Caribbean - Central America Weather

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
524 AM AST Sun Apr 16 2017

.SHORT TERM...A rich plume of moisture has been moving north over
Hispaniola and turning toward the east over the local area around
a ridge at 700 mb that extends from the Windward Islands to
Hispaniola. Yesterday most of the moisture from this flow stayed
over our local Caribbean waters and just south of there. Today it
is forecast to move over Puerto Rico. The center of a jet of west
winds at 22 degrees north latitude has been moving east and is
currently located northeast of the Leeward Islands. Although
convergence aloft was over the area yesterday at 15/18Z, today
good divergence aloft is expected in the right entrance of the jet
over the local area. This should bring better dynamics to the
area and enhance the local rainfall mainly over the interior of
Puerto Rico. Areas of moisture at mid levels can already be seen
in the latest GOES-IR clean channel moving into Puerto Rico out of
the southwest. Although this moisture may impede initial convection
as it shields the island from early heating, when convection does
fire off later this afternoon we should have ample moisture to keep
it going. The models did not end convection over the area during
the evening hours this evening, but rather kept some showers active
right through Monday. Expect most showers in the interior to end
before midnight though. With lower level winds increasing as high
pressure sags south in the western Atlantic onshore winds should
keep showers off the northern coast as flow from the north is not
particularly moist, but there is still a slight chance of one hundredth
of an inch.

Moisture fades insignificantly on Monday and Tuesday, and upper level
dynamics, that were not so favorable in previous runs, now appear to
increase and may cause another several rounds of heavy showers and
isolated thunderstorms. These will fight the approach of the mid
and upper level ridge to the west and the dry air that is encroaching
from the northeast and north, but the driest air remains northeast
of the forecast area as it is pulled into the low that will cut off
in the central Atlantic today. Therefore we will see better than usual
precipitation both of those days.


.LONG TERM...Weather conditions are forecast to significantly improve
across the region by Wednesday, as a surface high pressure ridge
will continue to spread eastward into the central Atlantic inducing
a dominant northeast wind flow. This expected pattern will tighten
the local pressure gradient consequently increase the east to northeast
low level winds. In addition, with the building and spreading of the
mid to upper level ridge just west of the region, expect increasing
subsidence aloft and a much drier airmass to filter in across the region.
Although the overall moisture transport will continue to decrease by
Wednesday and during the latter part of the upcoming work week, still
expect the moderate trade winds to advect occasional patches of shallow
low level moisture across the region from time to time. This will
be sufficient to combine with local and diurnal effect to produce
early morning showers and afternoon convection mainly over parts
of the interior and west to southwest sections of Puerto Rico.
Meanwhile, the remainder of the islands should experience partly
cloudy to mostly sunny skies with only brief early morning passing
showers followed by isolated areas of streamer like afternoon shower
activity mainly downwind of the islands each day.

&&

.AVIATION...Currently VFR. The GFS forecasts the best moisture of
next 7 days today with enhanced upper air dynamics begg aft 16/12z.
Therefore, aft 16/16Z expect areas of SHRA/isold TSRA with MVFR-LIFR
and hir trrn obscured to dvlp ovr much of interior PR. Brief pds of
MVFR are psbl at TJMZ, TNCM, TKPK otherwise VFR will prevail at TAF
sites. Some VCSH TJSJ, TJMZ, TJPS and in USVI and Leeward Islands
psbl. LLVL flow NNE-ENE but sea breezes dvlp aft 15/14Z arnd 10 to
15 kt. Max winds W up to 80 kt FL350-400 diminishing during the day
at the lower altitude.

&&

.MARINE...Mariners can expect increasing easterly winds of 10 to 15
knots and seas increasing up to 7 feet across the regional waters
today. Winds and seas are expected to continue to increase through
at least Wednesday. Therefore small craft advisories will be in effect
for the Atlantic Waters and portions of the local passages. Please refer
to the latest Coastal Waters Forecast and Marine Weather Message issued
by the WFO National Weather Service San Juan PR for the latest update
and information.

For the beach goers, the risk of rip current will increase to high
along the Atlantic Coastline of Puerto Rico and Culebra today, and
to moderate along most of the U.S. Virgin Islands.

&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
331 PM AST Sun Apr 16 2017

.SYNOPSIS...Mid to upper level ridge will hold through mid week.
Surface high pressure will maintain a moderate to fresh trade wind
flow across the region. Deep tropical moisture will continue
across the region through at least Wednesday.

&&

.SHORT TERM...Variably cloudy skies prevailed across the local
islands this morning. Early this afternoon, showers developed
across Saint Croix with up to two inches of rainfall observed at
the Airport. Moist and unstable weather conditions continues
across the region. This has resulted in the development of heavy
showers across the western interior and central interior Puerto
Rico. Latest guidance indicated a plume of high moisture content
will encompass the region through at least Monday night. As a
result, showers and thunderstorms are expected to continue
affecting the region, with the focus of the showers developing
along the Cordillera Central of Puerto Rico and mountainous areas
of the local islands. This weather pattern will continue to at
least Tuesday.

.LONG TERM...For Wednesday through Friday, slightly drier weather
conditions are expected. However, available moisture combined
with daytime heating and orographic effects will aid in the
development of showers and possible thunderstorms each afternoon
mainly across the interior and western sections of Puerto Rico.
For next weekend, models suggest another pool of moisture
affecting the local region.

&&

.AVIATION...TEMPO MVFR and possible IFR conds at TJPS/TJMZ thru
22z. SHRA/TSRA across the interior and from the USVI to E PR will
result in mtn top obscd and VCTS/VCSH periods. Additional SHRA/TSRA
en route from the Leeward islands to the USVI terminals are expected
to continue from time to time through the fcst period. Resulting in
brief MVFR periods. Surface winds expected to increase from the ENE
at 15-20 kts across the Atlantic waters and the Anegada passage
later this evening. Lighter land breezes should prevail across the
PR terminals with some brief higher gusts across the northern
coastal areas during the overnight. Gusty winds expected tomorrow
after 17/14z.

&&

.MARINE...Buoy 41043 around 180 miles north northeast of Puerto
Rico was showing seas up to 11 feet at around 9 seconds.
Meanwhile, Buoy 41053 in San seas are increasing with latest
observation showing 5 feet with a period of 8 seconds. Marine
conditions will deteriorate rapidly later tonight into Monday.
Small Craft advisories are in effect for most coastal waters.

&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
507 AM AST Mon Apr 17 2017

.SYNOPSIS...Moist flow from the south pushing up against a frontal
boundary extending out of a low pressure in the central Atlantic
will continue to produce copious rainfall for much of Puerto Rico
and Saint Croix today and tomorrow. North flow on Wednesday and
Thursday will allow some drying while still supporting afternoon
showers, but a fresh surge of moisture from the south will bring
back heavy rains over the weekend and into next week.

&&

.SHORT TERM...Today through Wednesday...
The Flash Flood Watch continues in effect through midnight tonight.
Another day with moderate to locally heavy rainfall in the afternoon
over PR is expected as good moisture will prevail over the local
area with precipitable water values close to 2 inches. There is also
a strong jet over the local area with a speed of 90 knots
expected according the the GFS forecast sounding. This same
forecast sounding also suggests that the dew point depression
will become yet smaller, to become more saturated, as the day
progresses. So given the saturated soils, the available moisture,
the upper level jet and the decent equivalent potential
temperature expected, all combined with the local effects, we
should be in store for a relatively active day with showers and a
few thunderstorms. The only limiting factor for today would be the
cloudiness that is currently present over the area, which could
inhibit some of the convection for the afternoon, however, if any
of that cloudiness thins out then we could have good convection in
the afternoon. The USVI should observe mainly isolated to
scattered showers.

