisture out of the cooler Atlantic will
arrive to continue the onshore pattern of up slope trade wind
showers Wednesday and beyond. Temperatures will remain seasonable,
but just above normal.

LONG TERM...Although the surface high pressure decays in the
east central Atlantic Ocean, a second weaker high moves out into
the western Atlantic at mid latitudes, causing the cold front to
become more east west at around 25 north. This will allow the
easterly trade wind flow to continue virtually uninterrupted and
cool mid-Atlantic air to carry brief trade winds showers across
the area. Moisture does decline Thursday through Saturday, but the
diurnal fluctuations will affect the area more than the weak
trend. Hence shower activity will depend more on the bands of
showers that form in the low level unstable air. Capping of these
showers around 16-18 kft is more due to the extremely dry air over
the area rather than any weak inversions that are present from
the 500 mb high that remains close to the local area through the
period. Although cooler air approaches the local area from the
northeast at the end of the 10 day period, it is not clear that
any frontal passage can occur.

AVIATION...Mainly VFR conditions will prevail across all terminals
through the forecast period. However, SHRA over SW PR will cont til
14/21Z with lcl MVFR and mtn obscurations and isold trade wind
showers will move across the Leeward/USVI/eastern PR terminals
through 15/14Z . Surface winds will be east at 12-18 kt with higher
gusts and sea breeze variations til 14/22Z Maximum winds 30 to 35 kt
btwn FL370-470 from WNW.

MARINE...Seas have begun to subside again at the outer buoy
after reaching 10.8 feet earlier this morning. They are still
over 9 feet. This surge is still working its way through the local
waters so some small craft advisories had to be added as seas in
the eastern end of the waters surrounding the northern U.S. Virgin
Islands rise above 7 feet. Seas in the inner Atlantic waters will
subside overnight below 6 feet and remain 6 feet or less until
Monday night when 7 foot seas return. It was decided to let the
SCA expire for Monday in those zones before raising them again
Monday night. Most SCAs will have to be raised again after Monday,
but should all be gone by Wednesday night.

&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
516 AM AST Mon Jan 15 2018

.SYNOPSIS...A mid to upper level ridge will gradually build from
the west and hold through the work week. A TUTT induced surface
trof will continue to move north of the region as it merges with
a front across the western Atlantic later today. Broad surface
high pressure across the north central Atlantic will continue to
slowly weaken and move over the Azores by midweek. A weak surface
high build across the western Atlantic during the weekend.
Moderate trades will continue for the next several days.

&&

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

An increase in low-level moisture from the east is expected today
through Tuesday with precipitable water values between 1.50-1.75
inches. This will result in an increase in shower activity across
the islands. Trade wind showers will affect the eastern half of PR
and the USVI at times throughout the day with afternoon convection
developing over interior and western PR. However, significant
rainfall amounts are not expected as a ridge in the mid to upper-
levels will limit the vertical extension and duration of the
showers. By Wednesday, the low-level moisture content is expected to
diminish somewhat with the mid to upper-level ridge to strengthen
over the eastern Caribbean. This will result in fair weather
conditions with limited shower activity expected. A broad surface
high over the central and eastern Atlantic will continue to result
in winds prevailing from the east throughout the period.

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

Ridge aloft is forecast to hold over the eastern Caribbean through
the long term period. Precipitable water content will gradually
decrease through the weekend. However, small pulses of low level
moisture will move with the trade winds and result in passing
showers at times across the local waters and portions of the
islands. Diurnally induced afternoon isolated to scattered showers
are expected to develop each day over portions of western PR.
Fronts are expected to remain over the open Atlantic waters and
not reach the local area.

&&

.AVIATION...Mainly VFR conditions expected throughout most of the
forecast period. However, trade wind showers could move in across
the Leeward/USVI/eastern PR terminals at times. Afternoon SHRA
development is expected over the western PR terminals with MVFR
conditions possible briefly. Surface winds will continue mainly
from the east between 10-15 kts with sea breeze variations after
14z.

&&

.MARINE...Northeast swell and wind driven seas will continue to
result in hazardous seas across the Atlantic waters and across
portions of the local passages and offshore Caribbean waters.
Moderate easterly winds will continue through the forecast period
at 10-15 kts. A moderate to high risk of rip currents will
continue through at least midweek across the Atlantic beaches of
Puerto Rico, Culebra and St. Croix.


&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
446 PM AST Mon Jan 15 2018

.SYNOPSIS...Relatively deep low level moisture prevails in the
area with showers propelled by moderate to fresh trade wind flow
that will prevail through most of the period. An upper level
ridge dominates the area and will cross the area from west to east
on Thursday to maintain mid and upper levels dry.

&&

.SHORT TERM...Tonight through Thursday...
Strong high pressure in the northeast central Atlantic is
generating east flow across the area with a trough to the north
that is aiding in shower development across the area today. Radar
showed up to an inch of rain in some areas of western Puerto Rico
but no flooding was reported. The surface trough will continue
north of the area as low level moisture provides for brief passing
trade wind showers along the windward side of Puerto Rico and
across the other islands night and mornings and across western
Puerto Rico and inland from the northern coast during the
afternoons. So far, no thunderstorms have been observed since
moisture generally ends above 15 kft. The GFS sees the rain but is
not quite moist enough in the lower levels in its forecast
soundings, hence the difference between the 15/12Z sounding
reporting 1.89 inches of precipitable water versus the GFS
forecast of 1.46. Models do not show any significant features to
change the pattern between now and Thursday, although the GFS does
show a marked drop in the precipitable water on Wednesday. Will
taper shower activity somewhat between Wednesday and Thursday.
Otherwise seasonably cool breezy conditions with showers will
prevail through Thursday.


