957
FXCA20 KWBC 171230
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
830 AM EDT MON JUL 17 2023
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM JUL
17/12UTC: A TROPICAL WAVE IS MOVING IN TODAY AND WILL CAUSE
SHOWERS AND THUNDERSTORMS ACROSS THE LOCAL ISLANDS. A DECENT
CONCENTRATION OF SAHARAN DUST WILL MOVE IN ON TUESDAY...AND WILL
PERSIST THROUGH THE REST OF THE WORKWEEK. THE AVAILABLE MOISTURE
WILL INCREASE TODAY WITH THE TROPICAL WAVE...AND WILL REMAIN ABOVE
NORMAL INTO EARLY TUESDAY. MOISTURE WILL DECREASE RAPIDLY THROUGH
THE DAY ON TUESDAY...AND WILL BE BELOW NORMAL BY TUESDAY
NIGHT...REMAINING BELOW NORMAL FOR THE NEXT SEVERAL DAYS
THEREAFTER. DURING THE 5-DAY PERIOD...TODAY IS EXPECTED TO BE THE
RAINIEST DAY...FOLLOWED BY SOME POSSIBLE RAIN EARLY TUESDAY...BUT
LATE TUESDAY THROUGH FRIDAY IS EXPECTED TO BE FAIRLY DRY AND HAZY.
A SFC HIGH PRESSURE OVER THE WEST CENTRAL ATLANTIC WILL KEEP E-ESE
WINDS DURING THE NEXT SEVERAL DAYS. A MID LEVEL HIGH PRESSURE IS
FORECAST TO MOVE FROM THE CENTRAL ATLANTIC TO WESTERN ATLANTIC
OVER THE COURSE OF THIS WEEK. THE EGDI ALGORITHM SUGGESTS THE
CHANCE OF ISOLATED TO SCATTERED THUNDERSTORMS TODAY INTO EARLY
TUESDAY. THE SAHARAN DUST IS EXPECTED TO START MOVING IN ON
TUESDAY...BUT THE DRY AIR ADVECTION IS EXPECTED FOR LATER IN THE
DAY...SO THERE COULD BE MODERATE SHOWERS ON TUESDAY MORNING. NOT
ONLY IS THE SAHARAN DUST MOVING IN...THERE IS ALSO A TRADE WIND
INVERSION AT AROUND 850HPA THAT IS EXPECTED FROM LATE TUESDAY AND
THROUGH THE REST OF THE WORKWEEK. THIS INVERSION WITH THE DRY AIR
AND SAHARAN DUST WILL LIMIT THE POTENTIAL FOR SHOWER DEVELOPMENT.
THE LATEST GUIDANCE INDICATES MOSTLY FAIR WEATHER FROM WEDNESDAY
ONWARD.
OVERALL...NUMEROUS SHOWERS AND A FEW THUNDERSTORMS ARE EXPECTED
TODAY...WITH EAST TO SOUTHEAST PR EXPECTING THE HIGHEST AMOUNTS OF
RAIN. THE DIFFERENT HI-RES MODEL GUIDANCE SUGGESTED ANYWHERE FROM
1.5 TO JUST OVER 3 INCHES OF RAIN FOR SE-PR TODAY INTO TUESDAY
MORNING. SOME LINGERING MOISTURE COULD CAUSE SHOWER ACTIVITY IN
THE MORNING HOURS OF TUESDAY BEFORE THE MUCH DRIER AIR AND SAHARAN
DUST MOVES IN. AFTER THE DRY AIR...SAHARAN DUST...AND TRADE WIND
INVERSION SETTLES IN LATER ON TUESDAY AND THE REST OF THE
WEEK...MOSTLY FAIR WEATHER AND HAZY SKIES ARE EXPECTED. ONLY A FEW
ISOLATED SHOWERS ARE FORECAST FOR THE MID TO LATTER PART OF THE
WORKWEEK.
ALAMO/ACOSTA...WPC (USA)
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