Area Forecast Discussion
Issued by NWS San Juan, PR

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FXCA62 TJSJ 041422
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
1022 AM AST MON MAY 4 2015

.UPDATE...DOPPLER WEATHER RADAR DETECTED ONLY ISOLATED SHOWERS
OVER EASTERN SECTIONS OF PUERTO RICO AND ACROSS THE SURROUNDING
COASTAL WATERS EARLY THIS MORNING. HOWEVER...BY MID MORNING THIS
SHOWER ACTIVITY DISSIPATES LEAVING THE REGION UNDER A CLEAR TO
PARTLY CLOUDY SKIES. A GENERALLY FAIR AND MAINLY STABLE WEATHER
PATTERN WILL CONTINUE TO PREVAIL ACROSS THE REGION FOR THE NEXT
SEVERAL DAYS. FOR THIS AFTERNOON THE LIMITED LOW LEVEL MOISTURE
ACROSS THE REGION IS EXPECTED TO COMBINE WITH DAYTIME HEATING AND
LOCAL EFFECT TO INDUCE SOME SHOWERS ACROSS WESTERN SECTIONS OF
PUERTO RICO. HAZY SKIES WILL CONTINUE ACROSS THE LOCAL ISLANDS FOR
THE NEXT SEVERAL DAYS AS A NEW AREA OF SAHARAN DUST ARRIVE TO THE
REGION TONIGHT AND INTO TUESDAY. LOOKING WELL AHEAD...AN INCREASE
IN LOW MOISTURE...SHOWERS AND POSIBLE THUNDERSTORMS ARE IN STORE
FOR THE REGION LATE DURING THE UPCOMING WEEKEND AND EARLY NEXT
WEEK.

&&

.AVIATION...MOSTLY VFR CONDITIONS WILL CONTINUE ACROSS THE LOCAL
FLYING AREA FOR THE NEXT 24 HRS...WITH ONLY FEW CLOUDS AND
ISOLATED SHOWERS POSSIBLE AFTER 04/17Z IN THE VICINITY OF TJBQ AND
TJMZ. WINDS AT 10-15 KNOTS WITH OCNL GUST UP TO 20 KNOTS EXPECTED
THIS AFTERNOON...DIMINISHING AFTER 04/22Z

&&

.MARINE...SMALL AND LONG PERIOD SWELL WILL CONTINUE TO REACH THE
LOCAL WATERS THIS AFTERNOON. WINDS ARE EXPECTED TO INCREASE
DURING THE NEXT 48 HOURS AS THE LOCAL PRESSURE GRADIENT TIGHTENS.
THIS WILL GENERATE CHOPPY CONDITIONS BEGINNING TONIGHT THROUGH
AT LEAST WEDNESDAY.

&&

.PREV DISCUSSION... /ISSUED 500 AM AST MON MAY 4 2015/

SYNOPSIS...UPPER LEVEL RIDGE WILL ERODE THROUGH MID WEEK...AS
TROUGH AMPLIFIES ACROSS THE WESTERN ATLANTIC AND INTO THE CENTRAL
CARIBBEAN. MID LEVEL RIDGE HOLDS THRU THE END OF THE WORK WEEK. AS
SURFACE HIGH ACROSS THE WESTERN ATLANTIC SHIFTS EASTWARD INTO THE
CENTRAL ATLANTIC...THE LOCAL PRESSURE GRADIENT WILL TIGHTEN WITH
TRADE WINDS STRENGTHENING ACROSS THE AREA.

DISCUSSION...MOSTLY CLEAR SKIES PREVAILED ACROSS THE LOCAL
ISLANDS OVERNIGHT...WITH BRIEF LIGHT SHOWERS OBSERVED OVER THE
LOCAL WATERS AND EASTERN PUERTO RICO. WINDS WERE LIGHT AND
VARIABLE WITH COASTAL TEMPS IN THE UPPER 70S TO LOWER 80S.

A GENERALLY FAIR AND MAINLY STABLE WEATHER PATTERN WILL CONTINUE
TO PREVAIL ACROSS THE LOCAL ISLANDS THROUGH AT LEAST FRIDAY.
ALTHOUGH...LOW LEVEL MOISTURE WILL REMAIN LIMITED...TRADE WIND
SHOWERS ACROSS WINDWARD AREAS IN THE MORNING... FOLLOWED BY
LOCALLY INDUCED AFTERNOON SHOWERS ACROSS WEST PUERTO RICO CANT
BE RULED OUT EACH DAY. A NEW AREA OF SAHARAN DUST WILL ARRIVE
LATE TONIGHT AND INTO TUESDAY...WITH HAZY SKIES EXPECTED MUCH
OF THIS WORK WEEK ALONG WITH FRESH WINDS IN RESPONSE TO BUILDING
SURFACE HIGH PRESSURE TO THE NORTH.

RIDGING WILL COLLAPSE THE UPCOMING WEEKEND AND NEXT WEEK AS THE
TROUGH ACROSS THE WESTERN ATLANTIC INTO THE CENTRAL CARIBBEAN
SHIFTS EASTWARD. THIS WILL RESULT IN BETTER MOISTURE ADVECTION
ACROSS THE FORECAST AREA.

AVIATION...VFR THRU THE NEXT 24 HRS...WITH FEW CLOUDS AND
ISOLD SHRA POSSIBLE AFT 04/17 IN THE VCNTY OF TJBQ & TJMZ. WINDS
AT 10-15 KT WITH OCNL GUST UP TO 20 KT AND SEA BREEZE VARIATIONS
AFT 04/12Z.

MARINE...SMALL AND LONG PERIOD SWELL WILL CONTINUE TO AFFECT THE
LOCAL WATERS TODAY. WAVE MODELS ARE RUNNING SLIGHTLY HIGHER THAN
WHAT THE BUOYS ARE REPORTING. THEREFORE...DROPPED THE WAVE HEIGHT
TO REPRESENT ACTUAL CONDITIONS...AT LEAST FOR THE FIRST 12 TO 18
HOURS.

WINDS ARE FORECAST TO INCREASE DURING THE NEXT 48 HOURS GENERATING
CHOPPY CONDITIONS BEGINNING LATE TONIGHT THROUGH WEDNESDAY.
ALTHOUGH THE FIRST HALF OF TODAY WINDS WILL REMAIN BELOW THE SMALL
CRAFT CRITERIA...WINDS WILL INCREASE THIS AFTERNOON AND TONIGHT
WITH SMALL CRAFT ADVISORIES GOING INTO EFFECT LATE TONIGHT.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  90  78  90  78 /  20   0  10  10
STT  88  78  88  78 /  20  10  20  20

&&

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

     SMALL CRAFT ADVISORY FROM 2 AM TUESDAY TO 8 PM AST WEDNESDAY FOR
     CARIBBEAN WATERS OF PUERTO RICO FROM 10 NM TO 17N-MONA
     PASSAGE SOUTHWARD TO 17N.

&&

$$

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