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Tropical Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1046Z Apr 17, 2015)
 
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TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
646 AM EDT FRI APR 17 2015

PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM APRIL
17/06 UTC: LOW LEVEL WINDS ARE VEERING TO THE EAST-SOUTHEAST AS
RIDGE RECEDES UNDER PRESSURE FROM POLAR TROUGH MOVING TO THE
WESTERN ATLANTIC. AS THE WINDS SHIFT...A MOIST ADVECTIVE PATTERN
IS TO ESTABLISH ACROSS THE LESSER ANTILLES TO THE NORTHEAST
CARIBBEAN. IN THIS PATTERN...A PLUME OF MOISTURE CLUSTERED EARLY
THIS MORNING ACROSS THE NORTHERN LEEWARD ISLES. UNDER INFLUENCE OF
A MID/UPPER LEVEL SHORT WAVE TROUGH...TRADE WINDS INVERSION IS TO
LIFT ABOVE 600 HPA LATER THIS AFTERNOON. THIS IS TO THEN ALLOW THE
MOIST PLUME TO SPREAD ACROSS THE FORECAST AREA EARLY THIS
AFTERNOON. PWAT AMOUNTS OF 25-30MM ARE TO THEN PERSIST THROUGH
MONDAY MORNING...WHEN PREVAILING EASTERLIES RETURN TO THE FORECAST
AREA.

AS THE INVERSION LIFTS...CONDITIONS WILL BECOME MORE FAVORABLE FOR
CONVECTION TO DEVELOP ACROSS THE FORECAST AREA...WITH BOTH THE
GFS-UKMET SHOWING POTENTIAL FOR SCATTERED SHOWERS OVER THE NEXT
THREE DAYS. THEY...HOWEVER...DIVERGE ON WHERE MOST ACTIVE
CONVECTION IS TO DEVELOP...WITH THE GFS SHOWING MOST ACTIVE OVER
THE VIRGIN ISLES-EASTERN PORTIONS OF PUERTO RICO WHILE THE UKMET
PUTS MORE WEIGHT ON DIURNAL EFFECTS ACROSS PUERTO RICO. ABSENT
MESO-SYNOPTIC FORCING...WE ARE LEANING TOWARDS THE UKMET SOLUTION.
MOST ACTIVE TODAY IS EXPECTED ACROSS UTUADO-JAYUYA AND WESTWARD TO
MARICAO/MAYAGUEZ...WITH BOTH VERSION OF THE HIGH RESOLUTION WRF
SHOWING MAXIMA OF NEARLY 4 INCHES FOR THE AREA. ON SATURDAY TO
SUNDAY...AS STEERING WINDS FROM THE SOUTHEAST PREVAIL...EXPECTING
MOST ACTIVE TO CLUSTER ALONG THE NORTH COAST TO THE WEST OF VEGA
BAJA/MANATI...WITH OTHER ACTIVITY POSSIBLE ALONG THE CORDILLERA/EL
YUNQUE RAIN FOREST. STREAMERS FORMING OVER SAINT CROIX ARE ALSO
LIKELY TO FAVOR MODERATE CONVECTION ACROSS HUMACAO IN A SLIGHT
RISK OF ECHO TRAINING OVER SOUTHEAST PORTIONS OF THE ISLAND.

CRAIG...TTMS (TRINIDAD AND TOBAGO)
SAMUEL...MDS (SURINAME)
DAVISON...WPC (USA)
GALVEZ...WPC (USA)