After today, it looks like it will gradually start to dry out but
Tuesday still looks like showers and thunderstorms are possible. A
slight shift to a ENE wind is possible on Tuesday, which will cause
the convection to develop more across the interior and the SW
quadrant of PR on Tuesday. For Wednesday, the available moisture
is expected to decrease significantly with precipitable water
values decreasing to about 1.5 inches and the upper level winds
decreasing to about 50 knots. This means that less shower activity
is expected on Wednesday. The USVI should observe mainly isolated
to scattered showers once again these 2 days.

.LONG TERM...Thursday through Monday
The ridge over the central Caribbean will drift over the local
area by late Friday followed immediately by a short wave trough
that will usher in the initiation of better dynamics fueled by
increasing moisture. The remains of an old frontal boundary that
was pushed into the central Caribbean south of the area Wednesday
and Thursday will return over the weekend in southerly flow at
700 mb to be followed by another plume of rich moisture out of
South America Monday into Tuesday.

Showers and isolated thunderstorms will continue in the
afternoons over interior Puerto Rico Thursday and Friday. The
surge in moisture and minor boost in upper level dynamics will
begin a gradual increase in overall showers and cloudiness
Saturday and Sunday that will continue into mid week next week. At
this point the amount of moisture suggests that we could return to
a potential for flash flooding by Monday, while the potential for
at least local urban and small stream flooding will by high again
beginning Friday or Saturday.

&&

.AVIATION...VFR conditions expected through 17/16Z across the local
terminals with winds generally at around 10 kt or less from the east
until 17/13Z. After 17/13Z the winds will increase to about 15-20 kt
with occasional gusts from the east. SHRA and isold TSRA expected
across PR this afternoon causing VCSH/VCTS and mtn obscurations.
TEMPO SHRA/TSRA is expected, causing MVFR conditions. Wx improving
after 18/00Z, leaving ISOLD/SCT SHRA across the local area. Brief
MVFR is expected thru at least 18/02Z in TNCM, TKPK. Maximum winds
WSW 90 kt FL390-450 thru 18/02Z.


&&

.MARINE...Seas are ramping up through the Atlantic waters in
northeast swell. Heights at the inner buoy near San Juan have
pushed above 7 feet, while heights at the outer buoy are just
under 10 feet. This swell event will extend itself through at
least Tuesday before it begins to subside. Current indications are
that the northern coasts of Puerto Rico and the U.S. Virgin
Islands will have high surf with 10 feet or better breaking waves
beginning Tuesday morning. Mariners will find conditions improving
Wednesday. Increased winds in the Caribbean will also support wave
development there and small craft advisories for swell entering
from the passages are already in place.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 85 74 83 74 / 60 40 30 10
STT 85 75 83 73 / 40 20 20 10

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
453 PM AST Mon Apr 17 2017

.SYNOPSIS...Very deep tropical moisture will continue across the
region through at least Tuesday night. North flow on Wednesday and
Thursday will allow some drying while still supporting afternoon
showers, but a fresh surge of moisture from the south will bring
back heavy rains over the weekend and into next week.

&&

.SHORT TERM...Very active weather this morning but mainly this
afternoon over mainland Puerto Rico, where up to 5 inches of
rainfall has been reported in some localized areas. Very deep
tropical moisture has moved across the region. This, in
combination with orographic lifting has produced very heavy
rainfall across the eastern,northeast and interior sections of
Puerto Rico. Another area which has received considerable amount
of rainfall is the southwest section of Puerto Rico. This weather
pattern will continue through at least Tuesday night. A drier
airmass will encompass the region Wednesday.

.LONG TERM...Although drier weather conditions are expected to
encompass the region Wednesday, as a High pressure system builds
across the region, this will not last for too long. Model
guidances indicated another area of deep tropical moisture will
encompass the region by the end of the week into next weekend. If
this verifies, we could see another episode with potential flood
problems for the local islands. Stay tuned.


&&

.AVIATION...TEMPO MVFR/IFR conds at TJMZ thru 22z. SHRA/TSRA across
eastern PR and across the west and interior sections of PR will
result in mtn top obscd and VCTS/VCSH periods across all PR
terminals. Additional SHRA from streamers across the Leeward and
the USVI terminals can result in tempo BKN cigs and -RA periods from
time to time through the fcst period. Low level E-ENE winds will
continue at 15-25 kts.

&&

.MARINE...Local buoys indicated seas already at 7 feet with a
period of 10 seconds. This is creating breaking waves of at least
10 feet along the northwest to northeast coasts of Puerto Rico. As
a result, A high surf advisory has been issued for these areas
until at least Wednesday afternoon. Seas up to 8 feet and winds up
to 20 knots are expected across most of local waters. Small Craft
advisories will continue in effect through at least Wednesday
afternoon.

&&

.HYDROLOGY...Very heavy rain has resulted in several flash
flooding across mainland Puerto Rico. Rainfall amounts between 3
to 5 inches have been observed mainly across the eastern section
of Puerto Rico and across the interior section of Puerto Rico. A
flash flood watch continues in effect until midnight.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 74 83 74 84 / 60 40 10 20
STT 75 83 73 85 / 60 40 10 10

&&

[cycloneye]

Area Forecast Discussion...CORRECTED
National Weather Service San Juan PR
523 AM AST Tue Apr 18 2017

.SYNOPSIS...Residual moisture and favorable upper level dynamics
will contribute to another round of showers and isolated
thunderstorms that will likely lead to local flooding and rapid
rises on area rivers in Puerto Rico. The remnant of a frontal boundary will
shift south today through Friday then gradually return to the area
with another plume of moisture from South America that will last
into mid-week next week. Moisture increasing over the weekend
will be accompanied widespread shower activities which may lead to
flooding that could extend through the first half of next week.

&&

.SHORT TERM...Today through Thursday...
The Flash Flood Watch for Puerto Rico and the the U.S. Virgin
Islands has been extended through this afternoon. For today, the
lingering moisture across the region is expected to combine with
daytime heating and local effects to produce another round of
showers and thunderstorms across the region. A slight shift to an
ENE wind is expected today, which will cause the convection to
develop across the interior and the southwest quadrant of PR this
afternoon. Due to saturated soils from previous rainfall across
most of Puerto Rico, urban and small stream flooding and river
flooding are possible again this afternoon. Drying should spread
across the area later tonight from the northeast.

Drier weather conditions are expected to encompass the region
Wednesday and Thursday as a high pressure system builds across the
region and precipitable waters values decrease to near 1.5
inches. However, some afternoon showers and thunderstorms are
expected both Wednesday and Thursday afternoon as lingering
moisture combines with diurnal heating and local effects that
could lead to very localized urban and small stream flooding.


.LONG TERM...Friday through Thursday...
The boundary that has plagued Puerto Rico and the U.S. Vrigin
Islands with record rainfall in some areas will move into the
central Caribbean. The upper level ridge that will be found over
the central Caribbean Wednesday will diminish in intensity and
move over the local area Friday. The passage of the ridge followed
immediately by a moderately strong jet segment over the local
outer Atlantic waters of up to 90 knots will again set in motion a
trend toward wetter weather. By Saturday local urban and small
stream flooding will return and by next week the plume of moisture
out of South America will likely be sufficient to generate more
widespread flooding.

&&

.AVIATION...Mostly VFR conditions expected across the local flying
area through 18/16Z. After 18/13Z the winds will increase to about
15-20 kt with occasional higher gusts as high as 30 kt. SHRA and
isolated TSRA expected across interior and western PR after 18/17Z
causing VCSH/VCTS across TJBQ and TEMPO SHRA/TSRA across TJMZ
with VCSH expected across the rest of the TAF sites. Hir trrn
will be obscured. Weather conditions are expected to improve after
19/00Z, leaving Partly cloudy skies with ISOLD/SCT SHRA across
the local flying area. Maximum winds will decrease from WSW at 85
knots around FL440.

