000 AXNT20 KNHC 121058 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT TUE SEP 12 2006 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN SECTIONS OF SOUTH AMERICA...AND THE ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR... AND METEOROLOGICAL ANALYSIS. BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1045 UTC. ...SPECIAL FEATURES... THE CENTER OF HURRICANE FLORENCE AT 12/0900 UTC WAS LOCATED NEAR 37.2N 62.4W OR ABOUT 365 MILES...585 KM...NORTH-NORTHEAST OF BERMUDA. FLORENCE IS MOVING TOWARD THE NORTH-NORTHEAST NEAR 17 KT...32 KM/HR. THIS GENERAL MOTION IS EXPECTED TO CONTINUE OVER THE NEXT 24 HOURS. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 980 MB. MAXIMUM SUSTAINED WINDS ARE NEAR 65 KT WITH GUSTS TO 80 KT. FLORENCE IS A CATEGORY ONE HURRICANE ON THE SAFFIR-SIMPSON SCALE. PLEASE READ THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC OR THE PUBLIC ADVISORY UNDER MIATCPAT1/WTNT31 KNHC FOR MORE DETAILS. HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 70 MILES...110 KM...FROM THE CENTER...AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 415 MILES...665 KM. FLORENCE HAS BECOME INCREASINGLY LESS TROPICAL-LOOKING ON SATELLITE IMAGERY WITH MOST OF THE CONVECTION DISPLACED TO THE N OF THE CENTER WITH DRY MID-LEVEL AIR ENTRAINING INTO THE SOUTHERN HALF OF THE CIRCULATION. FLORENCE IS EXPECTED TO CONTINUE TO SLOWLY LOSE ITS TROPICAL CHARACTERISTICS AND BECOME A STRONG EXTRATROPICAL SYSTEM IN ABOUT 24 HOURS. THE CENTER OF TROPICAL STORM GORDON AT 12/0900 UTC IS NEAR 22.6N 58.3W OR ABOUT 445 MILES/715 KM NORTH-NORTHEAST OF THE LEEWARD ISLANDS. GORDON IS MOVING TOWARD THE NORTHWEST NEAR 7 KT...13 KM/HR...AND A TURN TO THE NORTH-NORTHWEST IS EXPECTED DURING THE NEXT 24 HOURS. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1000 MB. MAXIMUM SUSTAINED WINDS ARE NEAR 50 KT WITH GUSTS TO 60 KT. TROPICAL STORM FORCE WINDS EXTEND OUTWARD 75 NM IN THE NE AND 25 NM IN THE SE QUADRANT. PLEASE READ THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC AND THE PUBLIC ADVISORY MIATCPAT2/WTNT32 KNHC FOR MORE DETAILS. DURING THE OVERNIGHT HOURS...A BALL OF CONVECTION WAS INCREASING AND CONSOLIDATING NEAR THE CENTER. OVER THE PAST FEW HOURS THE DEEPEST CONVECTION HAS WEAKENING BUT THE STRUCTURE OF THE BANDS REMAIN WELL DEFINED. IN ADDITION...THE OUTFLOW LAYER HAS IMPROVED ESPECIALLY TO THE WEST. THE TROPICAL CYCLONE WILL LIKELY SPEND ITS LIFE OVER WATER AS IT IS TRACKING TOWARDS A PROFOUND WEAKNESS LEFT FROM FLORENCE. SOME STRENGTHENING IS FORECAST AND GORDON COULD BECOME A HURRICANE IN A DAY OR SO. A STRONG TROPICAL WAVE IS LOCATED OFF THE COAST OF AFRICA ALONG 20W/21W S OF 19N. A 1008 MB LOW PRES SYSTEM IS ALONG THE WAVE NEAR 13N. THIS SYSTEM IS