ZCZC MIATCDAT2 ALL TTAA00 KNHC DDHHMM TROPICAL STORM OLGA DISCUSSION NUMBER 32 NATIONAL WEATHER SERVICE MIAMI FL 10 AM EST SUN DEC 02 2001 OLGA REFUSES TO GO AWAY. CONVENTIONAL AND MICROWAVE SATELLITE IMAGERY INDICATE THAT OLGA HAS BECOME BETTER ORGANIZED...DESPITE THE MORE SUBTROPICAL APPEARANCE...AND HAS ALSO STRENGTHENED. OLGA HAS MOVED UNDERNEATH AND MERGED WITH AN UPPER-LEVEL LOW...HENCE THE MORE SUBTROPICAL APPEARANCE IN SATELLITE IMAGERY. THE INITIAL INTENSITY WAS INCREASED TO 40 KT BASED ON A BLEND OF DVORAK SATELLITE INTENSITY ESTIMATES OF 35 KT...T2.5...FROM ALL THREE AGENCIES AND DATA T-NUMBERS OF 3.0...OR 45 KT...A 02/0947 QUIKSCAT OVERPASS INDICATING SEVERAL UNCONTAMINATED 40 KT WIND VECTORS...AND SHIP PGHT REPORTING A PRESSURE OF 1001.1 MB NEAR THE CENTER AT 02/12Z. OUTFLOW HAS ALSO IMPROVED IN ALL QUADRANTS AND IS NOW MORE SYMMETRICAL. THE INITIAL MOTION IS 345/07. A LARGE MID-LEVEL ANTICYCLONE IS SITUATED ABOUT 600 NM EAST OF OLGA AND IS ACTING TO LIFT THE SYSTEM NORTH-NORTHWESTWARD. WATER VAPOR IMAGERY CURRENTLY INDICATES A STRONG SHORTWAVE TROUGH OVER INDIANA MOVING EASTWARD AT 40 KT IN STRONG ZONAL FLOW. EXTRAPOLATION OF THIS FEATURE WOULD PLACE THE TROUGH DUE NORTH OF OLGA IN ABOUT 24 HOURS...A LITTLE FASTER THAN THE 06Z AVN MODEL RUN IS INDICATING...AND CLOSE TO THE UKMET AND NOGAPS POSITIONS. THE RESULT IS THAT THE WEAKNESS IN THE 500 MB RIDGE TO THE NORTH SHOULD DISAPPEAR IN ABOUT 36 TO 48 HOURS... CAUSING OLGA TO UNFORTUNATELY SLOW DOWN AND TURN BACK TO THE WEST... POSSIBLY EVEN LOOPING AGAIN. HOWEVER...ALL OF THE GLOBAL MODELS AGREE ON THE SURFACE TO 700 MB RIDGE AXIS REMAINING INTACT THROUGH THE PERIOD AND THAT SHOULD PREVENT OLGA FROM RECURVING NORTHEASTWARD AND GETTING CAUGHT UP IN THE STRONG POLAR WESTERLIES. THE OFFICIAL FORECAST TRACK IS SLIGHTLY EAST OF THE PREVIOUS TRACK THROUGH 48 HOURS...AND THEN TURNS OLGA BACK TO THE WEST SIMILAR TO THE PREVIOUS FORECAST AFTER THAT. THIS IS CONSISTENT WITH THE AVN...GFDL...AND GFDN MODEL SUITE...EXCEPT THAT MORE WEIGHT WAS PLACED ON THE AVN. THE INTENSITY FORECAST IS AS COMPLICATED AS THE TRACK FORECAST. I AM UNCERTAIN WHETHER OR NOT OLGA WILL GO BACK TO A SUBTROPICAL CYCLONE THAT COULD RESIST VERTICAL SHEAR...OR REMAIN A WARM-CORE TROPICAL CYCLONE WHICH WOULD MAKE VERTICAL SHEAR A SIGNIFCANT FACTOR IN THE INTENSITY FORECAST. THE SHIPS INTENSITY MODEL RAPIDLY WEAKENS AND DISSIPATES THE CYCLONE IN 60 TO 72 HOURS...WHICH IT HAS BEEN DOING FOR THE PAST 36 HOURS...YET OLGA HAS CONTINUED TO STRENGTHEN. THE AVN AND GFDN KEEP THE CYCLONE BETWEEN 50 AND 40 KT...RESPECTIVELY... THROUGH 48 HOURS WITH ONLY SLOW WEAKENING BELOW TROPICAL STORM STRENGTH BY 72 HOURS. THAT SCENARIO WAS FOLLOWED CLOSELY. HOWEVER... IF THE AVN MODEL IS CORRECT IN BUILDING A 200 MB ANTICYCLONE OVER THE SYSTEM IN 72 HOURS AND BEYOND...THE DECREASING VERTICAL SHEAR AND MORE FAVORABLE OUTFLOW PATTERN COULD KEEP OLGA ONGOING FOR SEVERAL MORE DAYS. AS SUCH...THE ONSET OF DISSIPATION WAS PUSHED BACK TO THE 72 HOUR TIME PERIOD. FORECASTER STEWART FORECAST POSITIONS AND MAX WINDS INITIAL 02/1500Z 25.9N 69.3W 40 KTS 12HR VT 03/0000Z 26.9N 69.6W 45 KTS 24HR VT 03/1200Z 27.8N 69.6W 45 KTS 36HR VT 04/0000Z 28.4N 69.5W 40 KTS 48HR VT 04/1200Z 28.7N 69.5W 35 KTS 72HR VT 05/1200Z 28.5N 71.5W 30 KTS...DISSIPATING NNNN