Prognostic Meteorological Discussion
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FXCA20 KWBC 271049
PMDCA

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
649 AM EDT WED JUL 27 2016

PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM JULY
27/06 UTC: TUTT MOVES ACROSS THE FORECAST AREA DURING THE DAY ON
THURSDAY...AND THROUGH FRIDAY IT IS TO SLOWLY MIGRATE WEST. THE
CAP INVERSION IS TO WEAKEN ENOUGH TO ALLOW FOR DEVELOPMENT ACROSS
WESTERN INTERIOR PORTIONS OF PUERTO RICO DURING THE AFTERNOON
HOURS. IN A NORTHEASTERLY STEERING FLOW...THE MOST INTENSE IS
LIKELY TO CLUSTER ACROSS WESTERN INTERIOR PORTIONS OF PUERTO RICO.
LACKING MESO SYNOPTIC FORCING...ACTIVITY OVER EASTERN PUERTO RICO
AND THE VIRGIN ISLES WILL LIMIT TO THE OCCASIONAL TRADE WIND
SHOWER AND STREAMERS FORMING UPSTREAM OF THE ISLANDS. THIS PATTERN
IS WELL DEPICTED BY THE ARW VERSION OF THE HRWRF.

DURING MEDIUM RANGE PERIOD...THE GLOBAL MODEL GUIDANCE SHOW A
FAIRLY WELL ORGANIZED TROPICAL WAVE MOVING ACROSS THE FORECAST
AREA ON SUNDAY. BOTH THE GFS AND ECMWF SHOW PWAT CONTENT IN EXCESS
OF TWO INCHES IN ASSOCIATION WITH THIS FEATURE. BUT THE MODELS
GENERALLY AGREE ON BEST MOISTURE CONVERGENCE TAKING PLACE JUST
NORTH OF THE FORECAST AREA. AS A RESULT...DETERMINISTIC MODEL
GUIDANCE ONLY SHOWING LIGHT CONVECTION ACROSS PUERTO RICO AND THE
USVI. THE GEFS ARE EVENLY SPLIT...WITH HALF SHOWING POTENTIAL FOR
MODERATE TO HEAVY SHOWERS WHILE THE REST SIDE WITH THE DRYER
GFS/EUROPEAN MODELS. HOWEVER...THE CLIMATOLOGICAL MODELS SHOW MJO
CONDITIONS GRADUALLY BECOMING MORE FAVORABLE AND CONDUCIVE TO
ORGANIZED CONVECTION LATER DURING THE WEEKEND...AND THIS IS ADDING
ENOUGH UNCERTAINTY TO THE MIX SO WE CANNOT RULE OUT THE WETTER
ENSEMBLE MEMBERS.

CABANERIT...INAMEH (VENEZUELA)
CONTRERAS...IMN (COSTA RICA)
CASTILLO...UCR (COSTA RICA)
DAVISON...WPC (USA)

















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