Caribbean - Central America Weather

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
602 AM AST Wed Jan 18 2017

.SYNOPSIS...
A trough aloft will continue its move across the region. A surface
low pressure exiting the eastern U.S. will continue to weaken a
surface high pressure across the southwestern Atlantic. This
pressure systems will induce a moderate east northeast wind flow
across the local islands and surrounding waters, which in turn
will push patches of low level moisture with embedded clouds and
showers across the U.S. Virgin Islands and the northern and
eastern sections of Puerto Rico at times.

&&

.DISCUSSION...
As a surge of moisture moved over the region overnight. This
surge produced scattered showers, but due to their rapid movement
the rainfall totals were minimals. Then, satellite imagery
indicated the intrusion of dry air across the region, producing a
diminish in shower activity across the islands of Puerto Rico and
the U.S. Virgin Islands early this morning. For the rest of this
morning and under the prevailing northeasterly wind, isolated
passing showers can not be ruled out across the windward sections
of PR and the USVI.

A surface low pressure is forecast to move across the western
Atlantic by Thursday. The pressure gradient is forecast to relax
as this low system move eastward across the Atlantic waters.
Also, as mentioned in the previous discussion, winds speed are
expected to diminish considerable becoming more from the east late
in the week and during the upcoming weekend. As this happens, a
frontal boundary is expected to move close to the local islands.
The proximity of this frontal boundary combined with a dry cool
air mass could result in cooler pleasant temperatures by the end
of the week and into the weekend.

&&

.AVIATION...
Mainly VFR conditions are expected to prevail across all
TAF sites through at least 18/22z. Some passing showers are expected
to affect TIST, TISX, TJSJ and TJBQ terminals from time to time. Low
level winds will be mainly northeast at 10 to 15 kts with higher
gusts.

&&

.MARINE...
Marine conditions are expected to slowly improve across the
region today. Mariners can expect seas up to 6 feet and winds
around 18 knots mainly across the Atlantic waters and the
Caribbean Passages. High risk of rip currents are in effect until
this afternoon.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 80 69 82 71 / 40 0 20 10
STT 80 72 79 71 / 40 20 20 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
125 PM AST Wed Jan 18 2017

.SYNOPSIS...Fair weather with isolated showers will prevail for
the next several weeks. Southerly flow beginning on Monday will
mark a warming trend for several days.

At upper levels...Weak short-wave troughs will pass Friday and
Saturday through the prevailing northwest flow downstream from
the ridge over the western Caribbean. That ridge will drift slowly
east and pass through the area to the Leeward Islands on Monday.
Another weak trough is expected Wednesday of next week.

At mid levels...High pressure over and west of the western
Caribbean will gradually replace the trough extending from the
northeast over the eastern Caribbean Sunday through Tuesday of
next week. High pressure will then strengthen over the western
Atlantic and Caribbean. Moisture will be lacking during the entire
period at mid levels.

At lower levels...High pressure extends across the sub-tropical
Atlantic from Florida to the Central Atlantic while lower pressure
persists across the southwest Caribbean. A low north of Puerto Rico
will deepen rapidly tonight and tomorrow as it moves northeast,
weakening the high to our north and gradients in general in the
local area. That weakened high pressure will then migrate eastward
across the Atlantic over the weekend. Strong low pressure will
exit Virginia and North Carolina into the Western Atlantic Monday
night bringing southerly flow Monday and Tuesday to Puerto Rico
and the U.S. Virgin Islands. After the low passes far to the
north, high pressure will begin building over the Bahama Islands
causing the flow to shift to the northeast again by Wednesday
next week.

&&

.DISCUSSION...Drier air in the mid levels is slowly filtering
down to clear the skies and shoo away the showers that have been
so persistent during the last week or so. Low pressures are
strong over the United States and, as they develop, across the
Atlantic, well north of the area, but models are currently
keeping most of the moisture associated with fronts that dissipate
over the area to the north, or, in the case of the southerly flow
mentioned above on Monday and Tuesday, just east of Culebra and
Vieques, possibly affecting the U.S. Virgin Islands. Gradients
that have been so strong will weaken considerably as the strong
low moves northeast tonight through Saturday allowing winds to
diminish. Such strong winds do not return this week or next even
though modest high pressure rebuilds over the sub-tropical
Atlantic.


&&

.AVIATION...Mainly VFR conditions are expected to continue across
all terminals through the forecast period. Limited shower activity
is forecast across the local waters. Low level winds will continue
from the ENE at 10-15 kts with lighter land breezes after 19/00z.
Maximum winds will continue from FL310-460 50-60 kt becoming more
NW overnight.

&&

.MARINE...Seas are slowly subsiding and the high risk of rip
currents will end tonight. Although northerly swell enters the
area on Saturday and Sunday it should be no more than 3 to 4 feet.
Small craft advisories are not expected this week or next week in
the San Juan marine forecast area.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 73 84 73 84 / 10 10 10 20
STT 72 84 72 84 / 10 10 20 20

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
600 AM AST Thu Jan 19 2017

.SYNOPSIS...
A mid to upper level ridge is building over the region. At the
surface, a low pressure centered over the Central Atlantic
continues to weaken a surface high pressure across the
southwestern Atlantic. As a result, winds are expected to continue
calm to light and variable. Mostly clear skies with pleasant and
cool temperatures were registered across the islands overnight.

&&

.DISCUSSION...
Satellite imagery detected a dry air mass filtering across the
region overnight, this air mass limited cloudiness and shower
activity across the islands of Puerto Rico and the U.S. Virgin
Islands. Weather stations across the islands registered coastal
minimum temperatures between low and mid 60s and across the
mountains and valleys in the low 50s.

