000
FXCA62 TJSJ 240214
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
1014 PM AST THU MAY 23 2013

.UPDATE...SATELLITE IMAGERY SHOWS MOSTLY CLOUDY SKIES ACROSS THE
FORECAST AREA TONIGHT. DOPPLER WEATHER RADAR INDICATED ISOLATED
TO SCATTERED SHOWERS ACROSS THE U.S. VIRGIN ISLANDS...CULEBRA AND
VIEQUES. SOME OF THESE SHOWERS WILL MOVE OVER EASTERN PUERTO RICO
LATER TONIGHT AND OVERNIGHT. SHOWER ACTIVITY IS EXPECTED TO INCREASE
AFTER 24/06Z...ESPECIALLY ACROSS THE REGIONAL WATERS...USVI AND
EASTERN PUERTO RICO. MODELS SUGGEST AN UNSTABLE AIR MASS AND
PRECIPITABLE WATER SURGING GRADUALLY OVERNIGHT...REACHING A
MAXIMUM OF 2.1 INCHES BY FRIDAY AFTERNOON. OVERALL...EXPECT WEATHER
CONDITIONS TO DETERIORATE AND BECOME MORE ACTIVE TOMORROW THROUGH
THE WEEKEND UNDER INFLUENCE OF AN AMPLIFYING UPPER TROUGH NORTH OF
THE ISLANDS. MINOR CHANGES WERE INTRODUCED TO THE FORECAST PACKAGE
THIS EVENING.

&&

.AVIATION...VFR CONDITIONS WILL PREVAIL ACROSS ALL TAF SITES THROUGH
AT LEAST 24/12Z. HOWEVER...BRIEF PERIODS OF MVFR CONDITIONS ARE
POSSIBLE OVER TNCM AND TKPK IN SHOWERS. VCSH SHOWERS WILL BE
POSSIBLE OVER TIST AND TISX. SURFACE WINDS WILL CONTINUE MAINLY EAST
AT 10 TO 15 KTS.

&&

.MARINE...SMALL CRAFT ADVISORIES REMAIN IN EFFECT FOR THE OFF
SHORE ATLANTIC AND CARIBBEAN WATERS DUE TO SEAS BETWEEN 7 AND 8
FEET. ELSEWHERE...SMALL CRAFT SHOULD EXERCISE CAUTION.

&&

.PREV DISCUSSION... /ISSUED 338 PM AST THU MAY 23 2013/

SYNOPSIS...UPPER TROUGH PATTERN WILL DOMINATE THE WRN ATLC INTO
THE CARIBBEAN REGION THRU MID NEXT WEEK. STRONG SFC HIGH PRES
ACROSS THE ATLC WILL MAINTAIN FRESH TRADE WINDS INTO NEXT WEEK.

DISCUSSION...MODEL FCSTS FOR TOMORROW SEEMS TO HAVE BROKEN
CONTINUITY FROM YESTERDAYS RUN BUT REMAIN CONSISTENT FOR THE
WEEKEND AND EARLY NEXT WEEK SHOWING THE POTENTIAL FOR SIGNIFICANT
HEAVY RAINS. BOTH ECMWF AND GFS SHOW RAPID MOISTURE RETURN OVR
THE AREA EARLY FRI AND THIS SEEMS UNLIKELY BASED ON THE BLENDED
TPW PRODUCT. LOOKING AT THE BIG PICTURE...GUIDANCE INDICATES
SHORTWAVE-RIDGE ALOFT FRI WHICH WOULD ARGUE AGAINST WIDESPREAD
RAINFALL.

LATE FRI NIGHT-SAT...APPROACHING SHORTWAVE-TROUGH FROM THE
BAHAMAS AND TRADE WIND CONVERGENCE SHOULD RESULT IN
NMRS/WIDESPREAD CONVECTION OVER THE USVI AND EASTERN PR. WITH
GENERAL TROF PATTERN TO PERSIST INTO EARLY NEXT WEEK...VERY
UNSETTLED CONDITIONS ARE LIKELY ACROSS THE ENTIRE REGION. AS
ALWAYS...TIMING OF THESE CONVECTIVE BLOWUPS IS QUITE CHALLENGING
BUT THE SCREAMING MESSAGE HERE IS FOR SIG HEAVY AND PROLONGED
RAINS. CONDITIONS APPEAR TO WORSEN MID NEXT WEEK AS ANOTHER TROUGH
CUTS OFF ACROSS THE BAHAMAS AND DEEP SOUTHEASTERLY FLOW
ESTABLISHES OVER THE REGION AND MOISTURE DEEPENS.

AVIATION...VFR CONDITIONS EXPECTED ACROSS THE LOCAL TERMINALS WITH
THE EXCEPTION OF TEMPO MVFR/IFR CONDITIONS ACROSS TJMZ AND POSSIBLY
TJBQ DUE TO AFTERNOON CONVECTION. MTN OBSCURATIONS AND VARIABLE
GUSTY WINDS EXPECTED NEAR THE SHRA/TSRA. WEATHER CONDITIONS EXPECTED
TO IMPROVE AFTER 23/23Z. THEREAFTER...PASSING SHRA EXPECTED OVERNIGHT
WILL CAUSE VCSH FOR TJSJ...TIST...TISX...AS WELL AS TNCM AND TKPK.
WINDS WILL BE AT 10 KNOTS OR LESS FROM THE EAST UNTIL 24/12Z.
INCREASING THEREAFTER TO 10 TO 15 KNOTS AND GUSTY.

MARINE...SCA REMAIN IN EFFECT BUT WILL LIKELY GO DOWN TOMORROW AS
WINDS WEAKEN BIT. TSTMS WILL BE THE MAIN HAZARD.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  76  85  76  85 /  40  70  70  70
STT  77  86  78  85 /  40  60  70  70

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...NONE.
VI...NONE.
COASTAL WATERS...SMALL CRAFT ADVISORY UNTIL 6 AM AST FRIDAY FOR ANEGADA PASSAGE
     SOUTHWARD TO 17N-CARIBBEAN WATERS OF PUERTO RICO FROM 10 NM
     TO 17N.

     SMALL CRAFT ADVISORY UNTIL 6 AM AST SATURDAY FOR ATLC WATERS OF
     PUERTO RICO AND USVI FROM 10NM TO 19.5N.

     SMALL CRAFT ADVISORY UNTIL 6 AM AST FRIDAY FOR COASTAL WATERS OF
     SOUTHERN USVI VIEQUES AND EASTERN PUERTO RICO OUT 10 NM.

&&

$$

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