THE WEATHER PREDICTION CENTER

COLLEGE PARK, MD


CARIBBEAN FORECAST DISCUSSION




TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
654 AM EST WED NOV 26 2014

NOTE: TROPICAL DESK PRODUCTS WILL NOT BE AVAILABLE ON NOV 27-28.

PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI. BROAD
MID/UPPER LEVEL RIDGE CONTINUES TO DOMINATE FLOW ACROSS THE
CARIBBEAN BASIN-WESTERN ATLANTIC...WHILE A DEEP TUTT NOW CENTERS
TO THE EAST-NORTHEAST OF THE LESSER ANTILLES. POLAR TROUGH EXITING
THE USA IS TO THEN PRESS AGAINST THE RIDGE TO THE WEST...LEADING
TO ITS GRADUAL EROSION THROUGH THURSDAY EVENING. AS THE RIDGE
WEAKENS THE TUTT IS TO RETROGRESS ACROSS THE LESSER ANTILLES TO
THE EASTERN CARIBBEAN...WITH CLOSED LOW TO REPOSITION NEAR THE
NORTHERN LEEWARD ISLES EARLY ON THURSDAY MORNING. CONSISTENT WITH
PREVIOUS FORECASTS...A SUBTROPICAL JET MAXIMA ON THE NORTHERN
FRINGES OF THIS TROUGH IS TO THEN MOVE JUST NORTH OF THE FORECAST
AREA LATER THIS AFTERNOON. PUERTO RICO AND THE USVI ARE TO THEN
REMAIN ON THE DIVERGENT SIDE OF THIS JET MAXIMA THROUGH MIDDAY ON
THURSDAY. THE MID LEVEL REFLECTION OF THIS TROUGH IS TO NEAR THE
NORTHERN LEEWARD ISLES EARLY ON THURSDAY...AND REMAINS ACROSS THE
NORTHEAST CARIBBEAN ISLES THROUGH THURSDAY EVENING. AS IT MEANDERS
ACROSS THE NORTHEAST CARIBBEAN ISLES...THIS IS TO FOCUS A SERIES
OF WEAK CYCLONIC VORTICES ACROSS THE FORECAST AREA...WITH BEST
INFLOW OF SHORT WAVE ENERGY EXPECTED LATER THIS AFTERNOON.

AT LOW LEVELS THE DEEP TROUGH ALOFT IS TO SUSTAIN AN
INDUCED/INVERTED TROUGH IN THE EASTERLY TRADES. THIS MOVES ACROSS
THE LESSER ANTILLES EARLY ON THURSDAY...INTO THE VI/EASTERN PUERTO
RICO LATER DURING THE DAY. ALTHOUGH UPPER DYNAMICS SEEM TO IMPROVE
AT A FAIRLY FAST PACE...MOISTURE IS TO REMAIN IN SHORT SUPPLY
THROUGH THE END OF THE WORK WEEK. HOWEVER...FAVORABLE JET DYNAMICS
AND INFLOW OF MID LEVEL VORTICES WILL LIKELY LEAD TO AN INCREASE
IN TRADE WIND SHOWERS AND DIURNAL CONVECTION DURING THE DAY TODAY
AND THURSDAY. MOST ACTIVE IS EXPECTED ACROSS THE VI/EASTERN PUERTO
RICO DURING THE MORNING HOURS AND WESTERN INTERIOR PORTIONS OF
PUERTO RICO IN THE AFTERNOON...WITH RAINFALL MAXIMA LIKELY TO PEAK
AT 10-15MM.

DURING MEDIUM RANGE PERIOD...POLAR FRONT EXITING THE USA IS TO
STALL FAR TO THE NORTH. ASSOCIATED SHEAR LINE...MEANWHILE...IS TO
MOVE ACROSS THE FORECAST AREA LATER DURING THE WEEKEND. AS IT
APPROACHES THE FORECAST AREA PWAT IS FORECAST TO
SURGE...INCREASING TO 35-45MM LATER ON SUNDAY AS THE SHEAR LINE
AND PREFRONTAL TROUGH NEAR THE FORECAST AREA. GLOBAL MODELS AGREE
QUITE WELL ON THIS EVOLUTION...SO EXPECTING A GRADUAL INCREASE IN
CONVECTION LATER DURING THE WEEKEND/EARLY NEXT WEEK.

JN BAPTISTE...MS (SAINT LUCIA)
MEDINA...ONAMET (REPUBLICA DOMINICANA)
DAVISON...WPC (USA)




Last Updated: 654 AM EST WED NOV 26 2014