Prognostic Meteorological Discussion
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FXCA20 KWBC 281045
PMDCA

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
645 AM EDT TUE JUL 28 2015

PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM JULY
28/06 UTC: RETROGRESSING TUTT LOW CENTERS OVER THE NORTHERN
LEEWARD ISLES. UNDER INFLUENCE OF A RIDGE TO THE NORTH...THIS IS
TO MOVE WEST ACROSS THE VIRGIN ISLES TO EASTERN PUERTO RICO EARLY
ON WEDNESDAY MORNING...AND THROUGH THE DAY IT IS TO TRACK ACROSS
THE ISLAND. ALTHOUGH WELL DEFINED...PERSISTENT MID LEVEL RIDGE
OVER THE NORTHERN CARIBBEAN IS TO NEGATE ANY POSITIVE INFLUENCE
THIS LOW/TROUGH MIGHT HAVE ON LOCAL WEATHER CONDITIONS.
ENHANCEMENT...IF ANY...WILL CONFINE TO WESTERN PUERTO RICO DURING
THE AFTERNOON HOURS. AT LOW/MID LEVELS...BRISK EASTERLY TRADES
ENVELOP THE EASTERN CARIBBEAN. THIS IS ADVECTING A SAHARAN AIR
LAYER ACROSS THE BASIN...WITH DRY AND DUSTY AIR EXPECTED TO
INHIBIT SIGNIFICANT RAINFALL OVER THE NEXT FEW DAYS.

LATER IN THE WEEK...A DEEPER TUTT LOW IS TO REACH THE EASTERN
CARIBBEAN. THIS APPEARS STRONG ENOUGH TO WEAKEN MID LEVEL RIDGE
PATTERN...RELEASING THE CAP INVERSION WHILE ALLOWING FOR DEEPER
MOISTURE TO CLUSTER ACROSS THE FORECAST AREA DURING THE DAY ON
FRIDAY. THE GFS AND EUROPEAN MODELS AGREE ON POTENTIAL FOR
MEASURABLE RAINFALL AMOUNTS IN ASSOCIATION WITH THIS FEATURE.
THIS...HOWEVER...WILL BE SHORT LIVED...WITH CAP TO RAPIDLY
STRENGTHEN AS THE TUTT MIGRATES FARTHER TO THE WEST.

SALMON...MS (ANTIGUA AND BARBUDA)
SAMUEL...MDS (SURINAME)
DAVISON...WPC (USA)
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