720
WTNT45 KNHC 080233
TCDAT5
TROPICAL DEPRESSION HENRI DISCUSSION NUMBER 6
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL102009
1100 PM AST WED OCT 07 2009
SATELLITE IMAGES AND MICROWAVE DATA INDICATE THAT THE LOW-LEVEL
CENTER OF HENRI IS LOCATED WELL TO THE WEST OF A PERSISTENT AREA OF
OF DEEP CONVECTION. THIS ASYMMETRIC STRUCTURE IS DUE TO ABOUT
25 KT OF SOUTHWESTERLY VERTICAL WIND SHEAR. DVORAK INTENSITY
ESTIMATES HAVE DECREASED AND ON THIS BASIS...HENRI IS BEING
DOWNGRADED TO A TROPICAL DEPRESSION WITH THE INITIAL INTENSITY SET
AT 30 KT. THE STRONG SOUTHWESTERLY SHEAR IS EXPECTED TO PERSIST
FOR ANOTHER 12 HOURS WHICH SHOULD CONTINUE TO DECOUPLE THE CYCLONE.
GLOBAL MODELS SHOW THAT HENRI...OR ITS REMNANTS...WILL BE MOVING
UNDER AN UPPER-LEVEL SHEAR AXIS BETWEEN 12 AND 36 HOURS.
THEREAFTER...STRONG NORTHEASTERLY MID- TO UPPER-LEVEL FLOW WILL
IMPACT THE SYSTEM. THIS UNFAVORABLE ATMOSPHERIC ENVIRONMENT SHOULD
LEAD TO CONTINUED WEAKENING AS UNANIMOUSLY SHOWN BY THE DYNAMICAL
MODELS. THE OFFICIAL FORECAST IS SIMILAR TO THE PREVIOUS ONE AND
CALLS FOR HENRI TO DEGENERATE INTO A REMNANT LOW WITHIN 24 HOURS.
THE INITIAL MOTION IS 285/13...SLIGHTLY TO THE SOUTH OF THE PREVIOUS
ADVISORY. THIS MOTION IS EXPECTED TO CONTINUE FOR ABOUT ANOTHER
DAY. THEREAFTER...A STRONG DEEP-LAYER RIDGE WILL BUILD OVER THE
WESTERN ATLANTIC CAUSING HENRI...OR ITS REMNANTS...TO TURN WESTWARD
OR SOUTHWESTWARD. THE NEW TRACK FORECAST IS NUDGED A LITTLE TO THE
SOUTH TO ACCOUNT FOR THE INITIAL HEADING AND IS NEAR THE BAM
SHALLOW.
FORECAST POSITIONS AND MAX WINDS
INITIAL 08/0300Z 19.5N 59.7W 30 KT
12HR VT 08/1200Z 20.1N 61.3W 30 KT
24HR VT 09/0000Z 20.7N 63.0W 25 KT...REMNANT LOW
36HR VT 09/1200Z 20.9N 65.0W 20 KT...REMNANT LOW
48HR VT 10/0000Z 20.6N 67.1W 20 KT...REMNANT LOW
72HR VT 11/0000Z...DISSIPATED
FORECASTER CANGIALOSI/BEVEN
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