In general, fair weather conditions with mostly sunny skies and
no shower activity is expected today. As the surface low pressure
moves across the western Atlantic the pressure gradient is
forecast to relax. Winds are expected to diminish considerable
becoming calm to light and variable through the upcoming weekend.
By the weekend, a frontal boundary is expected to move close to
the local islands. As a result, pleasant minimum temperatures are
expected to continue during this period.

&&

.AVIATION...
Mainly VFR conditions are expected to continue across all
terminals through the forecast period. Limited shower activity is
forecast across the local waters. Low level winds will continue
from the ENE at 10-15 kts with lighter land breezes after 19/00z.

&&

.MARINE...
Marine conditions will continue to improve the rest of the week.
Mariners can expect seas between 2 and 5 feet across the coastal
waters and winds around 10 knots. For the beach goers, there is a
moderate risk of rip current across the local beaches.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 81 69 83 71 / 10 10 20 40
STT 80 70 79 71 / 10 20 20 20

[cycloneye]

 https://twitter.com/NWSSanJuan/status/822020848127242240

[cycloneye]

[Tweet]
Area Forecast Discussion
National Weather Service San Juan PR
156 PM AST Thu Jan 19 2017

.SYNOPSIS...A gradual warming and moistening of the air mass will
occur beginning Friday. A weak pre-frontal boundary will pass
through on Saturday with a front approaching, and perhaps
entering, the forecast area on Sunday. Southerly flow will begin
Sunday with good moisture advection, followed by a stronger front
from the northwest on Wednesday/Wednesday night of next week.

At upper levels...A weak short-wave trough will pass through on
Friday afternoon with a secondary trough coming through early
Saturday morning. By Monday a ridge will be over the local area. A
weak trough will pass through on Tuesday followed by another weak
trough on Thursday.

At mid levels...Northwesterly flow will prevail until high
pressure now over the western Caribbean spreads across the entire
basin by Monday. Weak troughing will pass north of the area on
Tuesday. Mid-levels are almost completely dry except for a brief
shot of moisture on Tuesday.

At lower levels...Gradients will continue to be weak across the
area as high pressure over the Bahama Islands drifts into the west
central Atlantic. Strong low pressure over the southeastern United
States and the weak high over the west central Atlantic will
commence winds with a southerly component later on Sunday until a
likely frontal passage Wednesday. Trade wind flow will increase
Wednesday and Thursday.

&&

.DISCUSSION...No showers and only a few clouds were seen in the
area today. A few clouds were beginning to form over the higher
terrain of the Cordillera Central. The visible satellite image
showed a prefrontal band sweeping down from 28 north 60 west to 21
north 70 west with a cold front north of Puerto Rico around 26
degrees north. Currently models are expecting these bands to
remain intact for Saturday and Sunday passages respectively,
although the old boundary will linger over the area Sunday through
Tuesday. The increase in moisture expected Tuesday will be mainly
associated with moisture advected from the south with the
southerly flow ahead of the next front. The GFS has this moisture
about 55 miles farther west than it did 24 hours ago and over
eastern Puerto Rico as well as the USVI. Although rain chances
will increase--mainly on the north side of the Island and in the
northern U.S. Virgin Islands both Saturday and Tuesday, these
systems are not expected to bring more than slight accumulations
of rain. Another front from a stronger low pressure system will
pass through on Wednesday/Wednesday night, but it loses strength
quickly as it approaches. Mid-levels will have already dried so
that moisture associated with this front will be very limited.

&&

.AVIATION...Mainly VFR conditions are expected to continue across
all terminals during the next 24 hours. SKC overnight across all PR
terminals. Sea breezes should continue through at least 22z. Light
and variable winds at the surface overnight...increasing from the
north around 5-10 kts after 20/14z.


&&

.MARINE...Tranquil conditions exist with no advisories or
precautions. A northerly swell will enter the area Friday night
and increase seas up to 6 feet every 10 to 11 seconds by early
Saturday morning. Seas do not increase again after that until
Sunday afternoon. Then seas will rise to 6 or nearly 7 feet by
Monday night in north northeast swell of 12 to 14 seconds.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 69 82 72 82 / 0 10 40 40
STT 74 82 74 82 / 10 10 20 30
[/Tweet]

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
445 AM AST Fri Jan 20 2017

.SYNOPSIS...
Mid to upper level trough will shift further east of the region
today through Saturday as an upper level high pressure ridge is
expected to build over the western Atlantic then spread across
the region by Sunday and Monday. In the meantime weak a mid level
perturbation is to move just north of the region today and Saturday.

Surface high pressure over the western Atlantic and an area of
Low pressure across the north central Atlantic will create a very
light north to northeast trade wind flow across the region today
through Saturday. The remnants of a cold front is forecast to slowly
sink southwards across the local Atlantic waters Saturday through
Sunday. A high pressure ridge will then spread across the west and
southwest Atlantic. Local winds are to then become more southerly
by Sunday and Monday as this high pressure ridge will sink farther
south across the northeastern caribbean.

&&

.DISCUSSION...Mostly clear skies and little or no shower activity
was observed of reported over land area. light to moderate showers
were noted across the offshore waters and just northwest of PR.
these showers were slowly rifting southwards across the coastal
waters. Winds were light and variable to calm in most areas. Early
morning low temperatures were in mid 60s to near 70 degrees along
coastal areas and between 55-60 degrees in higher elevations and
valleys.

Mostly fair skies and pleasant seasonal weather conditions can be
expected today across most of the region. A few light showers may
form across parts of the islands but activity if any will be of
short duration.

For the weekend and into early next week, patches of low level
moisture along a weakening cold front/frontal boundary move across
the region and aid in the development of some showers across the
northern half and parts of the interior sections of Puerto rico
especially during the early morning and afternoon hours. Lesser
shower activity is expected across the remainder of the islands.
No significant rainfall or accumulations is expected through the
weekend. The low level easterly winds are to become more southerly
by late Sunday and into early next week resulting in slightly
warmer temperatures to the region.