&&

.MARINE...Seas have proven to be higher than model forecast with
the outer buoy showing 10 to 12 feet and the inner buoy near San
Juan showing 6.5 to 8.0 feet. Maximum wave height recorded at the
San Juan buoy was over 15 feet overnight. A high risk of rip
currents exist for almost all beaches with northern exposures. A
high surf advisory is also in effect. Mariners will find seas
growing up to 10 feet in the local Atlantic outer waters with some
action extending into the passages. Winds will increase today to
15 to 20 knots making the Caribbean rough as well. Conditions are
expected to begin improving by later today with more tranquil
condtions by Thursday. Weaker, but still significant northeast
swell, will return to the area Saturday evening.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 84 76 86 76 / 40 10 20 20
STT 86 76 86 73 / 40 10 10 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
318 PM AST Tue Apr 18 2017

.SYNOPSIS...Mid to upper level ridge will dominates the local
region through the weekend. At the surface, high pressure system
across the western Atlantic will continue to produce moderate to
fresh trade winds across the local area through the weekend. This
winds will bring patches of low level moisture across the region
from time to time.

&&

.SHORT TERM...High level cloudiness prevailed across the local
islands this afternoon. Very light passing showers were observed
across the eastern interior and central interior Puerto Rico.
Around 3pm, some showers developed across the southwestern section
of Puerto Rico. This shower activity was affecting mainly San
German, Hormigueros and Cabo Rojo. The activity will dissipate
near sunset. A drier airmass has moved across the region today.
Weather conditions will continue to improve tonight into
Wednesday, as this airmass continues to dominate the local region.
In general, relative dry and pleasant weather conditions are
expected through the weekend as a high pressure system dominates
the local area.

.LONG TERM...For early next week, model guidances indicated an
increase in low level moisture will occur starting Monday and
continuing through at least through mid next week, as an area of
low pressure develops across the western Atlantic.

&&

.AVIATION...BKN-OVC layers between FL040-FL050 and -SHRA expected to
continue across mainland PR through the early evening hours.
SHRA/TSRA possible across the SW quadrant of PR, impacting mainly
the flying area of TJPS/TJMZ. Mainly VFR elsewhere. Low level winds
will continue ENE at 15-25 kts. Westerlies abv FL150.

&&

.MARINE...Seas up to 8 feet and winds up to 20 knots are expected
over the local waters. Small Craft and High surf advisories
continues in effect. Hazardous marine conditions will continue
through at least Thursday.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 76 86 76 84 / 20 20 20 20
STT 76 86 73 85 / 20 20 20 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
510 AM AST Wed Apr 19 2017

.SYNOPSIS...The band of rich moisture over the area Monday has
moved into the central Caribbean. Drier air will prevail through
Friday. The band will return late in the weekend followed by
another plume of air with high moisture content during the first
half of next week. Local urban and small stream flooding will
return over the weekend with the possibility of flash flooding
Monday or Tuesday.

&&

.SHORT TERM...Today through Friday...
Abundant high level cloudiness prevailed across the local islands
overnight and early this morning. Doppler radar indicated only few
isolated showers across the Caribbean waters, but no significant
precipitation was observed over land areas. Relatively drier
weather conditions are expected to continue across the local
islands and surrounding waters until at least Friday as a drier
air mass moves in and a ridge pattern continues to build across
the region. At least through Friday, expect a seasonable weather
pattern with fair weather conditions each morning. However, some
afternoon convection is expected each afternoon as lingering
moisture combines with diurnal heating and local effects.

.LONG TERM...Saturday through Friday
A weak ridge in the upper levels will pass through on Friday
followed immediately by a weak jet segment and trough passage on
Saturday and Saturday night. This will herald the return of the
old frontal boundary from the south on Sunday. Although
another ridge at upper levels rolls through Sunday and Monday the
jetstream following it will produce some divergent flow aloft
Monday and Tuesday. This coupled with another plume of rich
moisture from South America will greatly increase the shower
activity Monday and Tuesday with isolated to scattered
thunderstorms. Moisture will be sufficient for urban and small
stream flooding with rapid river rises, and, the possibility of
flash flooding at the beginning of next week cannot be discounted.
Currently the GFS shows precipitable water near 2.3 inches at
25/00z. This will represent the peak of the moisture for this 7
day period. Moisture will return to current levels by the
following Friday as will shower activity. Low level flow is
easterly on Saturday, but gradually becomes southeast to south on
Tuesday. Showers and heavy rain will therefore be mainly north of
the Cordillera Central. The southerly flow continues through the
end of next week. Once the moisture abates beginning next
Wednesday, temperatures will rise--especially on the north coast.
1000 - 850 mb thicknesses rise from 1393 m Saturday to 1410 m the
following Friday to aid in this trend. Expect temperatures back in
the high 80s--possibly even 90 degrees just inland--in the
Greater San Juan Metropolitan area later next week.

&&

.AVIATION...Mostly VFR conditions expected across the local flying
area through 19/16Z. SHRA and are expected to develop across
interior and southwest PR after 19/17Z causing VCSH across TJBQ and
possible TEMPO SHRA across TJMZ. VCSH are also expected across TJSJ,
TIST and TISX during the afternoon hours. Latest TJSJ sounding
indicated an east to east-southeast wind flow up to 15 knots from
the surface to around 7k feet, becoming westerly and stronger
aloft. Maximum winds 70 to 80 knots around FL410.

&&

.MARINE...Seas are expected to diminish during the day today and
by tomorrow morning all small craft advisories and high surf
advisories will have been taken down. Expect the risk of rip
currents to remain high through Thursday on the northern beaches
of Puerto Rico. A northeast swell will return on Sunday in the
Atlantic waters provoking the issuance of small craft advisories
for a brief period.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 85 74 84 73 / 20 20 20 20
STT 86 73 85 72 / 20 20 20 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
323 PM AST Wed Apr 19 2017

.SYNOPSIS...A mid to upper level ridge extends from the eastern
Caribbean northwest through the western Atlantic. Surface ridge
over the northwest Atlantic extends south to eastern Caribbean.
Subtropical Depression One far over the north central Atlantic
moving North Northeast at 8 miles per hour.


&&

.SHORT TERM...Tonight through Friday Night...shower activity over
the southwestern Puerto Rico should diminish quickly during the
early evening hours as diurnal heating rapidly decreases. Both the
upper ridge and surface ridge will continue to dominate the
weather conditions across the eastern Caribbean. This will result
in an increase in subsidence at the mid to upper levels. Models
show a slight decrease in mean relative humidity. This, combined
with the subsidence mentioned before, will tend to limit rainfall
activity. However...Will expect enough moisture to combine with
diurnal heating to induce the development of afternoon showers
over the Interior/West portions of the big island of Puerto Rico.
Low level convergence could result in isolated nighttime and early
morning showers over the USVI...Vieques, Culebra and eastern
portions of the big island. Large northerly swells impacting the
Atlantic waters are resulting in large breaking wave along the
northern coasts of the islands. Therefore, a high surf advisory
and a high risk of rip currents remain in effect at least through
this evening.

.LONG TERM...Saturday through Wednesday Night...Models suggest an
increase in moisture as a surface to mid level low moves of the
Florida peninsula over the western Atlantic drawing deep tropical
moisture northward across the eastern Caribbean. This could result
in a significant increase in the chances for rain especially from
Sunday through the early part of next week.


&&

.AVIATION...BKN-OVC cld layers ...FL040...FL060...FL080 and
SHRA/SHRA expected to continue mainly across the central mountain
range of PR with VCSH psbl at TJMZ and TJPS...bcmg FEW-SCT aft
19/22z. VFR elsewhere. Low level winds will continue ENE at 15-20
kts...blo FL100...bcmg fm W and incr w/ht to max wnd of 70-80 kts nr
FL400.


