Area Forecast Discussion
Issued by NWS San Juan, PR

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FXCA62 TJSJ 310253
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
1053 PM AST FRI JAN 30 2015

.UPDATE...
SOME MINOR CHANGES WERE INTRODUCED TO THE FORECAST PACKAGE TO
ADJUST THE CURRENT CONDITIONS...BUT IN GENERAL THE FORECAST REMAINS
THE SAME. THE LATEST SATELLITE AND RADAR IMAGES SHOW PARTLY
CLOUDY SKIES ACROSS THE CWA WITH SCATTERED SHOWERS MAINLY OVER THE
OFFSHORE ATLANTIC WATERS. TRADE WIND SHOWERS ARE EXPECTED MAINLY
OVER THE WINDWARD SECTIONS AND LOCAL WATERS DURING THE OVERNIGHT
AND MORNING HOURS...BUT WITHOUT ANY SIGNIFICANT RAINFALL
ACCUMULATION. DURING THE AFTERNOON HOURS...THE AFOREMENTIONED
SURFACE TROUGH AND THE AVAILABLE LINGERING MOISTURE WILL BE ENOUGH
TO CREATE UNSETTLED WEATHER CONDITIONS MAINLY ACROSS THE INTERIOR
AND WESTERN SECTIONS OF PUERTO RICO...WITH NUMEROUS SHOWERS AND
ISOLATED T-STORMS OVER SOUTHWESTERN PR. ON SUN...BREEZY AND FAIR
WX CONDITIONS ARE EXPECTED WITH THE STRENGTHENING OF A RIDGE
SYSTEM OVER THE REGION THROUGH NEXT WORK WEEK.

&&

.AVIATION...MOSTLY VFR CONDITIONS WILL PREVAIL ACROSS THE FORECAST
AREA OVERNIGHT. SHRA/TSRA DEVELOPMENT EXPECTED ACROSS CENTRAL-
WESTERN-AND SW PR. MOUNTAIN OBSCURATION AND VCTS ARE LIKELY
ACROSS TJMZ/TJPS. THEREFORE BRIEF MVFR CONDS ARE POSSIBLE AT
TJMZ/TJPS BETWEEN 31/18Z AND 31/22Z. LIGHT TO CALM WINDS
OVERNIGHT...THEN E TO NE WINDS AT 5 TO 15 KTS WITH SEA BREEZE
VARIATIONS...AND HIGHER IN/AROUND TSRA/SHRA.

&&

.MARINE...SMALL CRAFT ADVISORY IN EFFECT FOR THE OFFSHORE ATLANTIC
WATERS AS SEAS OF 7 FEET ARE EXPECTED THROUGH EARLY SATURDAY
MORNING. BY EARLY NEXT WEEK...AS A HIGH PRESSURE BUILDS ACROSS THE
REGION TRADE WINDS WILL INCREASE. IN ADDITION A NEW PULSE OF
NORTHWESTERLY SWELLS IS EXPECTED TO REACH THE LOCAL WATERS EARLY
NEXT WEEK. THEREFORE STAY TUNED FOR ADDITIONAL INFORMATION
REGARDING THIS SITUATION.


&&

.PREV DISCUSSION... /ISSUED 304 PM AST FRI JAN 30 2015/

SYNOPSIS...WEAK SURFACE TROUGH WILL CONTINUE TO EXIT THE FORECAST
AREA THROUGH SATURDAY. MID TO UPPER LEVEL TROUGH ENTERING THE WESTERN
ATLANTIC WILL MOVE OVER THE OPEN ATLANTIC WATERS THROUGH THE
WEEKEND...WITH ASSOCIATED PREFRONTAL SHEAR LINE NEAR OUR FORECAST
AREA. SURFACE HIGH PRESSURE THEN BUILDS AND TIGHTENS THE PRESSURE
GRADIENT.

DISCUSSION...AFTER SHOWERS ENDED THIS MORNING ACROSS THE NORTHERN
COAST OF PUERTO RICO. SUNNY TO PARTLY CLOUDY SKIES PREVAILED UNTIL
EARLY IN THE AFTERNOON. AS OF 3 PM AST...SCATTERED TO NUMEROUS
SHOWERS WERE FORMING ACROSS THE SOUTH AND WESTERN SECTIONS OF
PUERTO RICO AND AN ISOLATED THUNDERSTORM COULD FORM.

SHOWER ACTIVITY OVER THE ATLANTIC WATERS ASSOCIATED TO THE SURFACE
TROUGH WILL REACH FROM TIME TO TIME THE NORTHERN PARTS OF THE
ISLANDS AS NORTHEASTERLY WINDS PUSH THEM ON SHORE. AS HIGH
PRESSURE SETTLES AND STRENGTHENS THE SUBSIDENCE CAP A FAIR WEATHER
PATTERN SHOULD PREVAIL FOR MUCH OF NEXT WEEK. HOWEVER...SCATTERED
SHOWERS CANT BE RULED OUT DURING THE WEEKEND...AGAIN MAINLY ON
THE NORTH COASTAL REGIONS IN THE NIGHT AND EARLY MORNING AND
INTERIOR AND SOUTHWEST DURING THE AFTERNOONS.

AVIATION...VFR CONDS WILL PREVAIL AT ALL TAF SITES WITH VERY BRIEF
MVFR IN SHRA...AND SOME MTN OBSCURATIONS IN PR. WINDS EASTERLY UP TO
12 KNOTS BLO 5 KFT. LIGHT AND VARIABLE UP TO 15 KFT. WINDS AT 38 KFT
WERE MEASURED AT 100 KT FROM THE WEST AT 30/12Z BUT ARE EXPECTED TO
DIMINISH.

MARINE...SMALL CRAFT ADVISORY IN EFFECT FOR THE OFFSHORE ATLANTIC
WATERS AS SEAS OF 7 FEET ARE EXPECTED THROUGH THE OVERNIGHT.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  73  83  75  83 /  20  50  50  50
STT  76  84  77  84 /  20  50  50  50

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...NONE.
VI...NONE.
COASTAL WATERS...SMALL CRAFT ADVISORY UNTIL 6 AM AST SATURDAY FOR ATLC WATERS OF
     PUERTO RICO AND USVI FROM 10NM TO 19.5N.

&&

$$

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