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FXCA20 KWBC 221238
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
838 AM EDT THU AUG 22 2024
WEEKLY DISCUSSION FOR PUERTO RICO AND THE USVI AUG 22/12UTC:
THE ANALYSIS OF CONDITIONS IN THE LARGE SCALE SHOWS A
PREDOMINANTLY UPPER CONVERGENT PULSE OF THE MJO OVER THE
AMERICAS...AND IS FORECAST TO PERSIST THROUGH THE NEXT WEEK. THIS
WILL GENERALLY LIMIT THE COVERAGE AND INTENSITY OF PRECIPITATING
SYSTEMS THAT AFFECT THE REGION.
THE CURRENT DATA ANALYSIS SHOWS A RETROGRADING TUTT CENTERING OVER
THE WINDWARD PASSAGE. THIS IS INTERACTING WITH A TROPICAL WAVE
LOCATED NEAR 72W. A MOIST PLUME TRAILS THE WAVE...AND ASSOCIATES
WITH PWAT VALUES NEAR 2 INCHES OVER THE NORTHEAST
CARIBBEAN...WHICH IS SLIGHTLY ABOVE NORMAL FOR THIS TIME OF THE
YEAR. THIS IS FAVORING SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS IN THE LEEWARD ISLANDS...AND WILL LIKELY SUSTAIN
SCATTERED LIGHT ACCUMULATION IN PUERTO RICO LATER IN THE DAY. A
DRY AIR MASS TRAILS THIS MOIST PLUME. SATELLITE IMAGERY SHOWS THE
EDGE OF THIS AIR MASS NEAR 59W...AND THE PRESENCE OF A SAHARAN AIR
LAYER.
REGARDING THE EVOLUTION FOR THE REST OF THE WEEK...CONFIDENCE
EXISTS ON THE DRY AIR MASS ARRIVING ON FRIDAY MORNING...AND
PRECIPITABLE WATER IS EXPECTED TO DECREASE TO NEAR 1.6
INCHES...WHICH IS SLIGHTLY BELOW NORMAL. THIS WILL YIELD TO A
DECREASE IN THE COVERAGE AND INTENSITY OF CONVECTION ON BOTH
FRIDAY AND SATURDAY. ACCOMPANIED BY EAST-NORTHEASTERLY
TRADES...EXPECT AFTERNOON DEVELOPMENT IN THE SOUTHWEST CORDILLERA.
A TUTT LOW IS THEN FORECAST TO MOVE INTO THE REGION FROM SUNDAY
THROUGH MIDDAY MONDAY. THE ASSOCIATED INDUCED TROUGH IS FORECAST
TO CROSS THE REGION EARLY ON SUNDAY YIELDING TO SOUTHEASTERLY
TRADES AND AN INCREASE IN MOISTURE. THIS WILL FAVOR A SHIFT IN THE
LOCATION OF AFTERNOON CONVECTION TO NORTHWEST PUERTO RICO...AND AN
INCREASE ACCUMULATION ON SUNDAY. AS THE MOIST PLUME EXITS...DRIER
CONDITIONS ARE EXPECTED ON MONDAY.
UNCERTAINTY RAPIDLY INCREASE FROM MONDAY EVENING ON. THE SYSTEM OF
INTEREST IS A TRADE WIND SURGE FORECAST TO ARRIVE SOMETIME BETWEEN
LATE WEDNESDAY AND THURSDAY NEXT WEEK. THE SURGE IS PRECEDED BY A
WAVE-LIKE STRUCTURE...WHICH SHOULD START ENHANCING RAINFALL AS
EARLY AS TUESDAY. ALL MODELS ARE CAPTURING BOTH FEATURES...BUT THE
UNCERTAINTY IS PRIMARILY ON THE TIMING AND ON THE AMOUNTS OF
AVAILABLE MOISTURE AND RESULTING PRECIPITATION. THE CURRENT DATA
SUGGESTS THAT WETTER CONDITIONS SHOULD START DEVELOPING DURING THE
DAY ON TUESDAY...AND PEAK SOMETIME ON WEDNESDAY/THURSDAY
ASSOCIATED WITH THE TRADE WIND SURGE. ONCE THE SURGE
PASSES...EXPECT A DRYING TREND INTO THE END OF THE WORK WEEK.
GALVEZ...WPC (USA)
LEDESMA...WPC (USA)
ACOSTA...WPC (USA)
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