ZCZC MIATCDAT2 ALL TTAA00 KNHC DDHHMM TROPICAL DEPRESSION OLGA DISCUSSION NUMBER 27 NATIONAL WEATHER SERVICE MIAMI FL 5 AM AST SAT DEC 01 2001 OLGA CONTINUES TO GENERATE CONVECTION OVER THE EASTERN QUADRANT... ALTHOUGH THE COVERAGE AND INTENSITY HAS DECREASED OVER THE PAST 6 HR. THE CONVECTION ALSO SEEMS TO BE FURTHER AWAY FROM THE CENTER. THE MAXIMUM INTENSITY REMAINS 30 KT BASED ON SATELLITE ESTIMATES FROM TAFB AND AFWA...AN EARLIER SSM/I OVERPASS SHOWING 30 KT WINDS IN THE NORTHERN SEMICIRCLE...AND REPORTS FROM DRIFTING BUOY 41647. THE PARTIALLY-EXPOSED CENTER OF OLGA IS A BIT DIFFICULT TO FIND... AND SMALL LOW CLOUD SWIRLS ROTATING AROUND THE LARGER-SCALE CENTER ARE COMPLICATING THE ISSUE. THE BEST ESTIMATE OF THE INITIAL MOTION IS 240/7...AND THIS MIGHT BE A TRIFLE FAST. SATELLITE IMAGERY AND SURFACE DATA SHOW LOW/MID LEVEL RIDGING NORTH OF OLGA...WITH WATER VAPOR IMAGERY INDICATING AN UPPER LEVEL LOW NEAR 27N 66W. SINCE OLGA IS SIGNIFICANTLY SHEARED...IT SHOULD BE STEERED GENERALLY WESTWARD BY THE FLOW AROUND THE LOW/MID LEVEL RIDGE. THE OFFICIAL FORECAST TRACK IS SIMILAR TO...BUT A LITTLE SOUTH OF...THE PREVIOUS FORECAST...CALLING FOR THE CURRENT WEST-SOUTHWESTWARD MOTION TO BECOME WESTWARD BY 24 HR AND WEST-NORTHWESTWARD BY 48 HR. IT SHOULD BE NOTED THAT THE FORECAST TRACK IS ALONG THE SOUTH EDGE OF THE GUIDANCE. ANALYSES OF VERTICAL SHEAR AND SHEAR TENDENCY FROM CIMSS AT THE UNIVERSITY OF WISCONSIN INDICATES THAT THE SHEAR OVER OLGA HAS DECREASED TO ABOUT 20 KT. SOME FURTHER DECREASE IN SHEAR IS POSSIBLE IN THE NEXT 24-36 HR AS THE UPPER LOW APPROACHES. HOWEVER...OLGA WILL LIKELY BE LOCATED ON WHAT IS NORMALLY THE SIDE OF THE UPPER LOW DOMINATED BY SUBSIDENCE...A LESS THAN IDEAL LOCATION. THUS...IF THE DECREASE IN SHEAR HAS ANY EFFECT...IT MOST LIKELY WOULD ONLY LENGTHEN THE LIFE OF OLGA AS A DEPRESSION BY 12-24 HR FROM WHAT IS CURRENTLY FORECAST. LARGE-SCALE MODELS INDICATE STRONGER WESTERLY FLOW IMPACTING OLGA FROM 48 HR ONWARD... AND THAT SHOULD FINISH THE CYCLONE OFF IF IT HAS NOT YET ALREADY DIED. FORECASTER BEVEN FORECAST POSITIONS AND MAX WINDS INITIAL 01/0900Z 22.9N 68.7W 30 KTS 12HR VT 01/1800Z 22.6N 69.6W 25 KTS...DISSIPATING 24HR VT 02/0600Z 22.6N 71.0W 25 KTS...REMNANT LOW 36HR VT 02/1800Z 22.7N 72.2W 25 KTS...REMNANT LOW 48HR VT 03/0600Z 22.9N 73.3W 20 KTS...REMNANT LOW 72HR VT 04/0600Z 23.5N 75.5W 20 KTS...REMNANT LOW NNNN