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#382102 (Received by flhurricane at: 4:34 PM 09.Oct.2010) TCDAT2 HURRICANE OTTO DISCUSSION NUMBER 15 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL172010 500 PM AST SAT OCT 09 2010 SATELLITE IMAGES INDICATE THAT OTTO IS GRADUALLY WEAKENING. WARMING CLOUD TOPS ARE PRIMARILY LOCATED NORTH OF THE CIRCULATION CENTER AS A CONSEQUENCE OF CONTINUED MODERATE SOUTHWESTERLY SHEAR. HOWEVER... SATELLITE CLASSIFICATIONS SUPPORT MAINTAINING OTTO AS A HURRICANE FOR THIS ADVISORY. FURTHER WEAKENING IS FORECAST AS OTTO ENCOUNTERS A HIGH SHEAR ENVIRONMENT AND PASSES OVER PROGRESSIVELY COOLER WATERS DURING THE NEXT FEW DAYS. EXTRATROPICAL TRANSITION APPEARS TO BE UNDERWAY AS EVIDENCED BY CURRENT CONVECTIVE TRENDS AND COLDER...DRIER AIR IMPINGING ON THE CIRCULATION FROM THE WEST. GLOBAL MODELS INDICATE THAT THIS PROCESS SHOULD BE COMPLETE BY 36 HOURS...ALTHOUGH IT COULD FINISH EARLIER. THE OFFICIAL NHC INTENSITY FORECAST IS ABOUT THE SAME AS THE PREVIOUS ONE AND IS IN LINE WITH THE SHIPS/LGEM GUIDANCE. OTTO IS STILL ACCELERATING...AND THE INITIAL MOTION ESTIMATE IS 055/28. SOME FURTHER ACCELERATION TOWARD THE NORTHEAST IS LIKELY DURING THE NEXT 12-24 HOURS AS THE CYCLONE IS EMBEDDED IN A DEEP LAYER OF STRONG SOUTHWESTERLY FLOW AHEAD OF A LARGE MID-LATITUDE TROUGH OVER THE WESTERN ATLANTIC. AFTER 36 HOURS....OTTO SHOULD ABRUPTLY DECELERATE AND TURN EASTWARD AND THEN SOUTHEASTWARD AS IT STEERED AROUND THE CIRCULATION OF A DEEP LAYER CYCLONE OVER THE NORTHEAST ATLANTIC. THE MODEL GUIDANCE...EXCEPT FOR THE NOGAPS AND THE CANADIAN...IS IN GOOD AGREEMENT ON THIS SCENARIO...AND THE OFFICIAL TRACK FORECAST IS CLOSE TO THE PREVIOUS ONE AND THE MULTI-MODEL CONSENSUS. FORECAST POSITIONS AND MAX WINDS INITIAL 09/2100Z 32.4N 52.6W 65 KT 12HR VT 10/0600Z 34.7N 47.6W 60 KT 24HR VT 10/1800Z 38.0N 40.3W 55 KT 36HR VT 11/0600Z 41.3N 33.6W 50 KT...POST-TROP/EXTRATROP 48HR VT 11/1800Z 43.4N 29.4W 45 KT...POST-TROP/EXTRATROP 72HR VT 12/1800Z 43.0N 25.5W 35 KT...POST-TROP/EXTRATROP 96HR VT 13/1800Z 39.0N 24.0W 30 KT...POST-TROP/EXTRATROP 120HR VT 14/1800Z 37.0N 22.0W 30 KT...POST-TROP/EXTRATROP $$ FORECASTER KIMBERLAIN |