.LONG TERM...Friday through Monday...
The cold front in the western Atlantic will be reinforced by
another surge of cold air that will carry it eastward, but it will
move no further south than about 25 north as the cooler and drier
air fills the western half of the Atlantic basin north of that.
This will allow the showery weather to continue across the area
with easterly trade winds and a few drier slots in the low-level
moisture through Sunday. On Monday the model has a patch of better
moisture moving through as high pressure rotates around several
hundred miles north. This will all result in little change to the
present temperature and precipitation pattern.

&&

.AVIATION...Mainly VFR conds expected through the 1518/1618 forecast
period with vcsh possible across the USVI, TJMZ and TJSJ terminals
today. TEMPO written for TJMZ between 15/18Z and 15/20Z as SHRA
develops over western PR, but wx conditions will improve by 15/23Z.
Winds from the east at 10-15KT with occasional gusts, decreasing
after 15/23Z. Maximum winds WNW 35-45 knots btwn FL410-490.


&&

.MARINE...Seas are showing signs of declining now as winds relax.
Small craft advisories are expected to all be down by Thursday.
Most areas will still be affected by the east northeast seas above
7 feet through Tuesday afternoon except in the shadow of the
islands. Seven foot seas return on Saturday of this week in north
north east swell.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 75 83 73 84 / 70 70 60 60
STT 74 83 72 84 / 20 30 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
436 AM AST Tue Jan 16 2018

.SYNOPSIS...A mid to upper level ridge will gradually build from
the west and hold through the end of the week. Broad surface high
pressure across the north central Atlantic will continue to
slowly weaken and move over the Azores on Wednesday. A weak
surface high build across the western Atlantic during the weekend.
Moderate trades will continue for the next several days.


&&

.SHORT TERM...Today through Thursday...Cloudiness with showers were
noted across the local coastal waters and the eastern half of Puerto
Rico, and the U.S. Virgin Islands. A patch of low level moisture
embedded in the trade winds was affecting the region early this
morning. This area of moisture will continue to move west and will
produce isolated to scattered showers across most of the area this
morning and into this afternoon. For Wednesday, this weather pattern
will continue as more patches of low level moisture moves across the
islands.

High pressure system across the central Atlantic will continue to
dominate the local area through at least Thursday. Although a slot
of drier air is anticipated for Thursday, moisture content will
remain steady through the forecast period, with precipitable water
values remaining between 1.5 to 1.6 inches. Surface winds will
continue mainly east to east northeast at times.

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

No major change from previous forecasts, as trade wind showers
will continue through the forecast period. Each afternoon, the
limited available moisture content and the local effects will
result in the development of showers over portions of the
west/western interior sections of Puerto Rico. Across the USVI
and eastern PR, streamers are expected to develop early in the
afternoon hours and continue to leave mainly minor rainfall
amounts over land areas. As a surface high pressure moves into the
western Atlantic, winds will shift more from the east- northeast
and passing trade wind showers will focus across the local
Atlantic waters and over the north/northeast sections of PR and
the northern USVI.


&&

.AVIATION...Mainly VFR conditions expected throughout most of the
forecast period. However, trade wind showers could move in across
the Leeward/USVI/eastern PR terminals at times. Afternoon SHRA
development is expected over the western PR terminals with MVFR
conditions possible briefly. Low level winds will continue mainly
from the east between 10-20 kts.


&&

.MARINE...Northeast swell will continue to result in hazardous
seas across the Atlantic waters and across portions of the local
passages and the offshore Caribbean waters. Moderate easterly
winds will continue through the end of the week between 5-15 kts.
A high risk of rip currents will continue through at least
Wednesday afternoon across the Atlantic beaches of Puerto Rico,
Culebra and St. Croix.


&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
437 AM AST Wed Jan 17 2018

.SYNOPSIS...A mid to upper level ridge will gradually build from
the west and hold through the end of the week. Broad surface high
pressure across the north central Atlantic will continue to
slowly weaken. A weak surface high build across the western
Atlantic during the weekend. Moderate trades will continue for the
next several days.

&&

.SHORT TERM...Today through Friday... A mid to upper level ridge of
high pressure will continue to provide easterly winds across Puerto
Rico and the U.S. Virgin Islands through Friday. Near the surface a
surface trough sits north of the forecast area with little to no
impact to San Juan and the U.S. Virgin Islands.

The surface high pressure and low level moisture will be the
features that drives the local weather through Friday. The GFS model
shows precipitable water values decreasing for most of day today and
finally reaching a value less than 1.3 on Thursday morning. The GFS
strengthens the mid to upper level ridge which will limit low level
moisture over the Islands but, the GFS quickly brings low moisture
back over the Islands early Thursday morning. This forecast is
depended on the low level moisture if it decreases rapidly than
drier conditions will prevail and if low level moisture remains over
the Puerto Rico and the U.S. Virgin Island then showers can be
expected.

Otherwise, easterly trade winds will cause isolated showers across
the coastal regions during the morning hours and then move inland
similar to a sea breeze during the afternoon. Similar to Tuesday
night there`s a possibility that some showers could produce periods
of moderate to locally heavy rainfall and cause hazardous driving
conditions.

