300
WTNT45 KNHC 071435
TCDAT5
TROPICAL STORM HENRI DISCUSSION NUMBER 4
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL102009
1100 AM AST WED OCT 07 2009
SATELLITE IMAGES SHOW THAT THE CENTER OF HENRI HAS BECOME EXPOSED
AGAIN TO THE WEST OF A MASS OF DEEP CONVECTION. IN ADDITION...THE
LOW-CLOUD CIRCULATION CENTER LOOKS A LITTLE LESS WELL-DEFINED THAN
YESTERDAY. DVORAK CLASSIFICATIONS HAVE DECREASED SOMEWHAT...AND
THE INITIAL WIND SPEED HAS BEEN REDUCED TO 40 KT FOR THE ADVISORY.
FURTHER WEAKENING IS LIKELY DUE TO SOUTHWESTERLY SHEAR FOR THE NEXT
DAY OR SO. AFTER THAT TIME...MOST OF GLOBAL MODELS INDICATE THAT
HENRI WILL ENCOUNTER A SHARP UPPER-LEVEL SHEAR AXIS...AND THEN COME
UNDER THE INFLUENCE OF STRONG...CONVERGENT...NORTHEASTERLY UPPER
FLOW. THESE ENVIRONMENTAL CONDITIONS ARE RATHER HOSTILE...AND THE
OFFICIAL FORECAST CONTINUES THE TREND OF THE PREVIOUS FORECAST
PACKAGES BY SHOWING THE CYCLONE DISSIPATING WITHIN A COUPLE OF
DAYS.
THE BEST ESTIMATE OF INITIAL MOTION IS 290/13...A LITTLE FASTER THAN
BEFORE. SUBTROPICAL RIDGING OVER THE WESTERN ATLANTIC OCEAN SHOULD
FAVOR A WEST OR WEST-NORTHWEST MOTION OF HENRI OVER THE NEXT 24-36
HOURS. THIS RIDGE IS EXPECTED BECOME STRONGER AFTER THAT
TIME...WHICH SHOULD CAUSE A WESTWARD TURN OF THE TROPICAL CYCLONE
OR ITS REMNANT. MOST OF THE MODEL GUIDANCE IS IN AGREEMENT ON THE
TRACK...AND THE OFFICIAL FORECAST IS CLOSE TO THE PREVIOUS
ADVISORY...AND ON THE SOUTHERN SIDE OF THE GUIDANCE ENVELOPE.
FORECAST POSITIONS AND MAX WINDS
INITIAL 07/1500Z 18.9N 57.4W 40 KT
12HR VT 08/0000Z 19.6N 59.2W 35 KT
24HR VT 08/1200Z 20.6N 61.2W 30 KT
36HR VT 09/0000Z 21.2N 62.7W 25 KT...REMNANT LOW
48HR VT 09/1200Z 21.2N 64.2W 20 KT...REMNANT LOW
72HR VT 10/1200Z...DISSIPATED
FORECASTER BLAKE/PASCH
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