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Tropical Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1106Z Jul 29, 2014)
 
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TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
706 AM EDT TUE JUL 29 2014

PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI. TUTT LOW NEAR
24N 65W ANCHORS A TROUGH ACROSS THE GREATER ANTILLES TO THE
NORTHERN CARIBBEAN. THIS REMAINS A FAIRLY WELL ORGANIZED SYSTEM
HAVING A STRONG MID LEVEL REFLECTION...WHILE ALSO SUSTAINING AN
INDUCED TROUGH IN THE EASTERLY TRADES. THE TROUGH EXTENDS ALONG
59W/60W TO 22N. THIS IS DRAWING ITCZ MOISTURE NORTHWARD TOWARDS
THE FRENCH ISLES. SYSTEM OF CONCERN IS THE TROPICAL DISTURBANCE
ALONG THE ITCZ NEARING 40W EARLY THIS MORNING. PER THE NHC
DISCUSSION...THIS SYSTEM HAS A HIGH PROBABILITY OF BECOMING A
TROPICAL CYCLONE OVER THE NEXT TWO DAYS.

ALOFT...THE TUTT LOW IS TO MEANDER WEST-SOUTHWEST INTO NORTHERN
HISPANIOLA/THE TURKS AND CAICOS THROUGH THE END OF THE WEEK. THIS
IS TO YIELD TO A BUILDING CELL OF THE SUBEQUATORIAL RIDGE THAT
EXPANDS ACROSS THE EASTERN CARIBBEAN ISLES TO THE SAN JUAN
FORECAST AREA LATER THIS WEEKEND. AS THE TUTT MEANDERS
WEST...INDUCED PERTURBATION IN THE EASTERLY TRADES WILL THEN DRIFT
WEST ACROSS THE VIRGIN ISLES TO EASTERN PUERTO RICO THROUGH EARLY
MORNING HOURS ON THURSDAY. AS IT PULLS ACROSS THE FORECAST AREA A
MOIST PLUME IS TO FOLLOW...WITH GFS PROJECTING PWAT OF NEARLY TWO
INCHES AS IT MOVES ACROSS THE FORECAST AREA....WHILE THE ECMWF
PEAKS AT AN INCH AND A HALF. IN RESPONSE TO WEAK MESO SCALE
FORCING WITH THIS PERTURBATION MODELS SHOW AN INCREASE IN
CONVECTION ACROSS THE FORECAST AREA. ALTHOUGH THEY ONLY PROJECT
ACCUMULATION OF LESS THAN AN INCH...WE WILL LIKELY SEE MORE THAN
THAT ACROSS PUERTO RICO. IN A SOUTHEASTERLY FLOW THE MOST INTENSE
IS LIKELY TO DEVELOP BETWEEN MANATI/VEGA BAJA AND
AGUADILLA/MAYAGUEZ.

THE DISTURBANCE IS TO THEN FOLLOW...WITH ECMWF NOW JOINING THE GFS
AND UKMET IN FORECASTING A BETTER ORGANIZED SYSTEM TO REACH THE
FORECAST AREA. THE SPREAD AMONG THESE MODELS IS SMALL ENOUGH TO BE
OF CONCERN. THE NHC WILL ISSUE THE OFFICIAL FORECAST.

FIGUEROA...MARN (EL SALVADOR)
VALVERDE...IMN (COSTA RICA)
DAVISON...WPC (USA)