FAIRLY LARGE WITH ITS BROAD CYCLONIC ROTATION COVERING AN AREA OF AT LEAST A FEW HUNDRED NM. SHOWER ACTIVITY WAS GENERALLY ON THE DECREASE LAST EVENING...HOWEVER SCATTERED MODERATE TO STRONG CONVECTION HAS FIRED AND EXPANDED SIGNIFICANTLY OVER THE LAST SEVERAL HOURS TO THE SOUTH AND WEST OF THE ANALYZED SFC LOW FROM 9N-15N BETWEEN 19W-25W. A QUIKSCAT PASS NEAR 0700 UTC SHOWED GUSTY WINDS S OF THE LOW. IT WAS ALSO HELPFUL IN LOCATING THE LOW CENTER WHICH WAS ADJUSTED TO THE NW FROM THE 00 UTC MAP. THIS SYSTEM IS SHOWING SIGNS OF ORGANIZATION AND HAS THE POTENTIAL TO BECOME A TROPICAL DEPRESSION OVER THE NEXT DAY OR SO AS IT MOVES WESTWARD 10 TO 15 KT. ...TROPICAL WAVES... A TROPICAL WAS ADJUSTED SLIGHTLY AHEAD ALONG 36W S OF 18N MOVING W 10 TO 15 KT. THIS ADJUSTMENT WAS BASED ON SATELLITE IMAGERY AND SFC OBSERVATIONS THAT SHOWED A FAIR AMOUNT OF LOW-MID LEVEL CYCLONIC TURNING ABOUT THE AXIS NEAR 7N. ONLY ISOLATED SHOWERS ARE NEAR THE WAVE AXIS. METEOSAT8 HOVMOLLER DIAGRAMS WHERE VERY HELPFUL IN THE PLACEMENT OF THE AXIS. A TROPICAL WAVE IS ALONG 46W S OF 16N MOVING W NEAR 10 KT. THIS WAVE IS LOW AMPLITUDE AND DIFFICULT TO LOCATE WITH HIGH LEVEL CLOUDS STREAMING ACROSS THIS FEATURE IN A PRONOUNCED SWLY FLOW MASKING ANY LOW-MID LEVEL SIGNATURE. SCATTERED SHOWERS AND TSTMS HAVE INCREASED OVER THE PAST FEW HOURS FROM 12N-15N BETWEEN 43W-49W. A TROPICAL WAVE HAS MOVED INTO THE E CARIBBEAN ALONG 62W S OF 16N MOVING W NEAR 15 KT. THIS WAVE SPLIT SUNDAY EVENING WITH THE NRN EXTENSION NOW T.S. GORDON. THE WAVE IS LOW AMPLITUDE AND BARELY DISCERNIBLE ON NIGHT CHANNEL VIS IMAGES. ONLY ISOLATED SHOWERS ARE IN THE VICINITY OF THE AXIS. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 10N22W 9N34W 9N44W 10N60W. BESIDES FOR THE CONVECTION DISCUSSED IN THE TROPICAL WAVES SECTION...SCATTERED MODERATE CONVECTION IS INLAND OVER SOUTH AMERICA S OF 8N BETWEEN 58W-70W. ...DISCUSSION... THE GULF OF MEXICO... THE WEATHER HAS CHANGED LITTLE ACROSS THE GULF OVER THE PAST FEW DAYS. AN UPPER LEVEL HIGH IS NEARLY STATIONARY OVER CENTRAL MEXICO NEAR 24N103W. THIS ANTICYCLONE HAS RIDGING THAT EXTENDS E ALONG 26N/27N. UPPER DIFFLUENT AIR BETWEEN THE FLOW AROUND THIS HIGH AND THE WESTERLIES OVER THE SRN U.S. IS HELPING TO SUPPORT ISOLATED SHOWERS AND TSTMS BETWEEN 25N-30N ACROSS THE GULF. THE MOST PERSISTENT ACTIVITY IS IN THE E GULF FROM 26N-28N BETWEEN 83W-86W BUT EVEN THIS AREA HAS DIMINISHED THIS MORNING. SCATTERED SHOWERS AND TSTMS HAVE DEVELOPED OVER NRN MEXICO/S TEXAS FROM 25N-28N BETWEEN 97W-101W WHERE UPPER DIFFLUENCE IS SLIGHTLY STRONGER. AN UPPER LEVEL LOW IS MOVING W IN THE BAY OF CAMPECHE WITH SCATTERED SHOWERS AND TSTMS ASSOCIATED WITH IT...MOST ORGANIZED OVER THE LANDMASS OF S MEXICO. AT THE