000 AXNT20 KNHC 020001 TWDAT TROPICAL WEATHER DISCUSSION...AMD NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SUN OCT 01 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...SPECIAL FEATURE... THE CENTER OF HURRICANE ISAAC AT 02/0000 UTC IS NEAR 37.3N 59.6W MOVING NORTH-NORTHEAST NEAR 20 KT. THIS POSITION IS ABOUT 715 MILES/1250 KM SOUTH-SOUTHWEST OF CAPE RACE NEWFOUNDLAND. A TURN TOWARD THE NORTH-NORTHEAST WITH AN INCREASE IN FORWARD SPEED IS EXPECTED DURING THE NEXT 24 HOURS. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 985 MB. THE MAXIMUM SUSTAINED WIND SPEED IS 70 KT WITH GUSTS TO 85 KT. ISAAC IS A CATEGORY ONE HURRICANE ON THE SAFFIR-SIMPSON SCALE. PLEASE READ THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC AND THE PUBLIC ADVISORY UNDER MIATCPAT4/WTNT34 KNHC FOR MORE DETAILS. ISAAC HAS BEGUN RACING NORTHWARD AHEAD OF THE LARGE WRN ATLC TROUGH WHICH HAS LIKELY MADE THE STORM MORE ASYMMETRIC WITH MUCH OF ITS CONVECTION TO THE N OF THE CENTER. CONVECTION HAS INCREASED OVER THE LAST FEW HOURS AND SCATTERED MODERATE COVERS THE AREA WITHIN 240 NM IN THE NRN SEMICIRCLE AND 90 NM IN THE SRN SEMICIRCLE. ISAAC WILL BEGIN TO LOSE TROPICAL CHARACTERISTICS AND IS FORECAST TO BECOME EXTRATROPICAL IN ABOUT 24 HOURS. REGARDLESS OF WHETHER ISAAC IS A TROPICAL OR EXTRATROPICAL CYCLONE WHEN PASSING NEAR OR OVER NEWFOUNDLAND...IT WILL LIKELY PRODUCE SUSTAINED WINDS OF TROPICAL STORM FORCE OVER THAT AREA. ...TROPICAL WAVES/LOWS... A 1010 MB LOW IS ABOUT 500 NM TO THE SOUTHWEST OF THE CAPE VERDE ISLANDS NEAR 9N29W. LOW-MID LEVEL ROTATION IS NOTED ON THE LAST FEW VIS IMAGES AND NIGHT CHANNEL IR. ASSOCIATED SHOWERS AND TSTMS ARE NOT VERY WELL ORGANIZED AND HAVE BEEN DECREASING IN INTENSITY OVER THE PAST FEW HOURS. THE ATMOSPHERIC ENVIRONMENT WILL BECOME VERY HOSTILE NEAR THE SYSTEM AS STRONG SWLY UPPER LEVEL WINDS WILL INCREASE AHEAD OF A DIGGING SHARP MID-UPPER LEVEL TROUGH TO THE NW OF THE SYSTEM. A TROPICAL WAVE IS ALONG 43W S OF 20N MOVING W 15 KT OVER THE PAST 24 HOURS. THIS WAVE IS NOT VERY ACTIVE ONLY PRODUCING A SMALL AREA OF SCATTERED SHOWERS AND ISOLATED TSTMS WITHIN 180 NM EITHER SIDE OF THE WAVE AXIS BETWEEN 12N-14N. DESPITE THE LIMITED SHOWER ACTIVITY...THE WAVE IS NOT VERY DIFFICULT TO TRACK WITH LOW-MID LEVEL CYCLONIC TURNING SEEN ON SATELLITE IMAGERY ABOUT THE AXIS. A TROPICAL WAVE IS IN THE ERN CARIBBEAN ALONG 67W MOVING W 10 TO 15 KT. THIS WAVE REMAINS FAIRLY WEAK WITH SLIGHT CYCLONIC VEERING IN THE WINDS FROM ESE E OF THE AXIS TO E OR ENE W OF THE AXIS. THE INTERACTION BETWEEN THE WAVE AND AN UPPER LOW 150 NM TO ITS WEST IS PRODUCING SCATTERED SHOWERS AND TSTMS WITHIN 90 NM OF THE AXIS. HOWEVER...MOST OF THIS ACTIVITY HAS DISSIPATED OVER LAST HOUR OR TWO. MUCH MORE IMPRESSIVE CONVECTIVE ACTIVITY IS NEAR THE BASE OF THE AXIS OVER S AMERICA HIGHLY CONTRIBUTED TO THE ITCZ. A TROPICAL WAVE IS IN THE CENTRAL CARIBBEAN ALONG 77W/78W S OF 21N MOVING W 10 TO 15 KT. CURRENTLY THIS WAVE HAS LITTLE SIGNATURE IN SFC OBSERVATIONS OR IN SATELLITE IMAGERY. THIS FEATURE IS LOCATED IN AN AREA OF UPPER DIFFLUENCE BETWEEN A LARGE UPPER TROUGH TO ITS NW AND A SMALL UPPER LOW TO ITS EAST...GENERATING SCATTERED SHOWERS AND TSTMS ACROSS JAMAICA...CUBA AND PARTS OF THE NW CARIBBEAN SEA. