Caribbean - Central America Weather

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
516 AM AST Fri Dec 30 2016

.SYNOPSIS...Showers embedded in the trades are expected at times
across US Virgin Islands as well as eastern Puerto Rico followed
by shallow afternoon convection over northwest Puerto Rico.
Moisture advection still expected as a shearline north of the
forecast area induces a surface trough across the northeast
Caribbean. A fair weather pattern is expected Sunday and into
midweek next week.

&&

.DISCUSSION...Partly cloudy skies were observed across the local
islands during the overnight and early morning hours. Scattered
passing showers were observed over the local waters as well as
US Virgin Islands and eastern Puerto Rico. Overnight minimum
temperatures were generally from 70 to 75 degrees at lower
elevations. Winds were mainly light and variable.

A shearline north of the forecast area will induce a short-lived
surface trough across the local islands which will promote moisture
advection through early Saturday. Although moisture is expected
to increase at lower levels, the mid levels will remain fairly dry.
As the aforementioned shearline and its associated surface trough
dissipates, a broad surface high pressure will build across the
western Atlantic and into the local area. This feature will hold
through at least midweek next week, bringing breezy conditions as
well as patches of low level moisture at times. Ridge pattern aloft
is also expected to strengthen.

As a result, continue to expect passing showers across USVI and E
PR in the late evening and early morning hours. The frequency of
these showers may increase late this evening and Saturday evening
as moisture advects across the eastern Caribbean. Afternoon convection
across west PR is likely this afternoon and Saturday afternoon
due to weaker trades which will allow sea breeze convergence,
but still expect shallow activity due to the lack of upper level
forcing.

A generally fair and mainly stable weather pattern is expected
Sunday afternoon and into midweek next week with trade wind
showers at times.

&&

.AVIATION...Prevailing VFR conds expected through the next 24 hours
across the local terminals. Sct brief SHRA moving across the area
through 30/14Z will continue to cause VCSH across the terminals
except for TJMZ. SHRA development across NW-PR is expected to affect
areas in and around TJBQ and TJMZ between 30/17Z and 30/22Z which
could affect the actual terminals briefly. Winds to continue from
the east at about 10KT through 30/14Z, slightly increasing
thereafter with sea breeze variations developing.

&&

.MARINE...Marine conditions will continue to improve through Saturday.
However, hazardous seas will come back early next week as strong
high pressure builds over the Western Atlantic. A moderate risk of
rip currents continues across most of the local waters.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 77 84 77 / 20 10 30 50
STT 85 77 83 77 / 30 20 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
148 PM AST Fri Dec 30 2016

.SYNOPSIS...High pressure across the central Atlantic will
continue to move east as an area of low pressure and associated
cold front will move across the north central Atlantic tonight and
Saturday. This front will remain well north of the area. A strong
high pressure will build across the western Atlantic behind the
front. This will result in an increase in trade winds across the
region.

&&

.DISCUSSION...Very dry weather conditions prevailed across Puerto
Rico and the U.S. Virgin Islands today. Very light passing showers
were observed across the Caribbean coastal waters early this
afternoon. Later, some showers began to develop across the western
interior and northwest sections of Puerto Rico. A slot of drier
air has moved across the region limiting any significant shower
development across the region. Surface high pressure system will
continue to dominate the local region next several days.

Latest satelite images are showing a patch of low level moisture
east of the Lesser Antilles. This patch of low level moisture
will continue to move west and is expected to approach the local
region late Saturday into Sunday. Therefore, an increase in low
level moisture, with cloudiness and showers activity is expected
mainly across the eastern section of Puerto Rico by Saturday
night.

&&

.AVIATION...Isold SHRA and mtn obscurations ovr wrn PR til arnd
30/22z. MVFR conditions if any will be brief at TJMZ, otherwise VFR
conds are expected to continue except in Leeward islands...SHRA and
areas of MVFR CIGS btwn 31/14-18Z. Winds alf easterly up thru FL070
but strongest winds in lyr up to 20 kt blo FL025. Maximum wind west
75-85 kt at FL410.

&&

.MARINE...Seas will continue to diminish through tonight and
Saturday as pressure gradient continues to relax. Winds will
increase late Saturday into Sunday which will result in increasing
seas. Seas up to 6 feet and winds up to 15 knots are expected to
continue tonight.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 77 84 77 84 / 10 30 50 30
STT 77 83 77 83 / 20 30 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
527 AM AST Sat Dec 31 2016

.SYNOPSIS...Surface low to the north of the local islands will
cause a decrease in the local wind speed today, then a surface
high pressure will move north of the local islands, tightening the
pressure gradient and increasing the local wind speeds once again
by late today into Sunday. Cold front to the north of the local
islands will remain well to our north while patches of moisture
pass through the local islands for the next couple of days.

&&

.DISCUSSION...Fair weather was observed overnight across the local
area with generally light easterly winds. This fair weather is
expected to continue through the morning hours and maybe even into
the early afternoon hours. This is because there is a relatively
dry patch of air over the local area. having said that, there is a
patch of moisture moving in but this is not expected to reach the
local area until the mid afternoon hours or even slightly later,
so the shower development associated with the increase in moisture
and local effects might start in the mid to late afternoon hours.
Due to the expected wind speed and direction for this afternoon,
the central, western, and southwestern portions of PR have the
highest chance of showers this afternoon, while mainly fair
weather is expected elsewhere.

