000
AXNT20 KNHC 092345
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SAT MAY 09 2009

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL 
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS
OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST
FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED
ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...WEATHER
OBSERVATIONS...AND RADAR.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...THE ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 6N9W 4N17W 2N32W CROSSING THE 
EQUATOR NEAR 42W EXTENDING TO NE BRAZIL NEAR 1S47W. SCATTERED 
MODERATE AND ISOLATED STRONG CONVECTION IS FROM 2N-7N BETWEEN 
8W-18W. SIMILAR CONVECTION IS FROM THE EQUATOR TO 2N BETWEEN 
47W-52W

...DISCUSSION...

GULF OF MEXICO...
SUBSIDENCE IN NORTHERLY FLOW ALOFT AND DEEP LAYER DRY AIR ARE 
PRESENT ACROSS MUCH OF THE REGION. THIS SUBSIDENCE IS BEING 
SUPPORTED BY A SURFACE RIDGE OVER THE N GULF. THE SUBSIDENCE AND 
STABLE ATMOSPHERIC CONDITIONS ARE RESULTING IN GENERALLY FAIR 
WEATHER ACROSS MUCH OF THE AREA. RETURN FLOW ON THE WRN 
PERIPHERY OF THE AFOREMENTIONED SURFACE RIDGE IS RESULTING IN SE 
WINDS ACROSS THE GULF...WITH WIND SPEEDS UP TO 20 KT ACROSS 
PORTIONS OF THE W AND MIDDLE GULF...AS REVEALED IN BUOY OBS AND 
RECENT SCATTEROMETER DATA. CONTINUED MAINLY FAIR WEATHER IS 
EXPECTED THROUGH THE REMAINDER OF THE WEEKEND AS THE DISCUSSED 
WEATHER PATTERN PERSISTS.

CARIBBEAN SEA...
STRONG SURFACE HIGH PRESSURE OVER THE CENTRAL ATLC IS RESULTING 
IN FRESH TRADE WINDS ACROSS THE CARIBBEAN SEA. THESE FRESH TRADE 
WINDS ARE FORECAST TO PERSIST ACROSS THE REGION INTO THE MIDDLE 
OF NEXT WEEK AS THE ATLC RIDGE REMAINS NEARLY STATIONARY. THE 
STRONGEST WINDS...NE-E 20-25 KT...ARE FOUND NEAR THE COAST OF 
COLOMBIA. THE TRADE WINDS ARE ADVECTING POCKETS OF LOW LEVEL 
MOISTURE WITH ISOLATED SHOWERS WESTWARD ACROSS THE CARIBBEAN. 
THE GREATEST CONCENTRATION OF THESE SHOWERS IS N OF 15N E OF 
71W...INCLUDING PORTIONS OF HISPANIOLA AND PUERTO RICO. 
ATMOSPHERIC STABILITY ASSOCIATED WITH A BROAD UPPER RIDGE OVER 
THE REGION IS ENHANCING FAIR WEATHER CONDITIONS ACROSS MUCH OF 
THE CARIBBEAN. UPPER LEVEL DIVERGENCE BETWEEN THE RIDGE AND A 
SHORTWAVE TROUGH OVER THE YUCATAN PENINSULA IS PRODUCING  
SCATTERED SHOWERS AND ISOLATED TSTMS OVER THE SW CARIBBEAN S OF 
11N W OF 78W. MORE WIDESPREAD TSTM ACTIVITY IS OCCURRING OVER 
PORTIONS OF CENTRAL AMERICA GREATLY ENHANCED BY LOCAL EFFECTS.

ATLANTIC OCEAN...
A SURFACE RIDGE ASSOCIATED WITH A 1027 MB HIGH OVER THE CENTRAL 
ATLC NEAR 32N48W IS DOMINATING MUCH OF THE ATLC PORTION OF THE 
DISCUSSION AREA. THE SURFACE HIGH IS FORECAST TO MOVE SLOWLY 
SOUTHWARD DURING THE NEXT DAY TO NEAR 30N49W AT 1025 MB. 
SUBSIDENCE ASSOCIATED WITH THE RIDGE IS RESULTING IN GENERALLY 
FAIR WEATHER CONDITIONS ACROSS MUCH OF THE ATLC PORTION OF THE 
DISCUSSION AREA. HOWEVER...POCKETS OF LOW LEVEL MOISTURE WITH 
ISOLATED SHOWERS ARE MOVING WESTWARD ACROSS PORTIONS OF THE SW 
NORTH ATLC...WITH THE GREATEST OF THESE SHOWERS S OF 24N BETWEEN 
60W-72W INCLUDING PORTIONS OF HISPANIOLA AND PUERTO RICO. ACROSS 
THE TROPICAL ATLC...AN UPPER LEVEL RIDGE IS PRESENT S OF 12N E 
OF 60W...WITH AN UPPER LEVEL HIGH NEAR 7N43W. DIVERGENCE ALOFT 
ASSOCIATED WITH THE UPPER LEVEL RIDGE IS ENHANCING THE ITCZ 
CONVECTION. THIS UPPER LEVEL DIVERGENCE ALSO SUPPORTED THE 
RECENT CONVECTION AND ASSOCIATED MAJOR FLOODING ACROSS PORTIONS 
OF NE BRAZIL. THE GREATEST CONCENTRATION OF CONVECTION OVER 
BRAZIL IS NOW LOCATED OVER WESTERN PORTIONS OF BRAZIL...THOUGH 
SCATTERED MODERATE CONVECTION ASSOCIATED WITH THE ITCZ IS 
AFFECTING THE COAST OF NE BRAZIL.

$$
CANGIALOSI/COHEN