Prognostic Meteorological Discussion
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FXCA20 KWBC 041042
PMDCA

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
642 AM EDT TUE AUG 04 2015

PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM AUG 04/06
UTC: MID/UPPER LEVEL RIDGE CONTINUE TO DOMINATE FLOW ACROSS THE
FORECAST AREA...FAVORING STRONG CAP INVERSION AND A PWAT MINIMA
ACROSS THE EASTERN CARIBBEAN. AT LOW LEVELS BRISK EASTERLY TRADES
PREVAIL...FAVORING GENERATION OF STREAMERS ACROSS THE
LEEWARD/VIRGIN ISLES. THIS...IN-TURN...SUSTAINS LIGHT BRIEF
SHOWERS AS THEY STREAM ACROSS THE FORECAST AREA.

MID/UPPER LEVEL PATTERN IS TO HOLD THROUGH THURSDAY...LONGER THAN
WHAT THE MODELS ORIGINALLY ANTICIPATED. LATER IN THE
WEEK...RETROGRESSING TUTT LOW IS TO PUT A DENT ON THE
PATTERN...WITH SHORT WAVE TROUGH TO ESTABLISH ACROSS THE FORECAST
AREA BY MIDDAY ON FRIDAY. WEAKNESS IN HEIGHT FIELD IS TO PERSIST
THROUGH THE WEEKEND. AS THE RIDGE PATTERN ALOFT STARTS TO WEAKEN
IT WILL ALLOW FOR PATCHY CLOUD CLUSTERS TO ADVECT ACROSS THE
FORECAST AREA...WITH A SIGNIFICANT INCREASE IN AVAILABLE WATER
LIKELY ON SATURDAY-SUNDAY AS THE MID LEVEL TROUGH ESTABLISHES
ACROSS THE FORECAST AREA. AT LOW LEVELS...BRISK EASTERLY TRADES
ARE EXPECTED THROUGH MIDMORNING ON WEDNESDAY. THEREAFTER WINDS
WILL DECREASE TO 10-15KT. THE LIGHTER WINDS ARE LIKELY TO FAVOR
ACTIVATION OF THE LAND/SEA BREEZE CYCLE ACROSS THE LARGER
ISLANDS...AND A GRADUAL INCREASE IN CONVECTION AS BOUNDARY LAYER
MOISTURE STARTS TO INCREASE. IF THE PATTERN HOLDS AS THE MODELS
NOW SUGGEST...SATURDAY-SUNDAY SHOULD SEE AN INCREASE IN CONVECTION
WITH MEASURABLE RAINFALL AMOUNTS TO AFFECT THE ENTIRE FORECAST
AREA.

SALMON...MS (ANTIGUA AND BARBUDA)
CABRERA...ONAMET (THE DOMINICAN REPUBLIC)
DAVISON...WPC (USA)
$$





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