This general pattern of east to ENE winds and patches of moisture
moving in is expected for the next several days. However, as the
wind increases on Sunday and into the first few days of the
upcoming week, the shower development over land areas will be over
smaller areas and will affect any one area for shorter amounts of
time before it moves offshore. For that reason, the local forecast
is for isolated to scattered showers to affect the local waters,
USVI, and eastern and northern PR in the overnight hours, leaving
little rain accumulations, while the afternoon hours we could
expect brief scattered showers developing and affecting portions
of western PR but also leaving small accumulations. It pays to
know that today, since the wind speeds are lower, some showers
could persist and maybe cause very minor ponding of water in poor
drainage areas, but this is not expected over large areas and it
also depends on how quickly the patch of moisture makes it the
local area.

&&

.AVIATION...VFR conds expected at all PR and USVI TAF sites this
morning. As an area of showers and clouds moves across the Leeward
terminals this morning, MVFR conds will remain possible. This
feature is expected to reach PR and USVI later this afternoon and
into the evening hours, bringing an increase in passing SHRA.
Therefore MVFR conds and mountain obscurations possible. Easterly
winds 10 to 15 knots with higher gusts and sea breeze variations.


&&

.MARINE...Choppy seas will be up to 6 feet and winds will be
generally between 10 and 20 knots. Therefore small craft operators
should exercise caution. Also, a Small Craft Advisory will go into
effect on Sunday morning as seas will become hazardous due to
increasing waveheights of up to 8 feet and winds will increase to
around 20 knots. There is a moderate risk of rip currents across
many of the local beaches today, later tonight and on Sunday some
of the local beaches will have a high risk of rip currents.


&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
158 PM AST Sat Dec 31 2016

.SYNOPSIS...Cold front northwest of the local area will remain
nearly stationary next 24 hours while dissipating. Strong surface
high pressure will build across the western Atlantic next couple
of days, tightening the pressure gradient. Patches of low level
moisture in the trade winds will continue to affect the local
region from time to time.

&&

.DISCUSSION...Partly cloudy skies prevailed across the local area
today. Some light passing showers were seen across the local
waters. Early this afternoon, an area of cloudiness with showers
began to affect the local area. Scattered showers affected the
eastern half of Puerto Rico, Vieques, Culebra and the northern
U.S. Virgin Islands.

For the next several days, patches of low level moisture will
continue to affect the local region from time to time. The weather
pattern will continue without any significant changes as a strong
surface high pressure builds across the western Atlantic. This
strong high pressure will continue to produce fresh to strong
trade winds across the region. These winds will transport patches
of low level moisture across the area from time to time. However,
no significant rainfall accumulation is expected.

&&

.AVIATION...VFR conditions expected at least until 31/21Z for TJMZ
and TJBQ, while MVFR and mountain obscurations conditions are
expected for the rest of the terminals. This is due to an area of
cloudiness and showers now located across portions of eastern PR, US
Virgin Islands and the rest of the northern Leeward Islands. This
will result in VCSH/-SHRA conditions and SCT to BKN ceilings between
2000 to 3500 feet. VFR conditions will return to all terminals
starting at around 01/02Z at TNCM/TKPK eastern to 01/06Z at
TJMZ/TJBQ. Easterly winds 10 to 15 knots with higher gusts and sea
breeze variations expected overnight, increasing to 15-20 knots in
the morning.

&&

.MARINE...Seas will deteriorated later tonight into Sunday as
winds increases. Seas up to 6 feet increasing to 7 feet late
tonight into Sunday are expected across the local waters next
couple of days. A High risk of rip current statement was issued
this afternoon through at least Sunday afternoon.


&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
535 AM AST Sun Jan 1 2017

.SYNOPSIS...SFC high pressure moving across the western Atlantic
will tighten the local pressure gradient and cause an increase in
the local wind speeds. Patches of moisture will pass through the
local area causing brief showers to pass by. East to ENE winds at
10-20 MPH expected for the next several days. Surface low pressure
will move across the eastern coast of the USA, causing a slight
weakening in the local wind speeds starting on Wednesday as it
pushes the SFC high pressure further to the north and east.

&&

.DISCUSSION...Isolated to scattered showers were observed across
the Caribbean waters overnight and into the early morning hours,
leaving minimal amounts of rain across the USVI and eastern PR
under easterly winds. This pattern of brief showers across the
waters, USVI, and eastern PR is expected for the rest of today.
This is also the pattern that is expected for the next few days
during the overnight and early morning hours. In addition, the
patches of moisture may help the development of showers in the
afternoon across the western sections of PR, particularly over the
areas where there is sea breeze convergence. There is no real
upper level dynamical support for these showers to develop into
something significant enough to cause hazardous flooding.

Late this week, the available moisture will become more constant
and even as opposed to patches of moisture, however the overall
forecast is expected to remain similar, brief showers in the
windward side of PR and the USVI in the nighttime hours and
showers developing in areas of sea breeze convergence in the
afternoon.