&&

.MARINE...A northerly swell will continue to impact our Atlantic
waters Tonight, but will subside gradually through Thursday night.
A small craft advisory remains in effect through early Thursday
morning. Subtropical Depression One will merge with another
deepening surface low over the north central Atlantic toward the
end of the week. The resultant large low will then generate a
large northeasterly swell that could begin to impact our local
waters by the approaching weekend.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 73 82 73 84 / 20 20 30 30
STT 74 85 72 85 / 20 20 30 30

[cycloneye]

[Tweet]Area Forecast Discussion
National Weather Service San Juan PR
404 AM AST Fri Apr 21 2017

.SYNOPSIS...Ridge pattern aloft and a surface high pressure
across the western Atlantic will remain as the main weather
features across the region through early next weekend. These
features will continue to limit the showers and thunderstorms
development for the next couple of days. An Upper low will then
move across the region late in the weekend and early next week.

&&

.SHORT TERM...Today through Sunday...An upper level ridge over the
region and a surface high pressure across the southwest Atlantic
will continue to dominates the local area through today through
Saturday. For this afternoon, the available moisture is expected to
combine with diurnal heating and local effects to induce the
development of some convection over the interior, western and
southwest portions of Puerto Rico, but this activity will diminish
quickly during the early evening hours as diurnal heating rapidly
decreases. Models suggest an increase in moisture as a surface to
mid level low moves over the western Atlantic late in the weekend.
This feature will bring a moist southeast wind flow across the
region to result in a significant increase in moisture and in the
chances of showers and thunderstorms across the northeast Caribbean.
Sunday looks like the wettest day of the week, with model guidance
suggesting precipitable water values increasing up to 2.20 inches by
Sunday afternoon.

.LONG TERM...Monday through Sunday
An upper level trough and an associated surface low is expected to
develop across the western Atlantic late in the weekend into early
next week. This will result in a significant increase in moisture
across the northeast Caribbean. In fact, PWAT values will increase
up to 2.20 inches early in the upcoming week. As the surface high
pressure drift slowly toward the central Atlantic, the local
winds will shift from the southeast beginning late Sunday. This
change in wind direction will bring a frontal boundary remnants
from the Caribbean waters across the local islands Sunday night
and early Monday. A moist and unstable tropical moisture will also
move across the region from the southeast Caribbean. This
moisture will result in a significant increase in shower and
thunderstorm activity across the region Monday and Tuesday. With
the ground across Puerto Rico still saturated from previous days
rainfall, urban and small stream flooding and possible river
flooding is likely to occur Monday Afternoon and Tuesday. Weather
conditions will slowly improve by Wednesday. Due to expected
southeast wind flow, warmer than normal temperatures are expected
especially along the northern coastal municipalities of Puerto
Rico Wednesday through at least Friday.

&&

.AVIATION...VFR conditions are expected to prevail across all TAF
sites through at least 21/16Z. Brief periods of MVFR conditions with
mountain obscurations can be expected across and in the vicinity of
TJMZ in the afternoon. Low level winds will be mainly east at 10 to
15 kts except for sea breeze variations in coastal areas.

&&

.MARINE...Marine conditions will continue to improve today with
seas up to 5 feet and northeast winds at 10 to 15 knots. Therefore
the risk of rip current decreased from high to moderate. However,
conditions will become hazardous once again late Saturday into
Sunday Morning as another NE swell invades the Atlantic Waters and
Caribbean Passages.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 84 74 83 74 / 30 20 50 10
STT 84 72 85 73 / 30 20 20 20
[/Tweet]

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
344 PM AST Fri Apr 21 2017

.SYNOPSIS...
An eroding ridge aloft will holds until Saturday afternoon, when a
short wave trough swing by the local region. A mid-level ridge is
inducing a trade wind inversion over the islands. In addition, a
subtropical jet will holds aloft through the weekend. A surface
high pressure north of the Hispaniola over the Western Atlantic
will drift eastward into the Central Atlantic ocean through early
next week.

&&

.SHORT TERM...
An easterly wind flow induced by a high pressure system to the
north of the Hispaniola will result in afternoon convection
across the islands. A mid level ridge is producing a strong trade
wind inversion aloft, which limit the vertical development of
this showers. Shallow clouds with embedded showers are forecast at
least until Saturday morning. However, periods of moderate to
heavy rainfalls can be expected with this showers.

A short wave trough will swing over the region by Saturday
afternoon. As a result, the combination of the available
moisture with the local and diurnal effect will aid in the
development of afternoon cloudiness and some showers over parts of
the central and west interior sections of PR. Model guidance
brings plenty of moisture advection by Sunday Afternoon.

.LONG TERM...Previous Discussion...
Sunday An upper level trough and an associated surface low is
expected to develop across the western Atlantic late in the
weekend into early next week. This will result in a significant
increase in moisture across the northeast Caribbean. In fact, PWAT
values will increase up to 2.20 inches early in the upcoming
week. As the surface high pressure drift slowly toward the central
Atlantic, the local winds will shift from the southeast beginning
late Sunday. This change in wind direction will bring a frontal
boundary remnants from the Caribbean waters across the local
islands Sunday night and early Monday. A moist and unstable
tropical moisture will also move across the region from the
southeast Caribbean. This moisture will result in a significant
increase in shower and thunderstorm activity across the region
Monday and Tuesday. With the ground across Puerto Rico still
saturated from previous days rainfall, urban and small stream
flooding and possible river flooding is likely to occur Monday
Afternoon and Tuesday. Weather conditions will slowly improve by
Wednesday. Due to expected southeast wind flow, warmer than normal
temperatures are expected especially along the northern coastal
municipalities of Puerto Rico Wednesday through at least Friday.

&&

.AVIATION...
VFR conds will prevail durg entire prd at all TAF sites.
-SHRA/SHRA with brief MVFR over the east and central Mtn range of PR
and mainly VCTY TJMZ/TJPS/TJNR and mainly downwind of the USVI til
21/22z...bcmg mostly CLR ovr land areas. Few passing -SHRA/SHRA en
route btw islands durg entire prd. Wnds fm E-NE 15-20 kts BLO
FL100...bcmg fm W and incr w/ht ABV. No sig AVN wx impact attm.

&&

.MARINE...
Tranquil marine conditions will continue today, with east to
northeast winds between 10-15 knots with higher gusts and seas of
less than 5 feet across the coastal waters and local passages. A
northerly swell is forecast to deteriorate the local marine
conditions across the Atlantic and Caribbean Passages from
Saturday afternoon through at least the upcoming week.

&&

AVIATION...VFR conditions are expected to prevail across all TAF
sites through at least 21/16Z. Brief periods of MVFR conditions with
mountain obscurations can be expected across and in the vicinity of
TJMZ in the afternoon. Low level winds will be mainly east at 10 to
15 kts except for sea breeze variations in coastal areas.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 84 74 83 74 / 30 20 20 10
STT 84 72 85 73 / 30 20 20 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
453 AM AST Sat Apr 22 2017

.SYNOPSIS...An upper level ridge over the region will begin to
erode rapidly Saturday and Sunday as an upper level trough and an
associated surface low move across the southwest Atlantic late in
the weekend and early next week. In addition, a subtropical jet
will holds aloft through the weekend. A surface high pressure
north of Hispaniola will drift eastward into the Central Atlantic
through early next week.

&&

.SHORT TERM...Today through Monday...
Surface high pressure north of the area will continue to move
into the Central Atlantic and promote a moderate to locally fresh
trade wind flow across the forecast area. Trade wind cap will
limit diurnally induced afternoon showers to the western sections
of Puerto Rico today. Isolated thunderstorms are possible as short
wave trof moves aloft later this afternoon.

