000
AXNT20 KNHC 111725
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT MON MAY 11 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...THE ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 6N10W 3N22W 1N30W CROSSING THE 
EQUATOR NEAR 37W EXTENDING TO NE BRAZIL NEAR 1S47W. SCATTERED 
MODERATE CONVECTION IS FROM 3N-6N BETWEEN 17W-21W...S OF 4N 
BETWEEN 21W-34W...AND S OF 1N BETWEEN 41W-44W.

...DISCUSSION...

GULF OF MEXICO...
W TO NW MID TO UPPER LEVEL FLOW IS PRESENT ACROSS THE REGION... 
THOUGH IT IS BEING PERTURBED SLIGHTLY BY A WEAK SHORTWAVE ALONG 
87W/88W. THIS TROUGH IS NOT MUCH OF A WEATHER PLAYER FOR THE 
GULF...BUT IT IS ENHANCING TSTM ACTIVITY OVER THE SE CONUS. IN 
FACT...MAINLY FAIR WEATHER EXISTS ACROSS THE ENTIRE ZONE. A SFC 
RIDGE CONTINUES TO BE NEARLY STATIONARY ACROSS THE NE GULF WITH 
AN EMBEDDED 1019 MB SFC HIGH CENTERED JUST OFF THE TAMPA COAST. 
THIS PATTERN IS PRODUCING GENERALLY LIGHT WINDS OVER MUCH OF THE 
E AND MIDDLE WATERS AND E TO SE 15-20 KT WINDS OVER A PORTION OF 
THE WRN WATERS...DUE TO THE TIGHTENED PRES GRADIENT BETWEEN 
THE HIGH AND BROAD TROUGHING OVER MEXICO. LITTLE CHANGE IN THE 
PATTERN IS EXPECTED OVER THE NEXT COUPLE OF DAYS. 

CARIBBEAN SEA...
BROAD RIDGING ALOFT COVERS MUCH OF THE CARIBBEAN...EXTENDING NW 
FROM AN UPPER HIGH CENTERED NEAR 2N55W. UPPER DIFFLUENCE BETWEEN 
THE HIGH AND BROAD TROUGHING OVER THE EPAC IS PRODUCING 
SCATTERED SHOWERS AND TSTMS OVER THE SW CARIBBEAN S OF 11N W OF 
78W. HOWEVER...THE LARGER CONVECTIVE ACTIVITY IS OCCURRING OVER 
THE PACIFIC WATERS S OF PANAMA AND COSTA RICA...WHERE LOW-LEVEL 
CONVERGENCE ALONG THE ITCZ IS PRESENT. MEANWHILE...SURFACE HIGH 
PRESSURE N OF THE CARIBBEAN SEA IS RESULTING IN FRESH E TRADE 
WINDS ACROSS THE CARIBBEAN SEA. THESE FRESH E TRADE WINDS ARE 
FORECAST TO PERSIST THROUGH THE WEEK. THE STRONGEST WINDS ARE 
FOUND NEAR THE COAST OF COLOMBIA...WHERE NE TO E WINDS OF 20 TO 
25 KT ARE OCCURRING. 

ATLANTIC OCEAN...
A SURFACE RIDGE ASSOCIATED WITH A 1025 MB SURFACE HIGH OVER THE 
CENTRAL ATLC NEAR 30N46W IS AFFECTING MUCH OF THE ATLC PORTION 
OF THE DISCUSSION AREA. THIS SURFACE HIGH IS FORECAST TO MOVE NE 
DURING THE NEXT DAY AND BE LOCATED NEAR 32N40W AS A 1027 MB 
SURFACE HIGH AT 12/1200 UTC. SUBSIDENCE ASSOCIATED WITH THE 
SURFACE RIDGE ARE 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 W ACROSS PORTIONS OF THE SW NORTH ATLC. THE GREATEST 
OF THESE SHOWERS IS LOCATED WITHIN 120 NM EITHER SIDE OF A 
RATHER DISORGANIZED SURFACE TROUGH THAT EXTENDS FROM 20N57W TO 
14N58W. THIS TROUGH IS MOVING W NEAR 15 KT TOWARD THE LEEWARD 
AND WINDWARD ISLANDS...AND WILL LIKELY IMPACT THOSE LOCATIONS 
DURING THE NEXT DAY WITH INCREASED SHOWER ACTIVITY. THIS 
ACTIVITY IS BEING SUPPORTED BY ATMOSPHERIC INSTABILITY 
ASSOCIATED WITH A WEAK UPPER LEVEL TROUGH IN THE VICINITY OF THE 
SURFACE TROUGH.  ALSO...A MID/UPPER-LEVEL TROUGH N OF THE 
DISCUSSION AREA IS ASSOCIATED WITH A SURFACE TROUGH OVER THE E 
ATLC THAT EXTENDS FROM 26N28W TO 28N19W TO 32N13W TO NE OF THE 
DISCUSSION AREA. LOW LEVEL CONVERGENCE IS SUPPORTING SCATTERED 
SHOWERS WITHIN 60 NM EITHER SIDE OF THIS COLD FRONT. ACROSS THE 
TROPICAL ATLC...AN UPPER LEVEL RIDGE IS PRESENT S OF 13N E OF 
43W...WITH AN UPPER LEVEL HIGH NEAR 4N35W. ASSOCIATED UPPER 
LEVEL DIVERGENCE IS ENHANCING ITCZ CONVECTION.

$$
CANGIALOSI/COHEN