Caribbean - Central America Weather

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
457 AM AST Sat Dec 22 2018

.SYNOPSIS...
A trade wind perturbation will move from the east across the
islands later this morning. As a result, frequent passing showers
will affect the U.S. Virgin Islands, eastern and northern Puerto
Rico and their surrounding waters at times. This activity will
make its way into the interior and western portions of Puerto Rico
during the afternoon hours. However, a mid-upper level high
pressure will make difficult vertical development during the
afternoon.

&&

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

A surge of moisture trailing an induced low level trough, was now
crossing the northern Leewards and will move across the region later
this morning and during the afternoon. This will bring a slight
increase low level moisture, a favoring a better chance for isolated
to scattered showers across portions of the islands. The activity
will however be of short duration with no significant rainfall
accumulations expected.

The mid to upper level high pressure ridge is to hold across the
region and therefore suppress any significant vertical development
through the weekend and into early next week. A seasonal weather
pattern is expected Sunday through Monday with occasional passing
late evening and early morning trade wind showers followed by
limited afternoon shower development, which should be focused mainly
over parts of the interior and west sections of Puerto Rico.
Elsewhere including the USVI, mostly fair weather skies and pleasant
near normal night and daytime temperatures are forecast to prevail.

.LONG TERM...Tuesday through Saturday...

Model guidance continues to suggest seasonal weather pattern
across the region throughout the long term period. At mid levels,
a strong high pressure will aid in a strong trade wind cap. At the
surface, a frontal boundary will dissipate north of the islands,
over the Atlantic waters, as a migratory surface high pressure
exits the Eastern Seaboard and move from the western to the
central Atlantic Ocean Wednesday into the second part of the
upcoming week. This weather pattern will increase moisture
transport, winds and seas across the islands. However, the high
pressure aloft will limit the intensity and coverage of any shower
activity that develops over the forecast area. As a result,
moisture advection with no significant rainfall accumulations are
forecast to continue.

&&

.AVIATION...
VFR conds expected across all terminals thru fcst pr. brief MVFR
with low clds and SHRA likely across the leeward terminals
TKPK/TNCM til 22/12Z with VCSH psbl at TISX/TIST/TJNR. Brief SHRA
psbl ovr ctrl Mtn range of PR and VCTY TJSJ/TJBQ/TJMZ
22/17Z-22/22Z . Wnd CALM to lgt/vrbl...bcmg fm E-SE 10-15 kts
w/ocnl hir gusts aft 22/14Z with sea breeze variations.

&&

.MARINE...
Small craft operators should exercise caution across the Outer
Atlantic waters due to choppy seas up to 6 feet. Seas of 5 feet
or less are expected elsewhere. The winds will be out from the
east at 10 to 15 knots. A northwesterly swell is forecast to reach
the Atlantic waters and Caribbean Passages by Sunday. A strong
surface high pressure is forecast to increase winds and seas
across the local waters by the second part of the upcoming week.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 85 75 84 74 / 30 30 40 50
STT 84 75 85 74 / 40 30 50 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
517 AM AST Mon Dec 24 2018

.SYNOPSIS...Although a few passing showers cannot be ruled out
across eastern and northern sections of the islands, fair weather
conditions will prevail today (Christmas Eve) and tomorrow
(Christmas Day). A tropical winter weather pattern will continue
across the northeastern Caribbean. As a result, trade wind showers
will move across the U.S. Virgin Islands and the windward
sections of Puerto Rico, followed by shallow afternoon convection
over the interior and western areas of Puerto Rico each day.
However, a mid-upper-level ridge will continue to hold and limit
vertical development across the region.

&&

Short term... Today through Wednesday...

A relatively dry and stable airmass is expected prevail across the
region under the dominance of high pressure ridging across the
region. However, periods of shallow passing clouds and occasional
showers can be expected especially during the early morning hours
steered by the prevailing easterly trades. This will be followed by
mostly sunny afternoons with only a chance for isolated to scattered
showers over parts of the interior and west sections of Puerto rico.
Mostly fair weather and sunny skies would prevail elsewhere.
Therefore for the next few days the seasonal weather patter will
continue, with occasional showers streaming over the waters into
windward areas of the local islands followed by limited shower
development over the interior and western Puerto Rico in the
afternoon. No significant rainfall accumulation is expected. Daytime
maximum temperatures will fluctuate between mid 70s to mid 80s,
whereas overnight minimum temperatures will range between low 60s to
mid 70s each day under an easterly wind flow ranging between 10-20
mph.

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

The seasonal weather pattern will continue throughout the long
term period. Model guidance has been persistently showing a ridge
pattern aloft, which is inducing a strong trade wind cap over the
region. At the surface, a migratory surface high pressure
displacing north of the region across the Atlantic Ocean will
bring a wind surge across the islands. This will increase moisture
transport, winds and seas through at least the end of the work-
week.

Models suggest the arrival of a dry airmass associated with the
remnants of a frontal boundary by the weekend into next-week. In
addition, at upper levels, a short wave perturbation could erodes
the ridge pattern aloft through this period. Confidence continues low
due to how far in time is this scenario.

&&

.AVIATION...
VFR conds at all terminals with passing -SHRA/SHRA en
route btw islands and along the north and east coastal sections of
the islands. SCT-BKN lyrs nr FL030...FL050. Few tops nr FL080. Brief
Mtn top obscr w/ passing shra ovr E PR TIL 24/12Z. Sfc lgt/vrb...
bcmg fm E E-NE 10-15 kts AFT 24/14Z with ocnl gusts and sea breeze
variations.

&&

.MARINE...
Mariners are urged to exercise caution due to choppy seas between
3 to 6 feet across the Atlantic Offshore waters, and across the
Caribbean southern waters due to winds between 15 and 20 knots
late this morning into the afternoon hours. Elsewhere seas and
winds will be at 5 feet or less and around 18 knots,
respectively. Winds and seas will increase and deteriorate by
mid-week into the weekend. As a result, Small Craft Advisories
may be required in the long term.

Beach goers, moderate rip current risk is expected to continues
for the north and east facing beaches of Puerto Rico and the U.S.
Virgin Islands.

&&

.FIRE WEATHER...A dry airmass will filters across the region from
the east later this morning into the afternoon hours. This will
increase the potential for fire weather danger across the
southern coastal areas of Puerto Rico where KBDI values are above
600. In addition, winds are forecast to increase above 15 knots
when RH values could drop into the mid 40s and low 50s. As a
result, a Fire weather statement was issued today. If this
drying trend continues, elevated fire weather conditions will
persist through the next few days.

&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
522 AM AST Tue Dec 25 2018

.SYNOPSIS...
A surface high pressure ridge will continue to exit the eastern seaboard
of the United States today. The ridge will build and spread eastward
into the west and central Atlantic on Wednesday and through the weekend.
As this ridge builds north of the region, the local pressure gradient
will tighten and result in moderate to strong trade winds. During the
rest of the morning hours, quick passing light to moderate trade wind
showers will persist across the regional waters, with some moving
inland over the north and east coastal areas of the islands from
time to time. By the latter part of the week, the increasing trade
winds will promote more frequent early morning passing showers and
overall breezy conditions during the day.

&&

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

A relative dry airmass will limit shower activity through the
morning hours. As a result, fair weather conditions are expected on
Christmas day. However, a trade wind perturbation will bring passing
showers over the U.S. Virgin Islands, east and north sections of
Puerto Rico as well over portions of the interior and western PR
late this morning into the afternoon hours. A mid-upper-level ridge
will limit vertical development, and rainfall accumulations will be
light to moderate with this activity. High temperatures should reach
the low and mid 80s across coastal areas. This weather pattern
should prevail through the short-term period, with occasional
passing clouds and showers during the early morning hours steered by
the prevailing easterly trades. Followed by mostly sunny afternoons
with isolated to scattered showers streaming downwind from the U.S.
Virgin Islands, over portions of eastern PR, and limited convection
across the interior and west sections of Puerto Rico.

Although a relatively dry and stable airmass will continue across
the region under the dominance of high pressure ridging aloft, a
migratory surface high pressure will increase winds and the frequency
of showers across the islands late Wednesday night into Thursday.
Easterly winds are expected to increase between 15 and 25 mph
especially over the coastal areas.

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

A seasonal advective weather pattern is forecast to continue with
periods of passing low to mid level clouds and trade wind showers.
Model guidance initialized well and has been persistent in suggesting
the upper level ridge to slightly erode through Friday, but will
again be reinforced by the weekend. Therefore, expect a moderate
to strong trade wind cap inversion to hold and limit convective
development. The strengthening of the surface high pressure ridge
across the Atlantic will tighten the local pressure gradient by
Friday and into the weekend. Increasing trade winds and breezy
conditions can therefore be expected through most of the weekend.
This in turn will increase moisture transport and more frequent
trade wind showers especially during the early morning and overnight
hours. No significant rainfall accumulations is forecast across
the region during the period, although the model guidance continued
to suggest the arrival of the more frequent moisture, remnants
from old frontal boundaries over the weekend. The associated cloudiness
and shower activity should however be fast moving and of short duration.
Improving conditions and decreasing trade winds is forecast by Sunday
and into early next week.