&&

.AVIATION...VFR conditions will continue across the local terminals
during the next 24 hours as fair weather is expected to prevail.
Calm to Light and VRB winds expected through 20/13Z...becoming light
and northerly thereafter with sea breeze variations. No significant
weather hazard expected.

&&

.MARINE...Marine conds will continue to improve today and into the
upcoming weekend as Seas will slowly subside to between 1-4 feet
nearshore and 3-5 feet offshore and local passages. A gentle
north to northeast wind flow will prevail today, becoming more
southerly by late Sunday and continuing into early next week.
There are hazardous impacts for the coastal waters today.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 81 72 82 71 / 0 30 30 40
STT 80 70 82 70 / 0 30 30 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
153 PM AST Fri Jan 20 2017

.SYNOPSIS...With mid levels remaining dry except for Tuesday only
a few shallow showers will be able to develop tonight through
Monday. On Tuesday moisture from the south will interact with an
approaching front to the northwest to yield light rain amounts.
Weather will turn drier and cooler for the rest of next week.

At upper levels...Northwest flow will prevail as a weak ridge
moves toward the area tonight through Monday. Troughing develops
in the western Caribbean and approaches, but does not actually
cross through until Friday.

At mid levels...High pressure over the western Caribbean will
spread across the entire Caribbean. When the trough passes through
the western Atlantic on Wednesday, the axis of this ridge will
shift to north of the area during the latter part of next week.
Mid levels remain quite dry except for a brief shot of moisture on
Tuesday.

At lower levels...Weak high pressure over and east of the Bahamas
will continue to drift east across the ocean immediately to our
north over the weekend and low pressure will deepen over the
western Atlantic. As this happens low level winds will shift
southeast and then south by early next week bringing a brief
episode of moisture over most of the forecast area. As high
pressure returns to the Bahama Islands by mid-week, dry air will
also end most of the shower activity for the remainder of the
week.

&&

.DISCUSSION...A weak boundary settled south over the local
Atlantic waters but did not cross into the inner waters north of
Puerto Rico or the U.S. Virgin Islands today. This boundary will
continue to produce scattered showers and may shift onshore or
even south into the Caribbean later tonight or Saturday morning. A
second weak cold front will begin to affect the islands on
Saturday afternoon/evening. Mid level moisture remains weak until
after Monday so expect any showers that form before Tuesday to be
light and brief and mainly on the north side of Puerto Rico and in
the interior during the afternoons. Temperatures will slowly
begin to warm up under the tropical sun, but continued advection
of cool air from the north will slow this process until Monday
morning. Then with southerly flow temperatures will warm
considerably. Temperatures in some spots on the north coast of
Puerto Rico will reach the upper 80s with considerable sunshine on
Monday. Temperatures in other lower elevations including the U.S.
Virgin Islands should easily move into the mid 80s.

Moisture moves north into the forecast area Monday night and
Tuesday and this will be the day with the most rain and best
shower coverage of any of the next 10 days. A cold front over
Haiti on Tuesday morning will approach rapidly and become
indistinct against the moisture injected from the south, but that
plume of moisture will move east and out of the area by Wednesday
evening. After which mostly dry weather is expected through Friday
of next week. As 1000-850 mb thicknesses fall after Tuesday we
should see temperatures as cool or cooler on Friday morning than
we have the last several days.

&&

.AVIATION...VFR conditions will prevail during the next 24 hours
across all terminals. Surface winds will continue light and variable
with a northerly component. SHRA associated to a weak frontal
boundary over the Atlantic waters could create brief VCSH periods
across the northern terminals of PR/USVI during the evening hours.

&&

.MARINE...A northerly swell of no more than 4 feet is expected to
sweep through the local Atlantic waters Saturday and then seas
will begin to increase slowly Sunday night through Monday. Current
forecast show seas in our local waters remaining below 7 feet
through Friday of next week, but seas of 6 feet are expected
Monday and Tuesday.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 71 83 73 83 / 30 30 40 40
STT 70 83 70 83 / 30 30 40 40

[cycloneye]

Area Forecast Discussion...CORRECTED
National Weather Service San Juan PR
540 AM AST Sat Jan 21 2017

.SYNOPSIS...A seasonable weather pattern will continue to prevail
across Puerto Rico and the U.S. Virgin Islands through at least
early next week with a few light passing showers possible. A mid
to upper level ridge will build across the northeast Caribbean as
a short wave trough continues to move east southeast and away from
the forecast area today. The ridge aloft will hold through early
next week.

&&

.DISCUSSION...A mid to upper level ridge will continue to build
across the forecast area as a short wave trough moves east southeast
and away from the northeast Caribbean today. The ridge aloft will
hold through early next week, resulting in a seasonable weather
pattern today through Monday. At lower levels, a high pressure
north of the area will continue to promote a gentle north to
northeast wind flow. Surface winds are expected to become southerly
on Monday as the surface high pressure moves into the central
Atlantic and a frontal boundary approaches from the west. The
frontal boundary and associated mid to upper level trough will
erode the ridge pattern to result in moisture advection from the
east southeast. This will increase the chance of rainfall late
Monday-early Wed.

A drier weather pattern will prevail Thu and into the upcoming
weekend as a mid level ridge builds across the area and a
surface high establishes across the west and central Atlantic.

&&

.AVIATION...VFR conditions will continue across the local
terminals during the next 24 hours as fair weather is expected
to prevail. Calm to Light and VRB winds expected through
21/13Z...becoming light and northerly thereafter with sea breeze
variations. No significant weather hazard expected.

