[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT43 KNHC 031430
TCDAT3
TROPICAL STORM HARVEY DISCUSSION NUMBER   4
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 AM EDT WED AUG 03 2005

WHILE THE CYCLONE STILL HAS SUBTROPICAL CHARACTERISTICS...
INCLUDING THE LARGE BAND WELL REMOVED FROM THE CENTER TO THE NORTH
AND EAST...THE DEFINITION OF THE CIRCULATION CENTER HAS IMPROVED
SINCE YESTERDAY.  A QUIKSCAT PASS AT 1036Z INDICATED A LARGE AREA
OF UNFLAGGED 30 KT WINDS...WITH QUITE A FEW UNFLAGGED 35 KT VECTORS
IN THE RELATIVELY DRY SOUTHEASTERN QUADRANT.  STORM INTENSITY IS
ALSO SUPPORTED BY A 35 KT REPORT FROM SHIP W6SOT AT 12Z NEAR THE
CENTER...AND BY A T2.5 DVORAK CLASSIFICATION FROM TAFB.  A
RECONNAISSANCE AIRCRAFT WILL BE INVESTIGATING HARVEY THIS
AFTERNOON.

AN UPPER-LEVEL LOW JUST TO THE SOUTH OF HARVEY IS PRODUCING EASTERLY
SHEAR AND SUBSIDENCE IN THE CYCLONE'S EASTERN QUADRANT.  GLOBAL
MODEL GUIDANCE INDICATES THAT THE INFLUENCE OF THE UPPER LOW WILL
DIMINISH...BUT THE GUIDANCE ALSO SHOWS MODERATE WESTERLY SHEAR WILL
OVERTAKE THE CYCLONE OVER THE NEXT FEW DAYS. THERE COULD BE A BRIEF
PERIOD IN A DAY OR SO WHERE THE SHEAR RELAXES AND PERMITS SOME
ADDITIONAL STRENGTHENING. THE OFFICIAL INTENSITY FORECAST IS A
BLEND OF THE SHIPS AND GFDL GUIDANCE.

THE INITIAL MOTION ESTIMATE IS 030/9. THERE HAS BEEN LITTLE CHANGE
TO THE TRACK FORECAST THINKING. A MID-TROPOSPHERIC SHORTWAVE TROUGH
CURRENTLY NEAR THE CANADIAN MARITIMES IS EXPECTED TO MOVE AHEAD OF
THE TROPICAL CYCLONE AND THE NEXT UPSTREAM SHORTWAVE SHOULD BE
NEARING THE LONGITUDE OF THE CYCLONE IN ABOUT 72 HOURS. ALTHOUGH
NEITHER OF THESE TROUGHS HAVE SUFFICIENT AMPLITUDE TO PULL HARVEY
INTO THE MID-LATITUDES...THE GUIDANCE INDICATES THAT THERE WILL BE
ENOUGH WEST-SOUTHWESTERLY FLOW TO STEER THE TROPICAL CYCLONE ON A
NORTHEASTERLY TO EAST-NORTHEASTERLY TRACK OVER THE FORECAST PERIOD.
TRACK GUIDANCE CONTINUES TO COME INTO BETTER AGREEMENT AND THE
OFFICIAL FORECAST IS CLOSE TO THE PREVIOUS ADVISORY AND THE
DYNAMICAL MODEL CONSENSUS.

HARVEY IS THE EARLIEST-FORMING EIGHTH TROPICAL STORM ON RECORD.  IN
THOSE YEARS THAT HAVE HAD AT LEAST EIGHT STORMS...WHICH IS ONLY
ABOUT HALF OF ALL SEASONS SINCE 1851...THE MEAN DATE OF FORMATION
FOR THE EIGHTH STORM IS SEPTEMBER 29TH.

FORECASTER FRANKLIN


FORECAST POSITIONS AND MAX WINDS

INITIAL      03/1500Z 30.8N  68.0W    35 KT
 12HR VT     04/0000Z 31.8N  66.6W    40 KT
 24HR VT     04/1200Z 32.6N  64.3W    45 KT
 36HR VT     05/0000Z 33.3N  61.7W    40 KT
 48HR VT     05/1200Z 34.0N  59.5W    35 KT
 72HR VT     06/1200Z 35.5N  56.0W    35 KT
 96HR VT     07/1200Z 38.0N  51.0W    30 KT
120HR VT     08/1200Z 41.0N  45.0W    30 KT


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