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FXCA20 KWBC 291246
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
846 AM EDT THU JUN 29 2023
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM JUN
29/12UTC: THE COMBINATION OF A STRONG TROPICAL WAVE AND AN UPPER
TROUGH HAS BEEN CAUSING HEAVY RAINFALL OVER PR/USVI SINCE
YESTERDAY...AND IT IS EXPECTED TO CONTINUE TODAY. THIS TROPICAL
WAVE HAS DEEP MOISTURE AND AN ADDITIONAL 1 TO 3 INCHES OF RAIN
COULD BE EXPECTED TODAY. HOWEVER...THE ECMWF ENSEMBLE MODEL IS
VERY AGGRESSIVE WITH THE RAIN ACROSS EASTERN PR...THEREFORE HIGHER
AMOUNTS OF RAIN ACROSS ISOLATED AREAS WILL NOT BE RULED OUT. THAT
BEING SAID...THE HIGHEST AMOUNTS OF RAIN TODAY ARE STILL EXPECTED
TO BE ACROSS SOUTHERN AND EASTERN PR.
THE TROPICAL WAVE IS EXPECTED TO LEAVE THE AREA BY LATE TONIGHT. A
LARGE HIGH PRESSURE OVER THE NORTHERN CENTRAL ATLANTIC WILL
DOMINATE THE GENERAL WIND FLOW THEREAFTER. THE UPPER TROUGH WILL
CONTINUE MOVING WEST...LEAVING A RIDGE OVER THE LOCAL ISLANDS FOR
THE WEEKEND... BUT AN UPPER LOW COULD DEVELOP OVER HISPANIOLA BY
TUESDAY...AND MOVE SOUTH INTO THE CARIBBEAN...WHICH COULD INCREASE
INSTABILITY OVER THE LOCAL ISLANDS. ANOTHER TROPICAL WAVE COULD BE
APPROACHING THE LOCAL ISLANDS LATE TUESDAY.
FOR TODAY...WIDESPREAD SHOWER ACTIVITY IS EXPECTED. THE EGDI
ALGORITHM SHOWS THE POTENTIAL FOR ISOLATED TO SCATTERED
THUNDERSTORMS WITH HEAVY RAIN. THE GR02T ALGORITHM IS INDICATING
ONLY A MARGINAL TO SLIGHT RISK OF SEVERE STORMS. WHILE SOUTH AND
EASTERN PR COULD OBSERVE GENERAL AMOUNTS NEAR 1 TO 3 INCHES
TODAY...THE USVI ARE FORECAST TO HAVE A MAX AMOUNT OF AROUND 1
INCH. AFTER THE TROPICAL WAVE PASSES...THE SAHARAN DUST IS
EXPECTED TO MOVE IN. THE LATEST GUIDANCE INDICATES THAT THE
SAHARAN DUST COULD MOVE IN AS EARLY AS LATE TONIGHT INTO EARLY
FRIDAY...CAUSING THE AVAILABLE MOISTURE TO GRADUALLY DECREASE. A
TRADE WIND INVERSION MAY BE PRESENT THEREAFTER...WHICH WILL ACT TO
LIMIT SIGNIFICANT SHOWER AND THUNDERSTORM DEVELOPMENT...ESPECIALLY
DURING THE WEEKEND INTO MONDAY. OVER THE NEXT 5 DAYS...SUNDAY AND
MONDAY APPEAR TO BE THE DRIEST DAYS. THE 5-DAY TOTAL RAINFALL
FORECAST ACROSS PORTIONS OF THE NORTHWESTERN QUADRANT OF PR UNDER
1.5 INCHES OF RAIN...EASTERN PR IS FORECAST JUST UNDER 5
INCHES...AND THE USVI BETWEEN 1.25 AND 2.00 INCHES.
ALAMO/ACOSTA/GALVEZ...WPC (USA)
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