&&

.AVIATION...VFR conditions expected to prevail during the
forecast period. By 01/18z...clouds and -SHRA/SHRA is expected to
affect PR/USVI. This will result in VCSH, -SHRA and SCT-BKN CIGS
btwn FL025-FL050. Easterly winds at 5-10 kt increasing 10-20kt
with higher gusts/sea breeze aft 01/13z.


&&

.MARINE...Small craft advisory will go into effect today for most
of the local waters due to an expected increase in winds and seas
starting this morning. Latest model guidance suggests that seas
could increase up to 8 feet across the offshore Atlantic waters
while the rest of the offshore waters and local passages could
observe seas up to 7 feet starting today or tonight and continuing
for the next few days. There is also a high risk of rip currents
across the northern beaches of Puerto Rico and Culebra today.
High risk of rip currents will spread tonight across some beaches
in northern Saint Thomas.


&&

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

[WeatherGuesser]

It's been said that very long threads with high post counts can cause loading problems and other issues on databases.

Given the date today, this might be a good time to consider starting fresh with a new thread.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
130 PM AST Sun Jan 1 2017

.SYNOPSIS...Strong high pressure system will continue to dominate
the local region through Tuesday. A cold front is expected to
exit the east coast of U.S. by mid week, eroding the high
pressure. Patches of low level moisture will continue to affect
the local islands from time to time.

&&

.DISCUSSION...Partly sunny conditions prevailed across the local
area this morning and early this afternoon. Only some isolated
showers were noted mainly across the Caribbean waters. Local area
continues under the influence of a high pressure system which
maintains fresh to strong trade winds across the region. These
winds will continue to transport patches of low level moisture
across the region from time to time. A drier airmass is expected
to encompass the region Monday and Tuesday which will limit the
chances for showers across the region.

For mid week, the aformentioned high pressure is expected to
weaken as a cold front exits the eastern U.S. By next
weekend, behind this front, another high pressure system is
expected to build across the region. As a result, winds are
forecast to increase once again by that time.

&&

.AVIATION...VFR conditions to prevail across all TAF sites.
Winds will continue generally from the east at 10-15 knots
increasing to 15-20 knots after 02/12Z with sea breeze
variations...especially across TJMZ and TJBQ after 02/12Z. SCT/BKN
skies will become FEW/SCT late afternoon into overnight hours
between FL020-FL060...as a patch of cloudiness moves away from
the area.

&&

.MARINE...Bouy 41043 around 180 miles northeast of Saint Thomas is
showing seas up to 8.5 feet with a period of 9 seconds. Marine
conditions will continue to deteriorate across most coastal waters
during the next 24 hours. Small Craft advisories in effect for
most waters. Marine conditions are expected to improve by mid week
as winds weakens.


&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
515 AM AST Mon Jan 2 2017

.SYNOPSIS...Strong surface high pressure over the Western Atlantic
will maintain breezy conditions across the local islands. Mid to
upper level ridge will hold through Tuesday. This will favor a trade
wind pattern across the region over the next few days. Then...an upper
level trough will swing across the region by midweek...bringing
mid-upper level clouds and cooler temperature aloft. However...
deep convection is not anticipated across the local area as dry
and relatively stable air prevails through the end of the week.

&&

.DISCUSSION...High pressure north of the area is favoring a brisk
easterly flow across the Northeast Caribbean region. As a result...a
mixture of sunshine and clouds will prevail over the next few days.
Showers embedded in the trade wind flow will likely affect the
windward side of the islands at times. Stable conditions aloft and
the breezy conditions will keep the rainfall accumulations relatively
light.

Midweek through the end of the week...Upper level trough will
cross the region on Wednesday. This feature aloft will have
little impact in the shower development...mainly because dry and
stable air will prevail at mid-levels. At the same time...high
pressure north of the area will move eastward over the Central
Atlantic. As a result...trade winds will relax across the local
islands. These moderate trade winds will allow land and sea
breeze to dominate the local weather pattern from Wednesday
through Sunday. Therefore...afternoon convection will be possible
over Western PR each afternoon.

&&

.AVIATION...Mainly VFR conditions expected across all terminals for
the next 24 hours. However, trade wind showers could create -RA/VCSH
at times across the Leeward/USVI and the northern PR terminals
through the forecast period. East-northeast winds blo FL100 at 15-25
kt, 25-30 kt gusts possible after 14z at TJSJ/TJBQ/TIST/TISX.

&&

.MARINE...Hazardous marine conditions will continue across the
regional waters. Fresh winds will lead to choppy seas of 5-7 feet
through at least Tuesday. Conditions will gradually improve by
midweek as winds and seas will subside across most of the regional
waters. Meanwhile...Small Craft Advisories and a High Risk of rip
currents continue in effect until at least Tuesday Morning.

&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
149 PM AST Mon Jan 2 2017

.SYNOPSIS...High pressure across the western Atlantic will
continue to dominates the local region through mid week. Patches
of low level moisture will affect the local region from time to
time.

&&

.DISCUSSION...Variably cloudy skies prevailed across Puerto Rico
and the U.S. Virgin Islands today. Very little shower activity
was observed across the local area during the morning hours. A
line of very light showers was seen across the eastern half of
Puerto Rico early this afternoon. Rainfall accumulation were
minimal. High pressure system continues dominating the local
region. Pleasant weather conditions are expected to continue next
couple of days as this high pressure holds. For mid week, high
pressure weakens as a cold front moves across the western
Atlantic. However, the front will remain well northwest of the
area without affecting the local region. Patches of low level
moisture embedded in the trade winds will continue to affect the
local islands from time to time next several days.

