Prognostic Meteorological Discussion
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FXCA20 KWBC 261056
PMDCA

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
656 AM EDT MON JUN 26 2017

PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM JUNE
26/06 UTC: DENSE SAHARAN AIR LAYER TRAILS A TROPICAL WAVE PULLING
ACROSS THE EASTERN CARIBBEAN EARLY THIS MORNING. THIS IS TO
QUICKLY ENTRAIN ACROSS THE NORTHEAST CARIBBEAN ISLES...WITH PWAT
CONTENT TO PLUNGE THROUGH THE DAY TODAY. BROAD MID LEVEL RIDGE
DOMINATING THE WESTERN ATLANTIC/NORTHERN CARIBBEAN IS TO THEN TRAP
THE DUST LAYER OVER THE FORECAST AREA DURING THE NEXT 72-96
HRS...LEADING TO MOSTLY FAIR WEATHER CONDITIONS. HOWEVER...IN
BRISK EASTERLY TRADES...PASSING TRADE WIND SHOWERS AND THE
OCCASIONAL STREAMER ARE TO AFFECT THE VIRGIN ISLES/EASTERN PUERTO
RICO FROM TIME TO TIME. BUT THESE ARE TO ONLY TRIGGER LIGHT
RAINFALL AMOUNTS. PER HIGHER RESOLUTION MODEL GUIDANCE MEASURABLE
AMOUNTS ARE TO CONFINE TO WESTERN MAYAGUEZ-RINCON IN LATE
AFTERNOON CONVECTION OVER THE NEXT COUPLE OF DAYS.

NEXT TROPICAL WAVE IS TO ENTER THE EASTERN CARIBBEAN LATER ON
THURSDAY. MODELS AGREE ON MOISTURE SURGING AS THE WAVE ENTERS THE
FORECAST AREA...WITH PWAT CONTENT OF NEARLY TWO INCHES POOLING ON
THE CARIBBEAN COASTAL WATERS OF PUERTO RICO PER THE GFS/ECMWF
GLOBAL MODELS. IN RESPONSE...THEY SHOW CONVECTION GRADUALLY
BECOMING MORE WIDESPREAD/BETTER ORGANIZED. BUT THIS IS ASSUMING
THAT THE MID LEVEL RIDGE PATTERN RELAXES ITS FOOTHOLD ACROSS THE
FORECAST AREA...AND WITH CLIMO MODELS SHOWING MJO ENVIRONMENTAL
CONDITIONS TO REMAIN ON ITS CONVERGENT/SUBSIDENT PHASE THROUGH THE
END OF THE MONTH...IT MIGHT BE DIFFICULT FOR ACTIVITY TO BECOME
ORGANIZED.

GAJADHAR...SLMS (SAINT LUCIA)
GALVEZ/DAVISON...WPC (USA)
$$




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