Later on Sunday through Monday, precipitable water content increases
across the forecast area as surface ridge northeast of the area
weakens due to deep polar trof deepening across the Western Atlantic
into the local area and an area of low pressure at the surface moves
across the south-southeast coast of USA and a moist southerly wind
flow pulls tropical moisture over the area. This will result in
periods of scattered to numerous showers and thunderstorms across
the waters and islands. The flood threat will increase across
mainland PR, specially on Monday. Also, periods of heavy rainfall
will result in mudslides in areas of steep terrain.

.LONG TERM...Tuesday through Monday...
An upper level trough and an associated surface low is expected
to develop across the western Atlantic early in the upcoming week.
This will result in a significant increase in moisture across the
northeast Caribbean. In fact, PWAT values will increase up to
2.20 inches early in the upcoming week and until at least early
Wednesday. A surface high pressure is expected to drift
northeast toward the central Atlantic early during the upcoming
week. As this happens, the local winds will shift from the
southeast. This change in wind direction will bring a moist and
very unstable tropical moisture across the region from the
southeast Caribbean. This moisture will continue to result in a
significant increase in shower and thunderstorm activity across
the region until at least early Wednesday. With the ground across
Puerto Rico still saturated from previous days rainfall, urban
and small stream flooding and possible river flooding is likely to
Monday Afternoon and Tuesday. Weather conditions will slowly
improve on Thursday as the local winds shift eastward. Due to
expected southeast wind flow, warmer than normal temperatures are
expected especially along the northern coastal municipalities of
Puerto Rico Tuesday and Wednesday.

&&

.AVIATION...Mainly VFR conditions are expected to prevail across all
terminals. However diurnally induced afternoon SHRA/TSRA across
western PR can result in MVFR conds at TJMZ and affect briefly the
flying area of TJBQ. Low level winds ENE at 10-15 knots with
higher winds in sea breeze variations after 14z.

&&

.MARINE...Seas up to 6 feet are expected across the Atlantic
waters and the local passages today. Marine conditions will begin
to deteriorate rapidly this evening as a north to northeast swell
invades the local waters and passages. Small craft advisories will
begin in effect this evening for some of the coastal waters and
a high risk of rip currents is expected today for the northwest to
northeast beaches of Puerto Rico and Culebra.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 84 74 85 74 / 10 10 20 30
STT 85 73 84 75 / 20 10 10 50

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
431 AM AST Sun Apr 23 2017

.SYNOPSIS...A ridge aloft will erode rapidly today as a short
wave trough swing across the region. A subtropical jet will hold
aloft through at least Monday. A polar trough is forecast to move
over the Western Atlantic Ocean today, then will reach the
islands into mid-week. This trough will increase the instability
across the region today through at least Wednesday. The low level
southeast wind flow, will pull tropical moisture from the
Caribbean waters over the region increasing the chance of showers
and thunderstorms today through at least mid week.

&&

.SHORT TERM...Today through Tuesday...
Surface high pressure northeast of the area moves further into
the Central Atlantic today, winds will shift from the east-
southeast and trof pattern establishes across the Western Atlantic
into the Central Caribbean. PWAT values are forecast to increase
above 2 inches across much of the forecast area and trof pattern
will provide good divergence aloft to enhance the development of
thunderstorm with periods of heavy rainfall, mainly over northwest
PR today and spreading across the rest of the forecast area
through at least late Tuesday night.

Currently global models indicate high moisture content and favorable
conditions for scattered to numerous showers and thunderstorms
across the Atlantic waters and over the northern USVI on Monday.
High res WRF model indicates best rainfall amounts this afternoon
across the northwestern coastal areas of PR. Other high res models
are indicating more widespread shower activity across the rest of
the interior and southeastern sections of PR later this evening and
increasing through Monday morning. Residents in PR and in the USVI
should monitor the progress of the weather conditions as periods of
frequent rainfall can result in urban and small stream flooding as
well as localized flash flooding with the heaviest showers.

.LONG TERM...Wednesday through Tuesday...
An upper level trough is expected to race over the northeast
Caribbean as an associated surface low moves northeastward across
the Canadian Maritime provinces. As this happens weather
conditions will remain unstable across the local islands Wednesday
but PWAT values are expected to decrease below 2.0 inches by that
time. Weather conditions will improve rapidly by Thursday and
thereafter as an upper level ridge build across the region. A
surface high pressure across the CentraL will shift the local
winds more from the east late Wednesday and Thursday. Although the
instability is expected to decrease by the middle of the week,
this change in wind direction is expected to induce the
development of some showers and possible a couple of thunderstorms
each afternoon across interior and western sections of Puerto
Rico due to the combination of daytime heating and local effects.
A weak surface trough will increase slightly the chances of
showers across the region by the upcoming weekend.

&&

.AVIATION...Mainly VFR conditions are expected to prevail
early in the forecast period across all terminals. BKN-OVC cigs abv
FL050 spreading from the west through the day. Afternoon SHRA/TSRA
across the northwestern quadrant of PR can result in MVFR conds at
TJBQ/TJMZ. -RA/SHRA possible near TJSJ due to SHRA streaming from
the eastern mountains. ESE winds below FL050 at 12-18 knots.
Cloudiness and SHRA increasing late in the forecast period into
Monday morning across the forecast area.

&&

.MARINE...Seas will continue to deteriorate for the next couple
of days as a northerly swell continue to invade the local waters.
Seas will increase up to 8 feet with breaking waves reaching 10
feet of more across the Atlantic waters. For this reason a High
Surf Advisory is in effect for the exposed Atlantic coastline of
Puerto Rico. Small Craft Advisories will remain in effect for most
of the coastal waters. A high Risk of Rip Currents potential
continues for the northwest to northeast beaches of Puerto Rico,
Culebra and Vieques and for the U.S. Virgin Islands beaches.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 75 87 76 / 20 40 50 40
STT 84 75 83 76 / 20 60 60 50

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
504 AM AST Mon Apr 24 2017

.SYNOPSIS...Moist and unstable conditions will keep the potential
for showers and a few thunderstorms high through at least Tuesday.
Conditions will gradually improve by midweek as mid level ridge
builds over the Central Caribbean.

&&

.SHORT TERM...Today through Wednesday...Surface low pressure across
the southwestern Atlantic and a surface high pressure northeast of
the area are promoting low level wind convergence and favoring a
moist southeasterly wind flow across the region. Precipitable water
is expected to remain above 2 inches across much of the forecast
area. Deep trof aloft is forecast to move from the west through
Wednesday. Providing good divergence aloft to enhance the
development of thunderstorm with periods of heavy rainfall.

For today, shower activity should continue to increase across the
USVI`s and the southeastern/interior sections of PR through the rest
of the morning hours. Hi-res models continue to suggest best shower
activity and possible isolated thunderstorm development over the
eastern half of PR into the USVI`s later this afternoon into the
evening hours. As trof aloft moves near the region on Tuesday,
organized convection and higher rainfall amounts are expected on
Tuesday afternoon, mainly over and to the north of the Cordillera
Central as well as across the USVI`s. On Wednesday, the base of the
trof should move to the northeast of the forecast area as ridge
builds from the west. However, sufficient moisture will linger
across the islands to aid the development of diurnally induced
afternoon showers over the islands.

Residents across the islands should continue to monitor the progress
of the weather conditions as periods of frequent rainfall can result
in urban and small stream flooding as well as localized flash
flooding.

.LONG TERM...Thursday through Tuesday...Overall moisture content
will decrease through Saturday as a mid-upper level ridge will
develop over the Western and Central Caribbean. Easterly winds
will return to the local area on Thursday as a strong high pressure
builds over the Central Atlantic. Weather conditions will remain
fairly stable from Thursday through the weekend as subsidence and
drier air aloft will limit the shower coverage across the local
region.

