Flash Flood Warning 139, NWS JSJ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
256 PM AST TUE NOV 9 2010

.SYNOPSIS...AT MID AND UPPER LEVELS...HIGH PRESSURE REMAINS OVER
THE CARIBBEAN SEA WHILE A MID LATITUDE TROUGH PASSES JUST TO THE
NORTH OVER THE WEEKEND. HIGH PRESSURE BUILDS OVER THE CENTRAL
CARIBBEAN NEXT WEEK.

AT LOWER LEVELS...A FRONT EXTENDS INTO A WEAK LOW PRESSURE TO THE
SOUTH SOUTH WEST OF PUERTO RICO. THIS FRONT WILL MOVE NORTH OVER
PUERTO RICO TONIGHT AND RETURN ON FRIDAY. BANDS OF MOISTURE WILL
MOVE ACROSS THE ISLAND DURING THE UPCOMING WEEK...BUT IT WILL
GENERALLY BE DRIER.

&&

.DISCUSSION...HEAVY RAIN WITH SOME CONVECTIVE TOPS EXCEEDING 50
THOUSAND FEET ARE MOVING NORTHEAST FROM JUST SOUTH OF SOUTHEAST
PUERTO RICO. RAIN HAS ALSO MOVED OVER MUCH OF SOUTHERN PUERTO
RICO AND IS APPROACHING THE U.S. VIRGIN ISLANDS. IT NOW APPEARS THAT
EASTERN PUERTO RICO AND THE U.S. VIRGIN ISLANDS WILL BEAR THE
BRUNT OF THIS PASSAGE...BUT MOISTURE REMAINS OVER THE AREA FOR THE
NEXT 72 HOURS...AT LEAST...AND WILL CONTRIBUTE TO A GENERALLY WET
SITUATION. AN UPPER LEVEL TROUGH WILL PASS JUST TO THE NORTH ON
FRIDAY THROUGH SUNDAY...THIS SHOULD ALLOW THE COOLER AND SOMEWHAT
DRIER AIR TO THE NORTH TO MOVE INTO THE AREA...BUT DEPENDING ON
HOW MUCH MOISTURE REMAINS IN THE BANDS THAT MOVE IN FROM THE
NORTHWEST...SOME SHALLOW CONVECTION COULD KEEP THE NORTHERN
SLOPES AND PLAINS OF PUERTO RICO AND THE U.S. VIRGIN ISLANDS WET
INTO NEXT WEEK. THIS SCENARIO IS ALSO SUPPORTED MORE BY THE ECMWF.

&&

.AVIATION...
PREVAILING MVFR CONDITIONS EXPECTED ACROSS ALL TAF SITES...WITH
BRIEF IFR CONDS POSSIBLE...ESPECIALLY ACROSS THE VI... TJSJ...TJMZ AND
TJPS FROM 09/21Z-10/06Z...AS SHRAS AND TSRAS ARE EXPECTED TO
CONTINUE TO DEVELOP.

&&

.MARINE...SEAS WILL SLOWLY SUBSIDE THROUGH FRIDAY...HOWEVER A NEW
TRAIN OF ELEVATED SEAS FROM A LOW PRESSURE THAT HAS MOVED INTO THE
WESTERN ATLANTIC WILL BEGIN TO ARRIVE LATE SATURDAY AND SUNDAY
THAT WILL BRING ANOTHER ROUND OF SMALL CRAFT AND HIGH SURF
ADVISORIES. SEAS MAY REACH 12 FEET WITH BREAKING WAVES OF 10 TO 15
FEET OR HIGHER.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  75  87  74  86 /  60  60  20  60
STT  76  85  77  85 /  70  60  20  40

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...FLASH FLOOD WATCH THROUGH EARLY THURSDAY MORNING FOR CENTRAL
     INTERIOR-CULEBRA-EASTERN INTERIOR-MAYAGUEZ AND VICINITY-
     NORTH CENTRAL-NORTHEAST-NORTHWEST-PONCE AND VICINITY-SAN
     JUAN AND VICINITY-SOUTHEAST-SOUTHWEST-VIEQUES-WESTERN
     INTERIOR.

     HIGH SURF ADVISORY UNTIL 8 AM AST WEDNESDAY FOR CULEBRA-MAYAGUEZ
     AND VICINITY-NORTH CENTRAL-NORTHEAST-NORTHWEST-SAN JUAN AND
     VICINITY.

     SCA...ALL.

VI...FLASH FLOOD WATCH THROUGH EARLY THURSDAY MORNING NIGHT FOR
     ST CROIX- ST. THOMAS/ST. JOHN/ADJACENT ISLANDS.

     HIGH SURF ADVISORY UNTIL 8 AM AST WEDNESDAY FOR ST. THOMAS/ST.
     JOHN/ADJACENT ISLANDS.

     SCA...ALL.

&&

23/12