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| #25787 (Received by flhurricane at: 11:24 PM 10.Jun.2005) TCDAT1 TROPICAL STORM ARLENE DISCUSSION NUMBER 11 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 11 PM EDT FRI JUN 10 2005 LAST MINUTE INFORMATION FROM A NOAA HURRICANE HUNTER REQUIRED SOME ADJUSTMENTS TO THE WORKING FORECAST TRACK. RECON FOUND A PRESSURE OF 989 MB IN WHAT APPEARS TO BE A NEW BUT STRONGER LOW-LEVEL VORTEX THAT DEVELOPED BENEATH A DEEP CONVECTIVE BURST THAT HAS BEEN ROTATING CYCLONICALLY AROUND THE EAST AND NORTH SIDE OF THE LARGER CYCLONIC GYRE. I AM NOT READY TO KEY IN ON THE WEST-NORTHWESTWARD MOTION OF THAT CIRCULATION DURING THE PAST 3 HOURS...SO THE INITIAL POSITION AND MOTION OF 330/14 IS A LONGER TERM BLEND OF RECON AND SATELLITE POSITIONS AND MOTION. THE INITIAL INTENSITY OF 60 KT IS BASED ON 850 MB FLIGHT-LEVEL WINDS OF 75 KT IN THE NORTHEAST QUAD. THE OFFICIAL FORECAST TRACK WAS SHIFTED A LITTLE TO THE LEFT OF THE PREVIOUS TRACK DUE TO THE MORE WESTWARD INITIAL POSITION... AND SUBSEQUENT TRACKS MAY HAVE TO BE SHIFTED A LITTLE MORE TO THE WEST IF THE WEST-NORTHWESTWARD MOTION TREND CONTINUES FOR ANOTHER 6 HOURS. HOWEVER...MY FEELING IS THAT SOME SIGNIFICANT WOBBLING WILL OCCUR ALONG A GENERAL NORTH-NORTHWEST TO NORTHWESTWARD TRACK UNTIL LANDFALL OCCURS. THIS IS MAINLY DUE TO VERTICAL SHEAR AND OCCASIONAL INTRUSIONS OF DRY AIR ERODING THE DEEP CONVECTION AND CAUSING THE LOW-LEVEL CENTER TO CONSTANTLY REFORM NEAR NEW CONVECTIVE BURSTS. THIS TRACK IS CONSISTENT WITH THE NHC MODEL CONSENSUS AND THE LOW- TO MID-LEVEL SOUTHEASTERLY STEERING FLOW. TIMING THE VARIOUS CONVECTIVE BURSTS IS NEARLY IMPOSSIBLE. HOWEVER ...ARLENE WILL BE GOING INTO THE CONVECTIVE MAXIMUM PERIOD LATER TONIGHT AND SATURDAY MORNING...SO SOME NEW DEEP CONVECTION SHOULD REDEVELOP NEAR THE LOW-LEVEL CENTER AND POSSIBLY ALLOW THE CYCLONE TO BECOME A CATEGORY 1 HURRICANE. HOWEVER...SOUTHWESTERLY VERTICAL SHEAR IS FORECAST TO GRADUALLY INCREASE AS ARLENE APPROACHES THE GULF COAST...SO SOME FLUCTUATIONS IN INTENSITY SHOULD BE EXPECTED. FORECASTER STEWART FORECAST POSITIONS AND MAX WINDS INITIAL 11/0300Z 27.1N 86.1W 60 KT 12HR VT 11/1200Z 28.7N 87.0W 65 KT 24HR VT 12/0000Z 31.0N 88.0W 55 KT...INLAND 36HR VT 12/1200Z 33.5N 88.0W 30 KT...DISSIPATING INLAND 48HR VT 13/0000Z 37.0N 87.6W 20 KT...DISSIPATING INLAND 72HR VT 14/0000Z...DISSIPATED INLAND |
