Prognostic Meteorological Discussion
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TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
648 AM EDT MON JUL 28 2014

PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI. TUTT LOW NEAR
22N 64W EXTENDS A SHORT WAVE TROUGH ACROSS THE NORTHEAST CARIBBEAN
ISLES. BEST CONVECTIVE INSTABILITY WITH THIS
FEATURE...HOWEVER...REMAINS TO THE NORTH OF 20N...WHILE STRONG CAP
INVERSION ENVELOPS THE NORTHEAST CARIBBEAN ISLES. AT LOW
LEVELS...BROAD CELL OF THE SUBTROPICAL RIDGE DOMINATES FLOW ACROSS
THE CENTRAL NORTH ATLANTIC. THIS FAVORS A BRISK EASTERLY FLOW
ACROSS THE LESSER ANTILLES INTO THE CARIBBEAN BASIN. EMBEDDED IN
THIS FLOW...A TUTT INDUCED PERTURBATION LIES TO THE EAST OF THE
LESSER ANTILLES...WITH AXIS NORTH ALONG 55W/54W TO 20N. THERE IS
ALSO A WELL ORGANIZED TROPICAL WAVE ALONG 37W/38W...WHICH THE NHC
IS MONITORING FOR POSSIBILITY OF TROPICAL CYCLONE FORMATION.

AT UPPER LEVELS...TUTT LOW IS TO DRIFT TO THE WEST-NORTHWEST
THROUGH THE MIDDLE OF THE WEEK...WHILE ASSOCIATED TROUGH IS TO
GENERALLY MEANDER OVER THE NORTHEAST CARIBBEAN. THIS LOW IS TO
HAVE A FAIRLY STRONG MID LEVEL REFLECTION...WITH ASSOCIATED
INDUCED TROUGH IN THE EASTERLY TRADES TO MEANDER ACROSS THE LESSER
ANTILLES LATER ON TUESDAY...AND ACROSS THE VIRGIN ISLES TO EASTERN
PUERTO RICO LATER ON WEDNESDAY/EARLY THURSDAY MORNING. ALTHOUGH
LOW LEVEL FORCING IS EXPECTED AS IT MOVES ACROSS THE VIRGIN
ISLES/EASTERN PUERTO RICO...THIS WILL STILL HAVE TO FIGHT MID
LEVEL CAP INVERSION OVER THE FORECAST AREA. SO POTENTIAL FOR
ORGANIZED CONVECTION REMAINS LOW. MOST ACTIVE IS LIKELY TO DEVELOP
ACROSS THE CORDILLERA CENTRAL AND WESTERN INTERIOR PORTIONS OF
PUERTO RICO...WHERE THE TUTT IS LIKELY TO INTERACT WITH SEA BREEZE
CONVERGENCE/DIURNAL HEATING TO TRIGGER SCATTERED AFTERNOON
CONVECTION.

THE TROPICAL WAVE ALONG 37W/38W IS THE SYSTEM OF CONCERN...WITH
THE GFS AND UKMET BOTH SHOWING POSSIBILITY OF TROPICAL CYCLONE
REACHING THE FORECAST AREA LATER IN THE WEEK. THE ECMWF IS NOT AS
OPTIMISTIC...INSTEAD FAVORING AN OPEN WAVE REACHING THE EASTERN
CARIBBEAN MUCH SOONER THAN WHAT THESE MODELS SUGGEST.

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





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