Areal Flood Advisory 430, NWS JSJ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
252 PM AST SUN SEP 26 2010

.SYNOPSIS...A MID LEVEL DISTURBANCE WILL CONTINUE MOVING WEST NORTHWEST
ACROSS THE LOCAL ISLANDS TONIGHT. A MID TO UPPER LEVEL HIGH PRESSURE
WILL EXTEND INTO THE LOCAL AREA MONDAY THROUGH WEDNESDAY.

&&

.DISCUSSION...SEA BREEZE CONVERGENCE COMBINED WITH LOW LEVEL MOISTURE
AND DIURNAL HEATING INDUCED AFTERNOON SHOWERS AND THUNDERSTORMS ACROSS
THE INTERIOR...NORTHWEST AND WEST SECTIONS OF PUERTO RICO AS WELL AS
ACROSS THE SAN JUAN METRO AREA. THIS ACTIVITY IS EXPECTED TO DIMINISH
BEFORE SUNSET...LEAVING PARTLY TO VARIABLY CLOUDY SKIES AND ISOLATED
SHOWERS ACROSS THESE AREAS. ISOLATED TO SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS STILL EXPECTED ACROSS PORTIONS OF THE SOUTHEAST COAST
OF PUERTO RICO AND THE VIRGIN ISLANDS TONIGHT THROUGH THE EARLY MORNING
HOURS.

COMPUTER MODELS...MIMIC TPW PRODUCT AND PROGNOSTIC SOUNDINGS INDICATED
ENOUGH MOISTURE ACROSS THE LOCAL ISLANDS WITH NO SIGNIFICANT DRYING
EXPECTED THROUGH THE FORECAST PERIOD. THEREFORE...THE NEXT FEW
AFTERNOONS AVAILABLE MOISTURE WILL COMBINE WITH LOCAL EFFECTS AND
DIURNAL HEATING TO PRODUCE CLOUDINESS...SHOWERS AND THUNDERSTORMS
ACROSS THE LOCAL ISLANDS. THE STEERING FLOW WILL REMAIN MAINLY
FROM THE SOUTHEAST TO EAST SOUTHEAST...MAINTAINING THE AFTERNOON
CONVECTION ACROSS THE NORTHWESTERN QUADRANT AND INTERIOR SECTIONS
OF THE PUERTO RICO EACH AFTERNOON.

LOOKING AHEAD...BY THE END OF WEEK...COMPUTER MODELS CONTINUE TO
ADVERTISE ADVECTION OF DEEP TROPICAL MOISTURE INTO THE LOCAL ISLANDS
AS A LOW PRESSURE SYSTEM DEVELOPS ACROSS THE FAR WESTERN CARIBBEAN.
AS A RESULT...BETTER CHANCES OF SIGNIFICANT PRECIPITATION ACROSS THE
LOCAL ISLANDS ARE POSSIBLE LATE THIS WEEK THROUGH THE NEXT WEEKEND.

&&

.AVIATION...SHRAS AND TSRAS TO CONT TIL AT LEAST 27/02Z THEN WILL
MOVE OFFSHORE AND CONT OVER LOCAL WATERS OVERNIGHT. TOPS BEFORE
26/22Z TO REACH 60 KFT. MTN OBSCURATIONS THRU 27/04Z. OCNL MVFR
CONDS AT TJBQ AND TJMZ. LLVL WINDS LESS THAN 20 KTS ESE UP THRU 26
KFT. GUSTY SFC WINDS IN AND NEAR THUNDERSTORMS TO 30 KTS. MVFR PSBL
AT TISX AFT 27/08Z IN SHRA. CONVECTION EXPECTED TO RETURN TO LAND
AREAS AFT 27/1530Z.

&&

.MARINE...GENERALLY EXPECT WINDS OF 17 KNOTS OR LESS AND SEAS OF 5
FEET OR LESS ACROSS THE REGIONAL WATERS THROUGH AT LEAST TUESDAY.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  88  78  89  78 /  40  40  40  30
STT  88  78  89  79 /  20  60  60  50

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...NONE.
VI...NONE.
&&

12/23