.LONG TERM...Saturday through Thursday...Upper level ridge will
build north of the area. As a result, dry and pleasant weather
conditions are expected Saturday and Sunday. For Monday next
week,forecast models indicated high pressure weaken and winds
shift southeasterly. Moisture is then forecast to increase at the
beginning of next week. no significant weather events are
forecast to affect the local region in the log term.


&&

.AVIATION...VFR conditions will prevail for the remainder of the
17/06z TAF period. Brief Isold SHRA are possible over the coastal
waters and islands until 17/15z then SHRA will increase across most
terminals by 17/18z. SFC winds light to variable then becoming
easterly by 17/12Z 5 to 15 kts.

&&

.MARINE...Hazardous seas will continue through at least late
tonight. Therefore, small craft advisories remain in effect for
portions of the coastal waters. A gradual decrease in seas is
expected by Thursday...however small craft operators should
continue to exercise caution due to a slight chop and seas of 5-6
feet.


&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
502 PM AST Wed Jan 17 2018

.SYNOPSIS...
A mid to upper level ridge continue as the dominant weather feature.
A surface high pressure across the Atlantic Ocean is inducing a
moderate trade wind flow which is pushing patches of low level
moisture from time to time. Under this pattern expect passing
showers across the U.S. Virgin Islands, east and north Puerto Rico
each day, as well as afternoon convection across west Puerto Rico.
A similar pattern will prevail through the end of the work-week.

&&

.SHORT TERM...
Shower activity was noted across the west interior and western
Puerto Rico. Between a quarter of an inch to almost one inch of
rainfall fall across those areas. On the other hand the eastern
coastal sections observed quick passing showers, which developed
downwind from the U.S. Virgin Islands into Culebra and eastern
Puerto Rico.

Later tonight a patch of dry air will limit shower activity to
the north and eastern sections of Puerto Rico and downwind from
the U.S. Virgin Islands. Elsewhere mostly clear skies with no
shower activity is expected. By Thursday morning a patch of
moisture will increase the amount of showers across the eastern
half portion of Puerto Rico and the U.S. Virgin Islands. Showers
are then expected across the western portion of Puerto Rico during
the afternoon hours. The trade wind inversion is forecast to
prevail through the end of the work-week limiting any vertical
development across the islands. Therefore no lightning activity is
expected.

.LONG TERM...
Saturday through Thursday...Upper level ridge will
build north of the area. As a result, dry and pleasant weather
conditions are expected Saturday and Sunday. For Monday next
week,forecast models indicated high pressure weaken and winds
shift southeasterly. Moisture is then forecast to increase at the
beginning of next week. no significant weather events are
forecast to affect the local region in the log term.

&&

.AVIATION...
VFR conds expected across the local terminals through the
forecast period. VCSH expected for the local terminals with a
probability of TEMPO MVFR conds at TJMZ between 17/18Z and 17/21Z,
but most of the activity is expected south of TJMZ. Winds from
the east at around 10KT with sea breeze variations for the rest of
today, decreasing winds overnight.

&&

.MARINE...
Marine conditions are expected to slowly improve overnight. For
that reason small Craft advisories continues for many of the
local waters due to seas up to 7 feet. Model guidance are
suggesting the arrival of a northerly swell by the upcoming
weekend, which could increase the seas above 7 feet especially
across the Atlantic Waters and Caribbean Passages.

For the beach goers...High risk of rip currents still in effect
along the northern coastline of Puerto Rico and Saint Croix.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 73 84 75 84 / 40 20 10 20
STT 74 84 74 84 / 50 20 10 10

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
428 AM AST Thu Jan 18 2018

.SYNOPSIS...A mid to upper level ridge continue as the dominant
weather feature. A surface high pressure across the Atlantic
Ocean is inducing a moderate trade wind flow which is pushing
patches of low level moisture from time to time. Under this
pattern expect passing showers across the U.S. Virgin Islands, and
the eastern half of Puerto Rico each day, as well as afternoon
convection across western Puerto Rico. A similar pattern will
prevail through the end of the work week.

&&

.SHORT TERM...Today through Saturday...Mid to upper level ridge
will influence Puerto Rico and the U.S. Virgin Islands weather, by
creating a trade wind cap over the area. Recent SJU Skew-T shows
drier air at 700 to 400 mb which will inhibit vertical development
of cloud tops for afternoon thunderstorms but, an occasional passing
shower will be possible today through Saturday.

At the lower levels of the atmosphere tropical moisture will
periodically move in from the east through late Friday thus aiding
in shower development. Saturday, the GFS brings a patch of drier air
that will limit shower activity but this drier air will move out
quickly before another surge of low level moisture moves in on
Sunday. Otherwise, pleasant weather will prevail through late Sunday
with daytime high temperatures near the mid 80s at lower elevations
and upper 70`s at higher elevations.

.LONG TERM...Sunday through Friday...Very dry weather conditions
are expected to prevail across the local area Sunday into early
Monday next week. Although upper level ridge will hold across the
region Monday and beyond, better moisture at lower levels will
induce the development of some showers across the local islands.
At this time,no significant weather events are forecast to affect
the local region in the near future.

&&

.AVIATION...VFR conds expected across the local terminals through
the remainder of the 18/06Z TAF period. Isold SHRA are possible over
the coastal waters and islands today with SHRA decreasing by 19/00Z.
SFC winds SFC winds light to variable then becoming easterly by
18/08Z 5 to 15 kt.

