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| #101703 (Received by flhurricane at: 11:00 AM 02.Aug.2006) TCDAT3 TROPICAL STORM CHRIS DISCUSSION NUMBER 8 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL032006 1100 AM EDT WED AUG 02 2006 DATA FROM THE SAN JUAN WSR-88D DOPPLER RADAR AND HIGH-RESOLUTION VISIBLE SATELLITE IMAGERY SUGGEST THAT CHRIS IS GRADUALLY BECOMING BETTER ORGANIZED AS IT CONTINUES TOWARD THE WEST-NORTHWEST NEAR 9 KT. INITIAL INTENSITY IS SET AT 55 KT IN ACCORDANCE WITH THE LAST RECON-MEASURED FLIGHT-LEVEL WINDS OF 67 KT AND DVORAK T-NUMBERS OF 3.5 FROM BOTH TAFB AND SAB. CIRRUS MOTIONS INDICATE THAT CHRIS CONTINUES TO BE EXPERIENCING SOME NORTHERLY SHEAR. ON THE PREDICTED TRACK...AND BASED ON THE 200 MB WIND FORECAST FROM THE GFS...CHRIS WILL BE IN A COL REGION BETWEEN TWO UPPER-LEVEL CYCLONES DURING THE NEXT FEW DAYS. THIS IS A REASONABLY FAVORABLE UPPER-LEVEL ENVIRONMENT...SO A GRADUAL INCREASE IN STRENGTH IS FORECAST. THE NHC WIND SPEED FORECAST IS SIMILAR TO THE LATEST SHIPS GUIDANCE AND A LITTLE ABOVE THE FSU SUPERENSEMBLE PREDICTION. AS ALWAYS...IT SHOULD BE RECALLED THAT TROPICAL CYCLONE INTENSITY FORECASTS AT 3-5 DAYS HAVE LITTLE SKILL. LATEST CENTER FIXES SUGGEST LITTLE CHANGE IN THE INITIAL HEADING OR SPEED. GLOBAL MODELS INDICATE THAT THE MID/UPPER-LEVEL LOW NEAR THE CENTRAL BAHAMAS WILL MOVE WESTWARD AND SLOWLY WEAKEN OVER THE NEXT FEW DAYS...WHILE A RATHER STRONG MID-TROPOSPHERIC RIDGE BUILDS TO THE NORTH OF CHRIS. THIS KIND OF FLOW PATTERN WOULD STEER THE TROPICAL CYCLONE ON A GENERAL WEST-NORTHWESTWARD TRACK. HOWEVER AN EVEN STRONGER RIDGE WOULD LIKELY DRIVE CHRIS WESTWARD. INDEED... THIS IS THE SCENARIO OFFERED BY THE GFDL MODEL WHICH EVEN TURNS THE SYSTEM WEST-SOUTHWESTWARD FOR A WHILE. WHEREAS THE GFDL IS A HIGHLY CREDIBLE MODEL...THE MOST PRUDENT COURSE AT THIS TIME IS TO USE THE CONSENSUS OF ALL OF THE DYNAMICAL MODELS. THIS IS ALSO VERY SIMILAR TO THE PREVIOUS NHC TRACK. FORECAST POSITIONS AND MAX WINDS INITIAL 02/1500Z 19.2N 63.4W 55 KT 12HR VT 03/0000Z 19.8N 64.8W 60 KT 24HR VT 03/1200Z 20.3N 66.4W 65 KT 36HR VT 04/0000Z 20.8N 68.0W 65 KT 48HR VT 04/1200Z 21.4N 70.1W 70 KT 72HR VT 05/1200Z 22.5N 74.5W 70 KT 96HR VT 06/1200Z 23.5N 79.0W 70 KT 120HR VT 07/1200Z 24.5N 83.5W 70 KT |
