Area Forecast Discussion
Issued by NWS San Juan, PR

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FXCA62 TJSJ 162106
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
506 PM AST Sat Dec 16 2017

.SYNOPSIS...A mid to upper level ridge will continue to dominate
the local weather conditions for the next several days. A surface
high pressure building across the western Atlantic will promote
a moderate to fresh wind flow from the east-northeast. Fair
weather conditions and a trade wind shower pattern will prevail
across the forecast area.


&&

.SHORT TERM...Saturday through Monday...Ridge aloft and surface
high pressure across the western Atlantic will keep a trade wind
shower pattern across the forecast area through the short term
period. These showers should affect mainly the northern areas of
Puerto Rico and a few of them could reach the interior areas, as
the steering winds from the northeast are between 18-25 kts.
Across the USVI, expect trade wind showers at times. However, no
significant rainfall amounts are expected at the moment. Breezy
conditions will continue through Monday.


.LONG TERM...From previous discussion...Tuesday through
Saturday...The ridge pattern aloft will hold across the islands
through the upcoming mid-week. Therefore, expect mostly mostly
clear skies with a few passing showers from time to time each day.
The ridge pattern is forecast to slowly erodes during the latter
part of next week, as a polar trough amplified from the Northeast
into the northeastern Caribbean. There is enough uncertainty about
the final solutions at this time. However, if weather guidance
are in the right track, this will result in a better chance for
shower activity across the local islands, as well as thunderstorm
development.


&&

.AVIATION...SCT-BKN cld lyrs FL025...FL050...passing SHRA en route
btw islands and ovr coastal waters durg prd. Prevailing VFR at all
local terminals but VCSH AT TJSJ/TJBQ/TJMZ/TJPS til 16/23z. Sfc wnds
mainly fm NE 15-20 kts with higher gusts. low level winds fm NE 20-
25 kts blo FL300...then backing and incr w/ht.


&&

.MARINE...Wind driven seas will result in choppy conditions across
most of the regional waters and passages through at least Monday.
Small craft advisories will be in effect starting overnight due to
7 ft seas. Moderate to fresh northeast trades will continue
between 15-20 knots. A moderate risk of rip currents will continue
across most of the local islands, especially along the north and
east facing beaches of the islands.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  77  84  76  83 /  20  30  30  50
STT  77  86  76  86 /  20  30  30  50

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...High Rip Current Risk until 6 PM AST this evening for Culebra-
     North Central-Northeast-Northwest-San Juan and Vicinity-
     Southeast-Western Interior.

VI...High Rip Current Risk until 6 PM AST this evening for
     St.Thomas...St. John...and Adjacent Islands.

     Small Craft Advisory from 2 AM Sunday to 8 AM AST Monday for
     St.Thomas...St. John...and Adjacent Islands.

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

     Small Craft Advisory from 2 AM Sunday to 8 AM AST Monday for
     Coastal Waters of Northern Puerto Rico out 10 NM-Coastal
     Waters of Southern USVI Vieques and Eastern Puerto Rico out
     10 NM.

&&

$$

DS



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