000 AXNT20 KNHC 131051 AAA TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT WED SEP 13 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 1030 UTC. ...SPECIAL FEATURES... THE CENTER OF HURRICANE GORDON AT 13/0900 UTC WAS NEAR 25.1N 57.9W OR ABOUT 605 NM/975 KM NORTH-NORTHEAST OF THE LEEWARD ISLANDS. GORDON IS MOVING NORTHWARD AT 8 KT AND THIS MOTION IS EXPECTED TO CONTINUE FOR THE NEXT 24 HOURS. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 987 MB. THE MAXIMUM SUSTAINED WIND SPEEDS ARE 65 KT WITH GUSTS TO 80 KT....THIS MAKES GORDON A CATEGORY ONE HURRICANE ON THE SAFFIR-SIMPSON SCALE. PLEASE READ THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC AND THE PUBLIC ADVISORY MIATCPAT2/WTNT32 KNHC FOR MORE DETAILS. A RAGGED EYE...ABOUT 40-50 NM IN DIAMETER...HAS BECOME EVIDENT ON INFRARED SATELLITE IMAGERY DURING THE OVERNIGHT HOURS. CONVECTIVE BANDS AND AN EYEWALL FEATURE HAS ALSO BECOME MORE APPARENT WITH THE STORM LOOKING INCREASINGLY MORE SYMMETRIC. IN ADDITION...THE OUTFLOW LAYER HAS BECOME IMPRESSIVE AND IS ONLY SLIGHTLY RESTRICTED TO THE E/SE. GORDON REMAINS A VERY COMPACT HURRICANE WITH ITS RAIN FIELD WITHIN 150 NM OF THE CENTER. HURRICANE FORCE WINDS EXTEND OUTWARD WITHIN 20 NM IN THE NE QUADRANT AND TROPICAL STORM FORCE WINDS WITHIN 75 NM. SOME ADDITIONAL STRENGTHENING IS FORECAST DURING THE NEXT 24 HOURS. GORDON IS ALREADY ON THE NORTHWESTERN PERIPHERY OF THE SUBTROPICAL RIDGE AND EXPECTED TO REMAIN IN THE OPEN ATLANTIC. THE CENTER OF TROPICAL DEPRESSION EIGHT AT 13/0900 UTC WAS NEAR 11.9N 26.7W OR ABOUT 255 NM/405 KM SOUTHWEST OF THE SOUTHERNMOST CAPE VERDE ISLANDS. T.D. EIGHT IS MOVING WEST AT 14 KT AND THIS GENERAL MOTION IS EXPECTED TO CONTINUE FOR THE NEXT 24 HOURS WITH A GRADUAL INCREASE IN FORWARD SPEED. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1007 MB. THE MAXIMUM SUSTAINED WINDS REMAIN NEAR 30 KT WITH GUSTS TO 40 KT. PLEASE READ THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC AND THE PUBLIC ADVISORY MIATCPAT3/WTNT33 KNHC FOR MORE DETAILS. UNLIKE GORDON...T.D. EIGHT IS A VERY BROAD ELONGATED GYRE WITH ITS CYCLONIC FLOW ENVELOPE COVERING A REGION OF SEVERAL HUNDRED NM WIDE. MULTIPLE LOW LEVEL SWIRLS ARE EVIDENT ON EARLY MORNING VIS IMAGES. CONVECTION IS LIMITED NEAR THE CENTER OF THE BROAD CIRCULATION...HOWEVER THERE ARE AREAS OF MODERATE TO STRONG CONVECTION TO THE NORTH AND WEST OF THE CENTER WITH THE COLDEST CLOUD TOPS NEAR -85C TO THE NW OF THE CENTER. A FAIR AMOUNT OF SAHARAN DUST LIES TO THE NORTH OF THE CYCLONE. DUE TO THIS INHIBITING FACTOR AND BECAUSE T.D. EIGHT IS LARGE/BROAD AND WILL TAKE SOME TIME TO CONSOLIDATE...ONLY SLOW STRENGTHENING IS FORECAST OVER THE NEXT 24 HOURS. ...TROPICAL WAVES... A TROPICAL WAVE IS ALONG 41W SOUTH OF 15N MOVING WEST 10 TO 15 KT. THERE IS SOME SLIGHT LOW TO MID LEVEL CYCLONIC TURNING IN THE SMALL AREA OF