Area Forecast Discussion
Issued by NWS San Juan, PR

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FXCA62 TJSJ 181002
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
602 AM AST Wed Jan 18 2017

.SYNOPSIS...
A trough aloft will continue its move across the region. A surface
low pressure exiting the eastern U.S. will continue to weaken a
surface high pressure across the southwestern Atlantic. This
pressure systems will induce a moderate east northeast wind flow
across the local islands and surrounding waters, which in turn
will push patches of low level moisture with embedded clouds and
showers across the U.S. Virgin Islands and the northern and
eastern sections of Puerto Rico at times.

&&

.DISCUSSION...
As a surge of moisture moved over the region overnight. This
surge produced scattered showers, but due to their rapid movement
the rainfall totals were minimals. Then, satellite imagery
indicated the intrusion of dry air across the region, producing a
diminish in shower activity across the islands of Puerto Rico and
the U.S. Virgin Islands early this morning. For the rest of this
morning and under the prevailing northeasterly wind, isolated
passing showers can not be ruled out across the windward sections
of PR and the USVI.

A surface low pressure is forecast to move across the western
Atlantic by Thursday. The pressure gradient is forecast to relax
as this low system move eastward across the Atlantic waters.
Also, as mentioned in the previous discussion, winds speed are
expected to diminish considerable becoming more from the east late
in the week and during the upcoming weekend. As this happens, a
frontal boundary is expected to move close to the local islands.
The proximity of this frontal boundary combined with a dry cool
air mass could result in cooler pleasant temperatures by the end
of the week and into the weekend.

&&

.AVIATION...
Mainly VFR conditions are expected to prevail across all
TAF sites through at least 18/22z. Some passing showers are expected
to affect TIST, TISX, TJSJ and TJBQ terminals from time to time. Low
level winds will be mainly northeast at 10 to 15 kts with higher
gusts.

&&

.MARINE...
Marine conditions are expected to slowly improve across the
region today. Mariners can expect seas up to 6 feet and winds
around 18 knots mainly across the Atlantic waters and the
Caribbean Passages. High risk of rip currents are in effect until
this afternoon.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  80  69  82  71 /  40   0  20  10
STT  80  72  79  71 /  40  20  20  20

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...High Rip Current Risk through this afternoon for Culebra-
     Mayaguez and Vicinity-North Central-Northeast-Northwest-San
     Juan and Vicinity-Southeast-Western Interior.

     Small Craft Advisory until 6 AM AST early this morning for
     Northeast.

VI...None.
AM...Small Craft Advisory until 6 AM AST early this morning for
     Anegada Passage Southward to 17N-Atlantic Waters of Puerto
     Rico and USVI from 10 NM to 19.5N-Mona Passage Southward to
     17N.

&&

$$

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