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| #101758 (Received by flhurricane at: 5:00 PM 02.Aug.2006) TCDAT3 TROPICAL STORM CHRIS DISCUSSION NUMBER 9 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL032006 500 PM EDT WED AUG 02 2006 REPORTS FROM AN AIR FORCE HURRICANE HUNTER AIRCRAFT INDICATE THAT CHRIS HAS WEAKENED A LITTLE. MAXIMUM 850 MB FLIGHT-LEVEL WINDS WERE 55 KT AND A DROPSONDE SHOWED A VERY SHALLOW LAYER OF 55 KT WINDS JUST ABOVE THE SURFACE. CURRENT INTENSITY IS SET AT 50 KT. THE VERY SMALL INNER CORE...I.E. RADIUS OF MAXIMUM WINDS OF ORDER 10 N MI...THAT WAS OBSERVED YESTERDAY HAS DISAPPEARED. FLIGHT-LEVEL DATA NOW SHOW THAT THE STRONGEST WINDS ARE 30 TO 40 N MI FROM THE CENTER. ALSO THE PRESENTATION FROM THE SAN JUAN WSR-88D DOPPLER SUGGESTS A LESS-ORGANIZED TROPICAL CYCLONE THAN EARLY THIS MORNING...AND ANIMATION OF VISIBLE SATELLITE IMAGERY SHOWS ARC CLOUDS EMANATING NORTHWESTWARD FROM THE STORM. ALL OF THE ABOVE SUGGEST THAT LITTLE INCREASE IN STRENGTH IS LIKELY IN THE SHORT TERM. HOWEVER...THE WIND MAXIMUM COULD CONTRACT AND INTENSIFICATION RESUME. NORTH-NORTHWESTERLY SHEAR CONTINUES TO AFFECT THE STORM AND...BASED ON THE RECON FIX...WHICH IS NEAR THE 5000 FT LEVEL...AND THE RADAR FIXES...WHICH ARE NEAR THE 25000 FT LEVEL...THE VORTEX IS TILTED SOUTH-SOUTHEASTWARD WITH HEIGHT. THE GFS CONTINUES TO FORECAST UPPER-LEVEL WINDS FAIRLY CONDUCIVE FOR THE INTENSIFICATION OF CHRIS...WITH THE STORM LOCATED BETWEEN TWO UPPER-LEVEL LOWS DURING THE NEXT FEW DAYS. HOWEVER OTHER GLOBAL MODELS....SUCH AS THE U.K. MET... SUGGEST THAT THE UPPER WINDS MAY NOT BE SO CONDUCIVE. THE LATTER GUIDANCE INDICATES THAT CHRIS COULD ENCOUNTER A SHARP EAST-WEST ORIENTED UPPER-TROPOSPHERIC SHEAR AXIS NEAR THE SOUTHEASTERN BAHAMAS IN AROUND 48 HOURS. THE CURRENT OFFICIAL INTENSITY FORECAST DELAYS THE STRENGTHENING TO A HURRICANE IN COMPARISON TO THE PAST FEW ADVISORIES...AND IS STILL A LITTLE ABOVE THE SHIPS AND FSU SUPERENSEMBLE GUIDANCE. INITIAL MOTION IS ROUGHLY THE SAME AS BEFORE AND IS ESTIMATED TO BE 300/9. BASED ON THE LARGE-SCALE DYNAMICAL MODELS...A MID/UPPER-LEVEL INVERTED TROUGH OVER THE BAHAMAS IS PREDICTED TO MOVE WESTWARD...AND THE DEEP-LAYER HIGH PRESSURE TO THE NORTH OF CHRIS IS LIKELY TO STRENGTHEN. CONSISTENT WITH THE HIGH PRESSURE BUILDING TO NORTH OF THE CYCLONE...THE MODEL CONSENSUS CALLS FOR A MORE WESTWARD MOTION TO DEVELOP OVER THE NEXT COUPLE OF DAYS. THE GFDL AND FSU SUPERENSEMBLE ARE THE SOUTHERNMOST OF THE TRACK MODELS AND THE U.K. MET. IS THE NORTHERNMOST...HOWEVER THE LATTER MODEL LOSES THE CIRCULATION AFTER 72 HOURS. THE TRACK FORECAST FOR THIS ADVISORY IS SLIGHTLY TO THE SOUTH OF THE PREVIOUS ONE BY DAYS 4-5. FORECAST POSITIONS AND MAX WINDS INITIAL 02/2100Z 19.9N 64.3W 50 KT 12HR VT 03/0600Z 20.4N 65.6W 55 KT 24HR VT 03/1800Z 21.0N 67.4W 60 KT 36HR VT 04/0600Z 21.3N 69.2W 65 KT 48HR VT 04/1800Z 21.7N 71.4W 65 KT 72HR VT 05/1800Z 22.5N 75.5W 70 KT 96HR VT 06/1800Z 23.5N 80.0W 70 KT 120HR VT 07/1800Z 24.5N 84.5W 70 KT |
