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FXCA20 KWBC 061235
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
735 AM EST MON MAR 06 2023
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM MAR
06/12UTC: A CELL OF THE MID-LEVEL RIDGE CENTERS OVER HISPANIOLA ON
MONDAY MORNING. THIS IS FAVORING A TRADE WIND CAP OVER THE
ISLANDS...WHICH SITS NEAR 850 HPA. SATELLITE IMAGERY SHOWS
SCATTERED STRATOCUMULUS DECKS OVER THE VI AND EASTERN PUERTO
RICO...AND VERY LIMITED VERTICAL DEVELOPMENT. IN THE MEAN TIME...A
SHORT WAVE UPPER TROUGH EXTENDS ACROSS CENTRAL FLORIDA. THIS IS
PROPAGATING TOWARDS THE NORTHEAST CARIBBEAN EMBEDDED IN A
LONG-FETCH NORTHWESTERLY FLOW. PRECIPITABLE WATER REMAINS LOW OVER
THE ISLANDS...WITH VALUES IN NEAR THE 1 INCH/25MM RANGE.
MODELS SHOW THE MID-LEVEL RIDGE WEAKENING ON MONDAY...WHILE A
BROAD MID-UPPER TROUGH DEEPENS ACROSS THE NORTH ATLANTIC. THIS
WILL CONTINUE TO SUSTAIN NORTHWESTERLY FLOW IN THE UPPER LEVELS.
THE AFOREMENTIONED SHORT WAVE TROUGH PROPAGATES ACROSS THE ISLANDS
ON TUESDAY AFTERNOON. ALTHOUGH PRECIPITABLE WATER IS FORECAST TO
REMAIN RATHER LOW...FORCING WILL BE SUFFICIENT TO ENHANCE
AFTERNOON CONVECTION SLIGHTLY ON TUESDAY. GIVEN THE PRESENCE OF
WEAK TRADES...DIURNAL BREEZES WILL PLAY A ROLE IN THE TRIGGERING
OF AFTERNOON CONVECTION ACROSS THE CENTRAL AND WESTERN CORDILLERA
OF PUERTO RICO...WHERE EXPECT MAXIMA OF 0.3-0.5 INCHES.
PRECIPITABLE WATER DECREASES ON WEDNESDAY...RESULTING IN A
SIGNIFICANT DECREASE IN THE COVERAGE OF PRECIPITATING CONVECTION
AND IN RAINFALL AMOUNTS. ON THURSDAY...A SURFACE FRONT IS FORECAST
TO RAPIDLY CROSS THE ISLANDS FROM NORTH TO SOUTH. THE FRONT IS
FORECAST TO ARRIVE BETWEEN 12 AND 18 UTC ON THURSDAY...WHICH WILL
LIKELY FAVOR A PEAK IN MORNING PRECIPITATION ESPECIALLY ALONG MOST
OF NORTHERN PUERTO RICO. THE ECMWF AND GFS ARE VERY DIFFERENT IN
RESOLVING THE AMOUNT OF INJSTABILITY WITH THIS SYSTEM...THE GFS
BEING THE MOST AGGRESSIVE. AT THE TIME...EXPECT SCATTERED
ACCUMULATION OF 0.2-0.3 INCHES ALONG MOST OF THE NORTHERN HALF OF
PUERTO RICO. ACTIVITY DECREASES ON FRIDAY AS THE DRIER
POST-FRONTAL AIR MASS SITS IN. YET...UNDER THE INFLUENCE OF WEAK
NORTHERLY TRADES...EXPECT SHALLOW CONVECTIVE INSTABILITY AND LIGHT
RAIN SHOWERS TO PERSIST NORTH OF PUERTO RICO...WHICH WILL LIKELY
FAVOR SCATTERED MAXIMA NEAR 0.1 INCHES ALONG THE NORTH COAST ON
MORNING HOURS OF FRIDAY.
ACOSTA/GALVEZ...WPC (USA)
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