ZCZC MIATCDEP1 ALL TTAA00 KNHC DDHHMM TROPICAL STORM NARDA DISCUSSION NUMBER 4 NATIONAL WEATHER SERVICE MIAMI FL 2 AM PDT SUN OCT 21 2001 THE INITIAL MOTION ESTIMATE IS 290/12. THE AVIATION MODEL MAINTAINS A RIDGE TO THE NORTH OF THE STORM THROUGH 72 HOURS AND THE GFDL...UKMET AND NOGAPS ARE IN GOOD AGREEMENT ABOUT A CONTINUED WEST-NORTHWEST MOTION. A COLD CDO FEATURE PERSISTS AND DVORAK INTENSITY ESTIMATES ARE 45 KNOTS FROM TAFB AND SAB AND THE INITIAL WIND SPEED IS INCREASED TO 45 KNOTS. THE SHIPS AND GFDL MODELS SHOW MODEST STRENGTHENING FOR ANOTHER 24 HOURS OR SO AFTER WHICH UPPER LEVEL WESTERLIES AND THEIR ASSOCIATED VERTICAL SHEAR SHOULD BEGIN TO WEAKEN THE STORM. FORECASTER LAWRENCE FORECAST POSITIONS AND MAX WINDS INITIAL 21/0900Z 12.6N 129.0W 45 KTS 12HR VT 21/1800Z 13.5N 130.7W 55 KTS 24HR VT 22/0600Z 14.5N 133.0W 60 KTS 36HR VT 22/1800Z 15.2N 135.3W 55 KTS 48HR VT 23/0600Z 16.0N 137.6W 50 KTS 72HR VT 24/0600Z 17.6N 142.3W 35 KTS NNNN