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HURRICANE LENNY DISCUSSION NUMBER   7
NATIONAL WEATHER SERVICE MIAMI FL
10 PM EST SUN NOV 14 1999

SATELLITE PICTURES SHOW LITTLE CHANGE IN THE CLOUD PATTERN OVER THE
PAST FEW HOURS...SO THE INTENSITY APPEARS TO HAVE LEVELLED OFF FOR
THE TIME BEING.  A BURST OF CONVECTION OVER THE CENTER HAS OBSCURED
THE EYE ON THE INFRARED IMAGERY.  HOWEVER AN EYE WITH A DIAMETER OF
15-20 N MI WAS EVIDENT ON A RECENT SSM/I PASS OVER THE HURRICANE.
CURRENT INTENSITY IS HELD AT 70 KNOTS...IN REASONABLE AGREEMENT WITH
DVORAK T-NUMBERS.  ANOTHER HURRICANE HUNTER AIRCRAFT IS SCHEDULED TO
PROVIDE A POSITION AND INTENSITY ESTIMATE AROUND 0600 UTC.

OBVIOUSLY...THE RAPID INTENSIFICATION OF THIS TROPICAL CYCLONE WAS
NOT ANTICIPATED.  THIS AGAIN UNDERSCORES OUR LIMITED ABILITY TO
PREDICT INTENSITY CHANGE.  LENNY IS DEVELOPING A FAIR UPPER-LEVEL
OUTFLOW ANTICYCLONE AND...PRESUMING THAT VERTICAL SHEAR DOES NOT
INCREASE TOO MUCH DURING THE NEXT COUPLE OF DAYS... ADDITIONAL
STRENGTHENING IS CERTAINLY POSSIBLE.  THIS IS INDICATED IN THE
OFFICIAL FORECAST.

THE CENTER HAS SLIPPED A LITTLE TO THE SOUTH BUT MOTION IS ESTIMATED
TO BE GENERALLY EASTWARD AT A SLIGHTLY FASTER FORWARD SPEED...7
KNOTS.  LENNY IS EXPECTED TO BE STEERED BY THE FLOW ON THE SOUTH
SIDE OF A DEEP-LAYER TROUGH OVER THE WESTERN ATLANTIC.  CURRENT
WATER VAPOR IMAGERY SHOWS A REINFORCING VORTICITY MAX MOVING OFF THE
U.S. EAST COAST...AND THE 18Z NCEP GLOBAL MODEL RUN SHOWS ADDITIONAL
VORTICITY ENTERING THE TROUGH DURING THE NEXT COUPLE OF DAYS.  THIS
SHOULD PRODUCE SOME AMPLIFICATION OF THE TROUGH AND AN INCREASED
WESTERLY STEERING FLOW FOR LENNY.  THE OFFICIAL FORECAST SHOWS A
GRADUAL INCREASE IN FORWARD SPEED AND A TURN TOWARD THE EAST-
NORTHEAST...IN GENERAL AGREEMENT WITH THE U.K. MET. OFFICE AND GFDL
MODELS.  THIS IS ALSO VERY SIMILAR TO THE PREVIOUS OFFICIAL TRACK
FORECAST. 

PASCH
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     15/0300Z 16.1N  78.3W    70 KTS
12HR VT     15/1200Z 16.1N  77.2W    75 KTS
24HR VT     16/0000Z 16.4N  74.9W    80 KTS
36HR VT     16/1200Z 16.8N  72.5W    85 KTS
48HR VT     17/0000Z 17.5N  70.0W    85 KTS
72HR VT     18/0000Z 19.0N  65.0W    80 KTS
 
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