SURFACE...HIGH PRES RIDGING EXTENDS FROM SE CANADA AND THE NE U.S. SOUTHWESTWARD INTO THE ERN GULF. E/SE WINDS ARE FAIRLY LIGHT ON THE SW PERIPHERY OF THE SFC RIDGE. THIS RIDGE WILL PUSH E AS A COLD FRONT ENTERS THE N GULF ON WED. SIMILAR WEATHER IS EXPECTED THRU TONIGHT AS THE UPPER LEVEL PATTERN IS NOT EXPECTED TO CHANGE MUCH. THE CARIBBEAN SEA... QUIET WEATHER CONTINUES IN THE CARIBBEAN TONIGHT WITH PLENTY OF DRY STABLE UPPER LEVEL AIR NOTED ON WATER VAPOR IMAGES BETWEEN 75W AND 85W. THIS REGION LIES IN AN AREA OF UPPER LEVEL RIDGING WITH AN ANTICYCLONE CENTERED NEAR 20N85W. E OF 75W...BROKEN DEBRIS MOISTURE FROM THE ATLC TROPICAL CYCLONES HAS PUSHED SOUTHWARD BETWEEN AN UPPER LOW JUST N OF THE LEEWARD ISLANDS AND THE UPPER HIGH IN THE NW CARIBBEAN. HOWEVER...DEEP MOISTURE IS VERY LIMITED WITH ONLY ISOLATED SHOWERS FOUND IN THE HIGH LEVEL MOISTURE PLUME. THE ONLY CONVECTION NOTED IN THE REGION IS IN THE SW CARIBBEAN S OF 12N W OF 75W...HIGHLY CONTRIBUTED TO THE ITCZ. AT THE SFC...TRADE WINDS APPEAR TO BE MOSTLY IN THE 10 TO 20 KT RANGE WITH LITTLE CHANGE IN THESE WINDS EXPECTED THRU MID-WEEK. GFS SLOWLY SHIFTS THE DRY AIR WEST OVER THE NEXT FEW DAYS WITH SOME INCREASE IN TROPICAL MOISTURE ACROSS THE LESSER ANTILLES. THE ATLANTIC OCEAN.. HURRICANE FLORENCE HAS MOVED N OF THE AREA BUT HAS HELPED TO PUSH A SURGE OF N/NE WINDS AND COOLER/DRIER AIR SOUTHWARD OFF THE EAST COAST...AS THE STORM INTERACTS WITH A STRONG 1031 MB HIGH OVER SOUTHEASTERN CANADA. A COLD FRONT HAS BEEN ADDED TO THE 00 UTC ANALYSIS IN ASSOCIATION WITH THIS SURGE OF AIR FROM THE NORTH. AN EARLIER QUIKSCAT PASS SHOWS THIS SURGE NICELY WITH WINDS IN EXCESS OF 20 KT BEHIND THE SURGE AND 10-15 KT TO THE S. THIS LARGE FETCH OF NE WINDS WILL CONTINUE TO GENERATE A MODERATE TO STRONG NE SWELL FOR THE SW NORTH ATLANTIC THROUGH MIDWEEK...AND DANGEROUS SURF CONDITIONS FOR BEACHES EXPOSED TO NE SWELL. THIS WILL SLOWLY SUBSIDE THROUGH THE SECOND PART OF THE WEEK...SEE STATEMENTS FROM LOCAL WEATHER SERVICE OFFICES FOR MORE INFO. TROPICAL STORM GORDON LIES ABOUT 1000 NM TO THE SE OF THE FLORENCE AND IS TRACKING NW INTO THE PROFOUND WEAKNESS IN THE SUBTROPICAL RIDGE LEFT BEHIND FROM FLORENCE. SCATTERED MODERATE CONVECTION LIES FROM 20N-25N BETWEEN 55W-59W. A WELL-DEFINED UPPER LEVEL LOW IS SPINNING NEAR 29N40W MOVING WESTWARD. THIS UPPER LOW IS ALSO WEAKENING THE SUBTROPICAL RIDGE. ISOLATED TO SCATTERED SHOWERS ARE SPIRALING CYCLONICALLY AROUND THE LOW FROM 27N-34N BETWEEN 36W-45W. AN UPPER HIGH IS MOVING WESTWARD OFF THE AFRICAN COAST WITH A HIGH CENTER NEAR 25N25W AND RIDGING EXTENDING TO 34W. AT THE SFC...A 1026 MB HIGH IS CENTERED JUST S OF THE AZORES WITH RIDGING COVERING THE CENTRAL AND EASTERN SUBTROPICAL ATLC. $$ CANGIALOSI