TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
700 AM EDT THU MAY 23 2013

PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI. LOW AMPLITUDE
MID/UPPER LEVEL TROUGH CONTINUES TO DOMINATE FLOW ACROSS THE
NORTHERN CARIBBEAN ISLAND. SHORT WAVE PERTURBATIONS EMBED IN THIS
FLOW AS THEY STREAM ACROSS THE GREATER ANTILLES. THIS IS A PATTERN
FORECAST TO PERSIST OVER THE NEXT FEW DAYS AS REINFORCED BY A
POLAR TROUGH ENTERING THE WESTERN ATLANTIC LATER ON FRIDAY. AT LOW
LEVELS...BROAD CELL OF THE SUBTROPICAL RIDGE DOMINATES THE WESTERN
ATLANTIC-NORTHERN CARIBBEAN...SUSTAINING AN EASTERLY FLOW ACROSS
THE LESSER ANTILLES INTO THE CENTRAL/EASTERN CARIBBEAN. THROUGH
MIDDAY ON FRIDAY THE HIGH IS EXPECTED TO RELOCATE TO THE CENTRAL
ATLANTIC...YIELDING TO POLAR TROUGH ENTERING THE WESTERN ATLANTIC.
AS THE HIGH/RIDGE PULLS AWAY THE LOW LEVEL WINDS ARE TO VEER TO
THE SOUTHEAST. THIS IS TO ENHANCE MOISTURE TRANSPORT/CONVERGENCE
ACROSS THE FRENCH ISLES INTO THE FORECAST AREA...WITH PWAT
FORECAST TO PEAK AT 50-60MM OVER THE NEXT FEW DAYS. GLOBAL MODEL
GUIDANCE AGREES ON LULL IN ACTIVITY DURING THE DAY TODAY...WITH
CONVECTION TO THEN GRADUALLY INTENSIFY THROUGH THE WEEKEND. THEY
SHOW THIS PATTERN LASTING INTO THE MIDDLE OF NEXT WEEK.

AS THE WINDS VEER TO THE SOUTHEAST...FOCUS OF THE CONVECTION IS
GOING TO BE NORTH COAST OF PUERTO RICO...WITH MOST INTENSE ACROSS
NORTHWEST PORTIONS OF THE ISLAND. ON FRIDAY EXPECTING RAINFALL
AMOUNTS TO PEAK AT 1-2 INCHES. ON SATURDAY TO SUNDAY...AS THE
MOISTURE POOL DEEPENS...THE MAXIMA IS TO INCREASE TO 3-5 INCHES.
HEAVY RAINS ARE TO THEN PERSIST INTO EARLY NEXT WEEK.

BLENMAN...BMS (BARBADOS)
MCKENZIE...BDM (BAHAMAS)
DAVISON/GALVEZ...WPC (USA)