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#381651 (Received by flhurricane at: 4:37 PM 07.Oct.2010) TCDAT2 TROPICAL STORM OTTO DISCUSSION NUMBER 7 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL172010 500 PM AST THU OCT 07 2010 BURSTS OF DEEP CONVECTION WITH CLOUD TOP TEMPERATURES OF -70C TO -80C HAVE CONTINUED TO DEVELOP OVER AND EAST OF THE LOW-LEVEL CENTER DURING THE PAST 6 HOURS. SHEAR PATTERN SATELLITE INTENSITY ESTIMATES HAVE BEEN VARYING BETWEEN T3.0/45 KT AND T3.5/55 KT. THEREFORE...THE INITIAL INTENSITY WILL REMAIN AT 50 KT. ALTHOUGH A SMALL UPPER-LEVEL ANTICYCLONE HAS DEVELOPED OVER THE CENTER OF OTTO...LOWER CIRRUS CLOUD ELEMENTS CAN BE SEEN UNDERCUTTING THE FAVORABLE OUTFLOW LAYER IN VISIBLE AND WATER VAPOR IMAGERY...WHICH IS CREATING SOME MODEST UPPER-LEVEL SHEAR CONDITIONS ON THE CYCLONE. THE INITIAL MOTION ESTIMATE IS 050/05. OTTO IS COMING UNDER THE INCREASING INFLUENCE OF A LARGE DEEP-LAYER TROUGH THAT HAS MOVED EASTWARD OFF THE U.S. EAST COAST. THE TROUGH IS FORECAST BY ALL OF THE MODELS TO CONTINUE MOVING EASTWARD AND STEADILY ACCELERATE OTTO TO THE NORTHEAST DURING THE NEXT 48 HOURS. BY 72 HOURS...OTTO IS EXPECTED TO MERGE WITH A FRONTAL SYSTEM AND BECOME AN EXTRATROPICAL CYCLONE AND GALE AREA THAT COULD AFFECT THE AZORES ISLANDS IN 96 TO 120 HOURS. THE OFFICIAL FORECAST TRACK IS SIMILAR TO THE PREVIOUS ADVISORY TRACK AND IS CLOSE TO THE CONSENSUS MODEL...TVCN. SLOW STRENGTHENING IS EXPECTED DURING THE NEXT 24 HOURS OR SO WHILE OTTO REMAINS OVER WARM SSTS AND ALSO MOVES INTO AN AREA OF INCREASING INSTABILITY LOCATED IN THE EASTERN SEMICIRCLE. VERTICAL WIND SHEAR IS EXPECTED TO DECREASE SLIGHTLY BETWEEN 24 AND 36 HOURS...AND THAT IS WHEN OTTO COULD POSSIBLY REACH HURRICANE STRENGTH AS SUGGESTED BY THE GFDL/HWRF MODELS. HOWEVER...THIS WOULD LIKELY BE SHORT-LIVED DUE TO INCREASING WESTERLY SHEAR. BY 72 HOURS...OTTO IS EXPECTED TO ENCOUNTER STRONGER SHEAR OF 35-40 KT...WHICH SHOULD HASTEN THE WEAKENING PROCESS. HOWEVER...OTTO IS EXPECTED TO BE AN EXTRATROPICAL GALE AREA BY THAT TIME...AND THE INFUSION OF BAROCLINIC ENERGY SHOULD HELP MAINTAIN THE CYCLONE. THE OFFICIAL OFFICIAL INTENSITY FORECAST IS SIMILAR TO THE PREVIOUS ADVISORY AND IS A BLEND OF THE NHC OBJECTIVE INTENSITY GUIDANCE. FORECAST POSITIONS AND MAX WINDS INITIAL 07/2100Z 24.0N 67.6W 50 KT 12HR VT 08/0600Z 24.7N 66.3W 55 KT 24HR VT 08/1800Z 26.1N 63.8W 60 KT 36HR VT 09/0600Z 28.4N 59.7W 60 KT 48HR VT 09/1800Z 30.8N 54.5W 55 KT 72HR VT 10/1800Z 35.7N 42.3W 50 KT...POST-TROP/EXTRATROP 96HR VT 11/1800Z 39.0N 29.0W 40 KT...POST-TROP/EXTRATROP 120HR VT 12/1800Z 37.0N 23.5W 35 KT...POST-TROP/EXTRATROP $$ FORECASTER STEWART |