Area Forecast Discussion
Issued by NWS San Juan, PR

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FXCA62 TJSJ 230905

Area Forecast Discussion
National Weather Service San Juan PR
505 AM AST SAT JUL 23 2016

.SYNOPSIS...An upper level low/TUTT just northeast of Puerto Rico
will move over the local islands later today. This will help to
increase the instability and the chance of showers across Puerto
Rico and the U.S. Virgin Islands during the weekend. Another surge
of moisture is expected on Tuesday next week. Then...drier and more
stable pattern will return to the islands by midweek.


.DISCUSSION...A generally stable air mass will prevail across the
islands most of today. Saharan dust particles will continue to
diminish throughout the day. Subsidence cap will gradually weaken
as the TUTT moves over the local islands. This will allow moderate
showers to develop over portions of the Cordillera Central and
Southwest Puerto Rico during the afternoon due to the sea breeze
convergence and orographic effects.

The upper level trough/TUTT over the area on Sunday will promote
moisture transport across the local area. In addition...the unstable
environment will help to increase the coverage and intensity of the
showers and thunderstorms. significant rainfall
accumulations are expected during the weekend...periods of heavy
rainfall can`t ruled out.

The next surge of moisture is associated with a tropical wave. At
this time...operational models suggest that moisture associated
with the wave will likely reach the local region on Tuesday. As a
result...showers and a few thunderstorms are likely with the wave.
Stable pattern is forecast from midweek to the end of next week.
Another pulse of Saharan Dust will likely reach the local islands
by midweek.


.AVIATION...Mainly VFR conditions are expected to prevail during
the next 24 hours. However, SHRA developing over western
interior/southwestern PR could create brief mvfr conditions and
mtn obscurations through at least 22Z, impacting mainly TJMZ and
the vicinity of TJPS/TJBQ. Low level winds will continue from the
ENE at 10-20 knots with sea breeze variations and higher gusts
after 14z.


.MARINE...Typical seas are forecast across the local waters. Mariners
can expect seas of 3-5 feet and winds around 10-15 knots over the
next several days. No Small Craft Advisories are anticipated over
the next 5-7 days.


SJU  89  78  89  79 /  20  40  40  30
STT  90  77  88  79 /  20  40  40  30


.SJU Watches/Warnings/Advisories...


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