&&

.MARINE...Seas are expected to build early next week but remaining
below the Small Craft Advisory criteria. There is a moderate risk
of rip currents along the Atlantic shoreline of Puerto Rico,
Culebra and St Thomas.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 82 73 82 74 / 30 30 30 20
STT 83 70 83 73 / 30 30 30 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
148 PM AST Sat Jan 21 2017

.SYNOPSIS...Weak boundary just north of the islands will continue
to move over the islands today. Surface high over the Bahamas
will continue to move north of the islands during the next few
days. As it enters the Central Atlantic, winds will shift from the
south as front moves from the west and another surface high builds
across the Western Atlantic by midweek next week. Short wave trof
will exit the local area as mid to upper ridge holds thru Tuesday,
when another trof swings aloft from the west.


&&

.DISCUSSION...Sunny to partly cloudy skies were observed today
across the islands. A weak boundary over the Atlantic waters
increased cloudiness and showers...but mainly over the Atlantic
coastal waters with some showers under a northerly steering wind
flow moved over sections of NW PR. Sea breeze convergence led to
light showers and partly cloudy skies across the Cordillera
Central and southern slopes of PR. For tonight, showers should
remain mainly across the coastal Atlantic waters of the islands but
with the northerly component of the wind some could reach portions
of the islands at times.

Remnants of the old frontal boundary could linger through Monday,
but overall dry and fair weather conditions are expected to
prevail. Winds are expected to shift from the southeast to south
through Tuesday as the surface high moves into the Central
Atlantic and a front and associated surface low moves across the
Western Atlantic approaching the forecast area. Some cloudiness
and the chances for showers should increase briefly by Tue-Wed.
However, a strong surface high and ridge aloft are expected to
build and spread across the Western Atlantic into the local area
by midweek next week. Returning a cool northerly wind flow and
drier conditions through the end of next week.

&&

.AVIATION...VFR is expected to continue over all TAF sites. VCSH may
occur at TJSJ after 21/22Z from SHRA offshore north of PR and TNCM,
but conditions should remain VFR. A few mountain obscurations may
occur in the central interior of Puerto Rico til aft 22/02Z. sfc
winds less than 10 kt with land/sea breeze variations. Winds aft
22/15Z becoming more easterly 6-12 kt. Maximum winds FL410-460 NW 50-
70 kt.

&&

.MARINE...Small pulses of northerly swell are expected to
continue across the Atlantic waters and passages for the next few
days. At the moment, NW swell should peak by Wednesday around 6
feet. Increasing rip currents and surf height along the northern
beaches of the islands. Across the southern waters of the islands,
seas should continue at 4 feet or less through the forecast
period.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 72 82 72 86 / 20 20 20 20
STT 71 83 72 83 / 20 20 20 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
530 AM AST Sun Jan 22 2017

.SYNOPSIS...A mid level ridge will prevail through much of the
forecast period, with a brief weakening expected on Tuesday as
a mid to upper level trough moves north of the area. The mid to
upper level trough and associated surface boundary will result in
moisture advection Tuesday-early Wednesday. Therefore, continue
to expect a seasonable weather pattern across Puerto Rico and the
U.S. Virgin Islands with an increase in passing showers on Tuesday.

&&

.DISCUSSION...As the mid level ridge holds across the forecast
area, a generally fair and mainly stable weather pattern will
continue to prevail with a few passing showers possible across
windward areas. The ridge will briefly erode as a broad mid to
upper level trough moves north of the area. The aforementioned
mid to upper level trough and associated surface boundary will
result in moisture advection Tuesday and possibly Wednesday.
However, the bulk of moisture is expected to remain over waters
and east of the forecast area. At lower levels, a high pressure
north of the area will continue to promote a gentle east northeast
wind flow today. Surface winds are expected to become southerly on
Monday as the surface high pressure moves into the central
Atlantic and the boundary approaches from the west. Therefore,
continue to expect a seasonable weather pattern across Puerto Rico
and the U.S. Virgin Islands with limited shower activity through
the forecast period. The chance of passing showers will slightly
increase on Tuesday. Temperatures may increase Monday and Tuesday
under the southerly wind flow.

&&

.AVIATION...VFR conds will prevail thru the forecast period.
SCT SHRA expected across central/western PR after 22/16Z which
could cause VCSH at TJBQ, TJPS, and TJMZ. SCT SHRA also expected
over the waters and near TISX after 22/16Z. Winds from the ENE at
5- 10 KT with sea breeze variations today.

&&

.MARINE...Seas will remain to 3-5 feet today. However...a northwest
swell will reach the local waters...with seas building to 4-6
feet by midweek. There is a high risk of rip currents along the
Atlantic shorelines of Puerto Rico. The high risk of rip currents
will continue to prevail during the next few days.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 83 73 85 74 / 20 20 30 20
STT 83 72 84 75 / 20 40 40 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
215 PM AST Sun Jan 22 2017

.SYNOPSIS...Generally dry air aloft will allow only a slight
chance of showers. The best chance will be on Tuesday. Winds will
shift to a southerly direction Monday and Tuesday but return to
light northerly with some land/sea breeze influences by Wednesday.
This will increase temperature--especially on the north coast of
Puerto Rico.

At upper levels...Northwest flow will increase tonight before a
ridge moves across the area Monday. A trough will develop over the
Dominican Republic beginning on Wednesday and hold southwest flow
over the forecast area through the rest of the week.

At mid levels...High pressure ridges in from the west early this
week and is mostly unaffected by a weak trough passage--mainly
north of the area--Tuesday night. High pressure then shifts to
northeast of the area over the weekend but remains in control of
the local area. Moisture will be lacking in the mid levels except
for a brief shot across the southeast corner of the forecast area
on Tuesday.

