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FXCA20 KWBC 011137
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
736 AM EDT FRI SEP 01 2023
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI SEP 01/12UTC:
SEVERAL TROPICAL CYCLONES ARE PRESENT IN THE ATLANTIC BASIN...BUT
THESE ARE NOT EXPECTED TO HAVE MUCH OF AN IMPACT IN THE RAINFALL
PATTERNS ACROSS PR. THIS IS BECAUSE THERE IS A SFC HIGH PRESSURE
OVER THE CENTRAL TROPICAL ATLANTIC THAT REACHES WEST TO THE LOCAL
ISLANDS. HOWEVER...A WEAKENING OF THE HIGH PRESSURE NORTH OF
PR/USVI MAY START ON SATURDAY...ALLOWING THE CURRENT POST-TROPICAL
CYCLONE IDALIA TO HAVE AN IMPACT IN THE GENERAL WIND FLOW...BY
CAUSING THE LOCAL WINDS TO START HAVING A SOUTHERLY COMPONENT
STARTING ON SATURDAY. IDALIA IS FORECAST...BY THE NATIONAL
HURRICANE CENTER...TO RESTRENGTHEN AND TRANSITION INTO A TROPICAL
STORM ON SATURDAY WELL TO THE NORTH OF THE THE LOCAL ISLANDS NEAR
BERMUDA...WHICH WILL CAUSE THE LOCAL WINDS TO BECOME SOUTHEASTERLY
THROUGH TUESDAY. THIS CHANGE IN WIND DIRECTION WILL INFLUENCE THE
LOCATION OF THE AFTERNOON CONVECTION OVER PR...FAVORING
NORTHWESTERN PR. BRIEF MORNING AND EVENING SHOWERS ARE FORECAST TO
AFFECT E/SE PR AND THE USVI.
PRECIPITABLE WATER IS EXPECTED TO BE NEAR TO BELOW NORMAL FOR THE
NEXT FEW DAYS...AS RELATIVELY DRY AIR MOVES IN WITH SOME SAHARAN
DUST THIS WEEKEND...POSSIBLY LINGERING INTO EARLY NEXT WEEK BASED
ON THE LATEST GUIDANCE. HOWEVER...LOCALLY INDUCED CONVECTION AND
BRIEF SHOWERS MOVING IN ARE STILL EXPECTED FOR THE NEXT SEVERAL
DAYS...ALBEIT PRODUCING SOMEWHAT LIMITED RAINFALL AMOUNTS. THE
GLOBAL MODELS ARE NO LONGER SHOWING A SIGNIFICANT INCREASE IN
MOISTURE BEING PULLED FROM THE SOUTH FOR EARLY NEXT WEEK...INSTEAD
HAVING THAT INCREASE IN MOISTURE LIMITED TO THE COASTAL SECTIONS
OF WESTERN AND NORTHWESTER PR INTO THE MONA PASSAGE ON
SUNDAY...WHILE THE INCREASE IN MOISTURE OVER THE REST OF PR AND
THE USVI WOULD BE LESS SIGNIFICANT AND ONLY BRINGING PRECIPITABLE
WATER UP TO AROUND NORMAL. GIVEN THE ADJUSTMENTS THE MID TO LONG
RANGE MODELS ARE MAKING...THERE IS CONSIDERABLE UNCERTAINTY FOR
THE LATTER PART OF THE FORECAST PERIOD.
AT THIS TIME...TODAY IS EXPECTED TO BE THE DAY WITH THE MOST
SIGNIFICANT RAINFALL OVER NORTHWESTERN PR...WITH OVER AN INCH OF
RAIN EXPECTED ACROSS THE NORTHWESTERN QUADRANT OF PR. SUNDAY MAY
HAVE A BIT MORE GENERALIZED RAINFALL COVERAGE BUT THE AMOUNTS ARE
EXPECTED TO BE MODEST...UNDER A HALF AN INCH ACROSS NORTHWESTERN
AND SOUTHEASTERN PR. THE 5-DAY RAIN TOTAL FORECAST SUGGESTS
NORTHWESTERN PR COULD TO RECEIVE NEAR 2.25 INCHES OF RAIN...AROUND
1 INCH FOR SOUTHEASTERN PR...AND NEAR 0.5 INCHES OF RAIN FOR THE
USVI.
ALAMO...WPC (USA)
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