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| #377127 (Received by flhurricane at: 10:34 PM 18.Sep.2010) TCDAT2 TROPICAL STORM JULIA DISCUSSION NUMBER 28 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL122010 1100 PM AST SAT SEP 18 2010 JULIA HAS MOVED INTO A REGION OF WEAKER VERTICAL SHEAR DURING THE PAST 6 HOURS AND VERY COLD TOPPED CONVECTION HAS DEVELOPED NEAR AND SOUTHEAST OF THE LOW-LEVEL CENTER AS A RESULT. SATELLITE CURRENT INTENSITY ESTIMATES ARE T3.5/55 KT FROM TAFB...T2.5/35 KT FROM SAB...AND ADT VALUES OF T3.4/43 KT FROM UW-CIMSS...RESPECTIVELY. GIVEN THE NEW DEVELOPMENT OF DEEP CONVECTION NEAR THE CENTER...THE INITIAL INTENSITY REMAINS 45 KT...WHICH IS AN AVERAGE OF THE THREE INTENSITY ESTIMATES. JULIA HAS TURNED TOWARD THE NORTH AND IS NOW ESTIMATED TO BE MOVING AT 360/12. JULIA EARLIER ACCELERATED NORTHWARD AT ABOUT 20 KT DURING THE PERIOD WHEN IT POSSESSED NO DEEP CONVECTION NEAR THE CENTER. HOWEVER...NOW THAT CONVECTION HAS REFORMED...THE CIRCULATION HAS LIKELY DEEPENED IN THE VERTICAL AND WILL BE SUBJECT TO A DEEPER AND SLOWER STEERING FLOW. THE NHC MODEL GUIDANCE IS IN GENERAL AGREEMENT ON JULIA MOVING NORTHWARD FOR THE NEXT 12 HOURS AND THEN NORTHEASTWARD AFTER THAT AS THE CYCLONE MOVES AROUND THE WESTERN PERIPHERY OF A LARGE SUBTROPICAL RIDGE LOCATED TO ITS EAST. BY 48 HOURS...A SEVERELY WEAKENED AND SHALLOW JULIA AT THAT TIME IS EXPECTED TO GRADUALLY BECOME ABSORBED INTO THE EASTERN PORTION OF THE VERY LARGE HURRICANE IGOR CIRCULATION. THE OFFICIAL FORECAST IS A LITTLE TO THE LEFT OF THE PREVIOUS ADVISORY TRACK...AND IS SIMILAR TO THE CONSENSUS MODELS...TVCN AND TVCC. WEAKER VERTICAL SHEAR CONDITIONS THAT JULIA HAS BEEN EXPERIENCING THE PAST 6 HOURS WILL BE SHORT-LIVED SINCE THE CYCLONE WILL BE MOVING NORTHWARD INTO A REGION OF STRONG WESTERLY SHEAR OF 30-50 KT EMANATING FROM THE MASSIVE OUTFLOW FROM HURRICANE IGOR IN 6-12 HOURS. BY 24 HOURS...JULIA WILL ALSO BE MOVING OVER SUB-26C SSTS...WHICH WHEN COMBINED WITH THE INCREASING WESTERLY SHEAR... SHOULD INDUCE RAPID WEAKENING. JULIA IS EXPECTED TO BECOME A REMNANT LOW IN 36-48 HOURS...IF NOT SOONER. THE OFFICIAL INTENSITY FORECAST IS SIMILAR TO THE PREVIOUS ADVISORY...AND CLOSELY FOLLOWS THE SHIPS/LGEM MODELS...WHICH DISSIPATE JULIA BY AROUND 48 HOURS. FORECAST POSITIONS AND MAX WINDS INITIAL 19/0300Z 32.4N 51.9W 45 KT 12HR VT 19/1200Z 34.3N 51.7W 40 KT 24HR VT 20/0000Z 36.1N 50.4W 30 KT 36HR VT 20/1200Z 37.6N 48.7W 25 KT 48HR VT 21/0000Z 39.1N 46.9W 25 KT...POST-TROP/REMNT LOW 72HR VT 22/0000Z 43.6N 41.8W 20 KT...POST-TROP/REMNT LOW 96HR VT 23/0000Z...DISSIPATED $$ FORECASTER STEWART |