At lower levels...High pressure retreats to the east over the
central Atlantic ocean while strong low pressure moves into the
western Atlantic east of Virginia on Monday. High pressure then
builds over the Bahama Islands on Wednesday as a weak front moves
through the area while dissipating. The ridge across the sub-
tropical Atlantic will reorganize during the latter part of the
week and remain through early next week.

&&

.DISCUSSION...A thin skiff of cirrus was seen over the area as
north northeast flow gently nudged some cumulus formation over
Puerto Rico north of and more solidly over the Cordillera Central
and the interior of Puerto Rico. No showers were seen except over
the outer Atlantic waters. A few streamers developed off the U.S.
Virgin Islands.

The GFS is backing off the moist conditions expected on Tuesday
and has not yet verified even the mediocre POPs that it had for
the central interior of Puerto Rico for today. Southerly flow will
commence beginning tonight due to the high in the central Atlantic
and the low advancing into the western Atlantic. And, for now,
this looks like a return of the somewhat drier air at lower
levels for Monday. The southerly flow over the island will bring
down-slope effects to the lower elevations north of the
Cordillera Central and temperatures Monday will be 3 to 4 degrees
warmer than today which saw light northerly winds in place.

Since the GFS is now taking the mid level moisture from the south
and southwest just southeast of Puerto Rico it now looks like
temperatures could warm even further on Tuesday with even 90
degrees possible just inland from the northeast Atlantic coast.

This also means that chances are less that significant shower
activity will form.

Mid levels then dry considerably, along with the precipitable
water so most of the rest of the week, beginning Wednesday will be
dry and sunny with only very few showers.

&&

.AVIATION...Mainly VFR conditions expected to prevail across all
terminals. Clouds and -SHRA have developed along the Cordillera
Central and southern slopes of PR. This could result mainly in BKN
cigs and -RA/VCSH periods at JPS/JMZ through the rest of the
afternoon hours with mtn tops obscured. Winds at TNCM/TKPK are
already E-ESE...NE at the USVI terminals and sea breeze variations
across the PR termimals around 10 kts or less. Light and variable
winds expected overnight at the sfc.

&&

.MARINE...Seas will come up slightly tomorrow and winds become
southerly. This will increase the risk of rip currents--but mainly
on the north coasts. Seas are still expected to remain below 7
feet for the next 7 to 10 days.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 73 85 74 87 / 0 10 0 20
STT 72 84 75 83 / 10 10 20 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
442 AM AST Mon Jan 23 2017

.SYNOPSIS...Weak surface high across the central Atlantic and a
surface low across the western Atlantic will promote a light to
moderate southerly wind flow today and Tuesday. Relatively dry
air expected today with an increase in moisture on Tuesday, mainly
for the USVI. Upper ridge to move in today, keeping a stable
atmosphere. Slightly warmer daytime temps expected today across
the San Juan area due to dry air and southerly winds.


&&

.DISCUSSION...Fair weather prevailed overnight across the local
area with a light and variable wind and variably cloudy skies.
Overnight temperatures dipped into the mid 60s to lower 70s
across the lower elevations and into the upper 50s to low 60s
across the higher elevations. For today, the local pattern is
expected to present a change when we compare to what we have been
observing the past several days. Southerly winds are expected
today which will cause rather warm temperatures across the San
Juan metro area, portions of northeastern PR, and the north
central sections of PR with max daytime temps into the upper 80s
possible, the rest of the local area should remain with temps in
the low to mid 80s. Very little shower activity is expected today
since the airmass is relatively dry, however there is some limited
moisture in the lower levels and the combination of the limited
moisture with the daytime heating and the sea breeze convergence
will give us a chance of rain across the NW quadrant of PR this
afternoon with only a slight chance of showers elsewhere.

Higher moisture is expected to move in on Tuesday but mainly for
the USVI as the SFC low across the western Atlantic moves
northeast. This will increase the chances of showers for the USVI, also
cause winds to shift direction from southerly to westerly late
Tuesday night into Wednesday morning then to northerly winds on
Wednesday afternoon. Even with this rather rare wind shift for our
area, the chance of rain remains mainly for the northern half of
PR, the USVI and the Atlantic waters, meaning that there is no
real significant change in the areas with higher chances of rain
in the early morning hours of Wednesday and on Wednesday
afternoon.

For the latter part of the week, the light to moderate winds will
be from the NE on Thursday and mainly easterly by Friday.
Relatively dry airmass to prevail on those days as well so the
shower activity is expected to be minimal.


&&

.AVIATION...VFR conds will prevail thru the forecast period. Shower
development will remain possible across NW PR after 23/16Z which may
result in VCSH at TJBQ. Shower activity expected to increase across
the Leeward terminals aft 24/00z. Light southerly winds with sea
breeze variations are expected today.

&&

.MARINE...A moderate northerly swell will continue affecting the
local Atlantic waters and Caribbean passages over the next few
days. Seas will build to 4-6 feet by midweek as a northwest swell
reaches the regional waters. At this time, the local buoys are
reporting seas of 3 to 4 feet across the nearshore waters and an
estimated 4 to 5 feet across the local Atlantic offshore waters.
Having said that, the local breaking waves across northern and
northwestern PR could be between 5 and 7 feet, which will cause a
high risk of rip currents across many of the Atlantic facing
beaches of Puerto Rico. There is a moderate risk of rip currents
for many of the remaining beaches in PR, Vieques, Culebra, and the
USVI.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 73 90 75 / 10 0 30 30
STT 81 74 82 75 / 20 20 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
202 PM AST Mon Jan 23 2017

.SYNOPSIS...Southerly flow is bringing back some moisture, but
flow will turn westerly with the approach of a weak cold front
and push the moisture east of the local area. Mostly dry weather
with few showers will ensue through at least Friday.