&&

.AVIATION...VFR conds will prevail at all terminals. Passing
SHRA/-SHRA cannot be ruled out at times, but no significant flying
impact is expected. Cloudiness is expected to increase mainly across
E-PR and the interior and western sections of PR between 25/16-22Z.
Light to calm and vrb surface winds are expected til 25/13z, then
easterly winds will increase around 15 kt with higher gusts and sea
breeze variations.

&&

.MARINE...Recent data from the surrounding buoys around PR and
the USVI suggested seas between 3-5 feet and east-northeast winds
between 10-15 knots. Overall, seas will range between 3-6 feet
with a slight chop and higher seas expected across the offshore
waters and local passages, and also over the near shore coastal
waters of north and southern Puerto Rico. Winds and seas will
increase and deteriorate by late Wednesday and into the weekend,
when hazardous marine conditions and Small Craft Advisories will
be required.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 83 73 84 74 / 50 50 40 50
STT 83 74 84 75 / 20 30 50 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
442 AM AST Wed Dec 26 2018

.SYNOPSIS...
A surface high pressure ridge will continue to exit the eastern United
and spread eastward across the western Atlantic today. This ridge will
build and hold across west and central Atlantic creating a tight pressure
gradient across the forecast area into the upcoming weekend. This will
result in moderate to strong trade winds and breezy conditions. In the
meantime, the mid to upper level ridge will slightly erode across the
region today through Friday as a short wave trough crosses the west
Atlantic. The upper ridge but will be reinforced once again across
the area by the weekend to maintain dry and stable conditions.

&&

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

Strong high pressure at the surface will build off the eastern
seaboard of the United States into the western Atlantic today and
Thursday, then move southeast to a position about 1500 miles north
of Saint Thomas. This will increase the surface gradient over the
area with a corresponding increase in easterly winds. In fact at 850
mb winds are forecast by the GFS to increase to nearly 35 knots by
Fri 28/12Z. For Friday, this could translate to east northeast
winds reaching 20-30 mph along the northern coast with higher
gusts possible. At mid levels high pressure over the area will
shift to the Bahama Islands on Friday, but will remain the major
influence. And finally at upper levels, weak ridging will give way
to a short wave trough passage around 28/12Z to coincide with the
wind surge at the surface and a significant patch of moisture
that increases the shallow showers as specified in the paragraph
below.

Patches of moisture at low levels will move through the area,
specifically this afternoon and evening, Thursday for most of the
day and then early Friday morning building to a maximum around
midday Friday. This and increasing winds will create scattered
showers through Thursday and numerous showers on Friday. Best
rainfall accumulations, however, will be over eastern Puerto Rico.
Accumulations will be persistent but lighter over the U.S. Virgin
islands. Maximum rainfall amounts over higher terrain are expected
to be 0.10-0.25 both Wednesday and Thursday and 0.50-1.00 on Friday.

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

Recent model guidance and overall weather pattern suggest a seasonal
cool advective weather pattern to continue with periods of passing
low to mid level clouds and trade wind showers dominated by the
strong surface high pressure ridge north of the region. The mid to
upper level ridge will again be reinforced by Saturday and therefore
expect a moderate to strong trade wind cap inversion to hold and
limit vertical development for the next several days.

However, the strengthening of the surface high pressure ridge across
the Atlantic will tighten the local pressure gradient and consequently
increase the trade winds supporting breezy conditions across the
region through much of the weekend. This in turn will increase moisture
transport and allow more frequent trade wind showers especially over
the north and east coastal sections and during the morning and overnight
hours.

No significant rainfall accumulations is forecast across the region
during the period, although the model guidance continued to suggest
the arrival of the more frequent pestering showers, remnants from
old frontal boundaries over the weekend. The associated cloudiness and
shower activity should however be fast moving and of short duration.
Improving conditions and decreasing trade winds is forecast by late
Sunday and into the early part of next week, but the typical early
morning passing showers can be expected on the windward side of the
islands followed by a mixture of sunshine and clouds and pleasant
temperatures.


&&

.AVIATION...VFR conds to prevail at all terminals. Ocnl passing SHRA/-
SHRA will occur and hir trrn will be obscured at times. Cloudiness
expected to incr mainly across ern PR and the interior and wrn PR
btwn 26/16-22Z. Easterly sfc winds with land breeze influences are
expected til 25/13z, then easterly winds will incr to arnd 10-20 kt
with hir gusts and sea breeze variations. Strongest winds nr the nrn
coast. Low-level winds to increase somewhat Thursday. Max winds WNW
30-35 kt btwn FL430-480 at 26/18z.


&&

.MARINE...Small craft should exercise caution across Caribbean
waters and most of the local passages due to gradually increasing
winds that could reach 20 kts later today. Wave heights will be
generally 3 to 5 feet this morning, but the arrival of a small
northerly swell and stronger easterly trades tonight and for the
rest of the week, will cause seas to deteriorate and become choppy
and very hazardous into the weekend. Small craft advisories will
therefore be required later tonight and through the rest of the
week for hazardous winds and seas.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 83 73 84 76 / 40 60 60 60
STT 85 74 85 75 / 50 50 60 60

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
434 AM AST Thu Dec 27 2018

.SYNOPSIS...
Strong surface ridge will maintain its hold over the region through
the weekend, and cause moderate to strong easterly winds, as well
as the occasional passage low-level moisture fragments ripped off
from old frontal boundaries which extend across the Atlantic north
and east of the region. The shallow moisture will help create periods
of cloudiness and scattered to isolated showers across portions of
east, central and western interior areas of Puerto Rico, as well
as over the Atlantic, Caribbean waters and parts of the U.S. Virgin
Islands. The fairly strong east northeast winds will help create
local forcing and the development of afternoon showers across parts
of the islands. The activity should however be fast moving and of
short duration although some localized wetting rains will be possible
in isolated spots.

&&

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

Strong high pressure at the surface will build into the western
Atlantic east of the New England states today and then move
southeast to a position about 1100 miles north northeast of the
Leeward Islands by Saturday. This will increase the surface gradient
over the area with a corresponding increase in easterly winds today
through Friday. In fact at 850 mb winds are forecast by the GFS to
increase to nearly 35 knots by Fri 28/12Z. For Friday, this will
translate to east northeast winds reaching 20-30 mph along the
northern coast with higher gusts possible. At mid levels, high
pressure over the area will shift to the Bahama Islands on Friday,
and will remain the major influence through Saturday. This drier
layer will definitively cap any convection below 15 kft with
extremely dry mid layers that will continue beyond the short term
period. And finally at upper levels, weak ridging will give way to
a short wave trough passage around 28/18Z to coincide with the wind
surge at the surface and a significant patch of moisture that
increases the relatively shallow showers expected.

Patches of moisture at low levels will move through the area, for
most of the day today and then early Friday morning building to a
maximum around midday Friday as the moist layer deepens to around 15
kft. This, plus cooling 500 mb temperatures which could reach minus
8 degrees by Friday and increasing winds will create scattered to
numerous showers today and Friday. Best rainfall accumulations,
however, will be over eastern Puerto Rico where heavier amounts
could be seen due to streamers that form off the minor islands east
of Puerto Rico and arrive on the eastern coast. Accumulations will
be persistent but much lighter over the U.S. Virgin islands. Maximum
rainfall amounts over higher terrain in Puerto Rico are expected to
be 0.50-1.50 inches today and up to 2 inches on Friday, but these
amounts will be very localized. Although showers taper off on
Saturday, moisture patches will still yield scattered showers on the
windward coasts and mountain slopes.

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

Recent model guidance and overall weather pattern all suggest that
the seasonably cool advective pattern with periods of passing low
to mid level clouds and trade wind showers will be maintained for
the next several days. Strong surface high pressure ridge north
of the region and the reinforced upper level ridge will be the main
influence and dominant weather feature during the entire period.
Therefore expect a moderate to strong trade wind cap inversion to
hold and limit widespread vertical development for the next several
days.

Sunday through Monday of next week, the strengthening of the
surface high pressure ridge will maintain a fairly tight local
pressure gradient and increase the trade winds. This will promote
breezy conditions across the forecast area at least into early
next week. This will also increase moisture transport and support
more frequent trade wind showers especially over the north and
east coastal sections and during the morning and overnight hours.