&&

.AVIATION...Mostly VFR conditions expected across all terminals.
Trade showers could create -RA/VCSH until 02/23Z across the forecast
area. E to ENE winds at 10-15 kt overnight increasing 15-20 kt in
the morning with 25-30 kt gusts possible after 14z at
TJSJ/TJBQ/TIST/TISX. Trade wind showers expected once again after
03/12z at TJSJ/TJPS/TISX/TNCM/TKPK that could result in
occasionally MVFR to IFR conds with the strongest showers.

&&

.MARINE...Seas up to 7 feet and winds up to 20 knots are expected
to continue through Tuesday afternoon. Small Craft advisories
continues in effect for most coastal waters. A gradual
improvement in marine conditions are expected mid week.


&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
453 AM AST Tue Jan 3 2017

.SYNOPSIS...Winds will weaken somewhat and become more
southeasterly allowing temperatures to warm slightly Wednesday
through Saturday. Otherwise mostly scattered fast moving showers
will continue on and off-through the week. A cold front will
approach early next week.

At upper levels...After a weak ridge passes through today a trough
will move through Wednesday morning. Stronger ridging will
commence thursday and persist until at least early next week.

At mid levels...After a weak trough draws close on Wednesday high
pressure will generally dominate the area until early next week.
The GFS is forecasting a trough passage early Thursday next week.
The best moisture will occur over the weekend and on the approach
of the aforementioned trough Tuesday and Wednesday of next week.

At lower levels...High pressure in the central Atlantic will drift
eastward but leave higher pressure north of the area until early
next week. A frontal boundary will approach the area mid week
next week and much higher pressure will invade the western
Atlantic.

&&

.DISCUSSION...Spotty showers of light to moderate rain dotted the
local waters upstream and along side of Puerto Rico. The showers
were moving at about 25 knots toward the west southwest and
entering eastern Puerto Rico before dissipating. Bands of moisture
will continue over and just north of the area, but the amount of
showers should decrease somewhat during the remainder of the week
as streaks of drier air pass by--especially Wednesday and
Thursday.

Models suggest a warming trend beginning Wednesday morning and
continuing through Friday or Saturday. Winds at 850 and 700 mb
will contain a southerly component during that period so the
warmth will be noticed more by those on the northern side of
Puerto Rico.

The approach of a strong trough and a cold front during the
upcoming week could bring a round of wet and cooler weather. But
more time is needed for models to sort out whether the front can
actually pass through the area. Certainly a large amount of very
cold air will be moving into the western Atlantic early next
week...but it will also stay well north of the area.

&&

.AVIATION...Mostly VFR conditions expected across all terminals
through the forecast period. Brief -RA/VCSH possible at times due to
trade wind showers across the flying area. Surface winds ENE at 10-
15 kts with higher gusts after 03/14z.

&&

.MARINE...Winds and seas will diminish today through Thursday. A
long period swell is expected over the weekend. Breaking waves on
the Atlantic coasts may approach 10 feet then.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 85 74 85 72 / 20 40 20 20
STT 85 73 83 74 / 20 50 20 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
200 PM AST Tue Jan 3 2017

.SYNOPSIS...High pressure northeast of the area will weaken as a
cold front moves east across the western Atlantic. This cold front
will remain well north of the area while dissipating. High
pressure will build across the central Atlantic by the weekend,
tightening once again the pressure gradient. Patches of low level
moisture will continue to move across the local region from time
to time.

&&

.DISCUSSION...A slot of drier air has moved across the region
today. Limited shower activity was observed across the local area
today. Although 03/12Z TJSJ sounding came with precipitable water
values of 1.47 inches, farther east in Saint Maarten, precipitable
water were as low as 1.01 inches. This dry weather pattern will
continue next several days as high pressure system continues dominating
the local area.

A cold front is expected to exit the U.S east coast by Thursday
and will remain nearly stationary across the Bahamas while
dissipating. In the long term, models are not consistent on
bringing a cold front close to the area by mid next week.
Therefore, expected passing showers across the local area from
time to time which is the normal weather pattern for the local
area for the month of January.

&&

.AVIATION...Mostly VFR conditions expected across all terminals
through the forecast period. Brief periods of VCSH/-SHRA due to
trade wind showers will result in occasionally MVFR conditions
across the flying area...especially over TJSJ/TIST/TISX. Surface
winds E to ENE at 10-15 kts with higher gusts until 03/23Z. Weak
land breeze variation between 04/03Z and 04/14Z across all terminals
of Puerto Rico. After 04/20Z, sea breeze variations at 5-10 knots
affecting mainly TJMZ and TJBQ.

