530
FXCA20 KWBC 051218
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
817 AM EDT THU SEP 05 2024
WEEKLY DISCUSSION FOR PUERTO RICO AND THE USVI SEP 05/12UTC:
THE LARGE SCALE PATTERN CONTINUES SHOWING UPPER CONVERGENCE
PERSISTING OVER THE AMERICAS...WHICH IS CONSISTENT WITH LIMITED
AREAS OF CONVECTION IN THE EASTERN CARIBBEAN.
NEVERTHELESS...SEVERAL MODELS ARE SUGGESTING A GRADUAL DECREASE OF
UPPER CONVERGENCE INTO NEXT WEEK. THIS AND INCREASING PRECIPITABLE
WATER IN THE EASTERN CARIBBEAN COULD POSSIBLY FAVOR A GENERAL
INCREASING TREND IN THE COVERAGE OF CONVECTION INTO NEXT WEEK.
WITH RESPECT TO THE MJO...MODELS CONTINUE STRUGGLING WITH
RESOLVING ITS PROPAGATION...WHICH IS CONSISTENT WITH OBSERVATIONS.
HOWEVER...THERE IS SOME AGREEMENT ON A CHANGE TOWARDS NEUTRAL OR
EVEN UPPER DIVERGENT CONDITIONS OVER THE CARIBBEAN TOWARDS THE END
OF THE MONTH.
THE CURRENT CONDITIONS SHOW A POTENT TUTT ACROSS THE EASTERN
CARIBBEAN...CURRENTLY CENTERING ON A LOW JUST TO THE NORTHEAST OF
THE LEEWARD ISLANDS. THE CONVECTION WITH THIS TUTT IS OCCURRING TO
THE EAST OF THE SYSTEM AND NEAR THE CENTER. HOWEVER...PRECIPITABLE
WATER IN THE REGION IS BELOW NORMAL. THIS AND ENHANCED UPPER
CONVERGENCE ARE LIMITING THE COVERAGE OF DEEP CONVECTION FAVORING
MOSTLY TRADE WIND SHOWERS AND ISOLATED THUNDERSTORMS WITH THE
TUTT. IN PUERTO RICO...AVAILABLE MOISTURE IS WELL BELOW AVERAGE ON
THURSDAY. THIS PARTIALLY ASSOCIATES WITH LITTLE CLOUD COVER. WINDS
ARE WEAK FROM THE EAST. THIS WILL LIKELY YIELD TO SIGNIFICANT
DIURNAL HEATING AND ESTABLISHMENT OF ROBUST SEA BREEZES LATER
DURING THE DAY...WHICH SHOULD FAVOR ISOLATED BUT STRONG AFTERNOON
CONVECTION IN AREAS OF WESTERN AND WEST-CENTRAL PUERTO RICO ON
THURSDAY AFTERNOON. WINDS ARE FORECAST TO ACQUIRE A
EAST-SOUTHEASTERLY DIRECTION ON FRIDAY...WHICH SHOULD RELOCATE
AFTERNOON CONVECTION TO NORTHWEST PUERTO RICO.
UNCERTAINTY RAPIDLY INCREASES ON SATURDAY...AS MODELS ARE
STRUGGLING RESOLVING THE WESTWARD/NORTHWESTWARD PROGRESSION OF THE
TUTT ACROSS THE ISLANDS. NORTHWARD AND FAST SOLUTIONS SUCH AS THAT
OF THE ECMWF AND CMC MODELS WOULD LIKELY YIELD TO DRIER CONDITIONS
AS THE BULK OF THE MOISTURE AND ASSOCIATED CONVECTION COULD PASS
WELL TO THE NORTH OF THE ISLANDS. SLOWER AND SOUTHERN SOLUTIONS
SUCH AS THAT OF THE GFS AND UKMET COULD YIELD TO WETTER CONDITIONS
ON SATURDAY AND SUNDAY. ALTHOUGH RECENT OBSERVATIONS OF MODEL
PERFORMANCE HAVE SHOWN THAT FASTER AND NORTHERN SOLUTIONS HAVE
BEEN TENDING TO VERIFY...UNCERTAINTY IS QUITE LARGE WITH THIS
PARTICULAR EVOLUTION.
INTERESTINGLY...THERE IS BETTER AGREEMENT LATER IN THE CYCLE
REGARDING MOIST PLUMES ARRIVING FROM THE TROPICAL ATLANTIC.
ALTHOUGH THE STRUCTURE OF THESE SYSTEMS IS NOT BEING WELL
RESOLVED...THERE IS AGREEMENT OF AN INCREASE IN PRECIPITABLE WATER
LATE ON MONDAY INTO TUESDAY. MODELS ARE SUGGESTING A WAVE-LIKE
FEATURE ASSOCIATED WITH THIS MOIST PLUME ARRIVING AROUND
TUESDAY...BUT GIVEN MODEL STRUGGLES SO EARLY IN THE CYCLE...EXPECT
IMPORTANT MODEL ADJUSTMENTS.
GALVEZ...WPC (USA)
ACOSTA...WPC (USA)
TINOCO...WPC (USA)
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