000 AXNT20 KNHC 201142 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1130 UTC. ...SPECIAL FEATURES... A BROAD AREA OF LOW PRESSURE WITH ACCOMPANYING SHOWERS/ THUNDERSTORMS ARE OVER THE W CARIBBEAN SEA SW OF OF GRAND CAYMAN. AT 20/0900 UTC A PARTIALLY EXPOSED 1008 MB LOW IS CENTERED NEAR 18N83W. SCATTERED/HEAVY SHOWERS AND ISOLATED THUNDERSTORMS ARE E OF THE LOW FROM 16N-19N BETWEEN 78W-82W INCLUDING THE WESTERN TIP OF JAMAICA. 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. REGARDLESS OF DEVELOPMENT...HEAVY RAINFALL IS POSSIBLE OVER THE CAYMAN ISLANDS AND JAMAICA DURING THE NEXT COUPLE OF DAYS. ...ITCZ... ITCZ AXIS IS ANALYZED ALONG 10N12W 6N22W 7N31W 6N41W 5N55W. A SURFACE TROUGH IS N OF THE ITCZ EXTENDING FROM 18N30W THROUGH A 1010 MB LOW NEAR 12N38W TO 10N37W WITH CLUSTERS OF SCATTERED MODERATE CONVECTION WITHIN 60 NM OF A LINE FROM 13N32W TO 17N34W AND WITHIN 120 NM E OF THE TROUGH FROM 11N-15N. CLUSTERS OF SCATTERED STRONG CONVECTION IS WITHIN 45 NM OF LINE FROM 11N17W TO 13N18W. CLUSTERS OF SCATTERED MODERATE/STRONG CONVECTION ARE FROM 7N-14N BETWEEN 15W-20W INCLUDING THE W COAST OF AFRICA AND N OF 1N TO INLAND OVER SW AFRICA AND E OF 6W TO ACROSS THE PRIME MERIDIAN. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 3N-7N BETWEEN 18W-24W. ...DISCUSSION... GULF OF MEXICO... A BROAD UPPER TROUGH COVERS THE GULF WITH THE ASSOCIATED FRONTAL BOUNDARY INLAND OVER THE E HALF OF THE US CONUS. THE BROAD UPPER RIDGE ANCHORED IN THE CARIBBEAN IS MOVING OUT OF THE FLORIDA STRAITS BUT CONTINUES TO PROVIDE DIFFLUENCE ALOFT AND COUPLED WITH RESIDUAL LOW LEVEL MOISTURE OVER THE FAR E GULF ARE PRODUCING SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS S OF 27N E OF 85W. STRONG SUBSIDENCE AND DRY AIR ALOFT COVER ALL BUT THE FLORIDA STRAITS GIVING THE REMAINDER OF THE AREA CLEAR SKIES THIS MORNING. A WEAK SURFACE RIDGE REMAINS OVER THE GULF ANCHORED BY A 1017 MB HIGH SW OF THE MISSISSIPPI DELTA NEAR 28N91W. CARIBBEAN SEA... SEE SPECIAL FEATURES ABOVE FOR THE ACTIVITY ASSOCIATED WITH THE 1008 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 SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS N OF 16N BETWEEN 74W-83W. ISOLATED SHOWERS DOT THE REMAINDER OF THE W CARIBBEAN W OF 75W. 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 70W. A BROAD UPPER RIDGE ANCHORED IN THE W CARIBBEAN EXTENDS AN AXIS OVER THE W ATLC THROUGH THE WINDWARD PASSAGE TO BEYOND 32N60W COVERING THE W ATLC WITHIN 450 NM OF THE RIDGE AXIS. THIS UPPER RIDGE IS PROVIDING DIFFLUENCE ALOFT TO GENERATE SCATTERED SHOWERS/ ISOLATED THUNDERSTORMS WITHIN 200 NM OF LINE FROM CUBA NEAR 22N76W ACROSS THE BAHAMA ISLANDS TO 27N71W THEN WITHIN 100 NM OF LINE FROM 27N72W TO BEYOND 32N68W. A SURFACE RIDGE EXTENDS FROM A 1023 MB HIGH N OF THE DISCUSSION AREA THROUGH 32N55W SW INTO THE W ATLC TO NEAR 26N70W. BROAD UPPER TROUGH IS OVER THE E/CENTRAL ATLC N OF 22N BETWEEN 25W-50W SUPPORTING A COLD FRONT THAT ENTERS THE REGION NEAR 32N25W SW TO 29N30W WHERE IT BECOMES A SURFACE TROUGH TO NEAR 22N50W WITH SCATTERED SHOWERS POSSIBLE WITHIN 60 NM E OF THE COLD FRONT AND WITHIN 60 NM W OF THE SURFACE TROUGH. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ PAW