&&

.MARINE...Latest buoy observations indicated seas have diminished
early this afternoon across most local waters. As a result, small
craft advisory was cancelled. Small Craft should exercise caution
across most local waters as seas up to 6 feet and winds up to 20
knots are expected.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 74 85 72 87 / 30 20 20 20
STT 73 83 74 84 / 40 20 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
541 AM AST Wed Jan 4 2017

.SYNOPSIS...Short wave trough will enter the forecast area from
the west today. Building upper ridge will follow through early
next week. Surface high pressure will persist northeast of the
area through the forecast period. A strong polar trough and
associated cold front are forecast to enter the Western Atlantic
and approach the forecast area by Tue-Thu next week.


&&

.DISCUSSION...Trade wind showers moved across the eastern portions
of Puerto Rico at times during the overnight hours. Around a
quarter of an inch was observed with the heaviest showers across
portions of the eastern interior. Little to no rain was observed
across the U.S. Virgin Islands. Although a short wave trough will
move from the west across the forecast area today...a drier air
mass is also forecast to enter from the east and suppress the
available moisture...with forecast soundings indicating very low
PWAT content and continuing through at least early Friday due to
building upper ridge.

Overall fair weather pattern is forecast to persist each
day...with shower activity confined to ESE trades and shallow
afternoon convection over W/NW PR. Models continue to suggest
moisture pooling across the area later next week as ridge
collapses due to a strong polar trough and associated surface
front moving across the Western Atlantic into the local area.

&&

.AVIATION...VFR conds expected at all the terminals through the
forecast period. Few SHRA moving westward between USVI and PR early
this morning. Then...minimal SHRA activity expected after mid-
morning. Mid-upper level clouds above FL250 will continue to reach
the flying area fm the west. East winds of 15 kt will continue thru
04/15Z... veering to the SE at 10-15 kt during the afternoon.


&&

.MARINE...East to southeast winds are expected today as cold front
lingers across the Western Atlantic and surface high pressure
north of the area continues to move into the Central Atlantic.
Seas will continue to subside for the rest of the work week. A
long period northeasterly swell is forecast to increase seas once
again on Saturday, resulting in hazardous marine conditions and
strong rip currents across the east and north facing beaches of
the islands.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 73 87 74 / 10 10 20 0
STT 83 74 84 75 / 10 10 20 10

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
200 PM AST Wed Jan 4 2017

.SYNOPSIS...Shortwave trough in the upper levels will pass through
the local area today and tonight but the impact appears to be
limited due to a patch of dry air that is over the area today.
Surface high pressure will keep the moderate East to ESE wind flow
for the next few days. Expected pattern for the next few days
continue to be of isolated to scattered brief showers in the
overnight and morning hours with limited shower activity during
the daytime hours depending on the overall moisture as it combines
with the local daytime effects.

&&

.DISCUSSION...Satellite imagery shows very little cloudiness over
the local islands as a patch of relatively dry air moves through.
Fair weather is expected for the rest of today with a slight
chance of brief showers across the NW corner of PR later in the
afternoon. The shortwave trough in the upper levels that is
currently over the local islands is not having much of an impact
in the local weather pattern other than some clouds and perhaps
some rain over the local waters. This upper trough is expected to
be to the east of the USVI by Thursday morning.

Overall fair weather pattern is expected to continue for the next
several days with possible brief showers mainly across the USVI,
as well as eastern and northern PR in the overnight and early
morning hours as patches of moisture continue to pass by. However,
by the middle of next week, a more persistent amount of moisture
is expected across the local islands ahead of a surface high
pressure moving east and north of the local area, at the same
time that a polar trough in the upper levels approaches the local
area. This setup could produce some rain over the local islands if
it were to materialize.


&&

.AVIATION...VFR conds should continue over all the terminals through
05/18z. Isold light showers could develop over the waters through
this period, but will not mention in TAFs as not significant impact
is expected.East-Southeast winds at 10-12 kts through 04/22z
becoming light overnight.


&&

.MARINE...East to ESE winds are expected for the rest of today and
tonight as the surface high pressure north of the area continues
affecting the local wind flow. Seas are expected to continue
subsiding slowly for the rest of the work week. A long period
northeasterly swell is forecast to invade the local waters and
increase seas once again on Saturday, resulting in hazardous
marine conditions and strong rip currents across the east and
north facing beaches of the islands.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 73 87 74 86 / 10 20 0 30
STT 74 84 75 85 / 10 20 10 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
539 AM AST Thu Jan 5 2017

.SYNOPSIS...Ridge aloft will persist through early next week.
Surface high pressure across the Central Atlantic will continue to
promote moderate E-ESE winds through the weekend. A strong polar
trough and associated frontal boundary are forecast to approach
the area by early next week. An increase in moisture and winds
from the NE is expected then.

&&

.DISCUSSION...Short wave trough enhanced the trade wind shower
activity across the Offshore Caribbean waters as it continued to
exit the forecast area during the overnight hours. Isolated
thunderstorms were also noted with this activity. A few showers
made it across the U.S. Virgin Islands and isolated area of
eastern and the southern coast of PR. Between 0.25-0.45 in. were
observed across St. Croix. However, rainfall was not significant
over land areas across PR.

Overall, a fair weather pattern is expected to continue through at
least Sunday. Under ridge pattern aloft...trade wind showers will
continue to bring brief periods of rainfall across the islands and
limited shallow afternoon convection over the interior/northwest
sections of PR. By early next week, a strong polar trough aloft and
associated frontal boundary are forecast to reach the local area.
This will result in breezy conditions under a strong NE wind flow
and increase shower coverage across the islands.

