National Weather Service Text Product Display

Area Forecast Discussion
Issued by NWS San Juan, PR
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FXCA62 TJSJ 191532
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
1132 AM AST WED JUN 19 2013

.UPDATE...PREVIOUS FORECAST ON TRACK...AS SHOWERS AND
THUNDERSTORMS CONTINUE TO DEVELOP AND MOVE ACROSS THE FORECAST
AREA. THESE SHOWERS ARE FAST MOVING AND RAINFALL AMOUNTS HAVE NOT
BEEN ENOUGH TO GENERATE ENOUGH RUNOFF FOR ANY SIGNIFICANT FLOODING
PROBLEMS...THUS FAR...OTHER THAN PONDING OF WATER IN POOR
DRAINAGE AREAS AND ROADWAYS. FLOODING POTENTIAL STILL EXISTS UNTIL
CONVECTIVE ACTIVITY DECREASES LATER TODAY INTO TONIGHT. SMALL
CRAFT ADVISORIES ARE IN EFFECT UNTIL THURSDAY FOR MOST OF THE
LOCAL WATERS.


&&

.AVIATION...NO CHANGES TO PREV FORECAST...PERIODS OF MVFR
CONDITIONS PSBL ACROSS TIST AND TISX IN SHRA/TSRA ASSOCIATED WITH
THE TROPICAL WAVE. SHRA/TSRA WILL INCREASE ACROSS THE LOCAL TAF
SITES...LESS SO AT TNCM AND TKPK...AS THE TROPICAL WAVE MOISTURE
MOVES OVER THE REGION. WIND FLOW OF 10-25 KNOTS THE WAY FROM THE
SURFACE TO 15K FEET.


&&

.PREV DISCUSSION... /ISSUED 506 AM AST WED JUN 19 2013/

SYNOPSIS...MID TO UPPER LEVEL TROUGH OVER PUERTO RICO THIS MORNING
WILL RELOCATE WEST OF THE FORECAST AREA TONIGHT. SHOWERS AND
THUNDERSTORMS ASSOCIATED WITH A FAST MOVING TROPICAL WAVE WILL
CONTINUE TO SPREAD ACROSS THE LOCAL ISLANDS TODAY. THE TROUGH
ALOFT WILL ENHANCE THE CONVECTIVE INSTABILITY ACROSS THE REGION...
RESULTING IN MORE INTENSE SHOWERS AND THUNDERSTORMS. CONDITIONS
WILL IMPROVE ON THURSDAY AS A DRIER AIR MASS WITH SAHARAN DUST
MOVES OVER THE ISLANDS.

DISCUSSION...DOPPLER RADAR SHOWED NUMEROUS SHOWERS AND SCATTERED
THUNDERSTORMS BETWEEN THE ANEGADA PASSAGE...U.S. VIRGIN ISLANDS
AND EASTERN PUERTO RICO THIS MORNING. MOST OF THE SHOWERS AND
THUNDERSTORMS ARE MOVING QUICKLY WESTWARD AT 20 KT. GUSTY WINDS
NEAR 37 KT WERE OBSERVED WITH THIS ACTIVITY...SPECIFICALLY AT BUOY
41052 JUST SOUTH OF ST JOHN. MOISTURE ASSOCIATED WITH THE WAVE
WILL QUICKLY SURGE ACROSS THE LOCAL AREA TODAY...REACHING A
MAXIMUM OF AROUND 2.25 INCHES BY 19/18Z. THIS TROPICAL WAVE WILL
BRING AN ACTIVE WEATHER PATTERN AS WELL AS SQUALLY WEATHER ACROSS
THE ISLANDS AND SURROUNDING WATERS THROUGH AT LEAST TONIGHT. THE
TROUGH ALOFT WILL COMBINE WITH THE DEEP MOISTURE AND INSTABILITY
OF THE WAVE TO ENHANCE THE CONVECTIVE DEVELOPMENT ACROSS THE FORECAST
AREA...INCREASING THE POTENTIAL FOR HEAVY RAINFALL...STRONG GUSTY
WINDS AND LOCALIZED FLOODING. OVERALL...EXPECT AN ACTIVE WEATHER
DAY WITH SEVERAL ROUNDS OF SHOWERS AND THUNDERSTORMS AFFECTING THE
LOCAL ISLANDS THROUGH TONIGHT. WEATHER CONDITIONS WILL IMPROVE ON
THURSDAY AS DRIER AIR WITH A DECENT AMOUNT OF SAHARAN DUST WILL
MOVE OVER THE FORECAST AREA.

AVIATION...PERIODS OF MVFR CONDITIONS PSBL ACROSS TNCM...TKPK...
TIST AND TISX IN SHRA/TSRA ASSOCIATED WITH THE TROPICAL WAVE.
SHRA/TSRA WILL INCREASE ACROSS THE LOCAL TAF SITES BY 19/12Z AS
THE TROPICAL WAVE MOISTURE MOVES OVER THE REGION. TJSJ 19/00Z
SOUNDING INDICATED AN EASTERLY WIND FLOW OF 10-25 KNOTS ALL THE
WAY FROM THE SURFACE TO 15K FEET...BECOMING WESTERLY ALOFT.

MARINE...A SMALL CRAFT ADVISORY...SCA...IS IN EFFECT THROUGH
THURSDAY EVENING FOR FRESH TRADE WINDS AND ROUGH SEAS ASSOCIATED
WITH THE PASSAGE OF THE TROPICAL WAVE. WINDS WILL SUBSIDE THURSDAY
NIGHT...PROBABLY ENOUGH TO ALLOW US TO DROP THE SCA.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  87  77  88  78 /  70  70  40   0
STT  87  78  88  80 /  90  90  20  10

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...NONE.
VI...NONE.
COASTAL WATERS...SMALL CRAFT ADVISORY UNTIL 3 PM AST THURSDAY FOR ANEGADA PASSAGE
     SOUTHWARD TO 17N.

     SMALL CRAFT ADVISORY UNTIL 9 AM AST THURSDAY FOR 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 UNTIL 9 PM AST THURSDAY FOR ATLC WATERS OF
     PUERTO RICO AND USVI FROM 10NM TO 19.5N-CARIBBEAN WATERS OF
     PUERTO RICO FROM 10 NM TO 17N-MONA PASSAGE SOUTHWARD TO 17N.

     SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 9 AM AST
     THURSDAY FOR COASTAL WATERS OF SOUTHERN PUERTO RICO OUT 10
     NM.

     SMALL CRAFT ADVISORY FROM 5 PM THIS AFTERNOON TO 7 PM AST THIS
     EVENING FOR COASTAL WATERS OF NORTHWESTERN PUERTO RICO OUT
     10 NM.

     SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 3 AM AST
     THURSDAY FOR COASTAL WATERS OF NORTHERN PUERTO RICO OUT 10
     NM.

&&

$$

15/54
National Weather Service National Headquarters
