682
FXCA20 KWBC 171245
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
844 AM EDT THU AUG 17 2023
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM AUG
17/12UTC: SAHARAN DUST PARTICLES ARE EXPECTED TO CONTINUE ACROSS
PR/USVI TODAY. ALTHOUGH A SLOT OF CLEANER AIR IS FORECAST FOR THIS
EVENING INTO VERY EARLY FRIDAY MORNING...THE SAHARAN DUST
CONCENTRATIONS WILL INCREASE ONCE AGAIN STARTING ON FRIDAY
MORNING...PEAKING IN CONCENTRATION IN THE LATE AFTERNOON AND
EVENING OF FRIDAY...THEN GRADUALLY DECREASING IN CONCENTRATION
WITH EACH PASSING DAY INTO EARLY NEXT WEEK. THE AVAILABLE MOISTURE
WILL BE ABOVE NORMAL TODAY AND FRIDAY...BECOMING NEAR NORMAL ON
SATURDAY ONWARD. THE LONG RANGE MODELS ARE SUGGESTING A TROPICAL
WAVE APPROACHING LATE MONDAY INTO TUESDAY...WHICH WOULD CAUSE AN
INCREASE IN MOISTURE...PARTICULARLY ON TUESDAY.
A SURFACE HIGH PRESSURE ACROSS THE CENTRAL ATLANTIC WILL DOMINATE
FOR THE NEXT SEVERAL DAYS...KEEPING EASTERLY WINDS ACROSS PR/USVI
INTO EARLY NEXT WEEK. IN THE UPPER LEVELS...A TUTT ACROSS THE
CENTRAL CARIBBEAN IS MOVING WEST...REACHING THE WESTERN CARIBBEAN
BY MONDAY. MEANWHILE ANOTHER TUTT WILL DEVELOP TO THE NNE OF PR
ACROSS THE WEST CENTRAL TROPICAL ATLANTIC...WITH A TILTED AXIS
JUST NORTH AND WEST OF PR...CAUSING SOME INSTABILITY ACROSS THE
LOCAL ISLANDS FROM SUNDAY THROUGH TUESDAY AND RELATIVELY STRONG
SOUTHWESTERLY WINDS ON MONDAY. THIS TUTT AND ASSOCIATED TROUGH MAY
COINCIDE WITH THE APPROACHING TROPICAL WAVE...THOUGH AT THE MOMENT
THE LATEST GUIDANCE IS SUGGESTING THE HIGHEST MOISTURE OF THE
TROPICAL WAVE ON TUESDAY...WHEN THE TUTT IS NOT IN THE MOST
FAVORABLE POSITION. THAT SAID...THE 700 AND 500MB VORTICITY DOES
INCREASE ON TUESDAY AND THE TROPICAL WAVE APPEARS TO HAVE
SIGNIFICANT MOISTURE. THEREFORE THE EGDI ALGORITHM DOES SUGGEST
SCATTERED THUNDERSTORMS OVER THE LOCAL AREA FOR TUESDAY OF NEXT
WEEK...WHILE ONLY SUGGESTING VERY ISOLATED TO ISOLATED
THUNDERSTORMS TODAY AND FRIDAY.
FOR TODAY...GIVEN THE INCREASE IN MOISTURE AND THE CLEANER AIR
EXPECTED OVERNIGHT...THE TOTAL RAINFALL FORECAST IS AROUND 1 INCH
ACROSS EAST AND NORTHEAST PR...AROUND 1.5 INCHES ACROSS THE
NORTHWESTERN QUADRANT OF PR. BETWEEN A TENTH AND A QUARTER OF AN
INCH FOR ST. CROIX...AND UP TO A HALF AN INCH FOR THE NORTHERN
USVI. THE 5-DAY TOTAL RAINFALL FORECAST IS NEAR 3.5 INCHES OF RAIN
FOR EAST/NORTHEAST PR...NEAR 2.5 INCHES FOR WESTERN PR...AND
BETWEEN 1 AND 1.5 INCHES FOR THE USVI.
ALAMO/ACOSTA...WPC (USA)
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