&&

.MARINE...Seas has diminished below 7 feet across all local
waters. However, seas up to 6 feet are still occurring across
most coastal waters. As a result, small craft should exercise
caution. Winds between 10 to 15 kts are expected.

&&

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

[cycloneye]

Area Forecast Discussion...CORRECTED
National Weather Service San Juan PR
514 PM AST Thu Jan 18 2018

.SYNOPSIS...
Once again, a mid to upper level ridge pattern induced a trade
wind inversion, which limited the vertical development of showers
across the islands. Local weather will be driven by low level
moisture advection from the surrounding waters. As a result,
expect passing showers across the U.S. Virgin Islands and the
eastern half portion of Puerto Rico during the overnight and
morning hours. Then, showers are forecast to move across the
interior and western sections of Puerto Rico during the afternoon
hours.

&&

.SHORT TERM...the rest of today through Saturday... Satellite
imagery and the terminal Doppler detected clouds and showers
across the interior sections of Puerto Rico and downwind from the
U.S. Virgin Islands. This activity will continue through the
evening hours. Under a easterly wind flow expect showers across
the surrounding waters of the USVI and some of them will move
inland from time to time. Also, passing showers are expected
across the eastern half portion of Puerto Rico, especially
downwind from El Yunque into the surrounding municipalities. The
maximum rainfall accumulations are forecast across the interior
and western sections of Puerto Rico where rainfall amounts will
range between a quarter and half an inch.

Although much of the islands will observe mostly clear skies with
no rainfall activity, an easterly wind flow will advect clouds and
showers across the Atlantic and Caribbean Waters as well as across
the U.S. Virgin Islands and the eastern half portion of Puerto
Rico overnight and tomorrow morning. This weather pattern is
forecast to continue through the weekend. However, breezy trade
winds are expected by the upcoming weekend as high pressure ridge
is forecast to build north of the region and increase the local
pressure gradient. Which will increase the frequency of the
passing showers across the local islands.

.LONG TERM...Sunday through Friday...
Model guidance suggest a seasonal weather pattern for Puerto Rico
and the U.S. Virgin Islands, as a mid to upper level ridge holds
through at least Monday. Then, as a short wave trough moves north
of the islands the upper level ridge is forecast to erodes.
Although no significant upper level dynamic will be in place,
low level moisture will induce shower development across the
windward sections each night and morning. Also, the available
moisture will combine with daytime heating, orographic effects and
sea breeze variations to produce showers over some locations of
the interior and western PR each afternoon.

&&

.AVIATION...
Mainly VFR conditions are expected to prevail across all
terminals. However, shra over western PR could impact the flying
area of TJMZ/TJBQ through at least 22z. Elsewhere, light trade wind
showers could move at times across the vcty of the sites. Low level
winds will continue from the east at 5 to 15 kt. Light and variable
winds are expected overnight due to land breeze variations.

&&
MARINE...Local seas are diminishing, mariners can expect seas
between 3 and 5 feet across the local waters, except across the
Atlantic and Anegada Passage where seas can reach up to 6 feet.

A long period northwest to north swell will reach the Atlantic
waters and local passages during the weekend. This will result in
hazardous seas and life threatening rip currents across the
Atlantic beaches of the islands, specially by Saturday afternoon
and on Sunday.

&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
447 AM AST Fri Jan 19 2018

.SYNOPSIS...At the surface, high pressure system located across
the southeastern U.S. will move across the western Atlantic
through the weekend. Patches of low level moisture embedded in
the trades will affect the local area from time to time. A frontal
boundary will stall north of the region through at least Saturday
and will become a weak shearline.

&&

.SHORT TERM...Today through Sunday... This might sound familiar but
a mid to upper level ridge is anchored across the forecast region
through Sunday. At the surface north of Puerto Rico there is light
to northeast flow. Recent Skew-T sounding shows drier air in the mid
to upper level of the atmosphere but advancing further in time it
shows the drier air decreasing slightly today. This is a result of
the low to mid level moisture which moved in yesterday, another
round of moisture will move across Puerto Rico and the U.S. Virgin
Islands later today. The increase in low to mid level moisture along
with strong easterly trades will spark convection across the
Atlantic waters, portions of northeast PR and interior today.

A low level ridge will build north of the forecast area thus
creating a strong pressure gradient that will bring breezy
conditions, and possible trade wind showers and streamers early
Saturday across portion of northern Puerto and the eastern U.S.
Virgin Islands. The increase trade winds will cause the cap
inversion to also increase across the region this weekend.
Precipitable water values will decrease to 1.0 to 1.5 inches on
Saturday this combined with the strong cap inversion should hinder
convection from organizing this weekend.

.LONG TERM...Monday through Saturday...Upper level ridge will
hold through the forecast period. Patches of low level moisture
embedded in the trade winds are forecast to affect the local
region as fresh trade winds dominates the northeast Caribbean.

&&

.AVIATION...VFR conditions are expected to prevail across all
terminals. -SHRA are possible for terminals TIST, TISX and TJSJ by
19/12Z while other terminals could see light trade wind showers are
periodically through the day. Sfc wind out of east to northeast at
10 to 20 kt.

&&

.MARINE...Seas up to 6 feet and winds up to 15 knots are expected
to prevail across the local waters today. A long dominant period
northwest to north swell will reach the Atlantic waters and local
passages by Saturday. As a result, small craft advisories has been
issued for the Atlantic waters and local passages from Saturday
morning through at least Monday morning. Please, refer to coastal
waters products for the latest information.


