Area Forecast Discussion
Issued by NWS San Juan, PR

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FXCA62 TJSJ 300059
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
859 PM AST FRI JUL 29 2016

.UPDATE...Showers and thunderstorms affected portions of central,
western, and northwestern PR in the afternoon hours. Doppler radar
rainfall estimates indicate that isolated areas across NW PR and
across northern Ponce received over 1 inch of rain. The rainfall
over land lasted through the late afternoon hours, thereafter the
showers were mainly over the waters. And this is what we expect
through the overnight hours, brief isolated to scattered showers
over the local area. Through the day Saturday, a patch of drier
air is expected to move in which will limit rainfall and
thunderstorm activity a little over the area for the afternoon
hours.

The tropical wave, now over 47W, is still moving quickly towards
the west and should be here by late Saturday night or very early
Sunday morning. Numerous showers and scattered thunderstorms are
forecast for Sunday while the tropical wave affects the local
islands. The moisture associated with the wave may be over the
area through Monday so there is still a good chance of showers and
thunderstorms on Monday. Drier air moves in behind the wave on
Tuesday.

&&

.AVIATION...VFR conditions across most of the terminals. Periods of
SHRA with OCNL VCSH expected for TJSJ. SHRA and mtn obscuration will
continue across E PR. Winds alf from FL025 to FL140 east 20-25 kt.
Winds at sfc genly less than 12 kt with limited land breeze
influences. Incrg winds tomorrow with sct SHRA. Aft 30/16z TSRA
dvlpg over SW PR and alg Cordillera Central west of TJPS and moving
WSW. Mtn obscurations aft there 30/17Z. Also MVFR to bcm likely aft
30/18z TNCM/TKPK due to apchg trop wave and sct SHRA/TSRA.

&&

.MARINE...Seas up to 6 feet and winds up to 20 knots are expected
tonight and Saturday morning. Seas are expected to start becoming
hazardous by Saturday afternoon across the offshore Atlantic
waters and the Anegada passage and then spread over the nearshore
Atlantic waters and the waters surrounding the USVI by Saturday
night. A small craft advisory will go into effect on Saturday
Afternoon.

&&

.PREV DISCUSSION... /issued 156 PM AST FRI JUL 29 2016/

SYNOPSIS...Upper level trough will aid in the development of
showers and thunderstorms through this evening. Subsidence up
front the tropical wave will generate a more stable and drier
conditions tonight across our local region. A strong Tropical
wave located in the central Atlantic is expected to move quickly
west across the atlantic and reach our local region Saturday night
into Sunday.

DISCUSSION...An upper level trough will continue to enhanced
shower and thunderstorm development mainly across the NW portions
of Puerto Rico. Most of these showers and thunderstorms will
quickly dissipate this evening or move west and over the Mona
Passage.

A subsidence area up front a strong tropical wave will generate a
dry and stable conditions across the local region on Saturday. A
strong tropical wave now located about 1100 miles east of Puerto
Rico will continue to move quickly west, at about 25 mph, and
reach the eastern Caribbean early Sunday. Showers and thunderstorms
could begin to affect the local area late saturday night due to
the large size of the leading edge. Models continue to suggest
large amounts of precipitable water associated to this wave,
suggested values of above 2.5 inches, therefore increasing the potential
for flooding to occur over isolated areas in PR and USVI. Also
another major impact associated to this weather feature will be
strong wind gusts mainly associated with thunderstorms and the
expected squally weather.

AVIATION...VFR conditions across most of the terminals. Periods of
SHRA with possible VCTS expected for TJSJ. SHRA/TSRA and mtn
obscuration will continue across the interior and W PR with periods
of MVFR expected for TJMZ/TJBQ thru 22Z. Low level winds from the
east to southeast at 10-20 kts with higher gusts and sea breeze
variations.

MARINE...Seas up to 5 feet and winds up to 15 kts expected across
the local waters today. Marine conditions will quickly
deteriorate on Saturday night as a strong tropical wave moves
quickly across the local waters. Mariners should expect squally
weather across all local waters. Showers and thunderstorms will
generate low visibilities, lightning, choppy seas and strong gusty
winds. These marine conditions will prevail through at least
Monday.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  80  90  80  86 /  30  30  60  60
STT  80  92  80  86 /  30  30  60  60

&&

.SJU Watches/Warnings/Advisories...
PR...VI...Small Craft Advisory from 8 PM Saturday to 8 PM AST Sunday for
     St.Thomas...St. John.. and Adjacent Islands.

AM...Small Craft Advisory from 2 PM Saturday to 8 PM AST Sunday for
     Anegada Passage Southward to 17N-Atlantic Waters of Puerto
     Rico and USVI from 10 NM to 19.5N.

     Small Craft Advisory from 8 PM Saturday to 8 PM AST Sunday for
     Caribbean Waters of Puerto Rico from 10 NM to 17N-Coastal
     Waters of Northern USVI and Culebra out 10 NM-Coastal
     Waters of Southern USVI Vieques and Eastern Puerto Rico out
     10 NM.

     Small Craft Advisory from 2 AM to 8 PM AST Sunday for Coastal
     Waters of Northern Puerto Rico out 10 NM.

&&

$$

12/25


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