ZCZC MIATCDAT2 ALL TTAA00 KNHC DDHHMM HURRICANE OLGA DISCUSSION NUMBER 18 NATIONAL WEATHER SERVICE MIAMI FL 10 PM EST WED NOV 28 2001 VERTICAL SHEAR...DUE TO UPPER-LEVEL NORTHERLIES...IS IMPACTING OLGA. THE LOW-CLOUD CIRCULATION IS BECOMING MORE EXPOSED OVER THE NORTHERN SEMICIRCLE OF THE SYSTEM...AND THE EYE IS BECOMING POORLY DEFINED. SUBSIDENCE ON THE WEST SIDE OF THE LARGE UPPER-LEVEL TROUGH...THAT OLGA HAS BEEN EMBEDDED IN...MAY ALSO BE CONTRIBUTING TO THE WEAKENING. THE CURRENT INTENSITY...65 KNOTS...IS CONSISTENT WITH SATELLITE-BASED ESTIMATES FROM TAFB MIAMI...SAB WASHINGTON...AND THE AIR FORCE WEATHER AGENCY. A STEADY DECREASE IN INTENSITY IS FORECAST...AT ABOUT THE SAME RATE AS SHOWN IN THE PREVIOUS ADVISORY. NUMERICAL GUIDANCE...IN PARTICULAR THE SHIPS MODEL...DOES NOT WEAKEN OLGA AS FAST AS SHOWN HERE. SHOULD THE VERTICAL SHEAR DIMINISH FOR SOME REASON...THE WEAKENING TREND COULD BE REVERSED SINCE THE CYCLONE IS MOVING OVER WARMER WATERS. HOWEVER...IF THE SYSTEM CONTINUES TO DECLINE AS IT IS DOING AT THE MOMENT...OLGA WOULD WEAKEN FASTER THAN INDICATED HERE. INITIAL MOTION IS ESTIMATED TO BE 220/11 AS THE CYCLONE IS BEING STEERED BY THE FLOW ON THE SOUTHEAST SIDE OF A MID-LEVEL RIDGE. A GRADUAL TURN TO THE RIGHT IS FORECAST OVER THE NEXT FEW DAYS. THIS IS JUST SLIGHTLY SOUTH OF AND FASTER THAN THE TRACK SHOWN IN THE PREVIOUS ADVISORY...AND ABOUT IN THE MIDDLE OF THE CURRENT NUMERICAL GUIDANCE SUITE. FORECASTER PASCH FORECAST POSITIONS AND MAX WINDS INITIAL 29/0300Z 29.9N 58.1W 65 KTS 12HR VT 29/1200Z 28.7N 59.5W 60 KTS 24HR VT 30/0000Z 27.5N 61.5W 55 KTS 36HR VT 30/1200Z 26.5N 63.7W 50 KTS 48HR VT 01/0000Z 26.0N 66.0W 45 KTS 72HR VT 02/0000Z 25.5N 70.0W 35 KTS NNNN