[Tropical] Tropical Cyclone Discussion

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WTNT41 KNHC 201438
TCDAT1
TROPICAL STORM JEANNE DISCUSSION NUMBER  28
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 AM EDT MON SEP 20 2004

THE INITIAL MOTION ESTIMATE IS 020/06. THE PARTIALLY EXPOSED TIGHT
LOW-LEVEL CIRCULATION SEEN IN THE DRY SLOT IN THE INNER-CORE REGION
OF JEANNE HAS BEEN MOVING NORTHEASTWARD UP THE EAST SIDE OF THE
INTERIOR PORTION OF THE CIRCULATION. HOWEVER...OVER THE PAST 2
HOURS...A BURST OF DEEP CONVECTION HAS DEVELOPED OVER THE LOW-LEVEL
CENTER AND HAS PULLED IT MORE NORTHWARD. SO THE FORWARD MOTION IS A
BLEND OF ALL THOSE WOBBLES. IN THE LONGER TERM...THE STEERING FLOW
IS FORECAST BY MOST OF THE NHC MODELS TO REMAIN WEAK...EXCEPT FOR
THE GFS AND THE GFS-BASED BAM MODELS...AS THE TROUGH TO THE NORTH
THAT IS FORECAST TO PICK UP HURRICANE IVAN RUNS OFF AND LEAVES
JEANNE BEHIND. A MID-LEVEL RIDGE IS THEN FORECAST TO BUILD TO THE
NORTH OF JEANNE IN THE WAKE OF THE STRONG TROUGH. THIS FEATURE IS
EXPECTED TO BLOCK ANY SIGNIFICANT NORTHWARD MOTION BY JEANNE
THROUGHOUT THE FORECAST PERIOD. THE OUTLIER MODELS ARE THE GFS AND
BAM MODELS...WHICH TAKE JEANNE DUE EAST...AND THE NAVY COAMPS MODEL
...WHICH MOVES JEANNE DUE WEST. THE OFFICIAL FORECAST TRACK IS JUST
AN UPDATE OF THE PREVIOUS TRACK...EXCEPT TO PUT A SMALL
ANTICYCLONIC LOOP IN THE FORECAST AFTER 72 HOURS...WHICH IS
CONSISTENT WITH THE NHC MODEL CONSENSUS.

JEANNE HAS GOOD BANDING STRUCTURE AND THE CYCLONE COULD REGAIN
HURRICANE STATUS AS EARLY AS TODAY IF IT CAN MIX OUT THE DRY AIR
THAT HAS BEEN WRAPPING INTO THE CENTER. THE UPPER-LEVEL ENVIRONMENT
IS FAVORABLE FOR SOME ADDITIONAL STRENGTHENING FOR THE NEXT 24-36
HOURS. AFTERWARDS...AN EAST-WEST ORIENTED UPPER-LEVEL TROUGH PUSHES
SOUTHWARD AND INDUCES WESTERLY VERTICAL SHEAR ACROSS THE CYCLONE.
THE OFFICIAL INTENSITY FORECAST IS JUST AND UPDATE OF THE PREVIOUS
FORECAST AND IS CONSISTENT WITH THE SHIPS INTENSITY MODEL.

FORECASTER STEWART

FORECAST POSITIONS AND MAX WINDS

INITIAL      20/1500Z 26.8N  71.5W    55 KT
 12HR VT     21/0000Z 27.3N  71.1W    60 KT
 24HR VT     21/1200Z 27.6N  70.3W    65 KT
 36HR VT     22/0000Z 27.5N  69.4W    70 KT
 48HR VT     22/1200Z 27.0N  69.0W    70 KT
 72HR VT     23/1200Z 26.5N  68.5W    70 KT
 96HR VT     24/1200Z 26.0N  69.0W    65 KT
120HR VT     25/1200Z 26.5N  69.0W    60 KT


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