000 AXNT20 KNHC 250549 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT THU SEP 25 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 WELL-DEFINED SURFACE LOW PRESSURE SYSTEM CENTERED ABOUT 200 NM SE OF THE SOUTH CAROLINA-NORTH CAROLINA BORDER IS MOVING SLOWLY WESTWARD. SHOWERS AND THUNDERSTORMS HAVE BECOME A LITTLE BETTER ORGANIZED THIS MORNING AND THIS SYSTEM COULD DEVELOP INTO A SUBTROPICAL OR TROPICAL CYCLONE LATER TODAY. REGARDLESS OF WHETHER OR NOT THIS SYSTEM BECOMES A SUBTROPICAL OR TROPICAL CYCLONE...STRONG WINDS...COASTAL FLOODING...HIGH SURF...AND DANGEROUS RIP CURRENTS WILL CONTINUE ALONG PORTIONS OF THE U.S. EAST COAST DURING THE NEXT COUPLE OF DAYS. OUTER RAINBANDS ARE ALREADY SPREADING ONSHORE THE SOUTHEASTERN COAST OF NORTH CAROLINA...AND BUOY AND SHIP REPORTS INDICATE WINDS IN EXCESS OF 50 MPH ARE OCCURRING NORTH AND WEST OF THE CENTER. A BROAD AREA OF LOW PRESSURE IS ANALYZED AS A 1005 MB LOW IS TO THE E OF THE TURKS AND CAICOS NEAR 22N70W MOVING NORTHWARD AT NEAR 10 KT. THIS SYSTEM HAS BECOME BETTER ORGANIZED DURING THE PAST SEVERAL HOURS...AND UPPER-LEVEL WINDS ARE EXPECTED TO GRADUALLY BECOME MORE FAVORABLE FOR A TROPICAL DEPRESSION TO DEVELOP DURING THE NEXT DAY OR SO. SCATTERED MODERATE/ STRONG CONVECTION IS FROM 19N-23N BETWEEN 66W-70W AND FROM 20N-23N BETWEEN 63W-66W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS REMAIN OVER THE NE CARIBBEAN AND THE SW ATLC FROM 16N-27N BETWEEN 62W-70W INCLUDING ISLANDS FROM THE LEEWARDS TO HISPANIOLA. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 41W S OF 18N MOVING W 10-15 KT. BROAD INVERTED-V CURVATURE IS OBSERVED ON SATELLITE IMAGERY WITH SCATTERED MODERATE/STRONG CONVECTION FROM 12N-16N BETWEEN 34W AND THE WAVE AXIS. TROPICAL WAVE IS ALONG 65W/66W S OF 18N MOVING W 10-15 KT. WAVE IS BENEATH AN UPPER RIDGE DRAWING TROPICAL MOISTURE N AS HIGH CLOUDS MASKING ANY SATELLITE SIGNATURE WITH NO ASSOCIATED SHOWERS/CONVECTION. TROPICAL WAVE IS ALONG 79W/80W S OF 16N MOVING W 10-15 KT. WAVE IS EMBEDDED WITHIN SOMEWHAT DRY STABLE AIR LIMITING CLOUD FORMATION AND SHOWERS. TROPICAL WAVE IS ALONG 92W S OF 20N MOVING W 10-15 KT. WAVE IS ALONG THE W COAST OF THE YUCATAN PENINSULA AND COMBINED WITH THE UPPER LEVEL RIDGE IS PRODUCING NUMEROUS STRONG CONVECTION INLAND AND WITHIN 60 NM ALONG THE COAST OF S MEXICO IN THE BAY OF CAMPECHE BETWEEN 92W-96W AS WELL AS SCATTERED MODERATE/STRONG CONVECTION S OF 21N E OF 92W TO INLAND OVER THE YUCATAN. ...THE ITCZ... ITCZ AXIS IS ANALYZED ALONG 12N16W 7N27W 10N40W 8N48W 10N62W. NUMEROUS STRONG CONVECTION IS FROM 13N-15N E OF 18W TO INLAND OVER SENEGAL AFRICA. SCATTERED MODERATE/STRONG CONVECTION IS WITHIN 60/75 NM OF LINE FROM 10N16W TO INLAND OVER SIERRA LEONE NEAR 