Prognostic Meteorological Discussion
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FXCA20 KWBC 241153
PMDCA

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
652 AM EST FRI FEB 24 2017

PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM FEB
24/06: A PREFRONTAL TROUGH EXTENDS ALONG 50W IN THE TROPICAL
ATLANTIC. AS THE ASSOCIATED UPPER TROUGH AND FRONT PULL TO THE
NORTHEAST INTO THE NORTH ATLANTIC...THIS TROUGH WILL BECOME
DETACHED OF THE SYSTEM AND START PROPAGATING WESTWARD IN THE
EASTERLY TRADES. MODELS ARE RESOLVING A TRADE WIND SURGE
DEVELOPING AND TRAILING BEHIND THIS TROUGH AS IT ARRIVES IN THE
BASIN DURING THE LATE WEEKEND. THIS WILL LEAD TO A CHANGE IN THE
TRADE WIND REGIME PATTERN FROM WEAK TRADES THROUGH SUNDAY...TO
FAST 15-25KT EASTERLIES BY MONDAY INTO EARLY NEXT WEEK.

AT UPPER LEVELS...THE TAIL OF THE CURRENT POTENT UPPER TROUGH
EXITING THE SOUTHEASTERN UNITED STATES WILL CROSS THE ISLANDS ON
SATURDAY EVENING...DURING A PERIOD OF VERY LITTLE MOISTURE AT
MOD-LEVELS AND A PRONOUNCED SUBSIDENCE CAP. BY THE TIME THE
AFOREMENTIONED TROUGH IN THE TRADES ARRIVES...LATE SUNDAY-EARLY
MONDAY...THE ISLANDS WILL BE IN THE CONVERGENT SIDE OF THE UPPER
TROUGH...WHICH WILL LIMIT THE POTENTIAL ACCUMULATIONS. STILL...THE
GDI INSTABILITY SUGGESTS THE POTENTIAL FOR A FEW ISOLATED EMBEDDED
THUNDERSTORMS ONCE THE SYSTEM ARRIVES EARLY ON MONDAY. THE GLOBAL
MODELS ARE SHOWING LIGHT RAINFALL ACCUMULATIONS...WHICH IS
CONSISTENT WITH THE SYNOPTIC EVOLUTION. ALL SHOW ISOLATED MAXIMA
IN THE ORDER OR 15MM PEAKING DURING MONDAY. AMOUNTS SHOULD
DECREASE AFTER.

JIMENEZ...IMN (COSTA RICA)
SUBRATH-ALI...TTMS (TRINIDAD AND TOBAGO)
GALVEZ...WPC (USA)

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