000 AXNT20 KNHC 251205 AAA TWDAT TROPICAL WEATHER DISCUSSION...UPDATED NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0945 UTC. ...SPECIAL FEATURES... A WELL-DEFINED SURFACE LOW PRESSURE SYSTEM CENTERED ABOUT 170 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 FROM SOUTH CAROLINA TO VIRGINIA. A BROAD AREA OF LOW PRESSURE IS ANALYZED AS A 1005 MB LOW IS JUST TO THE NE OF THE TURKS AND CAICOS NEAR 22N69W MOVING NORTHWARD NEAR 10 KT. THIS SYSTEM IS NOT WELL ORGANIZED...WITH THE LOW-LEVEL CIRCULATION CENTER DISPLACED TO THE WEST OF THE SHOWER AND THUNDERSTORM ACTIVITY. UPPER-LEVEL WINDS COULD BRIEFLY BECOME MORE CONDUCIVE FOR DEVELOPMENT AND THIS SYSTEM COULD BECOME A TROPICAL CYCLONE OVER THE NEXT DAY OR SO. THIS SYSTEM IS BEING SHEARED BY THE DEEP LAYERED TROUGH TO THE W WITH SCATTERED MODERATE/STRONG CONVECTION FROM 20N-24N BETWEEN 65W-68W AND SCATTERED SHOWERS/ISOLATED THUNDERSTORMS OVER THE SW ATLC FROM 18N-26N BETWEEN 61W-70W INCLUDING ISLANDS THE VIRGIN ISLANDS... PUERTO RICO AND HISPANIOLA. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 42W/43W S OF 17N MOVING W 10-15 KT. BROAD INVERTED-V CURVATURE IS OBSERVED ON SATELLITE IMAGERY WITH SCATTERED MODERATE/ISOLATED STRONG CONVECTION E OF THE WAVE FROM 13N-16N BETWEEN 34W-40W. TROPICAL WAVE IS ALONG 65W/66W S OF 16N MOVING W 10-15 KT. WAVE POSITION IS BASED ON CONTINUITY AS IT IS HAS NO SATELLITE SIGNATURE AND NO ASSOCIATED SHOWERS/CONVECTION. TROPICAL WAVE IS ALONG 80W/81W 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/93W S OF 20N MOVING W 10-15 KT. WAVE IS IN THE BAY OF CAMPECHE ACROSS S MEXICO INTO THE E PACIFIC REGION AND COMBINED WITH THE UPPER LEVEL RIDGE IS PRODUCING SCATTERED MODERATE/STRONG CONVECTION INLAND AND WITHIN 90 NM ALONG THE COAST OF THE YUCATAN AND S MEXICO BETWEEN 90W-95W. ...THE ITCZ... ITCZ AXIS IS ANALYZED ALONG 12N13W 7N24W 10N40W 7N54W 7N60W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 4N-11N BETWEEN 10W-21W AND TO THE COAST OF SW AFRICA. ...DISCUSSION... GULF OF MEXICO... A DEEP LAYERED TROUGH THAT COVERS THE SE US COAST AND THE W ATLC IS NO LONGER IN THE GULF OF MEXICO. HOWEVER...THE SOMEWHAT DRY STABLE UPPER AIR REMAINS OVER THE FLORIDA PENINSULA. A BROAD UPPER RIDGE DOMINATES THE GULF ANCHORED OVER CENTRAL MEXICO EXTENDING AN AXIS E TO W CUBA COVERING THE NW CARIBBEAN. UPPER DIFFLUENCE COUPLED WITH THE TROPICAL WAVE IS GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS S OF 25N W OF 87W TO INLAND OVER MEXICO AND THE YUCATAN PENINSULA AS WELL AS ENHANCING THE ACTIVITY ASSOCIATED WITH THE TROPICAL WAVE ALONG 92W/93W LEAVING THE N GULF RATHER CLEAR THIS MORNING. CARIBBEAN SEA... THE UPPER RIDGE OVER THE GULF OF MEXICO COVERS THE NW CARIBBEAN N OF 11N W OF 79W WITH THE DEEP LAYERED TROUGH OVER THE W ATLC EXTENDING ACROSS E CUBA TO 16N BETWEEN 71W-79W. UPPER LEVEL DIFFLUENCE CONTINUES TO GENERATING ISOLATED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS OVER THE GULF OF HONDURAS S OF 20N W OF 83W. AN UPPER RIDGE IS ANCHORED OVER THE E CARIBBEAN NEAR 16N65W AND COVERS THE REMAINDER OF THE AREA AND DRAWING TROPICAL MOISTURE N ACROSS THE CENTRAL CARIBBEAN. HOWEVER...THE CARIBBEAN IS BEGINNING TO CLEAR THIS MORNING AS THE ACTIVITY ASSOCIATED WITH THE LOW IN THE SPECIAL FEATURES ABOVE IS MOVING AWAY FROM THE N CARIBBEAN ISLANDS. ATLANTIC OCEAN... TWO 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 TO THE FLORIDA PENINSULA ACROSS CUBA INTO THE NW CARIBBEAN WITH THE ASSOCIATED COLD FRONT ENTERING THE REGION NEAR 32N71W TO 28N73W WHERE IT PULLS UP STATIONARY TO OVER THE N BAHAMA ISLANDS NEAR 24N79W GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS N OF 29N BETWEEN 68W AND THE FRONT. A SURFACE TROUGH EXTENDS FROM THE STORM CENTER NEAR 32N76W ALONG 28N76W TO THE FLORIDA COAST JUST N OF FORT LAUDERDALE. ISOLATED SHOWERS WITH POSSIBLE ISOLATED THUNDERSTORMS ARE FROM 23N-27N W OF 76W TO OVER S FLORIDA. STRONG WINDS ARE W OF THE SURFACE TROUGH ALONG THE N PORTION OF THE AREA REACHING TO NEAR GALE FORCE. AN UPPER RIDGE IS TO THE E OF THE SECOND LOW PRESSURE SYSTEM IN THE SPECIAL FEATURES EXTENDING FROM THE CARIBBEAN ACROSS THE VIRGIN ISLANDS TO 29N62W COVERING THE REMAINDER OF THE W ATLC. WEAKENING CUT-OFF UPPER LOW REMAINS IN THE CENTRAL ATLC NEAR 27N50W BUT IS STILL GENERATING ISOLATED SHOWERS FROM 23N-30N BETWEEN 46W-52W. A DEEP LAYERED LOW IS IN THE E ATLC N OF 22N E OF 32W TO OVER NW AFRICA WITH THE UPPER LOW NEAR 32N23W AND THE 1013 MB SURFACE LOW NEAR 31N23W AND A SURFACE TROUGH EXTENDING SSW TO 24N28W GENERATING ISOLATED SHOWERS FROM 29N-33N BETWEEN 19W-23W. THE TYPICAL E/W UPPER RIDGE THAT EXTENDS FROM AFRICA TO NEAR 40W ALONG 13N CONTINUES TO BE SUPPRESSED TO THE S DUE TO THE UPPER TROUGH MENTIONED ABOVE. A WEAK SURFACE RIDGE REMAINS OVER THE CENTRAL ATLC N OF 25N BETWEEN 30W-55W WITH A 1019 MB HIGH NEAR 31N38W. $$ WALLACE/AC