An upper level trough/TUTT will amplify over the Tropical Atlantic...
northeast of the region by early next week. As the TUTT retrogress
across the Northeast Caribbean Islands...weather conditions will
become unstable between Tuesday and Wednesday next week.

&&

.AVIATION...BKN-OVC cigs between FL040-FL090 will continue
across the forecast area with mtn top obscd across mainland PR.
Brief MVFR at times possible across much of the terminals today as
cloudiness and TSRA/SHRA increases over the waters and between the
Leeward/USVI/Eastern PR terminals during the afternoon/evening
hours. Southeast winds below FL050 will continue at 10-22
knots...westerlies abv and increasing w/height.

&&

.MARINE...Prevailing winds will shift to the south-southeast over
the next few days as a surface low moves over the Western Atlantic.
A decaying northerly swell of 5-7 feet will subside through tonight.
Hazardous marine conditions will continue across the Offshore Waters
and Caribbean Passages through late tonight. A high risk of rip
currents remains in effect for the Atlantic Beaches of Puerto Rico
and Culebra.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 76 89 76 / 40 40 50 50
STT 85 77 84 76 / 60 60 60 60

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
510 AM AST Tue Apr 25 2017

.SYNOPSIS...Trough aloft moves over the area from the west today.
Zonal flow follows with ridge building across the Western
Caribbean and TUTT low developing northeast of the area by late
in the weekend into early next week. At lower levels, broad ridge
pattern is to persist across the North Central Atlantic through
the rest of the week and a surface low will move north across the
mid Atlantic coast of the USA during the next few days. Moist
southeasterly winds will continue today.

&&

.SHORT TERM....Tuesday through Thursday...
Variably cloudy skies prevailed overnight and early this morning
across the local islands. Passing showers were observed across the
waters as well as eastern Puerto Rico and the U.S. Virgin
Islands. However, rainfall accumulations associated with these
showers were minimal. Coastal temperatures were in the upper 70s
to low 80s under southeasterly winds at 10 knots or less.

Ridge aloft will continue to erode as a broad mid to upper level
trough moves across the western Atlantic and over the local islands.
The jet maxima associated with the aforementioned trough will favor
a divergent pattern, particularly today. Trofiness is then expected
to move away on Wednesday with a second trough developing north of
the area Friday and into the upcoming weekend. At lower levels, a
surface low across the western Atlantic and a surface high across
the central Atlantic will continue to promote a moist southeasterly
wind flow during the next two days or so. Although easterly winds
will return to the forecast area Thursday, moisture advection will
persist across the forecast area.

Therefore, expect a few passing showers across USVI and E PR during
the morning hours with shower and thunder activity increasing
across the forecast area in the afternoon. These showers and
thunderstorms are expected mainly east and north of the Cordillera
Central as well as USVI. With the heaviest showers and thunderstorms
urban flooding is likely. As the trough moves away early Wednesday,
expect another round of overnight and early morning showers with
thunderstorms possible across USVI and E PR. Wednesday afternoon and
into Thursday, a more seasonable weather pattern is expected with
locally induced showers across west PR in the afternoon.


.LONG TERM...Friday through Wednesday...
Fair weather conditions are expected to prevail. Surface high
pressure builds further to the west and north of the area. Winds
expected to increase from the east-northeast. Trade wind shower
pattern and limited afternoon shower activity confined to the
interior and southwest quadrant of PR is expected as well as
streamers developing off the USVI`s. A TUTT low is forecast to
develop northeast of the region by early next week. As the TUTT
retrogress across the Northeast Caribbean Islands...weather
conditions will become unstable by midweek next week.

&&

.AVIATION...Mostly VFR conds expected this morning at all TAF sites
with -SHRA possible at the Leeward and USVI terminals as well as
JSJ. SHRA/TSRA development expected aft 25/16z and this may result
in MVFR or even IFR conds in and around JSJ and JBQ through 25/22z.
Southeasterly winds at 10 to 15 knots with sea breeze variations,
becoming light and variable overnight.


&&

.MARINE...Northerly swell will subside today across the Atlantic
waters. Small crafts should exercise caution due to seas up to 6
feet across the offshore Atlantic waters and due to southeasterly
winds up to 20 knots across much of the Caribbean waters and
passages. There is a moderate to high risk of rip currents for the
northern beaches of PR and Culebra. Moderate risk elsewhere
across the rest of the islands. Seas under 5 feet are expected
from Wednesday through the weekend. East winds will prevail after
Wednesday night between 10-15 knots.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 76 87 76 / 40 40 40 30
STT 85 76 84 76 / 50 60 60 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
518 AM AST Wed Apr 26 2017

.Synopsis...Ridge at the surface across the Atlantic will continue
for the next several days. Southeast winds continue through
Thursday, becoming east-northeast through next week. Upper ridge
builds west of the area and across the Central Caribbean. TUTT
develops northeast of the area during the weekend and persist
through early next week.

&&


.Short Term...Wednesday through Friday...

Mostly cloudy skies prevailed overnight and early this morning
across the local islands. Showers were observed across the regional
waters as well as over coastal municipalities of Puerto Rico.
Rainfall accumulations associated with these showers were between
one and three inches. Temperatures were in the upper 70s to low 80s
at the lower elevations.

Although the upper level trough across the Central Atlantic and into
the northeast Caribbean will continue to shift east and away from the
forecast area today, another trough aloft, a TUTT, is expected to
establish north of the area by Friday. At lower levels, a moist
southeasterly wind flow will continue to prevail today, becoming
more easterly Thursday and into the upcoming weekend as a surface
high across the north central Atlantic relocates across the central
Atlantic. Latest guidance continues to suggest a decrease in
precipitable water during the next two days or so, but remaining
above the normal range.

As a result, continue to expect passing showers across the coastal
areas of Puerto Rico as well as USVI during the morning hours with
shower and thunder activity increasing across the forecast area in
the afternoon. These showers and thunderstorms are expected mainly
across the northwest quadrant of the island as well as portions of
the San Juan Metro Area. With the heaviest showers, urban flooding
likely. A similar pattern should prevail Thursday and Friday,
although morning showers will be focused across E PR and USVI.

.Long Term...Saturday through Thursday...

TUTT pattern to the northeast is expected to provide instability
across the area to aid the development of showers and possible
isolated thunderstorms during Saturday afternoon across the
interior and western portions of PR. PWAT content erodes quickly
on Sunday and best moisture content remains below 800 mb through
the end of the forecast period. This in response to trade wind cap
as ridge pattern dominates the Western Atlantic. Therefore, best
chances for showers are during the weekend across the islands.
During the week, limited shower activity is expected across the
region...with brief periods of trade wind showers across the
USVI`s and the north and eastern portions of PR at times and
localized afternoon shallow convection over west/southwest PR.


&&

.AVIATION...VFR conds expected to prevail this morning at the
Leeward and USVI terminals with SHRA possible in and around JSJ.
SHRA/TSRA development expected aft 26/16z to result in brief periods
of MVFR conds in and around JBQ/JMZ and possibly JSJ through 26/22z.
Southeasterly winds at 10 to 15 knots with sea breeze variations,
becoming light and variable overnight.


&&

.MARINE...Coastal buoys across the islands are indicating seas
between 2-4 feet and east-southeast winds at 5-10 knots. Higher
gusts were observed with showers and thunderstorms across the
Atlantic waters and the southwestern coastal waters of Puerto
Rico. Seas should continue between 3-5 feet and east to
southeasterly winds up to 15 knots. Moderate risk of rip currents
continue for the northern and southern coasts of the islands.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 77 87 76 / 30 30 30 30
STT 86 76 86 76 / 40 30 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
310 PM AST Wed Apr 26 2017

.SYNOPSIS...A surface high pressure across the Central Atlantic
will remain as the main weather across the region until at least
late Friday. Low level winds are expected to shift more from the
east tonight and through the upcoming weekend. An upper level
trough is expected to develop across the central Atlantic,
amplifying across the northeast Caribbean during the upcoming
weekend.