&&

.AVIATION...VFR conds expected at all the terminals through the
forecast period. A few SHRA will move across the flying area but no
operational issues are anticipated today. SE at 10-15 kt will
prevail below FL150.

&&

.MARINE...Seas should continue between 3 to 5 feet and E-ESE
winds at 10-15 knots and locally higher through Friday. A long
period northeasterly swell is forecast to increase seas once again
on Saturday, resulting in hazardous marine conditions and strong
rip currents across the east and north facing beaches of the
islands through the weekend.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 74 86 74 / 30 0 10 0
STT 84 74 84 75 / 30 10 10 10

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
203 PM AST Thu Jan 5 2017

.SYNOPSIS...Surface high pressure will continue to cause a
moderate E to ESE wind flow for the next several days. A polar
trough with an associated frontal boundary is expected to exit
the eastern coast of the US during the weekend and approach the
local islands by late Monday. Upper ridge will continue over the
local area for the next several days as well. Mainly fair weather
is expected through Saturday.

&&

.DISCUSSION...Fair weather has been observed today across the
local islands. A small patch of moisture moved in early in the
morning hours but the dry air behind it moved in quickly. Fair
weather is expected to continue for the rest of the day with only
a slight chance of showers across the NW corner of PR. This
pattern of mainly fair weather is expected also on Friday and
Saturday as only patches of limited moisture with no real upper
level support will only allow brief passing showers and also
limited shower activity developing across areas of sea breeze
convergence across the western sections of PR. A larger patch of
moisture moves in on Sunday which could cause more widely
scattered showers over the local waters. Thereafter, a polar
trough and associated frontal boundary will approach the local
area for early in the upcoming week, keeping the local islands
under more persistent moisture and a northeasterly wind flow. That
should cause cloudiness and persistent scattered showers across
the local area through next Friday. However the confidence is low
to moderate as the latest model guidance shifted significantly
compared to the long range forecast it was showing yesterday.


&&

.AVIATION...VFR conds expected at all the terminals through
06/18z. Isold SHRA could develop and move in the vicinity of the
terminals...however no significant impact expected. E to SE at 10-15
kt will prevail through 05/22z becoming light and variable overnight
before increasing again to 10-15 kt after 06/12z.


&&

.MARINE...Local seas are relatively calm as reported by the local
buoys. Generally seas of under 6 feet and under 20 knots can be
expected for the rest of the day and tonight. Occasional moments
of winds of up to 20 knots can be expected across the nearshore
Atlantic waters to the north of Puerto Rico during the daytime
over the next few days. Otherwise the marine conditions should
remain relatively calm until this Saturday when a northeasterly
swell invades the local waters and the marine conditions may
become hazardous until Monday.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 74 86 74 86 / 0 10 0 10
STT 74 84 75 84 / 10 10 10 10

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
536 AM AST Fri Jan 6 2017

.SYNOPSIS...Broad upper level ridge will continue to dominate the
local area through at least early next week. Surface high
pressure across the Central Atlantic will continue to promote
moderate trades through the weekend. Ridge is forecast to collapse
on Monday as a strong polar trough moves across the Western
Atlantic and close to the forecast area. Associated prefrontal
trough at the surface will increase the available moisture by
Mon-Tue. A strong northerly wind flow will persist through much
of next week as a strong surface high enters the Western
Atlantic.

&&

.DISCUSSION...Light trade wind showers were noted mainly across
the waters with a few reaching portions of the islands from time
to time. However, no significant rainfall was detected over land
areas. Under ridge aloft, mostly fair weather and limited trade
wind shower activity pattern is expected to continue through at
least Sunday. Moisture is forecast to pool across the area on
Monday as deep polar trof and associated frontal boundary moves
across the islands through Tuesday. A cool advective pattern is
expected under a brisk northeasterly wind flow as a strong surface
high pressure builds across the Western Atlantic and drier air
filters once again across the region through much of next week.

&&

.AVIATION...Mostly VFR conditions are expected across the local
flying area through the next 24 hours. However, brief light showers
embedded in the trades will move from the local waters mostly across
the Leewards, USVI and TJSJ taf sites from time to time. Low level
winds will be light and variable through 6/13z becoming east
southeast at 10 to 15 kts after 06/12z.

&&

.MARINE...Seas should continue between 3 to 5 feet and Easterly winds
should increase from 10-15 knots to 15-20 kts later today across
the regional waters and continue through at least early Sunday. A
long period northeasterly swell is forecast to create hazardous
seas during the weekend. Small craft advisories are in effect
starting on Saturday morning due to 7 ft seas. Strong rip
currents are expected across the east and north facing beaches of
the islands through the weekend.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 74 86 74 / 10 0 10 30
STT 85 74 84 75 / 20 10 20 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
134 PM AST Fri Jan 6 2017

.SYNOPSIS...
Mid to upper level high pressure ridge will prevail across the region
through most of the weekend. It is so far forecast to erode by late
Sunday and Monday as a polar trough enters and becomes amplified across
the west and southwest Atlantic. In the low levels, high pressure centered
across the north central Atlantic will continue to dominate the overall
weather pattern through most of the weekend. This will maintain a moderate
southeast to east trade wind flow. The surface ridge is to then weaken
by Sunday as the Atlantic high shifts farther northeast and an induced
frontal trough and area of low pressure sets up north of the region
while a cold front enters and moves across the west Atlantic. The
cold front or its frontal remnants is so far forecast to sink southward
near to or across the region by the middle of next week.

