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FXCA62 TJSJ 211032 CCA
AFDSJU

AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE SAN JUAN PR
630 AM AST FRI NOV 21 2014

.SYNOPSIS...RETROGRESSING MID TO UPPER LEVEL TROUGH ACROSS THE
FAR EASTERN CARIBBEAN AND INTO THE TROPICAL ATLANTIC WILL REACH
THE LOCAL ISLANDS LATE TONIGHT AND EARLY SATURDAY AS SLOWLY
WEAKENS. THIS WILL RESULT IN GOOD MOISTURE ADVECTION WITH PERIODS
OF SHOWERS AND ISOLATED THUNDERSTORMS POSSIBLE THIS EVENING
THROUGH EARLY SATURDAY AFTERNOON. FAIR WEATHER IS THEN EXPECTED
TO PREVAIL LATE SATURDAY AND INTO EARLY NEXT WEEK AS RIDGE ALOFT
BUILDS ACROSS THE FORECAST AREA. AT LOWER LEVELS...HIGH PRESSURE
OVER THE CENTRAL ATLANTIC WILL MAINTAIN FRESH TRADE WINDS THROUGH
THE END OF THE WEEK.

&&

.DISCUSSION...MOISTURE ADVECTION IS EXPECTED ACROSS THE LOCAL
ISLANDS AS SOON AS EARLY THIS AFTERNOON AND INTO THE EVENING
HOURS AS A MID TO UPPER LEVEL TROUGH WITH ASSOCIATED AREA OF
LOW PRESSURE MOVES WESTWARD ACROSS THE EASTERN CARIBBEAN.
ALTHOUGH LATEST MODEL GUIDANCE INDICATED BEST DYNAMICS REMAINING
OVER THE WATERS...SHOWERS AND ISOLATED THUNDERSTORMS POSSIBLE
STILL EXPECTED TONIGHT THROUGH EARLY SATURDAY AFTERNOON. URBAN
FLOODING LIKELY...WITH SOME LOCALIZED FLASH FLOODING OF SMALL
STREAMS AND RIVERS POSSIBLE ACROSS THE EASTERN THIRD OF PR
WHERE THE AFOREMENTIONED FRESH TRADE WIND FLOW WILL RESULT IN
OROGRAPHIC ENHANCEMENT.

THEREFORE...CONTINUE TO EXPECT TRADE WIND SHOWERS ACROSS WINDWARD
AREAS FROM TIME TO TIME THIS MORNING AND EARLY IN THE AFTERNOON
WITH SOME SHALLOW AFTERNOON CONVECTION OVER WESTERN PUERTO RICO.
BY THE LATE AFTERNOON HOURS...FREQUENCY OF SHOWERS WILL INCREASE
ACROSS LOCAL WATERS...THE U.S. VIRGIN ISLANDS AS WELL AS THE
EASTERN THIRD OF PUERTO RICO. THESE SHOWERS WILL BE FAST MOVERS
UNDER A STEERING FLOW NEAR 12 KNOTS...BUT ANY PROLONGED PERIOD OF
MODERATE TO HEAVY RAINFALL...ENHANCED BY LOCAL EFFECTS ACROSS E
PR...MAY RESULT IN SOME LOCALIZED RAPID RISES ALONG RIVERS AND
SMALL STREAMS WITH URBAN FLOODING LIKELY.

RIDGE ALOFT WILL BUILD ACROSS THE LOCAL AREA SUNDAY AND EARLY
NEXT WEEK WITH MOISTURE EROSION EXPECTED AT MID LEVELS. AT LOWER
LEVELS...MOISTURE SHOULD REMAIN NEAR OR BELOW NORMAL VALUES.
THEREFORE...SUNDAY THROUGH MUCH OF THE NEXT WORK WEEK...EXPECT A
GENERALLY FAIR AND MAINLY STABLE WEATHER PATTERN EACH DAY WITH
TRADE WIND SHOWERS ACROSS WINDWARD AREAS FOLLOWED BY SHALLOW
AFTERNOON SHOWERS ACROSS WEST PR...IF ANY.

&&

.AVIATION...VFR CONDITIONS EXPECTED ACROSS PR AND USVI TAF SITE
OVERNIGHT. DETERIORATING WX CONDS AT TNCM/TKPK OVERNIGHT WITH
POSSIBLE MVFR AND IFR CONDS. INCREASING SHRA/TSRA ACTIVITY ACROSS
THE LEEWARD ISLANDS SPREADING THROUGH THE USVI AND EASTERN PR THIS
MORNING INTENSIFYING AFTER 21/18Z WITH VCTS/VCSH LIKELY FOR MOST
OF THE LOCAL TERMINALS AND POSSIBLY AFFECTING THE TERMINALS FOR
BRIEF PERIODS. THIS ACTIVITY MAY CAUSE BRIEF PERIODS OF MVFR
CONDS. SFC WINDS 10 TO 20 KTS WITH HIGHER GUSTS.

&&

.MARINE...SEAS REMAIN 5-7 FT AND WINDS 15-20 KT THROUGH THE DAY.
WINDS STRENGTHEN SAT THROUGH MON NEAR 22 KNOTS WITH SEAS BUILDING
6-8 FT.

&&

.HYDROLOGY...RETROGRESSING MID TO UPPER LEVEL TROUGH ACROSS THE
FAR EASTERN CARIBBEAN AND INTO THE TROPICAL ATLANTIC WILL REACH
THE LOCAL ISLANDS LATER TODAY AND EARLY SATURDAY AS SLOWLY
WEAKENS. THIS WILL RESULT IN GOOD MOISTURE ADVECTION WITH PERIODS
OF SHOWERS AND ISOLATED THUNDERSTORMS POSSIBLE TONIGHT THROUGH
EARLY SATURDAY AFTERNOON.

PROLONGED PERIODS OF MODERATE TO HEAVY RAINFALL ENHANCED BY LOCAL
EFFECTS ACROSS THE EASTERN THIRD OF PUERTO RICO MAY RESULT IN
SOME LOCALIZED RAPID RISES ON SMALL STREAMS AND RIVERS AS WELL AS
INCREASE THE POTENTIAL FOR MUDSLIDES IN AREAS OF STEEP TERRAIN
WITH URBAN FLOODING LIKELY.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  86  78  85  77 /  90  90  90  40
STT  87  74  87  76 /  70  70  70  40

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...

VI...NONE.
COASTAL WATERS...SMALL CRAFT ADVISORY FROM 9 AM THIS MORNING TO MIDNIGHT AST
     MONDAY NIGHT FOR ANEGADA PASSAGE SOUTHWARD TO 17N-ATLC
     WATERS OF PUERTO RICO AND USVI FROM 10NM TO 19.5N-CARIBBEAN
     WATERS OF PUERTO RICO FROM 10 NM TO 17N-COASTAL WATERS OF
     NORTHERN USVI AND CULEBRA OUT 10 NM-COASTAL WATERS OF
     SOUTHERN USVI VIEQUES AND EASTERN PUERTO RICO OUT 10 NM.

     SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO MIDNIGHT AST
     MONDAY NIGHT FOR MONA PASSAGE SOUTHWARD TO 17N.

     SMALL CRAFT ADVISORY FROM 9 PM THIS EVENING TO 3 PM AST SUNDAY
     FOR COASTAL WATERS OF NORTHERN PUERTO RICO OUT 10 NM.

&&

$$

25/23






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