000 AXNT20 KNHC 230535 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT TUE SEP 23 2008 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 0315 UTC. ...SPECIAL FEATURES... A BROAD AREA OF LOW PRESSURE ANALYZED AS A 1008 MB LOW ALONG THE N COAST OF THE DOMINICAN REPUBLIC NEAR 19N69W CONTINUES TO BRING HEAVY RAINS TO PUERTO RICO...THE DOMINICAN REPUBLIC...THE VIRGIN ISLANDS AND ADJACENT WATERS. SCATTERED STRONG CONVECTION IS FROM 16N-19N BETWEEN 68W-71W WITH CLUSTERS OF SCATTERED MODERATE/ ISOLATED STRONG CONVECTION ARE OVER THE AREA FROM 14N-21N BETWEEN 61W-71W. HEAVY RAINFALL WITH LIFE-THREATENING FLASH FLOODS AND MUDSLIDES ARE EXPECTED TO CONTINUE IMPACTING THE AREA FROM THE VIRGIN ISLANDS THROUGH HISPANIOLA FOR TONIGHT INTO TUE. THE ASSOCIATED SHOWERS AND THUNDERSTORMS REMAIN POORLY ORGANIZED AT THIS TIME DUE TO UPPER-LEVEL WESTERLY WINDS WITH LITTLE CHANGE IN ORGANIZATION. THIS SYSTEM HAS THE POTENTIAL TO BECOME A TROPICAL DEPRESSION AT ANY TIME DURING THE NEXT DAY OR TWO AS IT MOVES NORTHWESTWARD AWAY FROM HISPANIOLA. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 32W S OF 18N MOVING W 10-15 KT. WAVE REMAINS EMBEDDED WITHIN A BROAD AREA OF DEEP LAYER MOISTURE AS INDICATED BY MIMIC TPW ANIMATION. WAVE IS VERY BROAD COVERING THE AREA BETWEEN 25W-37W. ANY CONVECTION IS ASSOCIATED WITH THE ITCZ. TROPICAL WAVE IS ALONG 48W S OF 15N MOVING W 10-15 KT. WAVE IS LOW AMPLITUDE AND MOSTLY EMBEDDED WITHIN THE ITCZ. CLUSTERS OF SCATTERED MODERATE TO ISOLATED STRONG CONVECTION ARE WITHIN 150 NM EITHER SIDE OF THE WAVE AXIS. TROPICAL WAVE IS ALONG 70W S OF 17N MOVING W 10-15 KT. THIS WAVE HAS BECOME DIFFICULT TO LOCATE DUE TO THE CLOSE PROXIMITY OF THE LOW PRESSURE SYSTEM DESCRIBED IN THE SPECIAL FEATURES SECTION. NO ASSOCIATED SHOWERS/CONVECTION. TROPICAL WAVE IS ALONG 83W S OF 16N MOVING W 15-20 KT. WELL DEFINED INVERTED-V CURVATURE IS OBSERVED ON SATELLITE IMAGERY. NO ASSOCIATED SHOWERS/CONVECTION IS NOTED. TROPICAL WAVE IS ALONG 93W S OF 17N MOVING W NEAR 10-15 KT. THIS WAVE IS INLAND OVER S MEXICO AND INTO THE E PACIFIC REGION...NO LONGER IMPACTING THE ATLC BASIN. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 8N12W 12N30W 9N39W 12N62W. SCATTERED MODERATE/STRONG CONVECTION IS WITHIN 60/75 NM OF LINE FROM 4N38W TO 8N39W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN A 60/75 NM RADIUS OF 3.5N29.5W WITH CLUSTERS OF SIMILAR CONVECTION FROM 12N-16N BETWEEN 25W-38W AND FROM 5N-12N BETWEEN 33W-43W. ...DISCUSSION... GULF OF MEXICO... AN UPPER TROUGH THAT COVERS THE E US EXTENDS S TO OVER THE NE GULF E OF THE MISSISSIPPI VALLEY BRINGING DRY STABLE AIR TO THE GULF WATERS N OF 29N E OF 90W TO OVER THE N FLORIDA PENINSULA. A BROAD UPPER RIDGE COVERS THE REMAINDER OF THE GULF