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 11N15W 8N32W 12N42W 10N63W. BESIDES FOR THE AREA OF LOW PRES SW OF THE CAPE VERDE ISLANDS AND THE TROPICAL WAVE...A SMALL CLUSTER OF MODERATE CONVECTION IS NEARING THE COAST OF W AFRICA E OF 15W FROM 10N-12N. SCATTERED MODERATE EXISTS ACROSS A GOOD PORTION OF S AMERICA AND IN THE SW CARIBBEAN S OF 12N W OF 81W. ...DISCUSSION... THE GULF OF MEXICO... THE LARGE DEEP LAYER TROUGH THAT HAS COVERED THE GULF OVER THE PAST COUPLE OF DAYS HAS PULLED EASTWARD INTO THE WRN ATLC ALLOWING DEEP RIDGING TO BECOME ESTABLISHED. DIFFLUENT AIR BETWEEN THIS RIDGE AND A TROUGH OVER MEXICO IS PRODUCING A CONSIDERABLE AMOUNT OF CLOUDINESS OVER ERN MEXICO SPREADING INTO THE WRN GULF W OF 91W. ONLY ISOLATED SHOWERS ARE EMBEDDED IN THIS MOISTURE PLUME. E OF 91W...VERY DRY STABLE AIR IS IN PLACE KEEPING SKIES FAIR TO MOSTLY CLEAR. THE DRIEST AIR IS IN THE SE GULF E OF 88W S OF 27N. AT THE SFC...A 1020 MB HIGH IS CENTERED 60 NM S OF THE LOUISIANA COASTLINE NEAR 29N92W. SFC WINDS FLOW ANTICYCLONIC AROUND THIS HIGH MOSTLY IN THE 10 TO 15 KT RANGE. THE SFC HIGH IS FORECAST TO MOVE NORTHEAST AND STRENGTHEN CREATING SLIGHTLY STIFFER EASTERLY WINDS WHICH WILL MOISTEN THE ATMOSPHERE EARLY THIS WEEK. THE CARIBBEAN SEA... THE TAIL END OF THE DEEP WRN ATLC TROUGH EXTENDS INTO THE NW CARIBBEAN. DIFFLUENCE BETWEEN THIS TROUGH AND AN UPPER LOW 90 NM S OF HISPANIOLA AND SOME LOW LEVEL CONVERGENCE FROM A NEARBY TROPICAL WAVE IS GENERATING SCATTERED SHOWERS AND TSTMS ACROSS THE NW CARIBBEAN INCLUDING JAMAICA...THE CAYMAN ISLANDS AND CUBA. ISOLATED SHOWERS EXIST ACROSS PUERTO RICO AND THE LESSER ANTILLES INFLUENCED BY THE UPPER LOW MENTIONED AND AN E CARIBBEAN TROPICAL WAVE. THE MOST IMPRESSIVE ACTIVITY IS OVER NRN PORTIONS OF S AMERICA AND THE SW CARIBBEAN HIGHLY CONTRIBUTED TO THE ITCZ...FOR MORE DETAILS REFER TO THAT SECTION. TRADE WINDS ARE NEAR 20 KT ACROSS MOST OF THE CARIBBEAN E OF 78W...WITH SLIGHTER HIGHER WINDS NEAR 25 KT OFF THE N COAST OF COLOMBIA AND WRN VENEZUELA. A LARGE AREA OF DRY AIR IS IN THE CENTRAL ATLC ADVECTING INTO THE CARIBBEAN...GFS SUGGESTS THAT THIS WILL CONTINUE HELPING TO DRY OUT THE CENTRAL AND WRN CARIBBEAN A LITTLE MON AND TUE. THE ATLANTIC OCEAN... AN AMPLIFIED PATTERN EXISTS ACROSS THE ATLANTIC BASIN. A LARGE DEEP LAYER TROUGH EXTENDS FROM ERN CANADA SOUTHWARD TO THE NW CARIBBEAN. DRY AIR LIES TO THE W OF THE TROUGH AXIS WITH THE STRONGEST UPPER CONFLUENCE NEAR THE BASE ACROSS THE WRN BAHAMAS AND THE SE GULF. A SWATH OF MOISTURE ADVECTED BY A SWLY JET EXISTS BETWEEN 65W AND 74W. THE SFC FRONTAL BOUNDARY HAS BECOME LESS DEFINED AND IS NOW ANALYZED A TROF FROM 31N71W TO 24N78W. A MID-LEVEL SUBTROPICAL RIDGE LIES TO THE E OF THE LARGE TROUGH AND COVERS THE REGION FROM 42W TO 65W N OF 20N. HURCN ISAAC HAS REACHED THE WRN EDGE OF THE RIDGE AND IS ACCELERATING NNE AHEAD OF THE TROUGH. THE SRN PART OF THE SUBTROPICAL RIDGE IS ERODING DUE TO A FAIRLY LARGE WESTWARD MOVING UPPER LOW CENTERED NEAR 18N50W. THIS UPPER LOW IS THE SRN EXTENSION OF A LARGE TROUGH IN THE CENTRAL/ERN ATLC WHICH IS ANCHORED BY A LARGE UPPER CYCLONE NEAR 30N33W AND EXTENDS SW TO THE UPPER LOW NEAR 18N50W. AN ASSOCIATED SFC FRONT STRETCHES FROM A 1008 MB SFC LOW NEAR THE AZORES ALONG 31N27W 26N38W. SCATTERED SHOWERS ARE FROM 27N TO 33N BETWEEN 26W AND 35W. IN THE FAR ERN ATLC...A MID-UPPER ANTICYCLONE IS CENTERED OVER WRN AFRICA NEAR 16N16W WITH RIDGING EXTENDING TO THE ERN CAPE VERDE ISLANDS. $$ CANGIALOSI