ZCZC MIATCDAT2 ALL TTAA00 KNHC DDHHMM TROPICAL STORM OLGA DISCUSSION NUMBER 21 NATIONAL WEATHER SERVICE MIAMI FL 4 PM EST THU NOV 29 2001 THE CENTER OF OLGA HAS BECOME EXPOSED TO THE NORTH OF THE CONVECTION AS ANALYSES FROM CIMSS AT THE UNIVERSITY OF WISCONSIN CONTINUE TO SHOW 20-30 KT OF VERTICAL SHEAR OVER THE SYSTEM. SHIP HBEB REPORTED 34 KT WINDS AND A 1001.2 MB PRESSURE ABOUT 45 NM SOUTHWEST OF THE CENTER AT 18Z...AND THE SHIP WAS LIKELY NOT IN THE AREA OF STRONGEST WINDS. SATELLITE INTENSITY ESTIMATES ARE 55 KT...SO THAT IS THE INITIAL INTENSITY FOR THIS ADVISORY. THE INITIAL MOTION IS NOW 235/17. THERE IS LITTLE CHANGE IN THE SYNOPTIC PATTERN DRIVING OLGA...AS THE SYSTEM IS MOVING SOUTHWESTWARD AROUND THE SOUTHEAST SIDE OF A DEEP-LAYER RIDGE OVER THE SOUTHEASTERN U. S. AND THE ADJACENT ATLANTIC. THIS RIDGE SHOULD WEAKEN AFTER 24-36 HR AS A TROUGH AND ASSOCIATED FRONTAL SYSTEM MOVE TOWARD THE U. S. EAST COAST. THIS PATTERN SHOULD ALLOW OLGA TO MOVES SOUTHWESTWARD FOR 24 HR OR SO...THEN GRADUALLY SLOW DOWN AND TURN WESTWARD. THE TRACK GUIDANCE MODELS ARE IN GOOD AGREEMENT WITH THIS SCENARIO...WITH THE MAJOR DIFFERENCES BEING IN SPEED. THE OFFICIAL TRACK FORECAST IS SIMILAR TOO BUT CONSIDERABLY FASTER THAN THE PREVIOUS PACKAGE... BASED ON THE CURRENT MOTION AND ADJUSTING THE FORECAST CLOSER TO THE FASTER MODEL GUIDANCE. LARGE-SCALE MODELS INDICATE THE CURRENT VERTICAL SHEAR SHOULD CONTINUE FOR AT LEAST 36 HR...AND OLGA SHOULD CONTINUE TO STEADILY WEAKEN DURING THAT TIME. SOME DECREASE IN THE SHEAR MAY OCCUR IN ABOUT 36-60 HR...BUT THIS IS LIKELY TO BE SHORT-LIVED AND OLGA WILL LIKELY BE TOO DISORGANIZED TO TAKE ADVANTAGE OF THE DECREASE. THUS...THE CYCLONE IS FORECAST TO BE DISSIPATING IN 72 HR. FORECASTER BEVEN FORECAST POSITIONS AND MAX WINDS INITIAL 29/2100Z 26.9N 62.6W 55 KTS 12HR VT 30/0600Z 25.7N 64.8W 50 KTS 24HR VT 30/1800Z 24.8N 67.5W 45 KTS 36HR VT 01/0600Z 24.5N 70.1W 40 KTS 48HR VT 01/1800Z 24.5N 72.2W 35 KTS 72HR VT 02/1800Z 24.5N 75.0W 25 KTS...DISSIPATING NNNN