968
FXCA20 KWBC 201213
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
813 AM EDT THU APR 20 2023
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM APR
20/12UTC: THE AVAILABLE MOISTURE WILL BE NEAR TO BELOW NORMAL
THROUGH FRIDAY...INCREASING TO NEAR THE 75TH PERCENTILE ON
SATURDAY...THEN DROPPING TO NEARLY 2 STANDARD DEVIATIONS BELOW
NORMAL ON SUNDAY NIGHT INTO MONDAY MORNING...AS SUGGESTED BY THE
LATEST MODEL GUIDANCE. A WEAK UPPER LEVEL RIDGE WILL BE OVER
PR/USVI TODAY...WHILE MOVING EAST...BUT AN UPPER LEVEL TROUGH IS
APPROACHING THE AREA FROM THE WEST. THE TROUGH AXIS IS STILL
FORECAST TO PASS ACROSS PR/USVI ON SATURDAY. THE APPROACHING
TROUGH WILL CAUSE RELATIVELY STRONG WINDS ALOFT...POSSIBLY OVER
70KT...CAUSING UPPER LEVEL DIVERGENCE. A WEAK MID LEVEL RIDGE IS
ALSO PRESENT OVER THE LOCAL AREA AND IS MOVING EAST...WHILE A MID
LEVEL TROUGH ALSO APPROACHES THE NORTHEAST CARIBBEAN LATE FRIDAY
NIGHT INTO SATURDAY. WEAK SURFACE HIGH PRESSURE ACROSS THE WESTERN
ATLANTIC WILL MAINTAIN AN EASTERLY TO SOUTHEASTERLY WIND FLOW
THROUGH FRIDAY AFTERNOON. A WEAK SURFACE LOW WILL DEVELOP JUST
EAST OF THE SOUTHERN BAHAMAS LATE FRIDAY INTO SATURDAY...RELAXING
THE LOCAL PRESSURE GRADIENT AND CAUSING LIGHT WINDS OVER PR/USVI
STARTING LATE FRIDAY INTO EARLY NEXT WEEK.
LOCALLY INDUCED AND TRADE WIND SHOWERS ARE EXPECTED THROUGH THE
REST OF THE WORKWEEK...WITH CENTRAL TO WESTERN PR OBSERVING
AFTERNOON SHOWERS. GIVEN THE BELOW NORMAL MOISTURE EXPECTED
TODAY...THE RAINFALL AMOUNTS ARE EXPECTED TO BE MODEST...WITH A
MAX OF JUST OVER A HALF AN INCH OF RAIN ACROSS THE NORTHWESTERN
QUADRANT OF PR THIS AFTERNOON...AND UNDER A QUARTER OF AN INCH
ACROSS EASTERN PR AND PERHAPS A FEW HUNDREDTHS OF AN INCH ACROSS
THE USVI. THERE IS SOME DISCREPANCY IN THE HI-RES MODEL GUIDANCE
THOUGH. THE NBM SHOWS SOME AREAS OF OVER 1 INCH OF RAIN ACROSS
NW-PR...WHILE THE ECMWF SUGGESTS VERY LITTLE RAIN...AND ONLY
AROUND A QUARTER OF AN INCH OF RAIN ACROSS THE MUNICIPALITY OF
RINCON...IN THE EXTREME NORTHWEST OF THE ISLAND. FOR FRIDAY...AS
THE WINDS START TO DECREASE GRADUALLY...THE AFTERNOON CONVECTION
OVER PR MIGHT BE A BIT FURTHER EAST...WITH THE MODEL GUIDANCE
SUGGESTING THE HIGHEST AMOUNTS OF RAIN SOMEWHERE BETWEEN THE
MUNICIPALITIES OF CIALES TO SAN SEBASTIAN...IN THE NORTH CENTRAL
TO NORTHWESTERN PR. BECAUSE FRIDAY MAY HAVE SLIGHTLY HIGHER
MOISTURE...AND THE MID AND UPPER LEVEL TROUGHS ARE APPROACHING
FROM THE WEST...THE AMOUNTS OF RAIN IN THE FORECAST FOR FRIDAY
AFTERNOON ARE A BIT HIGHER...WITH MAX VALUES NEAR AN INCH WITH A
POSSIBILITY OF ISOLATED THUNDERSTORMS. AS THE UPPER TROUGH
CONTINUES TO APPROACH PR/USVI...ON SATURDAY AND SUNDAY...CENTRAL
TO EASTERN PR IS EXPECTED TO HAVE THE HIGHEST AMOUNTS OF RAIN WITH
THE BEST CHANCE FOR THUNDERSTORMS. BEST AREA FOR
CONVECTION...MEANING THAT CENTRAL TO EASTERN PR WOULD HAVE THE
HIGHEST RAINFALL ACCUMULATION ON SATURDAY AND SUNDAY. AT THIS
TIME...SATURDAY APPEARS TO BE THE DAY WITH THE HEAVIEST RAIN.
ALAMO/ACOSTA...WPC (USA)
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page