SCATTERED SHOWERS AND TSTMS JUST AHEAD OF THE ANALYZED AXIS FROM 6N-8N BETWEEN 42W-45W. TWO SHIP OBSERVATION HAVE BEEN VERY HELPFUL IN LOCATING THE AXIS AS THEY HAVE INDICATED A WEAK WAVE PASSAGE. OVERALL...THIS WAVE IS POORLY STRUCTURED AND IS NOT IN A CONDUCIVE UPPER LEVEL ENVIRONMENT FOR SIGNIFICANT DEVELOPMENT DUE TO THE CLOSE PROXIMITY OF T.D. EIGHT. A TROPICAL WAVE IS ALONG 50W SOUTH OF 14N MOVING WEST NEAR 10 KT OVER THE LAST 24 HOURS. THIS WAVE HAS BEEN CHALLENGING TO TRACK AS IT CONTINUES TO BE A LOW AMPLITUDE FEATURE. THIS FEATURE IS BARELY IDENTIFIABLE ON SATELLITE IMAGERY...SURFACE OBS AND QUIKSCAT DATA. SCATTERED SHOWERS AND TSTMS ARE NEAR THE BASE OF THE ANALYZED AXIS FROM 4N-6N BETWEEN 47W-51W. A WELL-DEFINED HIGH AMPLITUDE TROPICAL WAVE IS ALONG 58W SOUTH OF 18N MOVING WEST 10 TO 15 KT. UNLIKE THE TWO WAVES TO ITS EAST...THIS ONE IS VERY EASY TO FIND WITH A CLASSIC INVERTED V-SHAPE SEEN ON SATELLITE IMAGES. SCATTERED MODERATE CONVECTION IS INCREASING IN INTENSITY AND COVERAGE WITHIN 300 NM OF THE WAVE AXIS. SOME OF THE DEEPEST MOISTURE IS OVER THE WINDWARD ISLANDS. A TROPICAL WAVE IS IN THE CARIBBEAN ALONG 69W SOUTH OF 16N MOVING WEST NEAR 15 KT. THIS WAVE IS WEAK WITH ONLY A SLIGHT HINT OF LOW-MID CYCLONIC TURNING NEAR THE WAVE AXIS. CONVECTION IS MOSTLY INLAND OVER SOUTH AMERICA ASSOCIATED WITH THE ITCZ. ...THE ITCZ... ITCZ IS CENTERED ALONG 15N17W 9N28W 7N40W 8N49W 13N59W 11N67W. BESIDES FOR THE CONVECTION ASSOCIATED WITH T.D. EIGHT AND THE TROPICAL WAVES...SCATTERED MODERATE CONVECTION IS OVER WRN COLOMBIA FROM 3N-11N BETWEEN 71W-78W. ...DISCUSSION... THE GULF OF MEXICO... A 1010 MB LOW HAS FORMED JUST SOUTH OF THE FLORIDA PANHANDLE NEAR 30N86W. A WARM FRONT EXTENDS SOUTHEASTWARD FROM THE LOW ALONG 29N85W 26N83W. THIS FRONTAL BOUNDARY IS ACTUALLY FAIRLY WELL DEFINED IN SFC OBS AND ON DOPPLER RADAR WHICH SHOWS THE LEADING EDGE OF A LINE OF NUMEROUS SHOWERS AND TSTMS MOVING ACROSS THE W COAST OF FLORIDA N OF 26N. SFC WINDS ARE GENERALLY NEAR 10 KT FROM THE SW WITH LIGHT E-SE WINDS EAST OF THE BOUNDARY. IN THE UPPER LEVELS...AN ELONGATED MID TO UPPER LEVEL HIGH IS CENTERED OVER ERN WITH RIDGING EXTENDING TO NEAR 87W ALONG 26N/27N. ANOTHER SMALLER MID/UPPER HIGH IS OVER THE FAR SE GULF. UPPER DIFFLUENT AIR BETWEEN THESE FEATURES AND THE WESTERLY FLOW OVER THE SRN UNITED STATES IS GENERATING A FAIR AMOUNT OF UPPER LEVEL MOISTURE WITH EMBEDDED SCATTERED SHOWERS IN THE NW GULF. SCATTERED MODERATE CONVECTION HAS FIRED IN THE BAY OF CAMPECHE FROM 17N-22N BETWEEN 91W-95W ASSOCIATED WITH UPPER DIFFLUENCE BETWEEN THE UPPER HIGHS AND AN UPPER LOW NEAR 20N94W. THE WEATHER PATTERN WILL BE CHANGING AS A COLD FRONT PRESSES INTO N GULF LATE WED. GFS INDICATES THAT THIS FRONT WILL LIKELY DIG TO NEAR 25N BEFORE BECOMING STATIONARY AND LIFTING OUT. THE CARIBBEAN SEA... CONDITIONS REMAIN QUIET ACROSS THE CARIBBEAN