ZCZC MIATCDAT4 ALL TTAA00 KNHC DDHHMM TROPICAL STORM IVAN DISCUSSION NUMBER 7 NATIONAL WEATHER SERVICE MIAMI FL 11 PM EDT MON SEP 21 1998 SATELLITE IMAGERY INDICATES A SHEARED PATTERN WITH THE CENTER OF IVAN ON THE SOUTHWEST SIDE OF THE DEEPEST CONVECTION. INITIAL INTENSITY IS INCREASED TO 45 KNOTS...IN AGREEMENT WITH DVORAK ESTIMATES FROM BOTH TAFB AND SAB. DEEP CONVECTION CONTINUES TO DEVELOP IN SPITE OF THE SHEAR. WATER VAPOR IMAGERY SUGGESTS THE UPPER-LEVEL LOW CUTTING OFF TO THE SOUTHWEST OF THE STORM MAY ENHANCE THE OUTFLOW ...SO STRENGTHENING IS FORECAST. INITIAL MOTION IS CURRENTLY TOWARD THE NORTHWEST NEAR 10 KNOTS. THE FUTURE TRACK WILL DEPEND...IN PART...ON HOW STRONG THE SYSTEM BECOMES. THE CURRENT TRACK IS SIMILAR TO THE PREVIOUS TRACK...BUT IF IVAN BECOMES STRONGER THAN FORECAST THE ACTUAL TRACK MAY BE TO THE RIGHT AND IF IT BECOMES SHEARED...THE ACTUAL TRACK MAY BE TO THE LEFT OF THE FORECAST TRACK. MAYFIELD FORECAST POSITIONS AND MAX WINDS INITIAL 22/0300Z 20.2N 36.6W 45 KTS 12HR VT 22/1200Z 21.4N 37.6W 45 KTS 24HR VT 23/0000Z 23.0N 39.0W 50 KTS 36HR VT 23/1200Z 24.5N 40.2W 50 KTS 48HR VT 24/0000Z 26.0N 41.5W 55 KTS 72HR VT 25/0000Z 29.5N 43.5W 55 KTS NNNN