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FXCA20 KWBC 031221
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
821 AM EDT MON APR 03 2023
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM APR
03/12UTC: IN THE UPPER LEVELS...A BROAD TROUGH EXTENDS FROM THE
BERMUDA REGION SOUTH INTO CENTRAL VENEZUELA. THIS IS ASSOCIATES
WITH A MID-LEVEL LOW LOCATED OVER THE CENTRAL LESSER ANTILLES.
THESE SYSTEMS ARE...HOWEVER...PRODUCING VERY LITTLE IMPACT IN
PRECIPITATION IN THE NORTHEAST CARIBBEAN GIVEN THE PRESENCE OF A
DRY AIR MASS IN PLACE. TOTAL PRECIPITABLE WATER IS ESTIMATED AT
25-30MM BY SATELLITE RETRIEVALS...AND A DRY SLOT WITH VALUES UNDER
25MM IS MOVING IN FROM THE EAST ON MONDAY MORNING. UNDER THESE
CONDITIONS...EXPECT VERY LITTLE PRECIPITATION ON MONDAY AND
ISOLATED ACTIVITY CLUSTERING IN THE WESTERN CORDILLERA.
OF INTEREST IS THE EVOLUTION BY THE MIDDLE OF THE WEEK. AS AN
UPPER RIDGE BUILDS FROM NORTHERN CENTRAL AMERICA INTO THE
SOUTHEAST US...IT WILL STIMULATE NORTHWESTERLY FLOW ACROSS THE
BAHAMAS INTO THE NORTHEAST CARIBBEAN ON TUESDAY...EVOLVING TO
NORTHERLY FLOW BY WEDNESDAY. THIS COLD AIR ADVECTION WILL
STIMULATE THE DEEPENING OF THE CURRENT UPPER TROUGH...TO RESULT IN
A POTENT UPPER LOW/TUTT CENTERING JUST TO THE NORTH OF
AGUADILLA/MONA PASSAGE BY THURSDAY. THE POTENT SYSTEM IS EXPECTED
TO HAVE REFLECTION IN THE MID-LEVELS...AND INDUCED A PERTURBATION
IN THE TRADES. THIS EVOLUTION COINCIDES WITH THE ARRIVAL OF THE
UPPER DIVERGENT/WET TIER OF THE MJO AND A TROPOSPHERIC KELVIN
WAVE. THIS COMBINATION OF FACTORS SUGGEST A POTENTIAL FOR MODERATE
AND LOCALLY HEAVY PRECIPITATION FROM WEDNESDAY THROUGH
FRIDAY...LIKELY PEAKING ON THURSDAY.
IN TERMS OF FORECAST AMOUNTS...ON MONDAY AND TUESDAY EXPECT MAXIMA
UNDER 0.2 INCHES IN EASTERN PUERTO RICO IN TRADE WIND CONVERGENCE.
AFTERNOON CONVECTION WILL FAVOR MAXIMA OF 0.5-0.75 INCHES IN THE
SOUTHWEST CORDILLERA. WET CONDITIONS UNRAVEL ON WEDNESDAY...WHEN
MODELS AGREE ON THE DESTABILIZATION OF TRADE WIND CONVECTION IN
NORTHEAST PUERTO RICO AND THE NORTHERN VI. THIS WILL FAVOR MAXIMA
NEAR 1 INCH IN NORTHEAST PUERTO RICO AND MAXIMA OF 0.25-0.5 INCHES
IN THE NORTHERN VI. ON THURSDAY...EXPECT MODERATE TO LOCALLY HEAVY
RAINFALL IN THE NORTHWESTERN VI...WHICH TILL FAVOR MAXIMA OF 1-1.5
INCHES IN VIEQUES...CULEBRA AND NORTHEAST PUERTO RICO. IN THE REST
OF THE VI EXPECT MAXIMA OF 0.5-1 INCH. ON FRIDAY...AS THE BULK OF
THE ACTIVITY DRIFTS NORTHWARD AIDED BY THE UPPER TROUGH...EXPECT A
DECREASING TREND. STILL...ENHANCED TRADE WIND CONVERGENCE WILL
FAVOR DEEP CONVECTION IN THE NORTHERN VI AND EXTREME NORTHEAST
PUERTO RICO...WHERE EXPECT MAXIMA OF 0.75-1.25 INCHES. NOTE THAT A
DEFINED GRADIENT IS EXPECTED BETWEEN THE FAJARDO/LUQUILLO REGION
AND THE SAN JUAN METRO. FIVE DAY TOTALS IN THE FAJARDO/LUQUILLO
REGION ARE FORECAST TO EXCEED 3 INCHES...WHILE IN THE SAN JUAN
METRO WE EXPECT TOTALS OF 0.5-1.5 INCHES.
GALVEZ/ALAMO...WPC (USA)
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