ZCZC MIATCDAT5 ALL TTAA00 KNHC DDHHMM TROPICAL STORM NATE DISCUSSION NUMBER 9 NWS NATIONAL HURRICANE CENTER MIAMI FL AL152011 400 PM CDT FRI SEP 09 2011 THE HURRICANE HUNTER AIRCRAFT INVESTIGATING NATE THIS AFTERNOON FOUND A PEAK 850-MB FLIGHT-LEVEL WIND OF 55 KT AND PEAK SFMR VALUES OF 40-45 KT. BASED ON THIS...THE INITIAL INTENSITY IS SET AT 45 KT FOR THIS ADVISORY. WHILE NATE CONTINUES TO HAVE AN IMPRESSIVE BANDED STRUCTURE IN VISIBLE IMAGERY...DEEP CONVECTION IS LACKING...BUT HAS MADE A BIT OF A COMEBACK IN THE PAST HOUR OR TWO IN RAINBANDS WELL EAST AND WEST OF THE CENTER. THE SHIPS MODEL ANALYSIS CONTINUES TO SHOW RELATIVELY DRY AIR IN THE MID-LEVELS AND AND A LACK OF INSTABILITY IN THE PROFILE. HOWEVER...GIVEN THE VERY WARM SSTS OVER THE SOUTHWESTERN GULF OF MEXICO...NATE SHOULD BE ABLE TO INTENSIFY SOME IF CAN RE-ESTABLISH CONVECTION NEAR THE CENTER. GIVEN THE RECENT WEAKENING TREND THE STATISTICAL MODELS SHOW ONLY GRADUAL STRENGTHENING UNTIL LANDFALL WHILE THE DYNAMICAL MODELS ARE A LITTLE MORE AGGRESSIVE...BUT STILL LOWER THAN THE LAST CYCLE. THE OFFICIAL FORECAST HAS BEEN ADJUSTED DOWNWARD BY ABOUT 10 KT COMPARED TO THE PREVIOUS PACKAGE BUT IS ABOVE MOST OF THE GUIDANCE. AFTER LANDFALL NATE SHOULD QUICKLY WEAKEN OVER THE HIGH TERRAIN AND DISSIPATE BY 96 HOURS. AFTER APPEARING TO MOVE WEST-NORTHWESTWARD EARLIER TODAY...THE LATEST AIRCRAFT FIXES SUGGEST NATE HAS BEEN NEARLY STATIONARY. MODEL GUIDANCE CONTINUES TO SUGGEST THAT A MID-LEVEL RIDGE WILL REBUILD TO THE NORTH OF NATE OVER THE NEXT DAY OR TWO...WHICH SHOULD GET NATE MOVING AGAIN. THE GFS...HWRF...AND GFDL MODELS NOW SHOW MORE OF A TURN TOWARD THE WEST-SOUTHWEST AS NATE APPROACHES THE COAST...WHILE THE ECMWF AND UKMET SHOW A MORE WESTWARD TRACK. THE OFFICIAL FORECAST HAS BEEN SHIFTED SOUTHWARD FOR THIS CYCLE BUT STILL LIES NORTH OF THE MULTI-MODEL CONSENSUS...SHOWING A SLOW WESTWARD MOTION FOR 12 TO 24 HOURS AND A TURN SOUTH OF DUE WEST PRIOR TO LANDFALL. FORECAST POSITIONS AND MAX WINDS INIT 09/2100Z 20.0N 92.8W 45 KT 50 MPH 12H 10/0600Z 20.2N 93.4W 50 KT 60 MPH 24H 10/1800Z 20.2N 94.1W 60 KT 70 MPH 36H 11/0600Z 20.1N 95.0W 65 KT 75 MPH 48H 11/1800Z 20.0N 96.0W 70 KT 80 MPH 72H 12/1800Z 19.5N 98.5W 35 KT 40 MPH...INLAND 96H 13/1800Z...DISSIPATED $$ FORECASTER BRENNAN NNNN
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Page last modified: Tuesday, 17-Jul-2012 13:44:01 UTC