&&

.SHORT TERM...Tonight through Friday...
Shower and thunderstorm activity developed across interior and
northwest Puerto Rico this afternoon. This activity is expected to
continue until early this evening. The upper level trough
extending from the Central Atlantic into the northeast Caribbean
is expected to shift slowly eastward and away from the local
islands tonight and Thursday. However, another upper level trough
is expected to develop north of the area by Friday and then
amplifying across the northeast Caribbean by the upcoming weekend.
This will result in an increase in showers and thunderstorms
across the local islands especially Saturday and Sunday. The east
southeast low level wind flow is expected to shift more easterly
tonight into at least the upcoming weekend as a strong surface
high pressure prevails over the central Atlantic.

.LONG TERM...Saturday through Friday...
An upper level trough is expected to maintain a wet weather
pattern across the region Saturday and Sunday. Expect showers and
thunderstorms development both days mostly across interior and
western sections of Puerto Rico especially during the afternoon
hours. PWAT values are expected to decrease early next week as a
surface high pressure develop just northeast of the region and
holds across the central Atlantic most of the work week. However,
the combination of daytime heating with local effects will induce
the development of scattered showers and a couple of thunderstorms
each afternoon across interior and western sections of Puerto Rico
Brief periods of trade wind showers are possible across the
Vieques, Culebra, the USVI and eastern portions of PR during the
nights.

&&

.AVIATION...VFR conds expected across most of the local terminals.
VCTS across the terminals in PR with tempo SHRA/TSRA possible at
TJMZ between 26/17Z and 26/22Z. Winds from the E-ESE with variations
due to sea breeze and near the SHRA/TSRA for the rest of today.
Winds becoming easterly tonight at 5-10KT. VCSH across the local
terminals overnight in passing -SHRA.

&&

.MARINE...San Juan buoy 41043 indicated seas of 4 to 5 feet and
easterly winds at around 10-15 knots early this afternoon. Seas
are expected to continue in the range of 3-5 feet and mostly
easterly winds up to 15 knots. Moderate risk of rip currents will
continue overnight for the northern and southern coasts of the
islands.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 77 87 76 86 / 30 30 30 30
STT 76 86 76 86 / 30 30 30 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
458 AM AST Thu Apr 27 2017

.SYNOPSIS...Surface high will continue across much of the Atlantic
basin for the next several days. Moderate to fresh trade winds
will persist through the forecast period. Short wave trof moves
during the weekend and TUTT pattern is expected through early next
week. Upper ridge builds from the west across the Caribbean basin
by midweek next week.


&&

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

Mostly clear skies prevailed overnight and early this morning across
the forecast area with limited shower activity observed over land
areas. Temperatures were in the upper 70s to low 80s at the lower
elevations under light and variable winds.

A TUTT is expected to develop north of the area by Friday and hold
through the upcoming weekend with the forecast area remaining east
of its axis. At lower levels, a high pressure across the north
central Atlantic will continue to promote moderate trade winds
through early the upcoming weekend. The local pressure gradient is
then expected to tighten later during the weekend as the surface
high relocates across the central Atlantic and north of the islands.
This will result in moderate to fresh trades late Saturday. Although
the latest guidance continues to suggest decreasing trend in
precipitable water during the next day or so, precipitable water
will remain above the normal range.

As a result, expect a mainly fair weather pattern during the early
morning hours with shower and thunder activity increasing across the
forecast area late in the morning and afternoon hours. These showers
and thunderstorms are expected mainly across the northwest quadrant
of the island as well as portions of the San Juan Metro Area. With
the heaviest showers, urban and small stream flooding is likely.
Friday and Saturday a similar pattern with showers in the morning
across windward areas followed by afternoon showers and
thunderstorms across west Puerto Rico is expected, however intensity
and coverage will increase as the TUTT establishes north of the area.

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

TUTT pattern to the northeast is expected to provide instability
across the area to aid the development of showers and possible isolated
thunderstorms through at least Tuesday afternoon. As upper ridge
builds from the west and surface high relocates just north of the
islands...the available moisture will be confined below 800 mb
from Wednesday through the end of the forecast period. Trade wind
showers and streamers are expected mainly across the USVI`s,
Culebra and Vieques. Across the interior and western portions of
Puerto Rico, diurnally induced scattered showers are expected.


&&

.AVIATION....VFR conds expected to prevail at all TAF sites
through the morning hours. SHRA/TSRA development expected aft
27/16z to result in brief periods of MVFR conds and mountain
obscurations in and around JBQ/JMZ and possibly JSJ through
27/22z. Easterly winds 10 to 15 knots with sea breeze variations
today, becoming light and variable overnight.


&&

.MARINE...Moderate to locally fresh trade winds will continue for
the next several days as surface high pressure across the central Atlantic
continues to build and tighten the local pressure gradient. Short
period wind driven seas will increase across the offshore waters
and passages during the weekend. Overall, winds should remain
between 15-20 knots and highest seas around 6 feet during the
weekend across these waters. Moderate risk of rip currents
expected across much of the northern and southern beaches of the
islands.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 76 86 75 / 30 30 30 30
STT 86 76 86 74 / 30 30 50 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
312 PM AST Thu Apr 27 2017

SYNOPSIS...Surface high will persist across the Atlantic through
the weekend and remain the dominant weather feature. Moderate trade
winds will therefore persist through the forecast period. Short wave
trof is forecast to move through the region during the weekend with
a TUTT pattern is expected to form and linger north of the area through
early next week. Upper ridge then builds and spreads across the southwest
Atlantic by the middle of next week.

&&
.SHORT TERM...Rest of today through Sunday...Precipitable water
values are expected to increase to around 2 inches by Friday PWAT
values will remain nearly 2 inches thru Saturday due to subtle low
level convergence along an old boundary now lingering across the local
Caribbean waters. A gradually deepening trough in the upper levels...now
approaching the windward passage is expected to reach the local region
and enhance upper level dynamics across the area beginning Friday.
After the trough passes late Saturday, weak short waves and the approach
of a jet from the northwest will continue to provide ventilation across
the area despite slowly diminishing moisture. Showers and thunderstorms
will be a daily development,mainly over the western and interior portion
of the island with some showers on the windward side during the late
night and early morning hours Friday through Sunday. Expect areas of
afternoon urban and small stream flooding in these areas-- especially
Friday and Saturday. A Tutt low is expected to develop north of the
area late Sunday.

High pressure at the surface in the north central Atlantic will diminish,
but move south and then westward, effectively increasing the local pressure
gradient and winds across the area Friday night through Saturday. By
Sunday this will result in a return of the high risk of rip currents
to the north coast and possibly the eastern tip of Saint Croix.

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

TUTT pattern will develop and linger north to northeast of the region
late Sunday through Monday to provide instability across the northeastern
Caribbean. This will aid the development and enhancement of showers
and possible isolated thunderstorms at least through Tuesday. Thereafter,
an upper ridge is forecast to build from the west and surface high
is to relocate just north of the islands. This pattern will increase
the trade winds inversion and limit moisture availability to below
850 mb from Wednesday through rest of the the forecast period. By then
trade wind showers and streamers are expected mainly across the USVI`s,
Culebra and Vieques. Across the interior and western portions of Puerto
Rico, mainly locally and diurnally induced showers are expected.

