Prognostic Meteorological Discussion
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FXCA20 KWBC 241134
PMDCA

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
733 AM EDT THU JUL 24 2014

PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI. TUTT LOW NEAR
28N 62W EXTENDS A SHORT WAVE TROUGH TO THE NORTHEAST CARIBBEAN
ISLES. BEST INSTABILITY WITH THIS FEATURE...HOWEVER...CONFINES TO
AREA NORTH OF 20N...LEAVING THE NORTHEAST CARIBBEAN ISLES UNDER
INFLUENCE OF A TRADE WINDS CAP. AT LOW LEVELS...REMNANTS OF TD-TWO
ENTERED THE ISLAND CHAIN AS A TROPICAL WAVE. THIS WAVE SUSTAINS
THE NORTHWARD MODULATION OF THE ATLANTIC ITCZ INTO THE NORTHERN
FRENCH/LEEWARD ISLES-EASTERN CARIBBEAN.

TUTT PATTERN ALOFT IS EXPECTED TO PERSIST THROUGH THE
WEEKEND/EARLY NEXT WEEK...WITH CLOSED LOW TO GENERALLY MEANDER TO
THE NORTH OF 24N/25N. ALTHOUGH IT MAINTAINS A WELL DEFINED
CIRCULATION...SYSTEM IS NOT DEEP/STRONG ENOUGH TO PUT A DENT ON
TRADE WINDS CAP ACROSS THE NORTHEAST CARIBBEAN ISLES. AT LOW
LEVELS...TROPICAL WAVE TAKES A BEELINE ACROSS THE EASTERN
CARIBBEAN...REACHING THE MONA PASSAGE LATER THIS AFTERNOON. BEST
DYNAMICS WITH THIS FEATURE ARE EXPECTED OVER THE CARIBBEAN JUST
SOUTH OF SAINT CROIX. AS THE WAVE PULLS AWAY...THE ITCZ IS TO
RAPIDLY RETURN TO ITS CLIMATOLOGICAL POSITION DURING THE AFTERNOON
HOURS ON FRIDAY. DUST/HAZY CONDITIONS ARE TO THEN PREVAIL AS A SAL
EXPANDS ACROSS THE LESSER ANTILLES.

ON DAY 01...IN ASSOCIATION WITH THE TROPICAL WAVE...THE MODEL
GUIDANCE AGREE ON LIGHT CONVECTION LIMITING TO SAINT
CROIX-SOUTHEAST PUERTO RICO THROUGH THE EARLY AFTERNOON
HOURS...WITH HIGHER RESOLUTION MODEL GUIDANCE SHOWING POSSIBILITY
OF MODERATE CONVECTION ACROSS WESTERN INTERIOR PORTIONS OF PUERTO
RICO LATER THIS AFTERNOON. THIS SEEMS REASONABLE CONSIDERING
EVOLVING WEATHER CONDITIONS. AS THE ITCZ MOIST TONGUE MEANDERS
SOUTH OF THE FORECAST AREA EARLY ON FRIDAY...SOME OF THE MOISTURE
MIGHT ADVECT NORTHWARD ACROSS PUERTO RICO AS DRAWN BY SEA
BREEZE/DIURNAL HEATING. THE GFS IS BETTING HEAVILY ON THIS
POSSIBILITY...WHILE THE OTHER GLOBAL MODELS REMAIN QUITE
PESSIMISTIC. ALTHOUGH PERSISTENCE SUGGESTS THAT CONDITIONS ARE
LIKELY TO REMAIN UNFAVORABLE...IF THERE IS GOING TO BE SOME
INTERACTION BETWEEN TUTT ALOFT AND MOIST TONGUE THIS MIGHT BE IT.
IN RESPONSE...THE GDI IS SHOWING MODERATE RISK OF THUNDERSTORMS
DURING THE DAY ON FRIDAY. LETS HOPE FOR THE BETTER...

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





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