ZCZC MIATCDEP4 ALL TTAA00 KNHC DDHHMM TROPICAL STORM NORMA DISCUSSION NUMBER 8 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 2 PM PDT SAT SEP 24 2005 MICROWAVE SATELLITE DATA DURING THE PAST 6 HOURS INDICATE NORMA HAS CONTINUED TO MOVE SLOWLY NORTHWESTWARD WHILE BECOMING BETTER ORGANIZED WITH IMPROVED BANDING FEATURES NOTED. THE LOW-LEVEL CENTER IS NOW LOCATED CLOSER TO THE MIDDLE OF THE COLD CONVECTIVE CLOUD MASS... AND DVORAK T-NUMBERS HAVE INCREASED ACCORDINGLY TO T3.5/55 KT FROM BOTH TAFB AND SAB. THEREFORE... THE INITIAL INTENSITY HAS BEEN INCREASED TO 55 KT. THE INITIAL MOTION IS 335/04. THE MID-LEVEL RIDGE TO THE NORTH AND EAST OF NORMA REMAINS WEAK... AND IS FORECAST TO CONTINUE THAT WAY FOR THE NEXT 48 HOURS. THIS SHOULD KEEP NORMA MOVING IN A GENERAL NORTHWESTWARD DIRECTION... THEN TURNING MORE WEST-NORTHWESTWARD BY 48 HOURS. AFTERWARDS... AN UPPER-LEVEL TROUGH/LOW IS FORECAST TO DIG SOUTHWARD OFF THE CALIFORNIA COAST WITH ASSOCIATED DOWNSTREAM RIDGING CAUSING HIGH PRESSURE TO BUILD ACROSS THE SOUTHWESTERN U.S. AND MEXICO. BY DAYS 4 AND 5... RIDGING TO THE NORTHWEST OF NORMA IS FORECAST TO BUILD SOUTHWESTWARD... WHICH IS EXPECTED TO TURN THE CYCLONE SLOWLY WEST-SOUTHWESTWARD. THE OFFICIAL FORECAST TRACK IS SIMILAR TO THE CONSENSUS OF THE GLOBAL MODELS. THE CURRENT MODERATE EASTERLY VERTICAL SHEAR IS FORECAST TO SLOWLY DECREASE THROUGHOUT THE FORECAST PERIOD... REACHING A MINIMUM OF ABOUT 8 KT BY 120 HOURS. WHILE THE INTENSITY FORECAST ONLY CALLS FOR SLIGHT STRENGTHENING... IT IS POSSIBLE THAT NORMA COULD BECOME A HURRICANE AT ANY TIME DURING THE NEXT 48 HOURS BEFORE COOLER IS REACHED. BY 72 HOURS... NORMA IS FORECAST TO BE OVER 25C SSTS AND SLOW WEAKENING IS EXPECTED TO BEGIN. THE SHIPS MODEL IS NO LONGER DISSIPATING NORMA AFTER 72 HOURS AS IN PREVIOUS MODEL RUNS. FORECASTER STEWART FORECAST POSITIONS AND MAX WINDS INITIAL 24/2100Z 16.6N 110.9W 55 KT 12HR VT 25/0600Z 17.1N 111.3W 55 KT 24HR VT 25/1800Z 17.9N 111.9W 60 KT 36HR VT 26/0600Z 18.8N 112.9W 60 KT 48HR VT 26/1800Z 19.6N 114.0W 60 KT 72HR VT 27/1800Z 20.5N 115.8W 55 KT 96HR VT 28/1800Z 20.5N 118.0W 45 KT 120HR VT 29/1800Z 19.5N 120.5W 40 KT $$ NNNN
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Page last modified: Saturday, 24-Sep-2005 21:10:20 UTC