ZCZC MIATCDEP3 ALL TTAA00 KNHC DDHHMM TROPICAL STORM BLAS DISCUSSION NUMBER 4 NATIONAL WEATHER SERVICE MIAMI FL 2 AM PDT TUE JUN 23 1998 THE INITIAL MOTION ESTIMATE IS 300/09. THIS IS A PAST 24 HOUR MOTION. THE STORM HAS SLOWED IN FORWARD SPEED AND THE MOTION OVER THE PAST 12 HOURS MAY BE AS SLOW AS 6 KNOTS. ALL OF THE TRACK GUIDANCE MODELS SHOW A CONTINUED WEST-NORTHWEST TRACK FOR 72 HOURS. THIS IS BASED ON A RIDGE HOLDING TO THE NORTH OF THE STORM AS INDICATED ON THE 00Z AVIATION MODEL RUN. MOST OF THE MODELS MAINTAIN ABOUT A 10 KNOT SPEED EXCEPT THE UKMET WHICH IS MUCH SLOWER AND LBAR WHICH IS SOMEWHAT FASTER. THE OFFICIAL TRACK IS IN THE MIDDLE AND NEAR THE GFDL AND NOGAPS MODELS. A COLD CDO IS PERSISTING OVER THE CENTER OF THE STORM. INTENSITY ESTIMATES FROM SAB AND TAFB ARE DVORAK T NUMBER 3.5 OR 55 KNOTS WHICH IS THE BASIS FOR INCREASING THE CURRENT WIND SPEED TO THIS VALUE. THE FORECAST IS FOR CONTINUED STRENGTHENING TO 85 KNOTS IN 36 HOURS...SIMILAR TO THE PREVIOUS ADVISORY. THE SHIPS MODEL AND SHIFOR BRING BLAS TO 90 KNOTS IN 36 HOURS WHILE THE GFLD STAYS BELOW 70 KNOTS. LAWRENCE FORECAST POSITIONS AND MAX WINDS INITIAL 23/0900Z 11.2N 99.0W 55 KTS 12HR VT 23/1800Z 11.9N 100.2W 65 KTS 24HR VT 24/0600Z 13.0N 102.0W 75 KTS 36HR VT 24/1800Z 14.2N 103.7W 85 KTS 48HR VT 25/0600Z 15.5N 105.5W 85 KTS 72HR VT 26/0600Z 18.0N 110.0W 85 KTS NNNN