&&

.DISCUSSION...
Mostly fair weather conditions with mostly sunny to partly cloudy skies
prevailed across the region so far. Few passing clouds and trade wind
showers were observed and detected across the local waters, as well
as inland over portions of eastern Puerto Rico and the U.S. Virgin
Islands. So far no significant rainfall accumulations were observed
or reported.

Moderate easterly winds will prevail and continue to transport
occasional patches of shallow trade wind moisture and passing
showers across the coastal waters and parts of the islands during
the rest of today and over the upcoming weekend. These showers
should be mainly during the late evening and early morning hours.
This will be followed by mostly fair weather skies across much of
the islands during the late morning and afternoon hours each day.

This weather pattern however changes to increasing instability aloft
and low level moisture convergence by late Tuesday and Wednesday of
next week based on the most recent model guidance. The aforementioned
cold front and area of low pressure and associated polar trough aloft
is forecast to approach and/or move across and become amplified across
the region. During the latter parts of next week somewhat cooler, stable
conditions are expected once again following the approach of the frontal
boundary. Regardless, the moderate to fairly strong northeast trades
should continue to bring periods of passing showers mainly across parts
of the north and east sections of the islands each day.

&&

.AVIATION...Mostly VFR conditions are expected across the local
flying area through the next 24 hours. Brief trade wind showers may
move across TJSJ/TIST/TISX/TNCM/TKPK after 07/04Z, but operations
should not be affected. Low level winds will shift from east-southeast
to east after 07/12Z at 10-15 knots with occasionally wind gusts
up to 22 knots.

&&

.MARINE...Marines can expect seas up to 6 feet during the rest of
today, but increasing up to 7 feet overnight and on Saturday as a
northeast swell will arrive and spread across the atlantic waters
and local passages. East trade winds up to 20 knots are expected
across the regional waters during the weekend. Marine conditions
should improve by Monday, but is forecast to quickly deteriorate
once again by mid of next week as a cold front and a northerly swell
approaches the Atlantic waters.

&&

.FIRE WEATHER...Upper high pressure ridge will continue to dominate
the forecast area through Saturday allowing for continued drying
of fuels and lowering of RH values to the mid to high 40s along
portions of the south coastal plains. However light to moderate
easterly trade winds of 10-15 mph will prevail with some higher
gusts and local sea breeze variations. Satellite imagery and recent
reports suggests vegetation still fairly green across these areas and
therefore risk of fire danger will remain low for the next several
days.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 74 86 74 84 / 0 10 30 30
STT 74 84 75 83 / 10 20 30 30

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
427 AM AST Sat Jan 7 2017

.SYNOPSIS...Mid to upper level high pressure ridge will linger across
the region through most of the weekend. It is however forecast to
erode by late Sunday and Monday as a broad polar trough enters and
becomes amplified across the west and southwest Atlantic. In the
low levels, high pressure centered across the north central Atlantic
will dominate the overall weather pattern through the weekend to
maintain moderate southeast to east trade winds. The surface ridge
is to then weaken on Sunday as the Atlantic high shifts farther
northeast and an induced frontal trough and area of low pressure
develops along a cold front which will enter and move eastward across
the west Atlantic. The cold front and associated frontal remnants is
still forecast to sink southward near to or across the region by the
middle of next week as the area of low pressure develops northeast
of the region.

&&

.DISCUSSION...Moderate easterly winds will continue to transport
occasional patches of low level trade wind moisture and passing
showers across the coastal waters and parts of the islands during
the rest of the overnight and early morning hours. These showers
will be of light to moderate intensity and fast moving and should
gradually diminish by late morning. This will be followed by
mostly sunny and fair weather skies across much of the islands
during the afternoon and early evening hours. Expect this pattern
to mixture of sunshine and clouds with occasional passing showers
to continue for the rest of the weekend.

Model guidance continued to suggest that this overall synoptic
pattern is to change by mid week with increasing instability aloft
and low level moisture convergence across the forecast area. The
aforementioned cold front and area of low pressure along with the
associated deep layered polar trough aloft is forecast to approach
and eventually move across the area while becoming amplified near
to or across the region. For now, during the latter parts of next
week somewhat cooler, and stable weather conditions are expected
following the frontal boundary which should sink south of the region
while dissipating. Regardless of this scenario, the increasing
moderate to fairly strong northeast trades will bring periods of
passing low level clouds and showers mainly across parts of the
north and east sections of the islands each day under the
prevailingand dominant northerly wind flow. Stay tuned as we
will continue to monitor and see how this pattern unfolds.

&&

.AVIATION...Mostly VFR conditions are expected across the local
flying area through the next 24 hours. Brief trade wind showers may
move across the Leewards, USVI and TJSJ TAF sites this morning, but
aviation operations should not be affected. Low level winds will
continue mostly from the east at 10-15 knots with occasionally wind
gusts up to 20 knots.

