ZCZC MIATCDAT2 ALL TTAA00 KNHC DDHHMM TROPICAL STORM JULIA DISCUSSION NUMBER 33 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL122010 500 AM AST MON SEP 20 2010 JULIA AGAIN PROVIDED A SURPRISE FOR A SECOND NIGHT IN A ROW WITH STRONGER SURFACE WINDS MEASURED FROM THE ASCAT SCATTEROMETER THAN WHAT WAS SUGGESTED FROM CONVENTIONAL SATELLITE IMAGERY USING THE DVORAK TECHNIQUE. THE 0046Z ASCAT PASS SHOWED MAXIMUM WINDS OF AT LEAST 45 KT...DESPITE A FAIRLY DISHEVELED APPEARANCE TO THE DEEP CONVECTION. THE 0600Z TAFB AND SAB DATA-T DVORAK NUMBERS REMAIN AT A 2.0...OR 30 KT. THE INITIAL INTENSITY IS SET AT 40 KT...ASSUMING SOME WEAKENING SINCE THE ASCAT PASS. THE CENTER CONTINUES TO BE DISPLACED WEST OF THE LIMITED DEEP CONVECTION DUE TO STRONG WESTERLY VERTICAL SHEAR INDUCED BY EXTREMELY LARGE HURRICANE IGOR. THE INITIAL MOTION OF JULIA IS ESTIMATED TO BE 65 DEGREES AT 8 KT...AND THE CYCLONE IS BEING ADVECTED AROUND THE NORTHERN PERIPHERY OF THE DEEP LAYER SUBTROPICAL RIDGE. THE CYCLONE SHOULD ACCELERATE SOME TOWARD THE NORTH-NORTHEAST IN THE NEXT DAY OR SO. AROUND 36 HOURS...JULIA SHOULD BECOME ABSORBED INTO THE CIRCULATION OF IGOR AS SHOWN BY NEARLY ALL OF THE MODELS. HOWEVER...THE ECMWF MODEL KEEPS THE CYCLONE FAR ENOUGH SOUTH OF IGOR TO PREVENT THE ABSORPTION. INSTEAD...THE ECMWF MAINTAINS JULIA AS A SEPARATE CYCLONE FOR SEVERAL MORE DAYS...THOUGH BECOMING EXTRATROPICAL ABOUT TWO DAYS FROM NOW. THIS TRACK FORECAST GOES WITH THE CONSENSUS...MINUS THE ECMWF...AND IS SLIGHTLY TO THE LEFT OF AND FASTER THAN THE PREVIOUS ADVISORY. AS JULIA SHOULD GRADUALLY ENCOUNTER SUB-26C WATER TEMPERATURES ALONG WITH QUITE HOSTILE VERTICAL SHEAR...GRADUAL WEAKENING IS EXPECTED FOR THE NEXT TWO DAYS UNTIL DISSIPATION. THE INTENSITY FORECAST IS BASED UPON THE MODEL CONSENSUS AND IS SLIGHTLY HIGHER THAN THE PREVIOUS ADVISORY BECAUSE OF THE STRONGER INITIAL CYCLONE. THE AFOREMENTIONED ASCAT PASS ALLOWED FOR AN ENLARGEMENT OF THE TROPICAL STORM WIND RADII. FORECAST POSITIONS AND MAX WINDS INITIAL 20/0900Z 35.5N 47.9W 40 KT 12HR VT 20/1800Z 36.1N 46.8W 35 KT 24HR VT 21/0600Z 37.6N 45.3W 30 KT...POST-TROP/REMNT LOW 36HR VT 21/1800Z 39.6N 43.5W 25 KT...POST-TROP/REMNT LOW 48HR VT 22/0600Z...DISSIPATED $$ FORECASTER LANDSEA/BRENNAN NNNN
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Page last modified: Friday, 15-Apr-2011 12:09:16 UTC