9N13W. ...DISCUSSION... GULF OF MEXICO... A DEEP LAYERED TROUGH THAT COVERS THE SE US COAST AND THE W ATLC REMAINS OVER THE FLORIDA PENINSULA BRINGING DRY STABLE AIR TO THE FAE E GULF WATERS AND THE FLORIDA PENINSULA THROUGH THE FLORIDA STRAITS. A BROAD UPPER RIDGE COVERS THE GULF ANCHORED OVER CENTRAL MEXICO EXTENDING AN AXIS E TO THE FLORIDA STRAITS NEAR 24N81W. UPPER DIFFLUENCE COUPLED WITH THE TROPICAL WAVE IS GENERATING THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVE ALONG 92W AS WELL AS SCATTERED SHOWERS/ISOLATED THUNDERSTORMS S OF 26NW OF 88W TO INLAND OVER MEXICO. CARIBBEAN SEA... THE UPPER RIDGE FROM THE GULF OF MEXICO COVERS THE W CARIBBEAN W OF 81W WITH THE DEEP LAYERED TROUGH OVER THE W ATLC EXTENDING ACROSS CUBA TO 20N. A SHEAR AXIS EXTENDS FROM NEAR 20N78W SSW TO NEAR THE NICARAGUA/COSTA RICA BORDER. UPPER LEVEL DIFFLUENCE IS GENERATING ISOLATED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS OVER THE GULF OF HONDURAS S OF 20N W OF 85W. AN UPPER RIDGE IS ANCHORED OVER THE E CARIBBEAN NEAR 15N65W AND COVERS THE REMAINDER OF THE AREA AND DRAWING TROPICAL MOISTURE N ACROSS THE CENTRAL CARIBBEAN ENHANCING THE ACTIVITY ASSOCIATED WITH THE LOW IN THE SPECIAL FEATURES ABOVE. ATLANTIC OCEAN... TOW MAIN CONCERNS FOR THE W ATLC TONIGHT ARE THE ACTIVITY DESCRIBED IN THE SPECIAL FEATURES ABOVE. THE DEEP LAYERED TROUGH ASSOCIATED WITH THE FIRST SPECIAL FEATURE COVERS W ATLC W OF 70W ACROSS CUBA INTO THE NW CARIBBEAN WITH THE ASSOCIATED COLD FRONT ENTERING THE REGION NEAR 32N71W TO OVER THE N BAHAMA ISLANDS NEAR 24N78W GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS N OF 30N BETWEEN 67W AND THE FRONT AND ISOLATED SHOWERS WITH POSSIBLE ISOLATED THUNDERSTORMS FROM 23N-27N W OF 76W TO OVER S FLORIDA. STRONG WINDS ARE W OF THE FRONT ALONG THE N PORTION OF THE AREA REACH TO NEAR GALE FORCE WITH A RECENT SHIP REPORTING 50 KT JUST TO THE W OF THE STORM CENTER NEAR 32N75W. AN UPPER RIDGE IS OVER THE SECOND LOW PRESSURE SYSTEM IN THE SPECIAL FEATURES EXTENDING FROM THE CARIBBEAN ACROSS PUERTO RICO TO 27N62W COVERING THE REMAINDER OF THE W ATLC. WEAKENING CUT-OFF UPPER LOW REMAINS IN THE CENTRAL ATLC NEAR 27N51W GENERATING ISOLATED SHOWERS FROM 24N-30N BETWEEN 45W-52W. A DEEP LAYERED LOW IS IN THE E ATLC N OF 18N E OF 33W TO OVER NW AFRICA WITH THE UPPER LOW NEAR 32N22W AND THE 1013 MB SURFACE LOW NEAR 31N23W AND A SURFACE TROUGH EXTENDING SSW TO 21N29W GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 29N-34N BETWEEN 18W-22W. THE TYPICAL E/W UPPER RIDGE THAT EXTENDS FROM AFRICA TO 40W ALONG 12N CONTINUES TO BE SUPPRESSED TO THE S DUE TO THE UPPER TROUGH MENTIONED ABOVE. THE SURFACE RIDGE CONTINUES TO WEAKEN COVERING THE ATLC N OF 20N BETWEEN 30W-55W. $$ WALLACE