&&

.MARINE...A long period northeast swell has entered the local waters
and Seas will spread across the local waters and all passages. Small
craft advisories will remain in effect for the local Atlantic and
offshore Caribbean waters as well as local passages. Small craft
exercise caution elsewhere except for the near shore waters of west
PR.

Marine conditions will improve by Monday, but is forecast to quickly
deteriorate once again by the Tuesday and Wednesday, as a cold front
and an area of low pressure relocates and develops while lingering
just northeast of the region through the end of the week. This anticipated
pattern should generate large northerly swells across the regional waters
and local passages. Therefore, significantly high Seas and dangerous
surf conditions will remain likely across the forecast area beginning
early Tuesday and spread across most of our waters through at least
the end of next week.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 74 85 74 / 20 30 30 20
STT 84 74 84 72 / 20 30 30 30

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
141 PM AST Sat Jan 7 2017

.SYNOPSIS...Mid to upper level high pressure ridge will linger across
the region through most of the weekend. It is however forecast to
erode by late Sunday and Monday as a broad polar trough enters and
becomes amplified across the west and southwest Atlantic.


.DISCUSSION...An area of low level moisture moved westward
across the Anegada Passage this morning, generating isolated to
locally scattered showers across the eastern portions of Puerto
Rico including the adjacent islands. Although a dry pattern is
forecast to prevail through Sunday, expect isolated to scattered
showers moving over the eastern portions of Puerto Rico through
the overnight and morning hours.

High pressure centered across the north central Atlantic will
continue to dominate our local weather pattern through at least
Sunday. This feature is forecast to weaken late Sunday as cold
front and associated frontal remnants is forecast to sink
southward across the region by the middle of next week as the area
of low pressure develops northeast of the region.


&&

.AVIATION...Mostly VFR conditions are expected across all TAF
sited through the next 24 hours. Brief trade wind showers will
continue moving across the Leewards, USVI and TJSJ TAF sites until
at least 07/23Z. Afternoon convection and mountain obscuration over
TJMZ and TJBQ after 07/18Z. Shower activity across the region could
result in brief periods of MVFR conditions. Low level winds will
continue mostly from the east at 10-15 knots. Occasionally wind
gusts up to 25 knots are likely across TJSJ, TJBQ, TIST and TISX
until at least 07/23Z. Skies should clear up overnight, but
cloudiness and brief periods of shower activity may return once
again after 08/10Z over TNCM and TKPK, and after 08/12Z over TAF
sites in Puerto Rico and U.S. Virgin Islands.


&&

.MARINE...A Northeasterly swell began to affect the off shore
Atlantic waters this morning and they are expected to reach our
local northerly showers this afternoon. This swell will generate
dangerous rip current along the northern exposed beaches. This
swell event will peak this evening and then will slowly subside
through Sunday. A Major swell is forecast to reach our local
waters on Tuesday. The NWS in San Juan are paying close attention
to this swell event as it could generate dangerous marine
conditions, erosion and coastal flooding across the northern
exposed beaches.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 74 85 74 / 20 30 30 20
STT 84 74 84 72 / 20 30 30 30

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
527 AM AST Sun Jan 8 2017

.SYNOPSIS...Ridge aloft will continue to erode as polar trof
amplifies across the Southwestern Atlantic. TUTT is forecast to
develop northeast of the area by the end of the week. Cold front
will approach the area by Monday with associated prefrontaltrough
moving over the islands through mid week. Strong surface high
pressure will build across the Western Atlantic and a broad
induced area of low pressure is forecast to develop just northeast
of the Leeward Islands at the end of the forecast period.

&&

.DISCUSSION...Trade wind showers continued across the local waters
with a few moving from time to time over portions of the islands
during the overnight hours. However, no significant rainfall was
detected over land areas. As ridge aloft continues to erode slowly
today, trade wind showers will continue across the USVI and
eastern PR...and limited shower activity could develop once again
this afternon over western PR.

Moisture is forecast to pool across the area on Monday as deep
polar trof and associated frontal boundary moves across the
islands through Tuesday. A cool advective pattern is expected
under a brisk northeasterly wind flow as a strong surface high
pressure builds across the Western Atlantic and drier air filters
once again across the region through much of next week. However, a
broad area of low pressure is forecast to develop under a TUTT to
the northeast of the islands by the end of the week...promoting
more moisture advection into the region through the weekend.

&&

.AVIATION...Mostly VFR conditions are expected across the local
flying area during the morning hours. However, brief trade wind SHRA
will continue to cause vicinity SHRA across the Leeward, USVI and
TJSJ taf sites thru 08/16Z. After 08/18Z SHRA will develop across
western PR with isolated MVFR CIGS/VSBYS and mountain obscurations
affecting TJBQ and possibly TJMZ. Surface winds will remain mostly
from the east at 10 to 15 kts.

&&

.MARINE...Northeasterly swell continues to fade. Small crafts
should exercise caution across much of the waters due to seas up
to 6 feet. A large and long dominant northwest swell is forecast
to enter the Atlantic waters and passages early on Tuesday
morning. High surf advisory and high rip current risk is likely
with this swell event as breaking waves over 10 feet are expected
along the Atlantic coastline of the islands.

&&

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