At upper levels...A ridge will moving through the area will shield
us from the impacts of a mid latitude trough passing to the north.
A sharp trough will dig south across the Dominican Republic after
Tuesday causing flow to turn southwest. The trough will weaken
before it passes through the area late Sunday. High pressure
returns early next week.

At mid levels...High pressure will continue over the Caribbean Sea
from the west and slowly move north during the week. It will pass
just north f the area over the weekend to reside to the northeast
over the west central Atlantic Ocean. Mid level moisture will
approach the islands from the south, brush by Saint Croix on
Tuesday, but the main axis of the moisture will form over the
Leeward Islands with limited effect for the local area.

At lower levels...Southerly flow will increase overnight, but a
weak cold front will pass through Tuesday night and turn flow
lightly back to the north. High pressure will build just north of
the area and continue into the central Atlantic ocean bringing
relatively dry air through Friday. As the air passes over the
ocean it will gradually pick up moisture over the weekend to bring
back isolated shallow showers.

&&

.DISCUSSION...No showers were seen on our noisy back up radar as
mostly dry air returns from the south. Mid level moisture is
approaching the area, but the approach of a front will turn it
east before it has a chance to move over Puerto Rico and the
northern U.S. Virgin Islands. Saint Croix will have a slightly
better chance of showers on Tuesday. Then a weak cold front will
pass through and even low levels will dry somewhat. This will
cool the north coast somewhat, but will also end all but the
slimmest chances of rain for the next few days. A weak band of
moisture returns from the southeast on Saturday, but this will
bring only a slight chance of showers. Modest moisture from the
east in the lowest layers--generally below 700 mb--will continue
those showers which will fall mainly on the windward slopes nights
and early mornings and in the interior during the day. Little
change from this is expected through early next week.

&&

.AVIATION...Mainly VFR conditions expected to prevail across the
local flying area for the next 24 hours. However, the combination of
the limited low level moisture with sea breeze convergence will
induce the development of -SHRA across the NW quadrant of PR
possible affecting TJBQ after 23/18Z. Latest TJSJ sounding indicated
a southerly wind flow up to 10 knots from the surface to 9k feet,
becoming light and variable between 9-24K feet and then from the
northwest and stronger aloft.

&&

.MARINE...Seas will increase somewhat as swell move in from the
north northeast. The northern buoy (41043) never quite reached 7
feet as winds have remained gentle. Then, after a brief swell
episode on Wednesday from the northwest, seas will diminish. Seas
may reach 7 feet briefly in the northern outer local Atlantic
waters, but this is not expected to be a prevailing condition.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 73 90 75 84 / 0 20 0 10
STT 74 82 75 83 / 10 20 0 10

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
434 AM AST Tue Jan 24 2017

.SYNOPSIS...Surface low across the western Atlantic will promote
a light to moderate southerly wind flow today, then a surface high
moves in just north of the local islands, shifting winds to a
northerly direction on Wednesday. Relatively dry air expected
today with an increase in moisture mainly for the USVI. Upper
trough developing to our west by Wednesday. Slightly warmer than
normal daytime temps expected today across the San Juan area and
other portions of the northern half of PR due to dry air and
southerly winds.

&&

.DISCUSSION...Fair weather prevailed overnight across the local
area with a light and variable wind and variably cloudy skies.
Overnight temperatures dipped into the mid 60s to lower 70s
across the lower elevations and around 60 to the mid 60s across
the higher elevations. For today, we can expect southerly winds
once again and therefore warmer than normal temperatures for
portions of the northern coastal municipalities of PR including
the San Juan Metro Area, where temperatures are expected to reach
the upper 80s today. The rest of the local area should remain with
temps in the low to mid 80s. Very little shower activity is
expected today since the airmass is relatively dry, however there
is some moisture moving in from the south but it appears that it
will stay over the USVI briefly then move away. This may cause
isolated showers in the afternoon and then scattered showers
tonight around the local waters and particularly just to the east
of the USVI.

Surface low across the western Atlantic is causing the southerly
wind flow today, then there is a SFC high that will move over the
Bahamas on Wednesday. This will cause winds to shift direction
from southerly to westerly late tonight into Wednesday morning
then to northerly winds on Wednesday afternoon. This rare wind
shift for our area will also bring a patch of moisture on
Wednesday, which means that scattered showers are expected across
the local waters tonight into Wednesday morning then scattered
showers expected across the northern USVI and the northern half of
PR. However, the accumulations are expected to be modest.

For the latter part of the week, the light to moderate winds will
be from the NE on Thursday and mainly easterly by Friday.
Relatively dry airmass to prevail on those days as well so the
shower activity is expected to be minimal. In fact, predominantly
fair weather, with brief moments of clouds and showers, is
expected into the weekend.


&&

.AVIATION...VFR conditions will continue to prevail across all
terminals through 24/24z. Light southerly or variable winds expected
early this morning, becoming mostly S-SW at 5-10 kts aft 14z.


&&

.MARINE...North northeast swell continue to affect the local
Atlantic waters and passages. Small craft operators should
exercise caution as seas are between 4 to 6 feet and winds up to
20 knots. A slightly stronger northwesterly swell is expected to
invade the local waters by Wednesday night, causing an increase in
seas and possibly meeting small craft advisory criteria. There is
a high risk of rip currents today for the north and northwest
coast of PR and Culebrita beach in Culebra.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 75 82 72 / 20 20 30 30
STT 83 74 81 72 / 20 20 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
100 PM AST Tue Jan 24 2017

.SYNOPSIS...Surface low across the western Atlantic and a weak
surface high pressure over the central Atlantic will maintain a
light to moderate southerly wind flow across the region tonight.
Strong surface high pressure will move across the southwestern
Atlantic early Wednesday and to the north of the region by
Thursday. Winds will shift from the North northeast by Wednesday,
bringing a relatively dry and stable air mass with cooler
temperatures over the local islands Wednesday and for the next
several days.