No significant rainfall accumulations is forecast during the period,
although the model guidance continued to suggest occasional passing
clouds with isolated to scattered shower development each day across
the regional waters and parts of the islands. The associated cloudiness
and shower activity should however be fast moving and of short duration
with some in the form of streamers which will develop and move west
northwest across the surrounding municipalities. Gradually improving
conditions and decreasing trade winds is forecast throughout the
rest of the week. however, the typical early morning passing showers
can be expected on the windward side of the islands followed by a
mixture of sunshine and clouds and pleasant temperatures each day.

&&

.AVIATION....VFR conds to prevail at all terminals. Sct SHRA/-SHRA
will persist and hir trrn will be obscured at times. Cloudiness
expected to incr mainly across ern PR and the interior and wrn PR
btwn 26/16-22Z and streamers may cause heavier SHRA downwind of the
USVI, Culebra and Vieques. East northeast sfc winds to incr aft
27/14Z to 12 to 20 knots with gusts to 28 kt psbl alg the Atlantic
coasts. Max winds WNW 30-35 kt btwn FL420-480 thru 28/06Z, but
easterly LLVL winds also incrg to 20-25 kt FL023-140 drg the day.

&&

.MARINE...Northerly swell is expected to arrive and spread across
the local Atlantic and passages later today but the local seas
will remain up to 6 feet and during the early morning and afternoon
hours. However, starting later this afternoon and continuing through
the weekend, seas are expected to deteriorate as the northerly swell
combines with fresh to strong easterly winds to cause rough and
hazardous seas. Small craft advisories will therefore be in effect
for most of the local waters and passages. Please refer to the latest
Coastal Waters Forecast (CWFSJU) and Marine Weather Message (MWWSJU)
issued by the National Weather Service WFO San Juan PR.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 84 75 83 74 / 60 70 70 60
STT 84 75 84 74 / 60 60 60 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
515 AM AST Fri Dec 28 2018

.SYNOPSIS...A strong surface high pressure moving over the western
Atlantic will continue to cause fresh to strong easterly winds
across the region. This will result in an increase of moisture
transport along with cloud and shower frequency into the forecast
area. Afternoon convection over the interior and western Puerto
Rico, as well as downwind from the local islands, is possible.
However, a mid to upper level ridge that holds over the region
will suppress any widespread vertical development. Although
moisture transport is expected to decrease as the winds weaken by
midweek, this seasonal weather pattern will continue through the
long- term period.


&&

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

Strong high pressure at the surface is now 1550 miles north Saint
John and will rapidly weaken as it moves to a position 925 miles
northeast of Saint John by Sunday afternoon. This has increased the
surface gradient over the area with a corresponding maximum in
easterly winds today. In fact at 850 mb winds are forecast by the
GFS to increase to nearly 35 knots by today at 12Z. This will
translate to east northeast winds reaching 20-30 mph along the
northern coast with higher gusts possible. At mid levels, high
pressure over the area has shifted to the Bahama Islands and will
continue to be centered near there through Sunday with little change
in height so as to remain the major influence of the area`s weather
during the period. This drier layer will definitively cap any
convection below 15 kft with extremely dry mid layers that will
continue beyond well the short term period. And finally at upper
levels, weak ridging is giving way to a short wave trough passage
around 28/18Z today to coincide with the wind surge at the surface
and a significant patch of moisture that increases the relatively
shallow showers expected this afternoon. Winds at upper levels
behind the trough will veer to the northeast and increase to over 50
knots in a weak split of the sub tropical jet on Sunday.

An area of moisture at low levels passed through the area last night
in the evening. A dry slot is now moving through this morning,
although very light showers persist in the northeast flow impinging
over the higher terrain of Puerto Rico. Around noon today, a second
band will slowly sag into Puerto Rico and the U.S. Virgin Islands to
bring occasional showers that will persist through much of the night
tonight and bring as much as 1 to 2 inches of rain in isolated areas
of higher terrain. Where rains reach, amounts of one to three
tenths of an inch should be most common. The moist layer has already
deepened to around 15 kft. Also the 500 mb temperatures of minus 8
degrees promised today are still in the GFS sounding forecast for
28/18Z this afternoon, and will enhance the shower activity again
today. Best rainfall accumulations, will again be over eastern
Puerto Rico where heavier amounts could be seen due to streamers
that form off the minor islands east of Puerto Rico and arrive on
the eastern coast. Accumulations will be persistent but much lighter
over the U.S. Virgin islands. Maximum rainfall amounts over higher
terrain in Puerto Rico are expected to be up to 2 inches today
through tonight, although these amounts will be very localized.
Although showers taper off on Saturday, moisture patches will still
yield scattered showers on the windward coasts and mountain slopes
with as much as one inch possible. On Sunday, a dry slot is expected
to move across the area sandwiched between air to the north with
better moisture and the band of moisture that passed through on
Saturday. This is expected to greatly reduce showers and
accumulations as winds also subside somewhat.

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

Global models continue to suggest that a seasonal weather pattern
will prevail through the long-term period. This is the result of
a surface high pressure moving eastward into the north central
Atlantic and a mid to upper level ridge that will hold over the
region. This combination will bring patches of low- level moisture
to the area, decreasing in frequency as fresh to strong trade
winds weaken by midweek. These patches will promote showers
streaming over the waters into windward areas of the local
islands, particularly during the overnight and early morning
hours. Afternoon convection over the interior and western Puerto
Rico, as well as downwind from the local islands is possible.
However, the mid to upper level ridge will suppress vertical
development of any shower activity and as a result, no significant
rainfall accumulation is expected. Given the weather pattern
observed in recent days and consistency among the global models,
there is a high confidence level in this forecast.


&&

.AVIATION...VFR conds to prevail at all PR terminals. Brief MVFR
CIGS and VSBYs are psbl in sct-num SHRA/-SHRA in the USVI and
Leeward Islands. Hir trrn will be obscured at times entire FA.
Cloudiness expected to incr mainly across ern PR and the interior
and wrn PR btwn 28/16-22Z and streamers may cause heavier SHRA
downwind of the USVI, Culebra and Vieques in ern PR. East northeast
sfc winds to incr aft 28/14Z to 15 to 23 knots with gusts to 30 kt
psbl alg the Atlantic coasts. Max winds E 30-35 kt btwn FL030-065
and WNW btwn FL420-520 thru 29/00Z.


&&

.MARINE...The combination of a northerly swell with fresh to
strong easterly winds will continue to result in hazardous marine
and surf conditions today through the weekend. That is, seas of 8
to 12 feet with occasional seas up to 14 feet and winds up to 25
knots with gusts. This will create breaking waves between 10-11
feet, particularly along the northern coast of Puerto Rico,
Culebra and Saint Croix. As a result, small craft and high surf
advisories, as well as a high rip current risk are in effect.
Please refer to the latest Coastal Waters Forecast (CWFSJU) and
Marine Weather Message (MWWSJU) issued by the National Weather
Service WFO San Juan PR.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 82 74 84 74 / 90 80 50 50
STT 84 74 85 73 / 90 90 50 50

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
528 AM AST Sat Dec 29 2018

.SYNOPSIS...Drier air is beginning to enter Puerto Rico and the
U.S. Virgin Islands, but bands of moisture from the north and
easterly flow driven by high pressure to the north will bring
scattered to numerous showers to the islands for much of the next
7 days.

&&

.SHORT TERM...Today through Monday...
The strong 1033 mb high pressure ridge over the central Atlantic
is still holding across the region, and creating a strong pressure
gradient over the local Islands. Luis Munoz Marin International
airport reported a peak wind of 42 mph yesterday and 32 mph
already this morning since midnight. These strong winds affected
other areas of the Islands as well. Breezy conditions will
continue this morning and through the afternoon, but peak winds
are forecast to be slightly lower than yesterday`s reports. A
wind advisory is still in effect for all but interior portions of
Puerto Rico and adjacent Islands today. The advisory will continue
into tonight for Culebra, Vieques and the northern U.S. Virgin
Islands.

A vigorous upper-level trough is positioned just northeast of
Puerto Rico. This feature will remain to the northeast of the
Island and slowly weaken over the next several days. High
pressure will continue over Cuba for the next several days to
dominate the weather pattern and a weak northeast jet will move
over the area today through Monday.

The surface high will continue to push patches of moisture across
the region through late Saturday, therefore expect brief periods of
light to moderate rain across portions of eastern, interior, and
central Puerto Rico this morning and afternoon. In addition, the
Islands of Culebra, and the U.S. Virgin Islands will also
experience the showers. The GEOS-17 GOES Total Precipitable water
product shows the higher precipitable values of 1.7 inches south
of the southern plains, while precipitable waters values across
the Metro and other areas have precipitable values of 1.2 inches,
this is a result of drier air that has worked in behind the
moisture. However, as a result of wind convergence and upward
vertical motion, showers will once again increase across the
Metro, interior and coastal areas this morning. Analysis of the
850 mb relative humidity shows values ranging from 70 to 90
percent across the region, but pockets of drier air during the day
will cause the values to fall briefly. As a result of moist low
levels, as well as periods of light to moderate rain, skies will
be partly cloudy today. In addition, the mid to upper levels of
the atmosphere will remain dry and devoid of moisture, this will
continue through the short-term period.

