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Tropical Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1159Z Jan 22, 2015)
 
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TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
659 AM EST THU JAN 22 2015

PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI. STRONG
MID/UPPER RIDGE PATTERN MAINTAINS ITS FOOTHOLD ACROSS THE FORECAST
AREA...SUSTAINING A TRADE WINDS INVERSION WHILE CAPPING MOISTURE
TO LOW LEVELS OF THE ATMOSPHERE. AT LOW LEVELS...INVERTED
PERTURBATION IN THE EASTERLY TRADES ENTERED THE EASTERN CARIBBEAN.
MOISTURE IS CLUSTERING ALONG THE NORTHERN FRINGES OF THIS TROUGH
JUST NORTH OF THE VIRGIN ISLES. TROUGH THE DAY IT IS TO PULL
ACROSS THE FORECAST AREA...WITH BEST MOISTURE CONVERGENCE WITH
THIS FEATURE EXPECTED ACROSS THE VI TO EASTERN PORTIONS OF PUERTO
RICO THROUGH THE LATE MORNING HOURS...AND SOUTHWEST PUERTO
RICO/CORDILLERA IN THE AFTERNOON. HIGH RESOLUTION MODELS SHOW MOST
ACTIVE ON THE CORDILLERA...WITH MAXIMA OF NEARLY TWO INCHES IN
THIS AREA. THE GLOBAL MODELS ARE MORE CONSERVATIVE WITH THEIR
RAINFALL PROJECTIONS...WITH THE ECMWF ONLY SHOWING TRACE AMOUNTS
WHILE THE UKMET HAS MAXIMA OF HALF AN INCH. AS THE WAVE MOVES
ACROSS PUERTO RICO DURING MAX HEATING...WE ARE LEANING TOWARDS THE
WETTER SOLUTION.

STRONG MID/UPPER RIDGE PATTERN IS TO THEN HOLD THROUGH SATURDAY
EVENING/SUNDAY MORNING...THEN STARTS TO RAPIDLY ERODE EARLY NEXT
WEEK AS DEEP POLAR TROUGH ESTABLISHES ACROSS THE EASTERN USA TO
THE NORTHERN CARIBBEAN ISLES.  ASSOCIATED FRONT MOVES ACROSS THE
BAHAMAS-CUBA THROUGH TUESDAY EVENING...NEARING PUERTO RICO LATER
ON WEDNESDAY/EARLY THURSDAY MORNING. INVERTED/PREFRONTAL TROUGH IS
TO ESTABLISH ACROSS THE FORECAST AREA AS EARLY AS TUESDAY EVENING.
ALTHOUGH MODELS DIVERGE ON THE TIMING OF THIS FEATURE...AS THE
RIDGE ALOFT WEAKENS AND THE TRADE WINDS CAP LIFTS...THEY AGREE ON
DEEPER MOISTURE POOLING ACROSS THE FORECAST AREA. SO CONDITIONS
APPEAR FAVORABLE FOR ORGANIZED CONVECTION TO DEVELOP.

JN BAPTISTE...MS (SAINT LUCIA)
NANDA...MDS (SURINAME)
DAVISON...WPC (USA)