&&

.DISCUSSION...Terminal Doppler radar detected only few isolated
showers across the surrounding coastal waters as well as across
the U.S. Virgin Islands this afternoon. However, not significant
precipitation was observed elsewhere over land areas so far this
afternoon. A weak frontal boundary is expected to reach the region
tonight and early Wednesday morning. This feature will increase
the cloudiness and shower activity across the local islands and
surrounding waters tonight and Wednesday. However, not significant
or widespread precipitation is expected at this time.

Surface low across the western Atlantic and a weak surface high
across the central Atlantic will maintain a light to moderate
southerly wind flow across the region tonight. A strong surface
high pressure is expected to move across the southwest Atlantic
early Wednesday and then to the north of the local islands
Wednesday night and Thursday. This feature will cause winds to
shift from the north late Wednesday and Thursday. A relatively
dry airmass will encompass the region Thursday and Friday with
minimal shower activity.

&&

.AVIATION...Mostly VFR conditions will continue to prevail across
all terminals through 24/24Z. A slight increase in moisture and
-SHRA are expected mostly across the Leewards and USVI taf sites
after 25/02Z. Winds tonight will remain southerly or variable.

&&

.MARINE...North northeast swell continue to affect the local
Atlantic waters and passages. Small craft operators should
exercise across the offshore Atlantic as seas are between 4 to 6
feet and winds up to 20 knots. A slightly stronger northwesterly
swell is expected to invade the local waters by Wednesday night,
causing an increase in seas and possibly meeting small craft
advisory criteria. There is a high risk of rip currents for the
north and northwest coast of PR and Culebrita beach in Culebra.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 75 82 72 82 / 20 30 30 20
STT 74 81 72 81 / 20 30 30 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
543 AM AST Wed Jan 25 2017

.SYNOPSIS...Cold front just northwest of the region will move over
the local islands today. Clouds and scattered showers will affect
the local islands through tonight. Then...high pressure will build
in the wake of the front...bringing a fair weather pattern to the
local region through the end of the week.


&&

.DISCUSSION...Satellite imagery as well as the latest surface
analysis showed a frontal boundary located over the Mona Passage
this morning. This front will move across the local region through
tonight...increasing the cloudiness and shower activity over
Puerto Rico and the U.S. Virgin Islands. No significant rainfall
accumulations are anticipated with this feature...as moisture will
remain near normal levels. As the front crosses the islands, a
moderate northerly flow will establish across the local area.

Surface high pressure and a mid level ridge located over Cuba
will expand northeastward over the Western Atlantic on Thursday.
This will result in drier conditions across the Northeast
Caribbean region Thursday and Friday. The mid level ridge will
maintain a stable atmosphere and rainfall amounts will be limited.
Winds will return to the east on Friday and east-southeast on
Saturday. As the wind shift, warmer temperatures between 85-88
degrees are possible once again from Friday through early next
week. Moisture will likely surge on Sunday as an area of moisture
approaches the region from the east.

&&

.AVIATION...Weak front moving from the Atlantic waters into the
local flying area will create brief periods of -RA/VCSH and tempo
MVFR cigs across the west and northern terminals of PR through the
morning hours. Similar conditions expected to spread across the rest
of the terminals through the afternoon hours. Winds expected to
continue WNW around 10 kts thru 16z...then NNE with sea breeze
variations across southern terminals of PR.

&&

.MARINE...NW swell will bring hazardous seas across the offshore
Atlantic Waters later today. Seas are expected to build to 5-7
feet across the local Atlantic Waters between this afternoon and
Thursday. As a result...a Small Craft Advisory is in effect for
the Offshore Atlantic Waters from this afternoon. Seas across the
coastal waters of Puerto Rico are forecast between 3-5 feet
through the end of the week.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 83 74 83 73 / 40 20 10 10
STT 83 73 83 72 / 40 20 10 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
1245 PM AST Wed Jan 25 2017

.SYNOPSIS...Cold front is now passing through the local islands and
the drier air is expected to move in by Thursday morning. The local
wind will also change direction from a northerly direction today to
a northeasterly direction on Thursday and easterly by Friday.
Surface high pressure will move east and north of the local islands
for the next few days while an upper trough develops over the
area for the latter part of the week.

&&

.DISCUSSION...The cold front brought some cloudiness and scattered
showers across portions of PR, especially across the northern half
and portions of western PR. This cold front is expected to continue
moving south and affect the USVI tonight. The rainfall amounts were
not bad enough to cause flooding and it is not expected to cause
flooding later in the afternoon or tonight.

Fair weather should return for late tonight and Thursday after the
front passes. Daytime maximum temperatures are expected to be in
the low to mid 80s across the lower elevations and in the 70s
across the higher elevations, while the minimum temperatures will
be near normal on Thursday and Friday. For the weekend, the wind
becomes more easterly and with it comes slightly warmer
temperatures but still fair weather. No real significant weather
feature is expected for the next several days, even with the upper
trough developing over the area for the latter part of the week.


&&

.AVIATION...Brief periods of -RA/VCSH with tempo MVFR cigs across
TJBQ, TJMZ, and TJSJ during the rest of the day, clouds and rain
should spread across the rest of the local terminals in the
afternoon and evening. Winds expected to from the NNE with sea
breeze variations across southern terminals of PR.


&&

.MARINE...Small craft advisory will go into effect at 2PM AST for
the offshore Atlantic waters for seas up to 7 feet while the rest
of the local waters are expected to be up to 4 feet. There is a
moderate risk of rip currents across the north and northwest coast
of PR but a high risk of rip currents is expected starting late
this afternoon across the beaches of north central and
northwestern PR.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 74 83 73 86 / 20 10 10 20
STT 73 83 72 83 / 20 10 20 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
608 AM AST Thu Jan 26 2017

.SYNOPSIS...Mid level ridge located over the Bahamas will move
across the region during the next few days. As the ridge builds
over the area...trade wind cap will strengthen over the region
today. This will limit the potential of showers across the islands.
At low levels...surface high pressure north of the region is
producing a moderate northeast flow across the local islands.