ANCHORED OVER CENTRAL MEXICO WITH THE AXIS EXTENDING E TO OVER S FLORIDA. A SURFACE TROUGH IS BENEATH THIS UPPER RIDGE EXTENDING FROM OFF THE COAST OF BROWNSVILLE TEXAS TO THE BAY OF CAMPECHE NEAR 19N94W. UPPER DIFFLUENCE IS GENERATING SCATTERED SHOWERS/ THUNDERSTORMS OVER THE W GULF S OF 28N W OF 90W AND OVER THE E GULF FROM 24N-28N E OF 90W ACROSS S FLORIDA. CARIBBEAN SEA... THE MAIN CONCERN FOR THE NEXT FEW DAYS CONTINUES TO BE THE AREA OF LOW PRESSURE DESCRIBED IN THE SPECIAL FEATURES SECTION. THE UPPER RIDGE FROM THE GULF OF MEXICO COVERS THE NW CARIBBEAN W OF 83W PROVIDING UPPER LEVEL DIFFLUENCE TO GENERATE SCATTERED SHOWERS/ISOLATED THUNDERSTORMS S OF 20N W OF 83W TO INLAND OVER THE YUCATAN PENINSULA AND CENTRAL AMERICA. AN UPPER TROUGH FROM THE W ATLC EXTENDS OVER CUBA TO THE CAYMAN ISLANDS AND JAMAICA PUSHING AFTERNOON THUNDERSTORMS THAT DEVELOPED OVER CUBA INTO THE CARIBBEAN WATERS BUT ARE NOW BEGINNING TO DISSIPATE. THE UPPER RIDGE ASSOCIATED WITH THE LOW PRESSURE SYSTEM IN THE SPECIAL FEATURES COVER THE E CARIBBEAN FROM THE ABC ISLANDS AND THE COAST OF VENEZUELA ACROSS THE DOMINICAN REPUBLIC TO THE LEEWARD ISLANDS ENHANCING THE ACTIVITY ASSOCIATED THERE. BETWEEN THE UPPER RIDGES...THE CENTRAL CARIBBEAN REMAINS CLEAR TONIGHT. ATLANTIC OCEAN... A NARROW UPPER RIDGE EXTENDS FROM THE N BAHAMA ISLANDS NEAR 26N78W TO BEYOND 32N73W PROVIDING UPPER LEVEL DIFFLUENCE TO GENERATE SCATTERED SHOWERS/ISOLATED THUNDERSTORMS W OF THE UPPER RIDGE AXIS TO THE COAST OF GEORGIA AND SOUTH CAROLINA AND INLAND OVER PORTIONS OF FLORIDA. A WEAKENING SURFACE TROUGH EXTENDS ALONG THIS BOUNDARY. AN UPPER TROUGH IS TO THE E EXTENDING FROM AN UPPER LOW NEAR 29N66W TO ACROSS CUBA AND INTO THE N CARIBBEAN. DRY STABLE AIR COVERS THE SAME AREA LEAVING THE REMAINDER OF THE W ATLC CLEAR TONIGHT. THE UPPER RIDGE ASSOCIATED WITH THE LOW PRESSURE SYSTEM IN THE SPECIAL FEATURES EXTENDS FROM 24N59W SW INTO THE CARIBBEAN COVERING THE AREA BETWEEN THE THE DOMINICAN REPUBLIC TO THE LEEWARD ISLANDS ENHANCING THE ACTIVITY ASSOCIATED THERE. A CUT-OFF UPPER LOW IS IN THE CENTRAL ATLC NEAR 23N47W GENERATING ISOLATED SHOWERS FROM 22N-27N BETWEEN 47W-52W. A DEEP LAYERED LOW IS IN THE E ATLC N OF 25N BETWEEN 20W-35W WITH THE UPPER LOW N OF THE REGION AND THE SURFACE LOW NEAR 32N28W AND A SURFACE TROUGH EXTENDING SW TO 27N36W...GENERATING SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS N OF 28N BETWEEN 21W-29W. THE TYPICAL E/W UPPER RIDGE THAT EXTENDS FROM AFRICA TO 40W ALONG 15N HAS BEEN SUPPRESSED TO THE S DUE TO THE UPPER TROUGH MENTIONED ABOVE. THE SURFACE RIDGE THAT HAS BEEN IN CONTROL OF THE ATLC HAS FURTHER WEAKENED WITH A 1023 MB HIGH E OF BERMUDA NEAR 33N58W AND A 1020 MB HIGH IN THE E ATLC NEAR 25N26W. $$ WALLACE