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FXCA20 KWBC 071231
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
731 AM EST TUE MAR 07 2023
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM MAR
07/12UTC: A BROAD TROUGH CONTINUES EXPANDING ACROSS THE NORTH
ATLANTIC. THIS IS DISPLACING AN AXIS OF A MID-LEVEL RIDGE
SOUTHWARD. ON TUESDAY MORNING THE RIDGE CENTERS ON A HIGH OCER THE
CENTRAL GULF OF MEXICO AND EXTENDS AN AXIS ACROSS
CUBA...HAITI...16N 67W AND DOMINICA. THE TRADE WIND CAP IS STILL
PRESENT OVER THE ISLANDS AND LIEAS NEAR 800 HPA. TRADE WINDS ARE
VERY WEAK...WITH SPEEDS UNDER 10KT. SATELLITE IMAGERY SHOWS
SCATTERED CLOUDS OFF THE NORTHEAST AND EASTERN COASTS OF PUERTO
RICO...ACCOMPANIED BY ISOLATED LIGHT RAIN SHOWERS MOSTLY OFFSHORE.
ALSO OF RELEVANCE...A SHORT WAVE UPPER TROUGH EXTENDS ALONG 25N
62W INTO THE DOMINICAN REPUBLIC. ALTHOUGH THERE IS LIMITED
AVAILABLE MOISTURE IN THE REGION...THIS SYSTEM WILL FAVOR A
MARGINAL ENHANCEMENT OF DIURNAL CONVECTION LATER ON TUESDAY.
MODELS SHOW THE SHORT WAVE TROUGH CROSSING THE ISLANDS ON TUESDAY
AFTERNOON. GIVEN THE WEAKNESS IN THE TRADES...AFTERNOON CONVECTION
WILL RESPOND PRIMARILY TO THE CONVERGENCE OF DIURNAL BREEZES.
PRECIPITABLE WATER IS LOW...SHY OF 25MM. THIS WILL LIMIT
ACCUMULATIONS TO ISOLATED MAXIMA OF 0.3-0.4 INCHES IN THE WESTERN
CORDILLERA. ON WEDNESDAY...A BROAD TROUGH IN THE NORTH ATLANTIC
WILL START TO IMPACT THE LOW-LEVEL FLOW IN THE ISLANDS SHIFTING
THE WINDS TO NORTHWESTERLIES. THIS WILL FOCUS AFTERNOON CONVECTION
IN SOUTHEAST PUERTO RICO. GIVEN LIMITED AMOUNTS OF AVAILABLE
MOISTURE...EXPECT MAXIMA TO REMAIN UNDER 0.4 INCHES WHERE
CONVECTION FORMS. ON THURSDAY...A FRONT MOVES IN RAPIDLY FROM THE
NORTH. THE FRONT IS FORECAST TO ENTER NORTHERN PUERTO RICO IN THE
MORNING CIRCA 12 UTC. THIS WILL HIGHLIGHT MORNING SHOWERS ALONG
THE ENTIRE NORTH COAST AND NORTH INTERIOR OF PUERTO
RICO...FAVORING SCATTERED MAXIMA OF 0.2-0.35 INCHES. THIS INCLUDES
VIEQUES. NORTHERLY WINDS ARE EXPECTED TO CONTINUE ON FRIDAY...BUT
SPEEDS UNDER 10KT AND LIMITED AMOUNTS OF PRECIPITABLE WATER WILL
RESULT IN VERY LIGHT RAINFALL ACCUMULATIONS ALONG THE NORTH COAST
OF PUERTO RICO...WHERE EXPECT MAXIMA UNDER 0.1 INCHES. THE WINDS
ARE FORECAST TO SHIFT TO EASTERLIES LATE ON SATURDAY...BUT THE
TRANSITION WILL BE SLOW...WHICH WILL FAVOR THE DEVELOPMENT OF
DIURNAL BREEZES ENHANCING CONVERGENCE IN THE CORDILLERA ONCE AGAIN
ON SATURDAY. YET...LIMITED AMOUNTS OF AVAILABLE MOISTURE AND
RIDGING IN THE MID-TROPOSPHERE WILL RESULT IN VERY LITTLE
PRECIPITATION.
ACOSTA/GALVEZ...WPC (USA)
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