TONIGHT WITH AN ABUNDANT AMOUNT OF DRY STABLE UPPER LEVEL AIR NOTED ON WATER VAPOR IMAGES W OF 76W. A FEW LEFT OVER PATCHES OF CLOUDS AND ISOLATED SHOWERS FROM EARLIER TSTMS OVER CUBA ARE MOVING SOUTHWARD DRIVEN BY NLY UPPER LEVEL FLOW BETWEEN AN ANTICYCLONE OVER THE YUCATAN PENINSULA AND A LARGE UPPER LEVEL LOW IN THE E CARIBBEAN. OTHERWISE...MID-HIGH LEVEL CLOUDINESS AND MAYBE SOME ISOLATED SHOWERS LIE BETWEEN 64W AND 76W MOVING CYCLONICALLY AROUND THE UPPER LOW. THE DEEPEST MOISTURE IN THE REGION IS IN THE EXTREME SE CORNER WHERE NUMEROUS SHOWERS AND TSTMS ARE OVER THE WINDWARD ISLANDS ASSOCIATED WITH A WELL DEFINED TROPICAL WAVE ALONG 58W. THIS MOISTURE WILL CONTINUE TO SPREAD EAST-NORTHEASTWARD ACROSS THE EASTERN CARIBBEAN TODAY. LIGHT TO MODERATE TRADES NEAR 10-20 KT ARE OBSERVED IN THE REGION...THESE WINDS ARE LIKELY TO REMAIN THAT WAY OVER THE NEXT COUPLE OF DAYS. THE ATLANTIC OCEAN... A LARGE DEEP UPPER LEVEL TROUGH COVERS THE WRN ATLC AND THE EASTERN CARIBBEAN. A TAIL SFC TROUGH/COLD FRONT EXTENDS FROM THE EXTRATROPICAL STORM FLORENCE AND ENTERS THE AREA ALONG 32N60W 28N67W 24N74W TO THE FLORIDA STRAITS. THIS SFC TROUGH IS WELL DEFINED IN OBSERVATIONS AND ON SATELLITE IMAGERY. A WEAK LOW PRES AREA NOW APPEARS THAT IT MIGHT BE FORMING ALONG THE BOUNDARY NEAR 27N70W. SCATTERED SHOWERS ARE WITHIN 120 NM OF THE BOUNDARY. A LARGE FETCH OF N/NE WINDS PERSISTS OFF THE MID ATLC AND NE US COAST BETWEEN EXTRATROPICAL FLORENCE AND THE 1023 MB HIGH BUILDING INTO NEW ENGLAND. ASSOCIATED MODERATE TO STRONG NE SWELL WILL CONTINUE TO PRODUCE DANGEROUS SURF CONDITIONS AT BEACHES EXPOSED TO NE SWELL OVER THE NEXT COUPLE OF DAYS...BEFORE SUBSIDING THROUGH THE WEEKEND. SEE STATEMENTS FROM LOCAL WEATHER SERVICE OFFICES FOR MORE DETAILS. HURRICANE GORDON IS MOVING NORTHWARD AROUND THE NW PERIPHERY OF A WEAK SUB-TROPICAL RIDGE CENTERED NEAR 19N54W. THE MID TO UPPER LEVEL RIDGING IN THE REGION HAS BEEN SIGNIFICANTLY ERODED EARLIER BY FLORENCE AND NOW BY GORDON AND A LARGE UPPER LEVEL LOW CENTERED NEAR 31N46W...WHICH IS MOVING NORTHWESTWARD. SCATTERED SHOWERS ARE SPIRALING AROUND THE LOW FROM 27N-35N BETWEEN 40W-48W. BECAUSE OF THE LARGE BREAK IN THE SUBTROPICAL RIDGE...GORDON IS IN RECURVATURE AND IS EXPECTED TO STAY IN THE OPEN ATLANTIC. FARTHER EAST...A STRENGTHENING MID TO UPPER HIGH IS OVER THE ERN ATLC OFF THE COAST OF AFRICA NEAR 25N28W. THIS IS THE PRIMARY STEERING COMPONENT FOR TROPICAL DEPRESSION EIGHT KEEPING THE SYSTEM ON A GENERAL WESTWARD TRACK OVER THE NEXT COUPLE OF DAYS. ACCORDING TO THE CIMSS SAL TRACKING PRODUCT AND THE MILKY APPEARANCE ON EARLY MORNING VIS IMAGES...A WIDESPREAD AREA OF SAHARAN DUST HAS SPREAD TO NEAR 45W. THIS DUST IS LIKELY TO BE AN INHIBITING FACTOR FOR GORDON. AT THE SFC...A 1026 MB HIGH IS CENTERED SW OF THE AZORES NEAR 36N35W WITH RIDGING DOMINATING THE E ATLC. $$ CANGIALOSI