&&

.DISCUSSION...Surface high pressure north of the islands has
pushed the remnants the frontal boundary over the Caribbean
Waters. As a result...fair weather pattern is prevailing across
the local islands this morning. Satellite imagery shows mostly
clear skies over Puerto Rico and the U.S. Virgin Islands. Dry
advection and the presence of the mid level ridge will limit the
shower development across the forecast area over the next 24 hours.

Winds will become more easterly as surface high pressure relocates
over the Central Atlantic between Friday and Saturday. Easterly
winds will push the remnants of the old frontal boundary over the
region. This will increase the cloud and shower coverage on Friday.
Although...no significant rainfall accumulation is anticipated with
the remnants of the front...scattered showers will affect the islands
at times.

Trough pattern will establish over the Western Atlantic between
Sunday and early next week. As a result...moisture and instability
will increase across the forecast area. This will result in additional
cloudiness and scattered showers across Puerto Rico and the U.S.
Virgin Islands the first part of next week.

&&

.AVIATION...Mainly VFR conditions are expected across all terminals
during the next 24 hours. Low level winds will continue from the
northeast at 8-14 kts. Sea breeze variations expected at JMZ/JPS
after 14z.

&&

.MARINE...Local buoys continue to indicate a NW swell of 5-7 feet
across the Atlantic Waters. As a result, a Small Craft Advisory
continues in effect for the Offshore Atlantic Waters. In addition,
this NW swell is producing a high risk of rip currents along the
beaches of Northwest and North PR, Culebra and Saint Thomas.
Marine conditions will gradually subside across the local islands
during the weekend as the NW swell fades out.

&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
213 PM AST Thu Jan 26 2017

.SYNOPSIS...
A mid level ridge over the eastern Caribbean is enhancing a cap
inversion. TJSJ 26/12z sounding data showed the cap inversion at
around 850mb. A surface high pressure, to the north of the region,
is producing a northeasterly wind flow across the region. This
weather pattern will result in mostly clear skies with limited
shower activity.

&&

.DISCUSSION...
Satellite imagery indicated a dry air mass moving across the local
islands. This air mass combined with a mid level ridge and a cap
inversion around 850mb limited shower activity over the region
today. In general, a fair weather pattern prevailed across the
islands with coastal maximum temperatures between the mid and
upper 80s.

A surface high pressure to the north of the region will move
eastward across the Atlantic Ocean to produce a moderate northeast
wind flow through this evening and into early Friday Morning.
However, as the high pressure migrate into the Eastern Atlantic,
surface winds are expected to shift from the east. Under this
pattern, fair weather conditions with a few passing showers
embedded in the trades are expected from time to time across the
islands.

Trough pattern is forecast by Sunday into the upcoming week. If
this pattern materializes, moisture and instability will increase
across Puerto Rico and the U.S. Virgin Islands.

&&

.AVIATION...
Mostly VFR conditions are expected across the local flying area
for the next 24 hours with not significant hazards expected. Low
level winds will continue from the northeast at 8-14 kts.

&&

.MARINE...Seas will continue to diminish across the region.
However, there is a small craft advisory in effect for the
Atlantic Waters until this evening at 6 pm AST. In addition, there
is a high risk of rip currents for the beaches along the
Northwest and North PR, Culebra and Saint Thomas. Marine
conditions are expected to improve through the weekend.

&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
550 AM AST Fri Jan 27 2017

.SYNOPSIS...Mid level ridge located west of the region will expand
over the Northeast Caribbean and the Tropical Atlantic through Saturday.
As the ridge builds over the area...dry and stable conditions will
prevail aloft. A few upper level short-wave troughs will swing
across the local area between Sunday and early next week...
increasing the instability across the local islands. The overall
moisture transport will be enhanced the first part of next week as
a trough pattern establishes across the Western Atlantic.

&&

.DISCUSSION...Surface high pressure north of the islands will
push the remnants the old frontal boundary over the U.S. Virgin
Islands and Puerto Rico later today. As a result...scattered
showers will affect the local islands at times. Winds will become
southeast this afternoon as surface high pressure relocates over
the Central Atlantic. This will result in warmer temperatures
along Northern Puerto Rico and scattered convection over Northwest
Puerto Rico this afternoon. At this time...no significant rainfall
accumulation is anticipated with the remnants of the front as mid
level ridge will inhibit deep convection across the islands today
and Saturday.

Weather conditions will become more favorable for showers early
next week as a few short-wave troughs move over the local region.
As a result...moisture transport will be enhanced between Sunday
and Monday under the influence of the upper troughs. Operational
models continue to suggest that this wetter pattern will likely
persist through at least midweek next week.

&&

.AVIATION...Mainly VFR conditions are expected across all terminals
during the next 24 hours. However, fragmented clouds and SHRA
embedded on trade winds could create brief MVFR cigs and -RA periods
across the Leeward/USVI terminals through the morning hours. Similar
conditions are expected after 16z across the PR terminals as SHRA
develops over the mountain ranges. Low level winds should prevail
from the east at 10-15 kts with sea breeze variations after 14z.

&&

.MARINE...Local buoy observations show the overall seas subsiding
to 3-5 feet across most of the coastal waters. The NW swell peaked
yesterday, however seas up to 6 feet still possible across the offshore
Atlantic waters through tonight. Marine conditions will continue to
improve through Saturday. Winds will increase slightly again Sunday
and Monday creating seas of 4-6 feet once again across the offshore
waters.

&&

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