&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
437 PM AST Fri Jan 19 2018

.SYNOPSIS...
A surface high pressure will drift into the western Atlantic
through the weekend, tightening the local pressure gradient. As a
result breezy trade winds will continue to bring clouds and
showers across the islands from time to time.

&&

.SHORT TERM...Tonight through Monday...
Showers continue over eastern Puerto Rico from Gurabo to Bayamon
and within 5 miles of the airport TJSJ. Radar shows some amounts
have exceeded one half inch over San Juan and Guaynabo. Flash
flooding along roads and urban areas were reported across these
municipalities. Other cells developed from Orocovis to Rincon and
the area of convection is expected to diminish around sunset.

Trade winds dominate the synoptic picture at this time. High
pressure from the Alabama coast eastward into the western Atlantic
will continue north of the area through the period and trade
winds will increase somewhat during the period. At 700 mb a high
pressure just north of the area will drag some of the moisture
associated with the front about 200 miles north into the area, but
it will move west and out of the area by Saturday morning. This
will lead to decreasing showers late Saturday and Sunday.
Moisture begins to return on Monday and eastern slopes of Puerto
Rico will be most affected most with scattered showers in the U.S.
Virgin Islands. Upper levels will continue to be dominated by the
ridge that continues to be reinforced in the westerly flow. This
will keep it nearby first to the east then to the west and back
again.

.LONG TERM...Monday through Saturday...
Model guidance suggest a seasonal weather pattern for Puerto Rico
and the U.S. Virgin Islands, as a mid to upper level ridge holds
through at least Monday. Then, as a short wave trough moves north
of the islands the upper level ridge is forecast to erodes.
Although no significant upper level dynamic will be in place, low
level moisture will induce shower development across the windward
sections each night and morning. Also, the available moisture will
combine with daytime heating, orographic effects and sea breeze
variations to produce showers over some locations of the interior
and western PR each afternoon.

&&

.AVIATION...
Areas of mtn obscurations may be seen across western PR,
but otherwise VFR conds are expected to prevail. Any MVFR conds in
the Leeward islands should disappear before 19/18Z. Mtn obscurations
in the Luquillo range should end by 20/04Z. Sct SHRA have developed
across wrn PR but end by 20/00Z. Sfc winds east 10-15 kt. Maximum
winds genly 30-40kt btwn FL380-500, but 19/12Z sounding showed 50 kt
at FL450.

&&

.MARINE...
Mariner can expect seas between 4 and 6 feet across the Atlantic
and Mona Passage overnight. Elsewhere, seas at 5 feet or less are
expected. The winds will be from the east at 10 to 15 knots,
except across the Caribbean and Mona Passage where are expected
between 15 and 20 knots.

A long dominant period northwest to north swell will reach the
Atlantic waters and local passages by Saturday. As a result, small
craft advisories will be in effect across most of the local
waters.

&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
414 AM AST Sat Jan 20 2018

.SYNOPSIS...A surface high pressure system will remain over the
region through the weekend but, will weaken early next week and
allow low level moisture to surge over Puerto Rico and U.S. Virgin
Islands. The high pressure system will create a strong pressure
gradient over the area causing breezy conditions and strong trade
winds that will bring showers early next week for Puerto Rico and
the U.S. Virgin Islands.

&&

.SHORT TERM...Today through Monday...Variably cloudy skies prevailed
across Puerto Rico and the U.S. Virgin Islands overnight. Some
passing showers were noted over the coastal waters. Some of these
showers affected the east and northeast sections of Puerto Rico,
including the San Juan metropolitan area. Brief periods of moderate
to heavy rainfall occured with some of these showers.

Early this morning, a much drier air mass was evident in satellite
images approaching the local region. As a result, showers has
diminished in coverage and intensity. For this afternoon, this
slot of drier air will move across Puerto Rico, inhibiting the
development of showers across the area. Another patch of low level
moisture embedded in the trade winds is expected to affect the
islands late tonight into Sunday morning. Upper level ridge will
continue dominating the northeast Caribbean through at least
Monday. This will result in trade wind showers affecting the local
islands from time to time, mainly during the morning hours.

.LONG TERM...Tuesday through Sunday...Low level moisture will
periodically pass over Puerto Rico and the U.S. Virgin Islands
during the long term period. Several short wave troughs will move
north of the region with little to no effect on the area due to
the troughs energy remaining north of Puerto Rico. Therefore, the
long term weather will be influenced by the mid to upper level
ridge and low level moisture moving in from the east. The ridge
of high pressure will feel the effects of the the troughs and
become elongated from east to west. The weakening high will allow
low level moisture to sneak in from the south which will
induce showers across the windward islands and eastern Puerto
Rico during the night and morning hours. Also, low level moisture
combined with daytime heating along with orographic effects and
sea breeze variations will produce showers over portions of the
interior and western PR during the afternoon.

&&

.AVIATION...VFR conditions are expected to prevail across all
terminals. -SHRA are possible for terminals TIST, TISX and TJSJ by
20/12Z while other terminals could see light trade wind showers
through the day. Low level wind out of east to northeast at 10 to
15 kt.

&&

.MARINE...


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 83 74 85 75 / 30 30 40 40
STT 80 76 85 76 / 40 20 20 10

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
511 PM AST Sat Jan 20 2018

.SYNOPSIS...Frontal boundary will remain north of the region. Mid
to upper level ridge will continue to build and hold for the next
several days. Surface ridge to the northwest of the region will
merge with another surface high by early next week and continue
through the end of the week. Moderate to fresh trades will
continue to carry passing showers across the region through next
week.