&&

.AVIATION...SHRA/TSRA in progress over PR will continue thru 27/21z
then dissipate by 28/01z. LCL MVFR/IFR in SHRA and mtn obscurations,
but VFR expected to prevail elsewhere. SHRA will incrs aft 28/06z
mainly alg E coast PR, with mtn obscurations in Luquillo range.
Afternoon SHRA/TSRA expected again aft 28/16Z in wrn PR. Winds 5 to
15 kt with sea/land breeze variations. Maximum winds WNW 50 kt at
FL410 by 28/18Z.

&&

.MARINE...Moderate to locally fresh trade winds will continue for the
next several days, as strong surface high pressure across the central
Atlantic will maintain a fairly tight local pressure gradient.
Short periods wind driven seas are still expected to increase across
the offshore waters and passages during the weekend. Overall, winds
should remain between 15-20 knots and highest seas around 6 feet
during the weekend across these waters. Moderate risk of rip currents
expected across much of the northern and southern beaches of the
islands.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 76 86 75 86 / 50 50 30 40
STT 76 86 74 86 / 40 40 40 40

&&

[cycloneye]

Area Forecast Discussion...CORRECTED
National Weather Service San Juan PR
531 AM AST Fri Apr 28 2017

.SYNOPSIS...There is a chance of showers and thunderstorms each
day under developing TUTT and plenty of low level moisture. A more
seasonable weather pattern will prevail by the end of next week.

&&

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

A surge of moisture moved across the islands overnight resulting in
scattered to numerous showers across the local waters, the U.S.
Virgin Islands and east and south Puerto Rico. In general, the skies
over Puerto Rico and the U.S. Virgin Islands were partly to mostly
cloudy. Moist and unstable weather conditions are expected to
prevail today enhancing showers across the windward sections of
the islands during the morning hours. However, little or no shower
activity is forecast for the west half portion of Puerto Rico.
Shower activity is expected to increase in intensity and coverage
during the afternoon, with the strongest activity over the
interior and west portion of Puerto Rico. In addition, the local
effects will result in shower activity streaming downwind from the
U.S. Virgin Islands and moving into the eastern sections of
Puerto Rico. Thunderstorm activity is expected mainly along the
Cordillera Central.

Model guidance indicated an unstable weather pattern for the
upcoming weekend. Low level convergence with precipitable water
values around two inches are forecast for Saturday. These will
combined with a TUTT Low, which is forecast to swing by the islands
through the weekend. Showers and thunderstorms are expected each day
across the islands and surrounding waters. The activity will be
focused over the coastal waters and the windward sections overnight
and early in the morning. Then, thunderstorms can be expected
mainly over the western and interior portion of Puerto Rico during
the afternoon hours through Sunday. Urban and small stream
flooding can be expected especially today and Saturday afternoon.

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

TUTT will hold across the forecast area through midweek next week.
As this feature weakens Wednesday and into early Thursday, a mid to
upper level ridge is expected to build across the forecast area from
the west. The ridge aloft is then expected to hold through at least
the weekend. At lower levels, a high pressure across the central
Atlantic will move eastward Wed-Thu, promoting moisture advection
from the southeast Friday through Saturday under the prevailing east
southeast wind flow.

Therefore, early next week still expect periods of showers and
thunderstorms across E PR and USVI during the evening and early
morning hours followed by shower and thunder development across
west PR in the late morning and afternoon hours. As the ridge
builds and moisture erodes Thu-Fri, a more seasonable weather
pattern is expected. However, under the aforementioned moist
southeasterly wind flow, the shower coverage may increase Sat-Sun.

&&

.AVIATION...-SHRA/SHRA will continue mainly across TISX/TIST/TJPS/
TJSJ/TNCM during the morning hours. Then, mount obsc with
SHRA/TSRA are expected over the interior and west section of PR.
This will result in VCTS across the terminals in PR, and possibly
MVFR or IFR conds btwn 28/17Z-23Z at TJMZ/TJBQ/TJSJ. Sfc winds
from the east at 5 to 10 knots til 28/12z. Increasing easterly
winds at 10 to 20 with higher gusts

&&

.MARINE...Moderate to locally fresh trade winds will continue to
prevail during the next several days, as a strong surface high
pressure across the central Atlantic will maintain a fairly tight
local pressure gradient. Short period wind driven seas are still
expected to increase across the offshore waters and passages
today and during the weekend. A moderate risk of rip currents
expected across much of the local beaches.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 76 83 76 / 50 50 50 50
STT 86 75 83 75 / 40 50 50 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
446 PM AST Sat Apr 29 2017

.SYNOPSIS...The proximity of the TUTT and abundant amounts of low
level moisture transport across the forecast area will maintain
moist and unstable weather conditions through the weekend and into
early next week. Conditions will gradually improve by the middle of
next week, with a more seasonable weather pattern expected to prevail
by the end of the next week and into the following weekend.

&&

.SHORT TERM...Tonight through Tuesday...
Mostly cloudy and showery conditions prevailed across the entire
region today with showers and thunderstorms with areas of heavy rains
affecting several areas across Puerto Rico as well as the coastal waters
and U.S. Virgin Islands.

For the rest of evening hours expect variably cloudy conditions
to continue but shower activity should diminish over most land
areas. However by late night and early morning expect another
round of showers and thunderstorms to develop across the regional
waters. This activity should then stream west and northwest and
affect the east and south coastal sections of Puerto Rico and the
rest of the islands including the U.S. Virgin islands. The very
moist and unstable environment, will aid in further development of
showers and thunderstorms across the Cordillera Central of Puerto
Rico early in the afternoon, with the activity expected to spread
across the western interior and northwest sections of Puerto Rico.
periods of heavy rainfall will lead to urban and small stream flooding.

The upper level trough/Tutt is expected to linger just north and west
of the region enhancing the development of showers and thunderstorms
across the local area until at least Tuesday. Low level moisture transport
is also expected to remain high through this period with very unstable
conditions aloft. As a result, periods of enhanced showers and thunderstorms
can be expected to develop each afternoon across the Cordillera Central
of Puerto Rico and portions of the U.S. Virgin Islands.

.LONG TERM...Wednesday through Sunday...
TUTT is expected to continue to linger north of the forecast area at
least until Wednesday. However as this feature continues to weaken
during, a mid to upper level ridge is forecast to build across the
forecast area from the west. The ridge aloft is then expected to hold
through the upcoming weekend allowing for less favorable conditions
for convective development. The surface high pressure across the central
Atlantic will also lift farther northeast by Wednesday therefore weakening
the local pressure gradient. This in turn will support a light to moderate
east to southeast trade wind flow through Sunday.

Expect periods of showers and isolated thunderstorms across the coastal
waters E Puerto Rico and the U.S. Virgin Islands during the late evening
and early morning hours followed by shower and thunderstorm development
mainly across the west and interior sections of Puerto Rico by late
morning and during the afternoon hours. As the ridge builds aloft and
moisture erodes during the latter part of next week a more seasonable
weather pattern is expected with near normal or slightly warmer temperatures
under the expected east to southeast wind flow.

&&

.AVIATION...A lingering trough will produce periods of +SHRA/TSRA at
times. SHRA/TSRA development expected til 29/23z, with BKN-OVC
Ceiling at FL025-FL100 are expected across the islands. As a result
periods of MVFR or even IFR conds and mountain obscurations at most
of PR and USVI TAF sites are expected the rest of this afternoon.
SHRA/TSRA formation expected across the regional waters and into the
USVI/E-PR aft 30/02z. Low level winds will continue mainly east at
10-20 kts with higher gusts til 29/23, dropping at 10 knots or less
overnight.

&&

.MARINE... Mariners should exercise caution across the local waters
due to seas between 4 and 6 feet and winds between 15 and 20 knots.
Thunderstorm formation is likely across the local waters through at
least Sunday.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 76 84 76 86 / 60 60 50 50
STT 75 84 75 87 / 50 50 50 50

&&