Prognostic Meteorological Discussion
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FXCA20 KWBC 251048
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TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
647 AM EDT FRI JUL 25 2014

LAST NO AMENDS...NEXT BULLETIN ON MONDAY JULY 28.

PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI. AT UPPER
LEVELS...A TUTT LOW NEAR 30N 61W EXTENDS A SHORT WAVE TROUGH TO
THE NORTHEAST CARIBBEAN ISLES. ALTHOUGH UPPER LEVELS APPEAR
FAVORABLE FOR CONVECTIVE DEVELOPMENT... THE MID LEVELS REMAIN
QUITE HOSTILE TO DEVELOPMENT WITH PERSISTENT CAP INVERSION
ENVELOPING THE FORECAST AREA. AT LOW LEVELS...A TROPICAL WAVE
MOVED ACROSS THE EASTERN CARIBBEAN OVERNIGHT...ENTERING THE
DOMINICAN REPUBLIC EARLY THIS MORNING. THIS WAVE INDUCED THE
NORTHWARD MODULATION OF THE ATLANTIC ITCZ ACROSS THE FRENCH
ISLES/EASTERN CARIBBEAN. HOWEVER...THE ASSOCIATED DEEP MOIST PLUME
REMAINS JUST SOUTH OF THE FORECAST AREA...WITH SHALLOW MOISTURE ON
THE NORTHERN FRINGES TRAILING ACROSS PUERTO RICO AND THE USVI.
NEXT TROPICAL WAVE ENTERED FRENCH GUIANA EARLY THIS MORNING.
METEOSAT RGB PRODUCT SHOWS A DENSE DUST LAYER BETWEEN 10N-20N AND
EXPANDING ACROSS THE TROPICAL ATLANTIC TO JUST EAST OF THE LESSER
ANTILLES.

DURING SHORT RANGE PERIOD...THE TUTT LOW IS TO MEANDER NORTH OF
THE FORECAST AREA...WITH ASSOCIATED TROUGH TO GRAZE THE NORTHEAST
CARIBBEAN ISLES. ALTHOUGH MID LEVEL CAP INVERSION IS TO GENERALLY
HOLD...GFS SUGGESTING A GLIMMER OF HOPE THAT IT MIGHT WEAKEN
ENOUGH BY 18UTC TODAY FOR SOME CONVECTION TO DEVELOP. BUT...THIS
WILL BE SHORT LASTING...AS THE CAP IS TO RAPIDLY STRENGTHEN
THROUGH SATURDAY MORNING. SHALLOW MOISTURE OVER THE FORECAST AREA
IS TO RAPIDLY EBB DURING THE DAY AS THE TROPICAL WAVE MOVES
AWAY...SO ANY CONVECTIVE DEVELOPMENT TODAY WOULD MOST LIKELY BE
ISOLATED WHILE CONFINING TO THE CORDILLERA AND WESTERN INTERIOR
PORTIONS OF PUERTO RICO. THE NEXT TROPICAL WAVE OFFERS LITTLE HOPE
OF RELIEF...AS IT IS TO TAKE A BEELINE ACROSS THE
GUIANAS/VENEZUELA THROUGH SATURDAY EVENING. CONVECTION WITH THIS
FEATURE IS TO GENERALLY LIMIT TO SOUTH AMERICA-SOUTHERN WINDWARD
ISLES.

DURING SHORT RANGE PERIOD...THE GLOBAL MODEL GUIDANCE SHOW THE
TUTT LOW TO THE NORTH DRIFTING TO THE SOUTH-SOUTHWEST THROUGH
MONDAY AFTERNOON. THIS IS TO HAVE A FAIRLY STRONG MID LEVEL
REFLECTION...AND AT LOW LEVELS IT IS LIKELY TO INDUCE AN INVERTED
TROUGH IN THE EASTERLY TRADES. THE MODELS ARE IN SURPRISINGLY
CLOSE AGREEMENT ON THIS EVOLUTION...SO THERE IS HOPE THAT WE MIGHT
FINALLY SEE A SIGNIFICANT CHANGE TO MESO-SYNOPTIC ENVIRONMENT OVER
THE FORECAST AREA. ALL THE MODELS ARE PROJECTING LIGHT TO MODERATE
RAINFALL AMOUNTS...WITH ACCUMULATION RANGING BETWEEN 00-05MM...AND
MAXIMA PEAKING AT 10-15MM.

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




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