Area Forecast Discussion
Issued by NWS San Juan, PR

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FXCA62 TJSJ 141821
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
221 PM AST SUN FEB 14 2016

.SYNOPSIS...AS A BROAD MID TO UPPER LEVEL TROUGH ACROSS THE
WESTERN AND CENTRAL ATLANTIC SHIFTS FURTHER EAST WHILE WEAKENING...
RIDGE PATTERN ALOFT WILL BUILD BACK ACROSS THE LOCAL ISLANDS FROM
THE SOUTH. SURFACE HIGH PRESSURE WILL CONTINUE TO MOVE EASTWARD
INTO THE WESTERN AND CENTRAL ATLANTIC EARLY THIS WEEK. THIS WILL
RESULT IN A MODERATE TO FRESH TO LOCALLY STRONG EAST SOUTHEAST
WIND FLOW ACROSS THE EASTERN CARIBBEAN. FRONTAL BOUNDARY WILL
REMAIN NORTH...WITH ASSOCIATED INDUCED TROUGH AFFECTING THE LOCAL
ISLANDS THROUGH LATE MONDAY NIGHT.

&&

.DISCUSSION...VARIABLY CLOUDY SKIES PREVAILED ACROSS THE LOCAL
ISLANDS TODAY. SHOWER ACTIVITY ASSOCIATED WITH THE SURFACE TROUGH
WAS OBSERVED ACROSS THE AREA THROUGHOUT THE DAY...BUT WITH MINIMAL
RAINFALL ACCUMULATIONS SO FAR.

LOW LEVEL MOISTURE WILL CONTINUE TO POOL ACROSS THE LOCAL ISLANDS
AS THE AFOREMENTIONED INDUCED SURFACE TROUGH DOMINATES THE FORECAST
AREA TONIGHT AND MONDAY. THIS...IN COMBINATION WITH THE PROXIMITY
OF THE UPPER TROUGH WILL RESULT IN A BETTER CHANCE FOR PERIODS OF
SHOWERS THROUGH AT LEAST EARLY TUESDAY MORNING. BEST MOISTURE
ADVECTION IS EXPECTED ON MONDAY...AND THEREFORE THE BEST AREAL
COVERAGE FOR SHOWERS AS WELL. ATTM DECIDED TO KEEP JUST ISOLATED
THUNDERSTORMS IN THE AFTERNOON HOURS TODAY AND MONDAY...DUE TO
THE LACK OF UPPER VENTILATION.

HAVING SAID THAT...FREQUENCY OF SHOWERS WILL INCREASE ACROSS THE
USVI AND THE EASTERN HALF OF PUERTO RICO TONIGHT AND WILL THEN
SPREAD ACROSS THE WESTERN HALF OF PUERTO RICO TOMORROW AFTERNOON
WITH THUNDERSTORMS POSSIBLE.

AS RIDGE ALOFT BUILDS BACK FROM THE SOUTH...LOW LEVEL MOISTURE WILL
THEN ERODE WITH A SEASONABLE WEATHER PATTERN EXPECTED TUESDAY
THROUGH EARLY FRIDAY. FOR LATE FRIDAY AND THE UPCOMING WEEKEND...
LATEST GUIDANCE CONTINUES TO SUGGEST A SURFACE FRONT REACHING THE
LOCAL ISLANDS WITH A SHARP INCREASE IN LOW LEVEL MOISTURE.

&&

.AVIATION...CLOUDS/SCT SHRA WILL CONTINUE TO MOVE ACROSS THE FLYING
AREA. THE LEEWARD AND USVI TAF CAN EXPECT OCCASIONAL PASSING -SHRA
AND SHRA. SOME OF THIS SHOWERS CAN PRODUCE BRIEF MVFR CONDS MAINLY
OVER TNCM. SHRA/TSRA EXPECTED OVER THE INTERIOR AND WEST SECTIONS OF
PUERTO RICO AFFECTING TJMZ AND POSSIBLY OVER TJBQ BETWEEN 17-22Z.
SOME OF THESE ACTIVITY WILL PRODUCING BRIEF MVFR CONDITIONS.
SFC WINDS FORM THE E AT 10-15 KT WITH HIGHER GUSTS NEAR SHRA/TSRA
DECREASING AT 5 TO 10 KTS OVERNIGHT.

&&

.MARINE...MARINE CONDITIONS WILL DETERIORATE AS A MODERATE TO
FRESH TO LOCALLY STRONG EAST SOUTHEAST WIND FLOW ESTABLISHES
ACROSS THE AREA. AN INDUCED SURFACE TROUGH ACROSS THE LOCAL AREA
WILL CONTINUE TO RESULT IN PERIODS OF SHOWERS ACROSS THE REGIONAL
WATERS. SMALL CRAFT ADVISORIES WERE ISSUED FOR THE ATLANTIC
WATERS AND ANEGADA PASSAGE DUE TO INCREASING SEAS AND WINDS.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  75  85  74  88 /  50  50  40  40
STT  74  84  75  85 /  60  60  50  50

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...NONE.
VI...NONE.
AM...SMALL CRAFT ADVISORY FROM 2 AM MONDAY TO 8 AM AST TUESDAY FOR
     ANEGADA PASSAGE SOUTHWARD TO 17N-ATLC WATERS OF PUERTO RICO
     AND USVI FROM 10NM TO 19.5N.

     SMALL CRAFT ADVISORY FROM 2 PM MONDAY TO 8 AM AST TUESDAY FOR
     CARIBBEAN WATERS OF PUERTO RICO FROM 10 NM TO 17N.

&&

$$

27/23


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