Sunday and Monday, the region will begin to dry out as a result of
the upper-level trough weakening, and drying of the 850 mb level due
to drier air. However scattered showers will be possible due to
the lingering moisture that will remain.

.LONG TERM...Tuesday through Saturday...
Tuesday and Wednesday high pressure at the surface north of the
area forces some of the cooler air toward the area and a weak
shearline passage is indicated Wednesday with some showers moving
through the area from the north northeast in bands. After this the
high pressure slides east and blocks the approach of any other
frontal systems. The high pressure at mid levels over the Bahama
Islands will move east and cross north of the area on Thursday. It
will remain northeast of us in close proximity. Because of this
mid levels remain very dry through beyond New Year`s Day. The
upper level high that was west of us in the short term period will
cross over the area on Thursday and allow the sub tropical and
sub-equatorial jet to merge over the area over the weekend to
follow.

Due to the continuous easterly low level flow and the numerous
bands of moisture in the low levels, showers will continue over
Puerto Rico and the U.S. Virgin Islands, but they will mostly
favor the eastern slopes of Puerto Rico. Amounts will be mostly
light each day.

&&

.AVIATION...Gusty winds between 25 and 35 knots will continue to
affect all terminals through the fcst pd. Brief MVFR/VSBYs may
occur as a result of -SHRA/SHRA across the terminal sites thru
29/22Z. Sfc winds will be out of the east ranging from 20 to 35
kts, then winds turn to the east to northeast at 15 to 32 kft
with winds ranging from 15 to 30 kts. Some sct to bkn clouds at
019 t0 25 kft.

&&

.MARINE...Winds have likely peaked early yesterday evening and
will gradually subside below 25 knots on Sunday. Nevertheless
fresh to strong winds will continue over the outer waters and
maintain hazardous seas over portions of the local waters through
at least early Wednesday morning. This will also keep a high risk
of rip currents on the local beaches. High surf is expected to
subside on the northern coasts and should end by Sunday.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 83 74 84 72 / 60 30 20 30
STT 84 73 83 73 / 40 30 20 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
452 AM AST Sun Dec 30 2018

.SYNOPSIS...Patchy moisture upstream in the easterly flow around
persistent high pressure north of the area will supply scattered
showers to the USVI and eastern Puerto Rico for the next several
days. Conditions will improve later this week.

&&

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

A surface ridge across the central Atlantic will continue to hold
across the region, thus promoting moderate to strong northeast to
east winds. Today patches of low-level moisture embedded in the
trade winds will carry showers periodically over the northern,
interior and southeastern areas of Puerto Rico this morning and
during the afternoon. The GEOS-16 night-time Microphysics RGB
product shows a plume of moisture that extends from the central
Atlantic to Windward Islands, this moisture is a result of a sheared
frontal boundary in the central Atlantic waters. Once the frontal
boundaries shear out, the remaining moisture gets pulled into the
anti-cyclonic gyre. As a result of the continuous gyre effect
with moisture being pulled across the area scattered showers are
possible through Monday.

Recent guidance shows the region drying out quickly today, but
THE GOES-16 night-time microphysics products shows an abundant
amount of moisture still streaming across the Caribbean.
Therefore, the POPs forecast are higher than the GFS, due to
patches of moisture that will continue moving over the region. In
addition, rainfall amounts will be light due to the fast movement
of showers. Monday afternoon an increase in moisture is expected
across the area, which will increase rain chances through Tuesday.
The mid and upper levels of the atmosphere remains devoid of
moisture, but moisture remains in the 1000 to 850 mb levels. This
is depicted by the 30/00Z TJSJ sounding which showed saturated
lower levels. Otherwise, a seasonable weather pattern will
continue for most of the region through Tuesday.

.LONG TERM...Wednesday through Sunday...

High pressure over Cuba in the upper levels will weaken somewhat
and pass just north of the area on Thursday. Multiple jets will
then form in the west southwest flow ahead of a long wave trough,
one of which will move over the local area Saturday and Sunday. At
mid levels, high pressure just northwest of the local area will
begin to move east. Once it passes the local area to the north
later Thursday it will begin to stretch out into the eastern
Atlantic. This will maintain dry to extremely dry conditions in
the mid levels, and even the upper levels for the most part,
throughout the period. At lower levels an old frontal boundary
will finally move through the area Wednesday, followed by patches
of moisture out of the east central Atlantic through the end of
the period. The GFS shows low-level winds turning to the southeast
Thursday through Friday which will allow a warming trend--
especially on the north coast and around the Greater San Juan
Metropolitan area. Some drying will enhance the reduction in the
shower activity Saturday and Sunday. Currently the GFS suggests a
pleasant weekend next week, but the model has not shown any
consistency in its forecast after Thursday, so confidence in the
forecast is low beyond that time.

&&

.AVIATION...VRF/MVRF conds in fast movg SHRA will continue
through the 31/18Z TAF period. Breezy trade winds will continue to
bring occasional SHRA/-SHRA across the terminals through 31/18Z.
Gusty conditions will persist through at least this evening. East
to northeast winds at 15 to 25 knots from the surface to FL024,
then winds are expected to diminish to between 10 and 15 kt after
31/03z.

&&

.MARINE...Although winds will diminish from the 20 to 30 knots
seen last week, winds up to 20 knots will not completely disappear
from the forecast for at least 5 days. As such 7 foot seas will
continue in the outer waters and local passage through at least
Thursday. Some relief is suggested afterward. Gusty conditions
will persist at least through today as winds only gradually
diminish.

&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
502 AM AST Mon Dec 31 2018

.SYNOPSIS...Moisture levels will increase through Sunday morning
from these relatively dry conditions. A weak shearline will move
into the area and stall over Puerto Rico and the U.S. Virgin
Islands on Wednesday morning and then models show a good chance of
that line riding across the islands through Sunday bringing a
wetter period. When the line advances to the southwest drier
weather will intervene for one or two days.

&&

.SHORT TERM...Today through Wednesday...
A fair weather pattern will continue across the region over the next
several days with light to scattered showers mainly during the early
morning across the eastern portions of Puerto Rico as well as the
U.S. Virgin Islands. An elongated ridge of high pressure is
positioned north of Puerto that will help promote a drier weather
pattern through Tuesday afternoon. In addition, this ridge is
also creating a strong cap inversion at 800 mb, and drier air
extends from 800 to 200 mb. The precipitable water values over
the next several days will fall to the 25th percentile for the
month of December. However, the relative humidities at 850 mb are
ranging from 60 to 80 percent, which means there is moisture in
the lower levels of the atmosphere.

Tuesday afternoon guidance shows moisture moving in underneath the
surface ridge, this will increase the precipitable water value as
well as rain chances across portions of eastern and interior
areas of Puerto and the U.S. Virgin Islands during the afternoon.
This moisture is forecast to remain across the area through
Wednesday, and cause light to moderate passing showers.

Winds will increase today and will remain fresh to strong Tuesday
and Wednesday as the boundary moves through.

.LONG TERM...Thursday through Monday...
The upper level trough to our east will move into the western
tropical Atlantic and allow a broad ridge to dominate the
Caribbean. A sub-equatorial jet of moderate strength will move
into the area over the weekend and by Monday may actually have
some influence on re-moistening the pattern. At mid levels, high
pressure just north of Hispaniola on Thursday will shift to
northeast of Puerto Rico by Sunday and then regroup over the
western Caribbean as the southern periphery of a short wave
approaches the area on Monday. In any case, mid-levels will remain
quite dry through the period, although lower level moisture will
deepen considerably Thursday through Sunday as columnar moisture
improves.

The lower level pattern is still the main driver of the weather to
be seen in the long term. After a weak shear line moves into the
area Wednesday, the GFS has it stalling over the area Thursday through
Sunday. This will bring scattered to numerous showers to eastern
Puerto Rico and the U.S. Virgin Islands during the period with
light to moderate accumulations and isolated to scattered showers
to western Puerto Rico with generally light accumulations. Again
still cannot take this interpretation to the bank as any variation
would leave the boundary on either side of Puerto Rico and the
U.S. Virgin Islands. High pressure at the surface in the sub-
tropics will continue northeast of the area to drive moderate to
fresh trade winds holding the pattern in place. For now, however
the GFS has drier air moving into the area Sunday and Monday
behind the boundary, and with high pressure at mid and upper
levels, conditions should be considerably drier for the entry to
next week than is now expected after mid week this week. Winds
will also diminish next week.

&&

.AVIATION...VRF conds will continue through the 01/00z TAF period.
Breezy east to northeast trade winds of 15 to 20 kts with higher
gusts will continue across the terminals sites through 31/18Z. An
occasional SHRA is possible during the afternoon. Max winds NE 50
kt at FL360 bcmg less than 35 kt at all levels by 01/00Z.