&&

.SHORT TERM...Tonight through Tuesday...
The cold front continues about 240 miles north of San Juan, but is
now denoted by a rope cloud more than a solid deck of clouds. As of
20/1730Z showers were just beginning to form under partly cloudy
skies over the interior portion of Puerto Rico. Early indications
suggest less rain coverage than yesterday. The front is expected to
undergo frontolysis as it lays more east/west over the waters to the
north of us. High pressure at the surface is moving east out of the
western Atlantic and the southeastern U.S. and is reinforcing the
trade wind flow now through Sunday. This high pressure will merge
with a high in the northwest Atlantic Tuesday before moving east
into the northeast Atlantic, but trade wind flow will persist just
the same. Patches of moisture will continue to pass in that flow,
but GFS is showing less pronounced peaks to the precipitable water
than in previous forecasts and more general fluctuations. The most
pronounced is from 1.04 inches at 21/12Z to 1.61 inches 23/12Z. All
fluctuations between Tuesday and the following Monday remain within
these bounds. Scattered trade wind showers will continue--minimally
tonight and Sunday, but increasing somewhat Monday and Tuesday.

.LONG TERM...Tuesday through Sunday...From previous
discussion...Low level moisture will periodically pass over
Puerto Rico and the U.S. Virgin Islands during the long term
period. Several short wave troughs will move north of the region
with little to no effect on the area due to the troughs energy
remaining north of Puerto Rico. Therefore, the long term weather
will be influenced by the mid to upper level ridge and low level
moisture moving in from the east. The ridge of high pressure will
feel the effects of the the troughs and become elongated from east
to west. The weakening high will allow low level moisture to
sneak in from the south which will induce showers across the
windward islands and eastern Puerto Rico during the night and
morning hours. Also, low level moisture combined with daytime
heating along with orographic effects and sea breeze variations
will produce showers over portions of the interior and western PR
during the afternoon.

&&

.AVIATION...Limited mtn obscurations over the highest trrn,
otherwise wrn PR btwn 20/18-22Z. Sfc winds easterly 10 to 15 kt with
sea breeze influences til 20/21Z. Maximum winds 30-35 kt from FL410-
480 diminishing durg the next 24 hrs.

&&

.MARINE...Long period northwest swell will continue to affect the
regional waters through the weekend with seas ranging between 6-8
feet. Moderate to locally fresh easterly trades will continue
through the next several days. Hazardous seas will continue
through early next week. Small craft advisories are in effect for
the Atlantic waters and passages as well across portions of the
offshore Caribbean waters. High surf advisory is in effect for the
Atlantic beaches of Puerto Rico. High rip current risk continues
in effect for the northern beaches of the islands.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 74 85 75 85 / 30 40 50 50
STT 76 85 76 79 / 20 20 40 30

&&

[BZSTORM]

Anyone know what satellite system now shows the Western Caribbean i.e. Belize/Honduras since the old GOES EAST (13) was decommissioned. I can't find any sat images for our area anymore on the NHC sat links page.
Funny how you come to rely on Sat images, for me especially IR AVN and when none available along with your radar system weblink crashing sometimes multiple times of day. It's frustrating not to have a way of determining what is coming your way. thanks in advance for any links or insight to when we might as public have access to satellite images of our area again.

[cycloneye]

Anyone know what satellite system now shows the Western Caribbean i.e. Belize/Honduras since the old GOES EAST (13) was decommissioned. I can't find any sat images for our area anymore on the NHC sat links page.
Funny how you come to rely on Sat images, for me especially IR AVN and when none available along with your radar system weblink crashing sometimes multiple times of day. It's frustrating not to have a way of determining what is coming your way. thanks in advance for any links or insight to when we might as public have access to satellite images of our area again.

Hi my friend.After the change to the new GOES-EAST satelite,there was confusion in the first days as what you say happened to many people including me but then they have been creating sectors or areas that we can see and the images are better than before so I think we wont be blind.Here are the links.

Click the area you want to see and you get a closeup.

https://weather.msfc.nasa.gov/goes/abi/ ... and14.html

https://www.star.nesdis.noaa.gov/GOES/s ... _index.php

[cycloneye]

Area Forecast Discussion...CORRECTED
National Weather Service San Juan PR
713 AM AST Sun Jan 21 2018

.SYNOPSIS...Surface ridge and upper level ridge of high pressure
will create mostly fair weather conditions for Puerto Rico and the
U.S. Virgin Islands through Friday. Moderate to fresh trades winds
will cause isolated showers for most of the forecast area through
late next week. Friday, a trough of low pressure will move across
the Atlantic waters and possibly increase showers activity for
Puerto Rico and the U.S. Virgin Islands on Saturday.

&&

.SHORT TERM...Today through Tuesday...Partly cloudy skies prevailed
across Puerto Rico and the U.S. Virgin Islands overnight. Latest
satellite images depicted an area of low level moisture over the
U.S. Virgin Islands early this morning. This area of moisture will
spread across Puerto Rico this morning, bringing with it some
isolated passing showers. These showers will move quickly
westward. For this afternoon, some cloudiness with showers are
expected to develop across the western interior and west sections
of Puerto Rico.

High pressure system located north of the area will continue in
control of the weather locally. Trade winds will continue to
transport patches of low level moisture across the local islands
from time to time during the next couple of days.

