606
FXCA20 KWBC 291255
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
755 AM EST THU DEC 29 2022
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM DEC
29/12UTC: AN UPPER TROUGH EXTENDS FROM 25N 52W INTO THE CENTRAL
LESSER ANTILLES AND NORTHERN VENEZUELA. THIS TROUGH IS
DESTABILIZING TRADE WIND CONVECTION IN THE WINDWARD ISLANDS AND
AREAS TO THE EAST BY WEAKENING THE TRADE WIND CAP AND ALLOWING FOR
DEEPER INSTABILITY. OVER THE NORTHEAST CARIBBEAN...HOWEVER...DRIER
CONDITIONS ARE PRESENT IN ASSOCIATION WITH THE MID-LEVEL RIDGE
LOCATED FROM THE GULF OF HONDURAS INTO THE ATALNTIC TO THE NORTH
OF PUERTO RICO. THE SAN JUAN SOUNDING CONFIRMS THE PRESENCE OF A
TRADE WIND CAP NEAR 900 HPA AND PLENTY OF DRY AIR ABOVE THE CAP.
THE UPPER TROUGH IS FORECAST TO WEAKEN THROUGH SATURDAY
MORNING...BUT ANOTHER TROUGH IS THEN FORECAST TO AMPLIFY ACROSS
THE NORTH ATLANTIC AS A RIDGE BUILDS TO ITS WEST. THIS TROUGH IS
FORECAST TO GAIN AMPLITUDE ACROSS AND EAST OF THE LEEWARD ISLANDS
ON SUNDAY AND ON. THIS WILL CONTINUE TO ALLOW SOME VERTICAL
DEVELOPMENT IN TRADE WIND CONVECTION THAT ARRIVES IN THE EASTERLY
AND NORTHEASTERLY TRADES. AS THE TRADE WIND CAP PERSISTS THROUGH
THE CYCLE...EXPECT LIMITED AFTERNOON DEVELOPMENT IN WESTERN AND
SOUTHWEST PUERTO RICO ON A DAILY BASIS. YET...20-25KT EAST AND
EAST-NORTHEASTERLY TRADES WILL ENHANCE LOW-LEVEL MOISTURE
CONVERGENCE PRIMARILY IN NORTHEAST PUERTO RICO...WHERE THE LARGEST
RAINFALL TOTALS ARE EXPECTED. EXPECT GENERALLY MAXIMA OF 0.2-0.4
INCHES AND ISOLATED MAXIMA NEARING 0.6 INCHES IN EL
YUNQUE/LUQUILLO.
GALVEZ...WPC (USA)
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