&&

.Fire Weather...Relative humidities dipped into the 30s along the
southern coast yesterday, and although moisture may be improving
slightly, relative humidities below critical values are expected
again today. Winds will be borderline but are expected to increase
today into Tuesday. With KBDI values at Cabo Rojo, Guanica and
Camp Santiago all above 600, will issue a Red Flag Warning for the
south coast of Puerto Rico again today. Nevertheless these
hazardous conditions are only expected to exist for a few hours
around midday.

.MARINE...Seas were subsiding across the local waters, but winds
are forecast to increase slightly today and tomorrow and seas will
not be allowed to relax completely before a new round of hazardous
seas is generated. Therefore the small craft advisories in the
outer waters and passages will continue through either Wednesday
or Thursday and most inner waters (except on the southern and
western coasts of Puerto Rico) will have small craft advisories
beginning either tonight or Tuesday and lasting until Tuesday
night. Some relief is expected late this week, but some seas may
not fall below 6 feet even then.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 83 74 82 75 / 30 30 40 60
STT 85 74 84 74 / 20 30 40 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
348 AM AST Tue Jan 1 2019

.SYNOPSIS...
A relative dry weather pattern will continue today; then moisture
will increase across the area on Wednesday and remain through
Thursday. The increase in moisture will cause scattered showers
with light rainfall amounts. Then ridging at the surface and aloft
will reinforce its hold over the region, as well as, limit shower
development. A dry weather pattern is expected to continue
through the weekend into early next week, with an occasional
shower possible mainly during the early mornings and afternoon
across portions of eastern and interior areas of Puerto Rico.

&&

.SHORT TERM...Today through Thursday...
A drier than normal air mass with precipitable water values near
1.00 inch will promote mainly dry weather conditions across the
forecast area during the first day of 2019. Surface high pressure
anchored over the west-central Atlantic will continue to promote
breezy conditions across the region with east to northeast winds
between 15 and 20 mph with higher gusts expected.

An increase in low-level moisture, associated with the remnants of a
frontal boundary, is expected by Wednesday and Thursday. This will
result in an increase in trade wind showers across the region. The
showers that develop and move across the region are expected to be
brief and lead to light rainfall accumulations with minor ponding of
water on roadways expected. Most of the activity is expected to be
concentrated over portions of northern and eastern Puerto Rico,
Culebra, Vieques, and the USVI. Breezy conditions are expected to
prevail as surface high pressure will continue to hold over the west-
central Atlantic promoting moderate to fresh easterly winds.


&&

.LONG TERM...Friday through Tuesday...
High pressure at the surface and aloft will lead to relative fair
weather across most of the region through the long-term period.
The weather pattern will be steered by the low level flow over the
area. Therefore, expect patches of moisture to move into the
region from the east from time to time. The moisture will be
associated with remnants of frontal boundaries trapped underneath
the surface ridge.

The GFS as well as the NBM models show 850 mb relative humidity
values nearing 20 to 50 percent, due to dry stable air masses. The
low relative humidity values at the surface will limit shower
development across Puerto Rico and the U.S. Virgin Islands. In
addition, the mid to upper levels are devoid of significant
moisture to help in shower development. The factors listed above
combined with the lack of upper and low-level instability will
lead to a drier weather pattern through the long-term period.

&&

.AVIATION...
VRF conds expected to prevail across the region throughout the
forecast period. E to NE winds below 10 kts through 01/13z,
increasing to 15 to 20 kts with higher gusts afterwards.

&&

.MARINE...
A strong surface high pressure will continue to cause moderate to
strong easterly winds across the local and outer waters over the
next several days. Thus a small craft advisories are in effect for
most of the coastal waters today due to sea reaching 8 feet.
Elsewhere, seas will range from 4 to 6 feet therefore small craft
should exercise caution. Winds will be out of the east to
northeast ranging from 15 to 20 kts. A risk of rip currents for
the northern beaches of Puerto Rico, as well as, Culebra and the
U.S. Virgin Islands today.

&&


FIRE WEATHER...
A dry weather pattern will continue across the southern coastal
plains today, but rain chances will increase tomorrow through
Friday as moisture moves in from the east. KBDI are above 600 and
Minimum relative humidity values will ranging from the middle
40`s to the lower 50s. In addition, 20FT winds will be 15 to 20
mph, while Surface winds will be out of the east to northeast
ranging from 15 to 20 mph with higher gusts likely. The
combination of low relative humidity values, as well as
significant drying as a result of east to northeast winds will
cause a high fire danger threat.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 83 74 82 74 / 30 20 20 60
STT 85 74 84 74 / 20 20 20 50

[cycloneye]

Happy New Year 2019 to all our Caribbean and Central American friends.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
348 AM AST Wed Jan 2 2019

.SYNOPSIS...
Patches of moisture associated with a remnant frontal boundary is
forecast to move into region later today and remain through
Thursday. This moisture will increase rain chances mainly across
portions of northern and eastern Puerto Rico, as well as, the U.S.
Virgin Islands through Thursday. However, showers are expected to
be brief due to the lack of instability and upper level support.
Strong east to northeast winds will continue to prevail through
early next week, which will inhibit sea breeze development. Then
early next week guidance shows a pattern chance might occur, as
the ridging aloft will be replace by an upper-level trough to the
north of Puerto Rico.

&&

SHORT TERM...Today through Friday...

An increase in low-level moisture, associated with the remnants of a
frontal boundary, is expected for today and Thursday. This will
result in occasional trade wind showers moving across the region.
These showers, however, are expected to be brief and only lead to
light rainfall accumulations. Most of the activity is expected to be
concentrated across portions of northern and eastern Puerto Rico and
the USVI as well as the surrounding waters. Lesser rainfall activity
is expected across western Puerto Rico as the low-level flow will
continue to remain strong enough to inhibit sea breezes from
developing and triggering the development of significant shower
activity. Surface high pressure over the west-central Atlantic will
continue to result in breezy conditions with east to northeast winds
between 10 and 20 mph with higher gusts expected.

As the low-level moisture field associated the remnants of the
frontal boundary move southward over the Caribbean waters, a drier
airmass will move over the region for Friday. Therefore, mainly fair
weather conditions are expected.

&&

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

The long-term period will remain relatively dry due to the lack
of low level moisture, and strong ridging which will suppress
shower development. However, guidance shows moisture getting trapped
underneath the surface ridge late Saturday into early Sunday,
then moving west across the region. The moisture will come from a
remnant frontal boundary that sheared out in the Central Atlantic
waters.

The moisture will increase precipitable water values, as well as,
increase 850 mb relative humidity values to 60 to 70 percent, but
with every patch of moisture there is drier air right behind it.
In addition, the mid to upper level of the atmosphere continues to
be devoid of significant moisture to help in shower development.
Therefore, expect isolated to scattered showers across portions of
eastern, interior, and southern areas of Puerto Rico mainly
during the morning and late afternoon Sunday through Wednesday.

Late Wednesday model guidance shows a change in the weather
pattern with ridging aloft breaking down due to an approaching
front.

&&

.AVIATION...

Mainly VRF conds expected to prevail across the region throughout
the forecast period. Brief SHRA will be possible at times across
TIST/TISX/TJSJ/TCNM/TKPK terminals throughout the day. E to NE winds
below 10 kts will continue through 02/13Z, increasing to 15 to 20
kts with higher gusts afterwards.

&&

.MARINE...
Marine conditions will continue to be choppy due to moderate to
fresh winds across the local and outer waters. Seas are forecast
to range from 5 to 7 feet across most of the local waters.
Therefore, a small craft advisories are in effect due to seas of 5
to 7 feet. A risk of rip currents for the northern beaches of
Puerto Rico and the beaches of the U.S. Virgin Islands today.

&&

.FIRE WEATHER...

A dry weather pattern will continue across most of the local
Islands through Friday. KDBI values will be above 600 and 10 hour
relative humidity readings near the middle 40 to lower 50 percent.
In addition, 20FT winds will be 15 to 20 mph, while Surface winds
will be out of the east to northeast ranging from 15 to 20 mph
with higher gusts likely. Therefore, due to the conditions above
and the lack of low-level moisture for wetting rains, and continue
drying of fuels a high fire danger threat is expected today for
the southern coastal plains.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 82 74 83 75 / 40 40 30 20
STT 85 74 81 75 / 30 20 20 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
508 AM AST Thu Jan 3 2019

.SYNOPSIS...Mid to upper-level ridge pattern will hold across the
forecast area through early next week. This will maintain a fairly
stable weather pattern with mainly fair weather conditions
expected. Surface high pressure across the west-central Atlantic
will continue to promote breezy conditions through the weekend.
The ridging pattern aloft is forecast to erode by the middle of
next week and will be replaced by a mid to upper-level trough,
resulting more unsettled weather conditions by the latter half of
next week.

