000 AXNT20 KNHC 200539 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT WED OCT 20 2010 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0445 UTC. ...SPECIAL FEATURES... A BROAD AREA OF LOW PRESSURE WITH ACCOMPANYING SHOWERS/ THUNDERSTORMS ARE OVER THE W CARIBBEAN SEA SW OF THE CAYMAN ISLANDS. AT 20/0300 UTC A 1009 MB LOW IS CENTERED NEAR 18N83W. SCATTERED/HEAVY SHOWERS AND ISOLATED THUNDERSTORMS ARE FROM 17N-20N BETWEEN 80W-83W. ALTHOUGH UPPER-LEVEL WINDS ARE MARGINALLY CONDUCIVE FOR DEVELOPMENT...ONLY A SMALL INCREASE IN ORGANIZATION OF THE THUNDERSTORM ACTIVITY COULD LEAD TO THE FORMATION OF A TROPICAL DEPRESSION...THUS THERE IS A HIGH CHANCE OF THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS. INTERESTS IN THE NORTHWEST CARIBBEAN SEA SHOULD CONTINUE TO MONITOR THE PROGRESS OF THIS SYSTEM. ...ITCZ... ITCZ AXIS IS ANALYZED ALONG 7N11W 5N20W 9N31W 6N42W 2N52W. A SURFACE TROUGH IS N OF THE ITCZ EXTENDING FROM 16N37W THROUGH A 1010 MB LOW NEAR 12N38W TO 9N40W WITH CLUSTERS OF SCATTERED MODERATE CONVECTION WITHIN 60 NM OF A LINE FROM 13N31W TO 17N40W AND SCATTERED SHOWERS WITHIN 120 NM E OF THE TROUGH FROM 11N-14N. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 4N-13N BETWEEN 11W-20W AND FROM 2N-7N BETWEEN 20W-23W. ...DISCUSSION... GULF OF MEXICO... A BROAD UPPER TROUGH COVERS THE GULF WITH THE ASSOCIATED FRONTAL BOUNDARY INLAND OVER THE SE CONUS. THE BROAD UPPER RIDGE ANCHORED IN THE CARIBBEAN IS OVER THE FLORIDA PENINSULA PROVIDING DIFFLUENCE ALOFT AND COUPLED WITH RESIDUAL LOW LEVEL MOISTURE OVER THE FAR E GULF IS PRODUCING ISOLATED SHOWERS S OF 28N E OF 85W. STRONG SUBSIDENCE AND DRY AIR ALOFT COVER ALL BUT THE FLORIDA STRAITS GIVING THE REMAINDER OF THE AREA CLEAR SKIES TONIGHT. A WEAK SURFACE RIDGE REMAINS OVER THE GULF ANCHORED BY A 1016 MB HIGH OVER THE MISSISSIPPI DELTA NEAR 29N90W. CARIBBEAN SEA... SEE SPECIAL FEATURES ABOVE FOR THE ACTIVITY ASSOCIATED WITH THE 1009 MB LOW IN THE W CARIBBEAN. BROAD UPPER RIDGE DOMINATES THE CARIBBEAN ANCHORED OVER JAMAICA ENHANCING THE ACTIVITY IN THE SPECIAL FEATURES AND PROVIDING DIFFLUENCE ALOFT TO GENERATE CLUSTERS OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS N OF 15N BETWEEN 72W-80W AND SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS N OF 17N BETWEEN 80W-84W. ALTHOUGH AN ELONGATED N/S UPPER LOW REMAINS OVER THE LESSER ANTILLES...THE AREA IS DOMINATED BY DRY AIR ALOFT AND IS STILL NOT PRODUCING ANY SIGNIFICANT WEATHER LEAVING THE REMAINDER OF THE CARIBBEAN WITH MOSTLY CLEAR SKIES AND SOME POSSIBLE ISOLATED LOW LEVEL SHOWERS. ATLANTIC OCEAN... BROAD UPPER TROUGH THAT COVERS THE GULF OF MEXICO AND THE E CONUS EXTENDS INTO THE W ATLC N OF 26N W OF 73W. A BROAD UPPER RIDGE ANCHORED IN THE W CARIBBEAN EXTENDS AN AXIS OVER THE W ATLC THROUGH THE WINDWARD PASSAGE TO ACROSS BERMUDA COVERING THE W ATLC WITHIN 400 NM OF THE RIDGE AXIS. THIS UPPER RIDGE IS PROVIDING DIFFLUENCE ALOFT TO GENERATE SCATTERED SHOWERS/ ISOLATED THUNDERSTORMS S OF 25N ACROSS THE BAHAMA ISLANDS TO OVER CUBA AND HAITI BETWEEN 72W-78W AND SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS WITHIN 120 NM OF LINE FROM CUBA NEAR 23N79W TO 32N68W. A SURFACE RIDGE EXTENDS FROM A 1022 MB HIGH NEAR 33N54W SW INTO THE W ATLC TO NEAR 27N72W. BROAD UPPER TROUGH IS OVER THE E/CENTRAL ATLC N OF 22N BETWEEN 30W-55W SUPPORTING A DEVELOPING COLD FRONT THAT ENTERS THE REGION NEAR 32N27W SW TO 24N44W WITH SCATTERED SHOWERS POSSIBLE WITHIN 60 NM OF THE FRONTAL BOUNDARY. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ PAW