&&

.LONG TERM...Wednesday through Monday...
Easterly trade winds will bring patches of low level moisture
periodically over the region through the long term period thus
scattered showers are possible during the morning and afternoon
hours. Strong brisk easterly winds can be expected through
Wednesday due to the strengthening surface high pressure system
to north of Puerto Rico. Otherwise, mostly fair weather conditions
across the forecast area until the end of next week when a trough
of low pressure moves into the Atlantic waters with some guidance
showing a frontal passage on Saturday.

&&

.AVIATION...VFR conditions are expected to prevail across all
terminals through at least 21/22z. Some light to moderate showers
can be expected in the vicinity of TIST, TISX and TJSJ throughout
the forecast period. Low level winds will continue mainly from the
east at 10 to 15 kts with higher gusts.

&&

.MARINE...Hazards weather conditions will prevail through Tuesday.
A long period northerly swell will cause seas to rise to 6 to 8
feet through Tuesday. Small craft advisories are in effect for
the Atlantic waters and passages as well across portions of the
offshore Caribbean waters. High rip current risk continues in
effect for the northern coast of the local islands, excluding St.
John with moderate risk. High surf advisory is in effect for the
Atlantic beaches of Puerto Rico.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 85 74 85 74 / 40 20 40 30
STT 78 77 79 78 / 20 30 40 20

[BZSTORM]

Anyone know what satellite system now shows the Western Caribbean i.e. Belize/Honduras since the old GOES EAST (13) was decommissioned. I can't find any sat images for our area anymore on the NHC sat links page.
Funny how you come to rely on Sat images, for me especially IR AVN and when none available along with your radar system weblink crashing sometimes multiple times of day. It's frustrating not to have a way of determining what is coming your way. thanks in advance for any links or insight to when we might as public have access to satellite images of our area again.

Hi my friend.After the change to the new GOES-EAST satelite,there was confusion in the first days as what you say happened to many people including me but then they have been creating sectors or areas that we can see and the images are better than before so I think we wont be blind.Here are the links.

Click the area you want to see and you get a closeup.

https://weather.msfc.nasa.gov/goes/abi/ ... and14.html

https://www.star.nesdis.noaa.gov/GOES/s ... _index.php

Thank Cycloneye (hope things are improving for you in Costa Rica). First link for some reason not working time out issues maybe they re updating site
Second one Caribbean sector doesn't reach to Belize at all only far East side of Honduras covered, neither does the GOM only Yucatan covered, so looks like wide view is all we can get for now, hope they include that sector before hurricane season starts as these unusually strong cold fronts that have been lasting for weeks unlike the usual 3 days has really messed with our weather here. Whats band would be equiv to AVN? I'm used to figuring out intensity of rain storms from the AVN color map. Looks like I need to learn how to read and understand the different bands.

[BZSTORM]

Anyone know what satellite system now shows the Western Caribbean i.e. Belize/Honduras since the old GOES EAST (13) was decommissioned. I can't find any sat images for our area anymore on the NHC sat links page.
Funny how you come to rely on Sat images, for me especially IR AVN and when none available along with your radar system weblink crashing sometimes multiple times of day. It's frustrating not to have a way of determining what is coming your way. thanks in advance for any links or insight to when we might as public have access to satellite images of our area again.

Hi my friend.After the change to the new GOES-EAST satelite,there was confusion in the first days as what you say happened to many people including me but then they have been creating sectors or areas that we can see and the images are better than before so I think we wont be blind.Here are the links.

Click the area you want to see and you get a closeup.

https://weather.msfc.nasa.gov/goes/abi/ ... and14.html

https://www.star.nesdis.noaa.gov/GOES/s ... _index.php

Thank Cycloneye (hope things are improving for you in PR). First link for some reason not working time out issues maybe they re updating site
Second one Caribbean sector doesn't reach to Belize at all only far East side of Honduras covered, neither does the GOM only Yucatan covered, so looks like wide view is all we can get for now, hope they include that sector before hurricane season starts as these unusually strong cold fronts that have been lasting for weeks unlike the usual 3 days has really messed with our weather here. Whats band would be equiv to AVN? I'm used to figuring out intensity of rain storms from the AVN color map. Looks like I need to learn how to read and understand the different bands.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
445 PM AST Sun Jan 21 2018

.SYNOPSIS...Front will remain north of the region as it dissipates
slowly during the next day. Mid to upper level ridge will
continue to build and hold for the next several days. Surface
high pressure north of the region will continue to result in a
moderate to fresh trade wind flow through the forecast period. A
frontal boundary is forecast to move close to the area during the
end of the week.

&&

.SHORT TERM...Tonight through Wednesday...

The cold front continues about 200 miles north of Saint Thomas, and
is now denoted by an undulating and decaying rope cloud. As of
21/1730Z showers were remaining north of the islands in the forecast
area and only a few clouds were seen over land except near Saint
Thomas and in a semi-circle around Mayaguez. The entire forecast
area is in a drier area of the atmosphere and synoptic surface flow
is continuing parallel to this drier band, therefore showers will be
few overnight. The GFS is bringing in an area of moisture Monday
morning through the Leeward Islands tonight and across Saint Croix
and into eastern Puerto Rico. First frames of the model had one
quarter inch of rain over the waters around the Leeward islands, but
there are less clouds and little rain in this area now, so solution
may be suspect. Therefore tempered higher POPs in models and will go
with 20-40% for eastern Puerto Rico Monday morning. Moisture is
forecast by the GFS to improve, or increase, through Tuesday evening
to as much as 1.71 inches and drop off only slightly Wednesday. So
expect showers to increase in frequency and coverage through
Wednesday.

