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| #90958 (Received by flhurricane at: 11:00 PM 11.Jun.2006) TCDAT1 TROPICAL STORM ALBERTO DISCUSSION NUMBER 8 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL012006 1100 PM EDT SUN JUN 11 2006 DATA FROM SATELLITES AND AN AIR FORCE RESERVE RECONNAISSANCE AIRCRAFT THIS EVENING INDICATE ALBERTO HAS CHANGED LITTLE IN OVERALL STRUCTURE. SEVERAL SMALL-SCALE CIRCULATIONS HAVE BEEN NOTED IN SATELLITE IMAGERY ROTATING CYCLONICALLY AROUND A MEAN CENTER... AND THE ADVISORY POSITION IS THE MIDPOINT BETWEEN THOSE SWIRLS. THE ADVISORY POSITION IS TO THE WEST OF THE LAST RECON POSITION AT 12/0143Z... AND IS CLOSE TO THE CENTROID OF THE LARGE SURFACE PRESSURE ENVELOPE. THE 40-KT INTENSITY IS BASED ON THE ASSUMPTION THAT THE RECON AIRCRAFT MAY NOT HAVE SAMPLED STRONGER WINDS TO THE EAST OF THE FLIGHT TRACK WITHIN SOME OF THE STRONGER CONVECTION. UPPER-AIR DATA THIS EVENING INDICATE THE MID- TO UPPER-LEVEL RIDGE PREVIOUSLY LOCATED ACROSS CENTRAL FLORIDA HAS ERODED AND LIFTED NORTHWARD TO NORTHERN FLORIDA...WHILE THE LOW-LEVEL RIDGE HAS ALSO SHIFTED NORTHWARD BUT HAS REMAINED INTACT ALL THE WAY WESTWARD TO EASTERN TEXAS. THIS...COUPLED WITH THE SOUTHWESTERLY UPPER-LEVEL FLOW...HAS MAINTAINED A MODERATE TO STRONG SHEAR PATTERN ACROSS THE CYCLONE...WHICH IS EXPECTED TO CONTINUE FOR THE NEXT 12-18 HOURS. AFTER THAT...MOST OF THE MODELS AGREE THAT THE DEEP LAYER FLOW WILL BECOME VERTICALLY ALIGNED FROM THE SOUTHWEST...AND THAT SHOULD ACT TO TURN ALBERTO NORTHEASTWARD TOWARD NORTHERN FLORIDA. THE GFDL ONCE AGAIN APPEARS TO BE OVERCOMPENSATING FOR THE VERTICAL SHEAR AS IT TAKES THE CYCLONE MORE NORTHWARD INTO GEORGIA... AS DOES THE FSU SUPERENSEMBLE BY 36H. THE OFFICIAL FORECAST TRACK IS SIMILAR TO THE PREVIOUS TRACK AND FOLLOWS THE GENERAL MID-LEVEL WEST-SOUTHWESTERLY STEERING FLOW PATTERN AFTER 24 HOURS...WHICH KEEPS ALBERTO SOUTH OF THE SUBTROPICAL JETSTREAM AND IN THE DIVERGENT RIGHT-REAR QUADRANT. ONCE ALBERTO TURNS TOWARD THE NORTHEAST...THE VERTICAL SHEAR IS EXPECTED TO ABATE SOMEWHAT. THIS MAY ALLOW FOR SOME SLIGHT STRENGTHENING IN THE 24-36H TIME FRAME...AS SUGGESTED BY THE SHIPS INTENSITY MODEL... BUT NOT AS ROBUST AS THE GFDL MODEL. FORECASTER STEWART FORECAST POSITIONS AND MAX WINDS INITIAL 12/0300Z 25.3N 87.7W 40 KT 12HR VT 12/1200Z 26.6N 87.2W 45 KT 24HR VT 13/0000Z 27.9N 85.9W 50 KT 36HR VT 13/1200Z 28.7N 84.2W 50 KT 48HR VT 14/0000Z 30.1N 81.7W 40 KT...INLAND 72HR VT 15/0000Z 34.0N 75.0W 40 KT...EXTRATROPICAL 96HR VT 16/0000Z 40.0N 63.5W 40 KT...EXTRATROPICAL 120HR VT 17/0000Z 46.0N 52.0W 40 KT...EXTRATROPICAL |
