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| #382031 (Received by flhurricane at: 10:37 AM 09.Oct.2010) TCDAT2 HURRICANE OTTO DISCUSSION NUMBER 14 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL172010 1100 AM AST SAT OCT 09 2010 THE CLOUD PATTERN ASSOCIATED WITH OTTO HAS GRADUALLY BEEN DECREASING IN ORGANIZATION DURING THE LAST SEVERAL HOURS. THE CENTRAL DENSE OVERCAST THAT THE CYCLONE HAD BEEN MAINTAINING HAS BECOME INCREASINGLY DISTORTED...AND CONVECTIVE CLOUD TOPS HAVE WARMED. A SERIES OF MICROWAVE OVERPASSES SUGGEST THAT THE CENTER IS LOCATED ON THE SOUTHWEST SIDE OF THE DEEPEST CONVECTION...AND GIVE EVIDENCE OF A PRONOUNCED TILT OF THE VORTEX DUE TO THE EFFECT OF MODERATE SOUTHWESTERLY SHEAR. THE INITIAL INTENSITY IS LOWERED TO 65 KT BASED UPON DVORAK T-NUMBERS OF 3.5 AND 4.0 FROM SAB AND TAFB... RESPECTIVELY. FURTHER WEAKENING IS LIKELY OVER THE NEXT SEVERAL DAYS AS OTTO ENTERS A STRONGLY SHEARED ENVIRONMENT AND MOVES OVER PROGRESSIVELY COOLER WATERS. GLOBAL MODELS SUGGEST THAT EXTRATROPICAL TRANSITION MAY HAVE ALREADY BEGUN...AND THE COMPLETION OF THIS PROCESS...ALTHOUGH STILL A BIT UNCERTAIN...IS FORECAST BY ABOUT 48 HOURS. THE OFFICIAL INTENSITY FORECAST IS ADJUSTED DOWNWARD BASED UPON RECENT TRENDS AND IS IN GOOD AGREEMENT WITH THE STATISTICAL-DYNAMICAL GUIDANCE. THE MICROWAVE FIXES WERE HELPFUL IN FINDING THE CENTER OF OTTO AND SUGGEST THAT THE HURRICANE HAS CONTINUED TO ACCELERATE...WITH AN INITIAL MOTION ESTIMATE OF 055/25. OTTO IS FORECAST TO ACCELERATE FURTHER ON A GENERALLY NORTHEASTWARD COURSE DURING THE NEXT 24-36 HOURS IN BETWEEN A LARGE DEEP-LAYER TROUGH OVER THE NORTHWEST ATLANTIC AND A SUBTROPICAL RIDGE TO ITS EAST. ONCE POST- TROPICAL...OTTO IS EXPECTED TO ABRUPTLY DECELERATE AND TURN EASTWARD AND SOUTHEASTWARD AS IT ROUNDS THE TOP OF A SHORTWAVE RIDGE AND DIVES INTO THE WEST SIDE OF A TROUGH OVER THE NORTHEAST ATLANTIC. ALTHOUGH THE MODEL GUIDANCE CONTINUES TO HAVE DIFFICULTY IN PREDICTING THE SHARPNESS OF THIS TURN...THE SPREAD IN THE MODEL SOLUTIONS HAS DECREASED SOME SINCE THE LAST CYCLE. THE OFFICIAL TRACK FORECAST IS BASICALLY AN UPDATE OF THE PREVIOUS ONE AND IS CLOSE TO THE MULTI-MODEL CONSENSUS. FORECAST POSITIONS AND MAX WINDS INITIAL 09/1500Z 30.7N 55.7W 65 KT 12HR VT 10/0000Z 32.9N 51.4W 60 KT 24HR VT 10/1200Z 36.2N 44.2W 55 KT 36HR VT 11/0000Z 39.7N 36.7W 50 KT 48HR VT 11/1200Z 42.5N 31.0W 45 KT...POST-TROP/EXTRATROP 72HR VT 12/1200Z 43.0N 26.0W 35 KT...POST-TROP/EXTRATROP 96HR VT 13/1200Z 39.6N 24.0W 30 KT...POST-TROP/EXTRATROP 120HR VT 14/1200Z 36.5N 21.5W 30 KT...POST-TROP/EXTRATROP $$ FORECASTER KIMBERLAIN |
