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FXCA20 KWBC 151238
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
838 AM EDT TUE AUG 15 2023
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM AUG
15/12UTC: THE SIGNIFICANT PLUME OF SAHARAN DUST THAT IS AFFECTING
PR/USVI IS EXPECTED TO CONTINUE AFFECTING THE ISLANDS FOR THE REST
OF THIS WEEK...WITH A SHORT BREAK ON FRIDAY. HOWEVER...THE BELOW
NORMAL AVAILABLE MOISTURE WILL CONTINUE THROUGH WEDNESDAY...WITH
NEAR NORMAL MOISTURE ON THURSDAY THEN ABOVE NORMAL ON FRIDAY.
BECAUSE OF THE SAL THAT IS EXPECTED...MOSTLY HAZY SKIES WOULD BE
EXPECTED WITH LIMITED SHOWER ACTIVITY OVER THE ISLANDS TODAY AND
WEDNESDAY. THE TJUA DOPPLER RADAR IS SHOWING SOME SHOWER ACTIVITY
ACROSS EASTERN PR CURRENTLY...BUT THESE SHOWERS ARE BRIEF AND IT
IS EXPECTED TO DRY OFF AS THE MORNING PROGRESSES. THAT BEING
SAID...THERE IS A CHANCE OF AFTERNOON SHOWER DEVELOPMENT ACROSS
WESTERN PR...THOUGH THE RAINFALL TOTALS...IF ANY...ARE EXPECTED TO
BE UNDER A QUARTER OF AN INCH. A SIMILAR RAINFALL PATTERN CAN BE
EXPECTED FOR WEDNESDAY...BUT THINGS COULD CHANGE FROM THURSDAY
ONWARD. THE GEOS GUIDANCE CONTINUES TO INDICATE THAT SAHARAN DUST
WILL CONTINUE INTO THURSDAY...THEN A BREAK OF THE DUST DURING THE
DAY ON FRIDAY...BUT THE DUST WILL RETURN LATE FRIDAY INTO
SATURDAY. THAT SAID...THERE IS AN AREA OF DISTURBED WEATHER...WITH
RELATIVE STRONGER WINDS AT 700MB AS WELL AS RELATIVE HIGHER
VORTICITY AT THAT SAME 700MB LEVEL...THAT COULD APPROACH PR/USVI
LATE WEDNESDAY INTO THURSDAY. THERE IS ALSO A TUTT TO THE NORTH OF
PR/USVI THAT IS MOVING WEST. IT IS EXPECTED TO BE TO THE WEST
NORTHWEST OF PR BY THIS EVENING. THIS TUTT WILL ELONGATE ACROSS
THE NORTH CENTRAL CARIBBEAN AS IT STRENGTHENS FURTHER
SOUTH...CENTERING NEAR JAMAICA ON THURSDAY THROUGH FRIDAY AND
CAUSING STRONGER SOUTHERLY WINDS OVER PR/USVI ON THURSDAY.
THEREFORE...AS OF NOW...IT LOOKS LIKE THURSDAY WOULD BE THE
RAINIEST DAY OF THE 5-DAY PERIOD AFTER CONSIDERING THE MOISTURE
ADVECTION...700MB INSTABILITY AND THE TUTT TO THE SOUTHWEST OF PR
CAUSING STRONGER SOUTHERLY WINDS ALOFT. FRIDAY IS EXPECTED TO HAVE
ABOVE NORMAL MOISTURE...HOWEVER...THERE WILL BE A RIDGE IN THE
UPPER LEVELS AND THE LOW TO MID LEVELS WILL NOT HAVE AS MUCH
INSTABILITY OR FORCING COMPARED TO THURSDAY...THOUGH SOME SHOWER
ACTIVITY IS ALSO EXPECTED ON FRIDAY...JUST NOT QUITE AS MUCH AS
THURSDAY BASED ON THE LATEST AVAILABLE GUIDANCE.
FROM TODAY INTO WEDNESDAY...THE TOTAL RAINFALL FORECAST IS AROUND
0.6 INCHES NEAR THE LUQUILLO MOUNTAIN RANGE OVER NORTHEAST
PR...BETWEEN 0.75 AND 1 INCH ACROSS A SMALL PORTION OF WESTERN
PR...AND UNDER A TENTH OF AN INCH FOR THE USVI. SINCE THE SHOWER
ACTIVITY IS FORECAST TO INCREASE FOR THURSDAY AND FRIDAY...THE
5-DAY TOTAL RAINFALL FORECAST IS NEAR 2.75 INCHES OF RAIN FOR
EAST/NORTHEAST PR...NEAR 2 INCHES FOR WESTERN PR...AND BETWEEN
0.25 AND 0.75 INCHES FOR THE USVI.
ALAMO...WPC (USA)
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