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TROPICAL STORM DEAN DISCUSSION NUMBER 11
NATIONAL WEATHER SERVICE MIAMI FL
11 AM EDT TUE AUG 28 2001
DEAN HAS WEAKEND AND IS RAPIDLY BECOMING EXTRATROPICAL. DEEP
CONVECTION NEAR THE LOW-LEVEL CENTER IS NON-EXISTENT AND MODERATE
CONVECTION ON THE SOUTH SIDE OF THE CIRCULATION ALSO CONTINUES TO
WEAKEN. THE INITIAL INTENSITY OF 50 KT IS A BLEND OF A SATELLITE
DVORAK INTENSITY ESTIMATE OF 35 KT...T2.5... AND A CURRENT INTENSITY
ESTIMATE OF 55 KT...CI3.5...FROM TAFB.
THE INITIAL MOTION ESTIMATE IS 065/20. DEAN HAS TURNED BACK TO THE
EAST-NORTHEAST AS A SHORTWAVE TROUGH HAS SPLIT AND DROPPED TO THE
SOUTH OF THE CYCLONE...WHILE SHORTWAVE RIDGING HAS INCREASED TO THE
WEST. THE BACKING FLOW AHEAD OF THE DIGGING LONGWAVE TROUGH OVER
SOUTHEAST CANADA AND THE NORTHEAST U.S. SHOULD ACT TO TURN DEAN BACK
ON A NORTHEASTWARD TRACK AFTER 12 TO 24 HOURS. THE OFFICIAL TRACK
IS A LITTLE TO THE RIGHT OF THE PREVIOUS FORECAST TRACK AND CLOSE TO
THE AVN AND GFDL MODELS.
DEAN IS OVER SUB-20C SST WATER WITH COLDER WATER AHEAD OF THE
SYSTEM. AS SUCH...RAPID EXTRATROPICAL TRANSITION SHOULD OCCUR WITH
ONLY SLOW WEAKENING EXPECTED UNTIL THE SYSTEM IS ABSORBED BY OR
MERGES WITH AN EXTRATROPICAL LOW SOUTH OF GREENLAND AFTER 36 TO 48
HOURS.
THIS IS THE FINAL ADVISORY ON TROPICAL STORM DEAN. ADDITIONAL AND
FUTURE INFORMATION ON THIS SYSTEM CAN BE FOUND IN THE HIGH SEAS
FORECAST ISSUED BY THE MARINE PREDICTION CENTER UNDER AWIPS HEADER
NFDHSFAT1 AND WMO HEADER FZPN02 KWBC.
FORECASTER STEWART
FORECAST POSITIONS AND MAX WINDS
INITIAL 28/1500Z 44.3N 52.2W 50 KTS...BECOMING EXTRATROPICAL
12HR VT 29/0000Z 45.6N 48.6W 50 KTS...EXTRATROPICAL
24HR VT 29/1200Z 48.2N 44.5W 45 KTS...EXTRATROPICAL
36HR VT 30/0000Z 51.1N 39.2W 35 KTS...EXTRATROPICAL
48HR VT 30/1200Z 54.3N 33.8W 30 KTS...EXTRATROPICAL
72HR VT 31/1200Z...ABSORBED BY EXTRATROPICAL LOW
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