&&

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

The weather pattern in the short term is expected to be mainly
benign, with little to no rainfall accumulations even though
isolated to scattered showers are possible. A decrease in moisture
is expected today across the local area, even drier air expected on
Friday, but slightly higher moisture expected on Saturday. The
satellite imagery is showing cloudiness over the local area, which
is expected to continue through the morning hours as it moves south,
slightly. By this afternoon, most of the dense cloudiness is
expected to be across the Caribbean waters, scattered clouds over
the local islands. The shower activity is also expected to gradually
decrease as the day progresses with mainly isolated showers by this
afternoon across the local islands, although scattered showers are
expected across eastern PR. That said, the rainfall accumulations are
expected to be minimal across all areas.

Easterly winds are expected today but turning more ESE on Friday,
which will combine with the much drier air expected to cause higher
than normal daytime temps across northern PR, particularly across
the San Juan Metro and the north central sections of PR. Otherwise,
temperatures should be fairly close to normal.


.LONG TERM...Sunday through Thursday...

The aformentioned mid to upper-level ridge pattern is forecast to
hold across the forecast area through at least Tuesday of next
week. This will continue to maintain the mid to upper-levels of
the atmosphere very dry, resulting in a fairly stable weather
pattern to continue with mainly fair weather conditions expected.
However, some small patches of low-level moisture embedded within
the trade wind flow could result in some occasional trade wind
showers mainly affecting portions of northern and eastern PR and
the USVI, especially during the overnight and early morning hours.

Both the GFS and ECMWF models suggest that a major change in the
synoptic pattern will ensue by the middle of next week as the mid
to upper-level ridge pattern that has been the dominant feature
for the last 4 to 6 weeks will erode and give away to an
amplifying mid to upper-level trough that will be moving across
the western Atlantic. If model guidance is correct on this change
in the synoptic pattern, more unsettled weather conditions could
be expected by the latter half of next week with the potential for
more significant rainfall activity.

&&

.AVIATION...VFR conds expected across the local terminals for the
next 24 hours with only ISOLD/SCT brief -SHRA in the morning,
becoming more ISOLD in the afternoon. Winds will be mainly from
the east at around 15KT with occasional gusts until 03/23Z,
decreasing winds thereafter.


&&

.MARINE...Moderate to fresh east to northeast winds will continue
to result in rough and choppy seas between 5 and 7 feet across
the regional waters for today. By Friday, seas are expected to be
below Small Craft Advisory criteria across all regional waters,
however, they will continue to be choppy as breezy conditions will
continue. There is a high risk of rip currents across the north
facing beaches of PR, Culebrita Beach in Culebra and Cramer Park
in Saint Croix.


&&

.FIRE WEATHER...Recent observations continue to indicate that the
vegetation across the southern coastal plains of Puerto Rico
continues to be very dry with KDBI values well above 600. For
today, winds out of the east near 15 mph with higher gusts along
with relative humidity values dropping below 50% are expected.
Therefore, a fire weather statement (RFDSJU) has been issued given
that the fire danger threat will be elevated. It should be noted
that by Friday Red Flag Warning criteria may be reached once again
as a drier air mass is expected to move over the area, resulting
in relative humidity values reaching the criteria.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 84 73 88 75 / 40 30 20 30
STT 83 74 85 74 / 20 10 20 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
448 AM AST Fri Jan 4 2019

.SYNOPSIS...Mid to upper-level ridge pattern will continue to hold
across the forecast area through the weekend, resulting in mainly
fair weather conditions. Occasional patches of low-level moisture
embedded within the trade wind flow may result in some brief
showers in a few areas through the weekend. A gradual transition
to a wetter weather pattern is expected by next week as the
ridging pattern aloft gives way to an amplifying mid to upper-
level trough moving across the western Atlantic.

&&

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

Patches of moisture will pass through the local area for the next
few days. Today will be a predominantly dry day with precipitable
water values will below normal, estimated to be below an inch over
Puerto Rico and just over an inch around the USVI. This will cause
mainly fair weather, but isolated to scattered brief showers would
be expected across the local waters and near the USVI. For Saturday
the moisture will remain low overall, but a surface low moving into
the northwestern Atlantic will pull some moisture, causing an area
of slightly higher moisture to move over the Caribbean waters and
the coastal sections of SE-PR as well as the waters to the NW of PR.
Then on Sunday, the moisture will hold steady except for a patch of
moisture that could move across the USVI, causing a higher chance of
showers across the local waters and USVI. Regardless of setup and
chances of showers, it appears that the rainfall totals would be
generally less than a tenth of an inch for most areas.

Surface high pressure will remain to the north northeast of the
local islands, keeping moderate easterly winds for the next few
days, with the exception of ESE winds expected over portions of PR
today. Given the much drier than normal air today and the slight ESE
wind component, the high temps today may be in the mid to upper 80s
across the lower elevations of PR and the USVI. The temps in the
upper 80s combined with the lower moisture may cause lower than
normal relative humidity values for the southern coastal areas of PR
today.

.LONG TERM...Monday through Friday...

An upper-level trough will be situated near Cuba Monday into
Tuesday, which will result in an upper-level jet of near 70 knots
moving over the area. However, there is some discrepancy between
the GFS and ECMWF models on how much moisture will be available
over the area as the GFS model shows precipitable water values
reaching as high as 1.8 inches while the ECMWF model is much
drier with precipitable water values only reaching as high 1.3
inches. Either way, given that the upper-level dynamics may be
favorable for some upward vertical motion, an increase in shower
activity is likely on Monday into early Tuesday across the area.

Both the GFS and ECMWF models continue to be consistent in
indicating that a mid to upper-level polar trough will be
amplifying across the western Atlantic by the second half of the
work week. This would most likely result in unsettled weather
conditions with more rainfall activity possible. Having said that,
it is still too early to determine how much rainfall could be
expected during the second half of the work week as it will all
depend on how much low to mid-level moisture will be available
and where the best upper-level dynamics will set up.

&&

.AVIATION...VFR conditions expected across the local terminals
with fair weather expected. ISOLD -SHRA is expected across the
local flying area but is it not expected to cause a significant
impact. Winds will be from the east at around 15KT with occasional
gusts today, decreasing after 04/23Z. SHRA activity may increase
after 05/00Z causing SCT SHRA across the local flying area.

&&

.MARINE...Surface high pressure across the west-central Atlantic
will continue to result in moderate to locally fresh easterly
winds of 15 to 20 knots across the regional waters through the
weekend. This will result in choppy wind-driven seas of up to 6
feet. Therefore, small craft operators should exercise caution.

&&

.FIRE WEATHER...Due to the lack of wetting rains across the Southern
Coastal Plains of Puerto Rico during the last several days, the
vegetation continues to be very dry. For today, a dry air mass
will prevail across the region. The combination of this dry air
mass along with moderate east to southeast winds of greater than
15 mph with higher gusts will result in relative humidity values
dropping between the 35 and 45 percent range. As a result, a Red
Flag Warning (RFWSJU) has been issued for the Southern Coastal
Plains of Puerto Rico given that the factors mentioned above will
produce a high fire danger threat.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 74 86 74 / 40 40 30 40
STT 84 74 85 73 / 30 30 20 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
514 AM AST Sat Jan 5 2019

.SYNOPSIS...Surface high pressure will prevail across the west
central Atlantic through the weekend while a surface low moves
to the north northeast across the western Atlantic. This will keep
moderate winds through the first half of next week, but another
surface low across the northwest Atlantic will cause winds to
diminish for the second half of next week. Upper level ridge will
hold over the local area this weekend, then an upper low will dig
across the western Caribbean on Monday, causing an upper jet over
the local area.

&&

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

Below normal moisture content combined with a mid to upper level
ridge pattern will aid in a fair weather pattern across the U.S.
Virgin Islands and Puerto Rico today. But a surface low with its
associated cold front will continue to pull moisture across the
local waters early this morning. Although mostly sunny skies will
prevailed over land, isolated trade wind showers should not be ruled
out across the windward sections of PR/USVI early this morning,
followed by localized induce showers across the interior and western
sections. A similar weather pattern with patches of moisture moving
across the region at times will persist on Sunday. As previous days
rainfall accumulations would be minimal for most of the area.

An upper level trough over the western Caribbean will slowly moves
closer to the region, which will bring a jet-stream near and over
the region. If model guidances are correct, instability may increase
improving vertical development across the islands on Monday.
Although thunderstorm activity was not included, if this trend
continues may be needed especially during the afternoon hours.

