Tropical Storm HENRI

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TROPICAL DEPRESSION HENRI DISCUSSION NUMBER  21
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 PM EDT MON SEP 08 2003

THE GUILLOTINE HAS FALLEN ON HENRI.  CONTINUOUS VERTICAL SHEAR OF
25-35 KT DURING THE LAST DAY OR TWO HAS WEAKENED ANY WELL-DEFINED
LOW-LEVEL CIRCULATION.  IN ADDITION... THE NORTHWEST SIDE OF THE
CYCLONE IS BECOMING INCREASINGLY INVOLVED WITH A FRONTAL ZONE OVER
THE COASTAL WATERS OF THE SOUTHEAST UNITED STATES.  SATELLITE
IMAGES SHOW COLD-AIR CUMULUS POURING INTO THE WESTERN SEMICIRCLE OF
HENRI...NOT AN ATTRIBUTE OF A TROPICAL CYCLONE.  LARGE-SCALE
SATELLITE IMAGES SHOW A CLOUD PATTERN MORE LIKE AN EXTRATROPICAL
SYSTEM WITH A COMMA-LIKE APPEARANCE ON VISIBLE IMAGERY AND A WARM
FRONTAL FEATURE NORTHEAST OF HENRI.  THUS... HENRI HAS LOST
TROPICAL CHARACTERISTICS.  THERE IS SOME QUESTION ON WHETHER THIS
WEAK SYSTEM IS SUBTROPICAL... BUT THE APPEARANCE OF FRONTAL
FEATURES AND A RADIUS OF MAXIMUM WINDS OVER 100 MILES FROM THE
CENTER LEAD US TO CONCLUDE THAT IT IS INDEED EXTRATROPICAL.  

INITIAL MOTION IS ESTIMATED AT 050/6 WITH A LOT OF UNCERTAINTY DUE
TO THE ELONGATION OF THE LOW-LEVEL CENTER FROM NORTHEAST TO
SOUTHWEST.  THE GFS MODEL SHOWS THE SYSTEM SLOWLY MOVING TO THE
NORTHEAST FOR A COUPLE OF DAYS BEFORE A SHORTWAVE INDUCES WHAT
APPEARS TO BE A NEW LOW PRESSURE AREA ABOUT 300 MILES SOUTH-
SOUTHEAST OF MASSACHUSETTS.  THE NHC TRACK IS JUST A BIT FASTER
THAN THE PREVIOUS ADVISORY IN REASONABLE AGREEMENT WITH THE GFS
MODEL.
 
FORECASTER BLAKE/PASCH
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      08/2100Z 33.0N  75.0W    25 KT...BECOMING EXTRATROPICAL
 12HR VT     09/0600Z 33.5N  74.0W    25 KT...EXTRATROPICAL
 24HR VT     09/1800Z 34.0N  73.0W    25 KT...EXTRATROPICAL
 36HR VT     10/0600Z 34.5N  72.0W    25 KT...EXTRATROPICAL
 48HR VT     10/1800Z 35.0N  71.0W    25 KT...EXTRATROPICAL
 72HR VT     11/1800Z 35.5N  70.0W    20 KT...DISSIPATING
 96HR VT     12/1800Z...DISSIPATED

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