High pressure will continue moving eastward into the central
Atlantic to our north but, as it recedes gradients and winds at the
surface will relax somewhat by Wednesday. A slight warming trend is
expected to end on Wednesday.

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

Easterly trade winds will bring patches of low
level moisture periodically over the region through the long term
period thus scattered showers are possible during the morning and
afternoon hours. Strong brisk easterly winds can be expected
through Wednesday due to the strengthening surface high pressure
system to north of Puerto Rico. Otherwise, mostly fair weather
conditions across the forecast area until the end of next week
when a trough of low pressure moves into the Atlantic waters with
some guidance showing a frontal passage on Saturday.


&&

.AVIATION...VFR conds to prevail through 22/04Z BUT SHRA to cont ovr
Atlantic north of islands. Some clouds will top lcl mtns aft 21/17Z
till 22/02Z. Moisture expected to move thru Leeward islands aft
22/04Z past TIST/TISX arnd 22/08-12Z and into ern PR 22/10-15Z. Some
MVFR psbl durg passages at TNCM/TKPK/TIST/TISX. Sfc winds east 10 -
15 kt with gusts to 20 to 25 kt along the north coast of PR til
21/21Z. Sfc winds east less than 15 kt 22/00-14Z. Max winds west 30-
40 kt from FL410-510.


&&

.MARINE...Northerly swell and wind driven seas will continue to
create choppy and rough seas through at least Tuesday across the
Atlantic waters and portions of the local passages. Easterly
winds will prevail between 15 to 20 knots. Small craft advisories
continue in effect for much of the regional waters. For beach
goers, a high risk of rip currents will continue for the Atlantic
beaches of the islands through at least early in the week. High
surf advisory was extended through the overnight hours for
northern Puerto Rico as breaking waves up to 10 feet are still
possible during the evening hours and the advisory was set to
expire at 6 pm ast today.



&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 74 85 74 86 / 30 30 30 30
STT 77 79 78 79 / 30 20 20 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
416 AM AST Mon Jan 22 2018

.Synopsis...Frontal boundary and associated shear line will remain
north of the region as it dissipates slowly today through Tuesday.
Mid to upper level ridge will hold across the region for the next
several days. Surface high pressure north of the area will maintain
moderate east to northeast trade winds across the forecast areas
through the period. A cold front and associated boundary is forecast
to sink southwards and approach the region by the upcoming weekend.

.SHORT TERM...Today through Wednesday...
Clear to partly cloudy skies prevailed across the local islands
overnight. A dissipating frontal boundary remains across the Atlantic
waters well northeast of the local islands. Terminal Doppler Radar
indicated only few showers across the Atlantic waters as well as across
the surrounding waters of the northern U.S. Virgin Islands. Not precipitation
was detected elsewhere across the region overnight and so far this morning.

A surface high pressure located across the Atlantic waters just to the
north of the region will continue as the main weather feature across
the local islands for the next couple of days. Trade winds will continue
to transport patches of low level moisture across the local islands
from time to time during the next couple of days. Small patches of
low level moisture embedded in the trades will continue to produce
brief passing showers across the U.S. Virgin Islands and eastern Puerto
Rico from time to time, especially overnight and early in the mornings
for the next couple of days. These showers will move quickly westward
with minimal rainfall accumulations. During the afternoons, some cloudiness
with showers are expected to develop across the interior and west sections
of Puerto Rico. The GFS model guidance suggests an increase in low level
moisture by the middle of the week.

.LONG TERM...Thursday through Tuesday of next week.
The upper level high pressure ridge will hold across the region through
Friday. However the prevailing easterlies will continue to transport
sufficient moisture across the region to support periods of passing
late evening and early morning showers, as well as isolated to scattered
afternoon convection. Saturday through Sunday, a polar trough will amplify
and spread eastward across the west and central Atlantic causing a slight
erosion of the upper level ridge. By Monday and Tuesday the mid to upper
level ridge will reestablish over the region and again limit shower
development.

In the meantime, the a cold front is forecast to move across the west
Atlantic and reach the local area by the upcoming weekend. Model guidance
continued to suggest a gradual increase in trade winds moisture during
the latter part of the week with more favorable conditions for moisture
convergence and shower development over the weekend, as the cold front
sinks southwards and stalls just north of the region by Sunday. Improving
weather conditions are however expected by Monday and Tuesday with a
return of more typical passing trade wind showers.

&&

.AVIATION...Mainly VFR conditions are expected across the local
flying area through the forecast period. Little to no shower activity
is expected until 22/15Z. Thereafter, SHRA will begin to develop affecting
mostly TJMZ between 22/18Z and 22/21Z. Easterly winds expected to increase
to about 15 kts with sea breeze variations developing after
22/14Z.

&&

.MARINE...A northerly swell and and moderate to locally fresh trades
winds will affect the local waters today but will continue to slowly
subside and diminish today through Tuesday. Due to the rough and
choppy seas, small craft advisories will remain in effect today for
the Atlantic, local passages and offshore Caribbean waters. Easterly
winds will prevail between 15 to 20 knots. For beach goers, the
high surf advisory has been cancelled as the breaking waves are
now expected to be less than 10 feet. However, high risk of rip
currents will continue for the northwest to north facing beaches
of Puerto Rico, Culebrita beach and also for Saint Thomas.

&&

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