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

Moderate easterly winds will continue as the surface high remains
over the west central Atlantic. However, a surface low will move
NNE along the western Atlantic and will cause the local winds to
diminish significantly starting on Wednesday and becoming light
and southerly on Thursday and early Friday. A shortwave upper
trough is forecast to approach the local area late Wednesday but
the upper levels will flatten out by Thursday. The available
moisture will be near normal in the long term, but slightly
higher moisture expected on Thursday through Saturday. The overall
rainfall pattern is expected to be somewhat typical with showers
over the local waters, USVI and eastern PR in the morning and
evening hours, while stronger showers would be possible in the
afternoons across western PR, especially on the days with higher
moisture.

&&

.AVIATION...Under a fair weather pattern VFR conditions will
prevail today. Winds will continue calm to light and variable,
increasing around 15 kt with occasional gusts out from the E-ESE
after 05/13z.

&&

.MARINE...Small craft operators are urged to exercise caution
today across the local waters due to seas up to 6 feet and winds
up to 20 knots. There is a moderate risk of rip currents across
many of the local beaches. Seas are expected to diminish slightly,
mostly up to 5 feet on Sunday, but still choppy due to moderate to
fresh winds.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 85 73 85 75 / 40 40 40 50
STT 84 74 84 73 / 40 50 50 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
457 AM AST Sun Jan 6 2019

.SYNOPSIS...Surface high pressure will continue across the central
Atlantic for the next few days, causing moderate easterly winds.
Meanwhile there is a surface low pressure moving northeast across
the northwestern Atlantic, which will pull some moisture from the
south and will cause the moisture to increase today and Monday
across the local area. Upper level low still expected to dig into
the western Caribbean, causing a 70-80kt jet over the local area,
but it might be a bit too far west to cause upper level divergence
locally.

&&

.SHORT TERM...Today through Tuesday..

A trade wind perturbation will bring a slight increase in moisture
which will result in passing showers across the local waters, USVI
and the eastern half portion of Puerto Rico. The rest of the region
will have mostly sunny skies with no shower activity. Localized
induce shower activity is also expected to develop across the
western areas during the afternoon hours.

An upper level trough over the western Caribbean will continue to
drift closer to the region bringing a jet-stream near and over the
region. In addition, moisture is expected to increase somewhat on
Monday. Although the intensity and coverage of showers should
increase, the mid-levels are extremely dry which would limit
vertical development. The islands will continue under a similar
weather pattern on Tuesday.

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

A surface high pressure will replace the current high pressure
over the west central Atlantic on Wednesday, but will move to the
east northeast into the northeast Atlantic by Friday. Which will
keep a moderate easterly wind of Wednesday but winds will diminish
significantly by Thursday and Friday as a COL develops, but
moderate easterly winds may return by next weekend. This setup
will also keep the local moisture to be near or slightly above
normal. Although the upper levels will not be particularly
conducive for an unstable atmosphere, the available moisture may
combine with the diurnal heating and local effects to cause at
least scattered showers in the afternoon across the local area.

&&

.AVIATION...A patch of moisture will bring passing SHRA across
the USVI/E-PR terminals at times through the morning hours.
Surface winds will continue from the E to ESE at less than 10
knots but are expected to increase around 15 knots after 06/13z.

&&

.MARINE...Choppy seas of 3 to 5 feet expected across the local
waters for the next few days with a moderate easterly wind. A
small northerly swell is expected on Monday but the wave heights
should remain between 3 and 5 feet. There is a moderate risk of
rip currents across many of the local beaches today.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 85 75 84 73 / 40 30 60 60
STT 84 74 83 72 / 40 60 60 60

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
520 AM AST Mon Jan 7 2019

.SYNOPSIS...
A trade wind perturbation will bring an increase in moisture
across the islands today. As a result, showers will move more
frequent across the local waters, the U.S. Virgin Islands and
eastern and northern Puerto Rico in the morning, followed by
afternoon convection across the interior and western sections. A
drier air mass will limit shower activity on Tuesday. At upper
levels, the high pressure is forecast to weaken as an upper level
trough over the western Caribbean move closer to the region. A
jet stream is forecast to filter from the west into the region
increasing upper level dynamic and instability later tonight into
mid-week.

&&

.SHORT TERM...Today through Wednesday..

The available moisture will increase today with a trade wind
perturbation, which will result in passing showers across the local
waters, USVI and the eastern half of Puerto Rico through the day. It
will also combine with the local effects to cause showers across
western Puerto Rico in the afternoon. The rest of the region will
have variably cloudy skies with only a slight chance of showers. The
showers across western Puerto Rico could cause ponding of water on
poor drainage areas this afternoon. Drier air moves in on Tuesday,
which will cause less shower activity than what is expected today.
However things change for Wednesday.

An shortwave trough in the upper levels will develop and position
over Hispaniola by Wednesday afternoon. This will cause an increase
in upper level instability which will combine with the increasing
moisture expected for Wednesday into Thursday. The model guidance
has been consistent in showing this upper trough. The timing of it
seems to coincide with the time of max heating over PR, so the upper
trough could combine with the moisture and diurnal heating, which
would cause showers and thunderstorms over central into western PR.
For that reason the forecast for Wednesday afternoon has numerous
showers and isolated thunderstorms for the northwestern quadrant of
PR. The high resolution models were very bullish on the amounts of
rain but we held back a little in the rain totals until we see more
consistency among the high resolution guidance. That said, with the
expected rainfall, urban flooding would not be out of the realm of
possibilities on Wednesday afternoon. As the upper trough moves
east, by the nighttime hours from Wednesday into Thursday, the upper
trough would be over the local islands, which would cause the area
of highest instability over the waters and probably east of the
USVI. We will see if the model guidance continues to be consistent
with this increase in moisture as the upper trough passes through
the area, because if it does, this could mean that the USVI could
observe some showers and isolated thunderstorms at some point on
Wednesday late afternoon into evening.

.LONG TERM...Thursday through Tuesday...
An upper-level short wave trough with a jet stream will exit the
region Thursday leaving a zonal flow aloft through the rest of the
work-week. Another upper level ridge is forecast to build the
upcoming weekend and hold into early next week. At the surface,
winds will diminish and veer from the southeast/south as a
frontal boundary moves well north of the islands across the
Atlantic Waters. Under this wind flow, moisture could increase
somewhat over the local archipelago. Therefore, additional shower
activity is likely by the middle to latter half of the work week.

Model guidance seem to suggest the return of a fair weather
pattern by the weekend as a mid to upper-level ridge builds once
again over the local area. However, the seasonal trade wind
showers should not ruled out across the windward sections and
local waters each day, especially overnight and early in the
morning.

&&

.AVIATION...
VFR conditions expected across most of the local terminals for the
next 24 hours. SHRA activity is expected after 07/17Z near and
around TJMZ and TJBQ. The expected SHRA across TJMZ could cause
moments of MVFR conds, while VCSH is what is expected for TJBQ. SHRA
could affect TJSJ also, but the activity is expected to affect the
terminals brief moments at a time. The local winds will be from the
east at 10-15KT with occasional gusts and sea breeze variations.

&&

.MARINE...Mariners can expect tranquil marine conditions with
seas below 5 feet and winds will continue from the east around 15
knots. However, small craft operators should exercise caution
across the northwest and southwest coastal waters during the
afternoon hours due to increasing winds between 15 and 20 knots. A
small northerly swell is expected to arrive today, however, it is
not expected to increase seas. A moderate risk of rip currents is
expected to continue across several of the local beaches, except
along the west coast of Puerto Rico and St John where the rip
current risk is expected to remain low.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 84 73 83 73 / 60 20 20 20
STT 84 72 83 73 / 40 20 30 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
518 AM AST Tue Jan 8 2019

.SYNOPSIS...
The high pressure north of the area will induces a northeast wind
flow across the region today, which will bring a slot of dry air
limiting shower activity today. At upper levels, the ridge
pattern will continue to weaken as a TUTT-Low, over the western
Caribbean, move west of Puerto Rico by Wednesday. A jet stream
associated with this upper level feature will enhance upper level
dynamic and instability over the northeast Caribbean.

&&

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

Generally fair weather is expected today as drier than normal air
mass is expected over the area. There is also an upper and mid level
ridges over the local area. The surface wind will be mostly from the
ENE which may cause a few afternoon showers across the southwestern
quadrant of PR in the afternoon, but the rainfall accumulations
would be generally less than a quarter of an inch of rain. However,
starting tonight, moisture will gradually increase and continue to
increase through Thursday. The upper and mid levels may also turn
slightly more unstable towards Thursday, which may help in the
development of more significant showers.

