Area Forecast Discussion
Issued by NWS San Juan, PR

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FXCA62 TJSJ 280924

Area Forecast Discussion
National Weather Service San Juan PR
524 AM AST THU JUL 28 2016

.SYNOPSIS...A surface high pressure will continue to dominates
the local region through Saturday night. An upper level trough
will move across the area today. An active tropical wave will
affect the local area Sunday and Monday. Saharan Air Layer will
encompass the region after the wave.


.DISCUSSION...Passing showers were seen across the coastal waters
overnight. Some of these showers affected the local islands...but
rainfall accumulation were minimal. This increase in moisture is
associated with an approaching upper level trough which is located
northeast of the U.S. Virgin Islands. Although this trough is not
strong enough...will aid in the development of showers and
thunderstorms mainly over the western interior and west section of
Puerto Rico.

An active tropical wave...currently located in the central
Atlantic it is expected to approach the local area by Sunday. At
this time...models agreed on the timing of the wave but disagree
somewhat on the strength of the wave. The ECMWF model forecast a
stronger wave affecting the local area...compared to the GFS. The
most important thing it is that both models agreed on active
weather beginning on Sunday morning and continuing through Monday
morning. We will continue to closely monitor the evolution of this
wave next few days. Stay tuned.


.AVIATION...Mostly VFR conditions with a Saharan air layer could
slightly reduce VIS at the local terminals but still expected to be
P6SM during the next 24 hours. For this morning, VCSH and brief SHRA
possible over the Leewards, USVI and TJSJ TAF sites. Easterly winds
to increase to around 10-15 KT and gusty after 28/13Z prevailing
from the E with sea breeze variations. SHRA/TSRA expected to develop
over PR after 28/16Z with mountain obscurations. VCTS/TSRA likely to
affect areas in and around TJPS and TJMZ, VCSH/SHRA at TJBQ.


.MARINE...Tranquil marine conditions are expected to continue
through at least Saturday. Seas up to 4 feet and winds up to 15
knots are expected.


SJU  91  79  89  80 /  20  30  30  20
STT  90  79  89  81 /  40  30  30  20


.SJU Watches/Warnings/Advisories...


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