The high resolution guidance insists in good amounts of rain for the
afternoons of Wednesday and Thursday, although Wednesday looks more
limited in coverage than Thursday. The latest guidance shows some
divergence in the upper levels on both days in the afternoons. In
addition, the upper ridge will gradually weaken as the upper trough
approaches from the west. Forecast soundings indicate that the mid
levels will gradually moisten as well. There is however some
uncertainty on the amounts of rain and coverage at this time. The
high resolution models seem to have underestimated the rainfall
potential yesterday and it did for a few days within the past week,
so that puts a question mark on the performance of these high res
models when the pattern turns a bit wetter. The global models have
backed off some on the amount of moisture on Wednesday, but it does
put more on Thursday. That said, the models have been consistent for
the most part on the upper trough moving in and the mid level ridge
also weakening, gradually giving way to a mid level trough
transitioning from Wednesday into Thursday. So, the bottom line is
that the middle of the week looks a bit more active than we observed
last week.

.LONG TERM...Friday through Wednesday...
Model guidance suggest a zonal flow aloft with a jet stream
through at least early this weekend, when a ridge pattern is
forecast to build and hold into early next week. At the surface,
winds will diminish and veer from the southeast/south as a frontal
boundary moves well north of the islands across the Atlantic
Waters on Friday.

Winds are forecast to return from the east, and patches of
moisture will reach the islands from time to time each day. Model
guidance continues to suggest the seasonal trade wind showers
across the windward sections and local waters each day, especially
overnight and early in the morning. Limited afternoon convection
across the western sections should not be ruled out each day.
A frontal boundary is forecast to move close to the islands by
Wednesday.

&&

.AVIATION...
VFR conds expected across the local terminals today. SCT SHRA
expected across SW-PR after 08/16Z, which could affect the vicinity
of TJMZ. Winds will be from the ENE at around 15KT with some sea
breeze variations.

&&

.MARINE...Mariners can expect tranquil marine conditions today
across the USVI/PR waters with seas between 3 and 5 feet and east
to northeast winds between 10-15 kt. A surface high pressure
north of the region will keep moderate easterly winds through at
least Wednesday, when winds are forecast to veer from the east-
southeast as a frontal boundary move off to the north of the
islands. A northerly swell will increase seas between 4-6 feet
across the Atlantic waters between Wednesday and Thursday.

For the beach goers, a moderate risk of rip currents will
continue for most of the east, north and southern beaches of
Puerto Rico and the U.S. Virgin Islands.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 83 73 82 72 / 20 40 40 10
STT 84 74 82 72 / 20 30 30 10

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
523 AM AST Wed Jan 9 2019

.SYNOPSIS...The chance for shower activity will increase today
and Thursday. Isolated thunderstorm activity cant be ruled out. A
more seasonal weather pattern is expected the upcoming weekend
with trade wind showers at times.

&&

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

A high pressure located over the western Atlantic will drift into
the central Atlantic inducing a northeast trade wind flow across the
islands. Satellite imagery depict an area of clouds and showers
between the U.S. Virgin Islands and the Leeward islands, this surge
of moisture will move into the islands throughout the day. As a
result, showers activity is expected to affect the windward sections
of Puerto Rico and the U.S. Virgin Islands during the morning hours
and then will spread into the interior and western sections late in
the morning into the afternoon hours. At mid-levels, high pressure
will continue to erode today and Thursday and moisture will increase
from midday today through late Thursday. At upper levels, a strong
jet will continue over the area from the west-southwest and peaking
this afternoon. Instability is expected to increase somewhat late
this afternoon into the evening hours, as a result thunderstorm
activity was included over western Puerto Rico.

GFS guidance is suggesting a cold front moving into the western
Atlantic which is expected to shift the winds from the south at the
surface advecting moisture over the islands. GFS Forecast sounding
also showed veering winds by Thursday afternoon, with a southerly
wind flow at the surface and a westerly flow at 200 mb. In addition,
TPW is forecast to increase around 1.53 inches, which is above the
75th percentile for January climatology. That`s said, Thursday seems
to have the best chance for widespread showers and isolated
thunderstorms.

By Friday, the cold front and a pre-frontal trough will continue to
create favorable conditions for shower development across the
islands. Under a southerly wind flow the U.S. Virgin Islands and the
southern and eastern sections of Puerto Rico could expect shower
activity overnight and early in the morning followed by afternoon
convection across the northern sections during the afternoon hours.
Under a light southerly wind flow maximum temperatures should
increase somewhat along the northern coastline Thursday and Friday.

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

As trofiness aloft moves away early on Saturday morning, a mid
level ridge pattern will build across the local isles from the
west Saturday afternoon into Sunday. The ridge aloft is then
expected to hold much of the next week with a brief weakening
anticipated Wed-Thu. At lower levels, a moderate easterly wind
flow will prevail during the upcoming weekend and into early next
week, becoming east southeast by mid week as a frontal boundary
approaches the forecast area.

Under the aforementioned pattern, trade wind showers will prevail
Saturday and Sunday. These showers are expected to mainly affect
the eastern third of Puerto Rico as well as the USVI. Fair weather
is then anticipated Monday and Tuesday as a drier air mass encompasses
the forecast area. There is a better chance for shower activity
Wednesday and Thursday as the ridge aloft erodes and the frontal
boundary approaches from the west. Pleasant temperatures to continue
during the weekend and early next week.

&&

.AVIATION...Occasional SHRA will move across the terminals of
E-PR/USVI through the morning hours, spreading into the interior
and western PR during the afternoon hours into the evening hours.
Brief MVRF conditions are possible across TJMZ/TJBQ in T-STORM
between 09/16-23z. A wet pattern with SHRA and possibly isolated
T-Storm could begin after 10/02z, mainly over the local water and
possibly over E-PR/USVI. Winds will continue calm to light and
variable, increasing at 10-15 kt from the E-ESE with sea breeze
variations after 09/13z.

&&

.MARINE...Gentle to moderate easterly winds today. However, winds
will continue to diminish during the rest of the workweek as the
local pressure gradient relaxes and a weak trough develops north
and west of the region. A small northerly swell is forecast to
enter the Atlantic waters today. This will slightly increase seas
across the offshore Atlantic with a high risk of rip currents
expected along the north facing beaches tonight.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 84 74 84 73 / 50 10 30 50
STT 84 73 84 73 / 50 10 30 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
445 AM AST Thu Jan 10 2019

.SYNOPSIS...A mid to upper level trough will provide some instability
through Friday to result in cloudiness and periods of scattered
to numerous showers across the local isles. A more seasonal weather
pattern is expected the upcoming weekend into early next week with
trade wind showers across the eastern coastal areas of Puerto Rico
and the outlying islands.

&&

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

A cold front over the western Atlantic is expected to stall north of
the area through Friday. Meanwhile, a surface high over the central
Atlantic will continue to loose influence over the region. Winds are
expected to decrease and a deep layer southerly wind flow will
prevail. A mid to upper level trough will provide some instability
through Friday and in combination with the available low level
moisture, will result in cloudiness with periods of scattered to
numerous showers over portions of the regional waters and across the
U.S. Virgin Islands and Puerto Rico. For this afternoon, light
steering south-southwest winds and sea breeze convergence over
northern PR should lead to shower development along the northern
slopes as well across the eastern sections of the islands.

Moisture is expected to peak from tonight through Friday morning and
periods of intermittent showers are possible across the USVI and the
eastern sections of PR. A more southeasterly wind flow is expected
on Friday afternoon and shower development is expected mainly over
the northwest quadrant of PR. A mid to upper level ridge is forecast
to build from the west on Saturday and moisture content is expected
to erode. A surface high pressure is also expected to build over the
western Atlantic and northeast trades will return across the region.

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

The mid to upper level ridge pattern will prevail much of the forecast
period across the local isles with a brief weakening anticipated
Wed-Thu as a deep mid to upper level trough moves across the
western Atlantic into the central Atlantic. At lower levels, a
moderate easterly wind flow will prevail Sunday into early next
week, becoming southeast by midweek as a frontal boundary approaches
from the west. Under the aforementioned pattern, trade wind
showers will prevail Sunday followed by fair weather Mon-Tue as a
drier airmass encompasses the forecast area.

There is a better chance for shower activity Wednesday and Thursday
as the ridge aloft erodes and the frontal boundary approaches
from the west. A more seasonal weather pattern with trade wind
showers will prevail Friday into the weekend. Pleasant temperature
to continue, particularly by the end of the forecast period.

&&

.AVIATION...Mainly VFR conditions are expected early in the forecast
period across all the terminals. SHRA and sct/bkn layers btw FL030-
FL250 are expected this afternoon and through the evening hours
across portions of the islands and the surrounding coastal waters.
Tempo MVFR conds are possible across the PR/USVI terminals with this
activity. Low level southerly winds are expected between 5-10 kt,
sea breeze variations expected at TJMZ/TJBQ/TJSJ after 14z.

&&

.MARINE...A light to gentle east southeast wind flow will prevail
across the local waters through Friday, becoming more easterly
during the weekend. Although seas are expected to subside
throughout the day, another northerly swell is forecast to move
into the local waters during the weekend. However, seas will
remain below SCA criteria.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 84 73 84 73 / 40 50 50 20
STT 83 72 83 72 / 50 50 50 30