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HURRICANE LENNY DISCUSSION NUMBER  16
NATIONAL WEATHER SERVICE MIAMI FL
4 AM EST WED NOV 17 1999
 
REPORTS FROM AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT INDICATE
LENNY CONTINUES TO STRENGTHEN. THE CENTRAL PRESSURE HAS DROPPED TO
950 MB WITH MAXIMUM 700 MB WINDS OF 120 KT IN THE SOUTHEAST
QUADRANT. A SOUTHEAST EYEWALL DROPSONDE HAD 132 KT WINDS AT 924 MB
AND 110 KT JUST ABOVE THE SURFACE. AN EYE IS BECOMING APPARENT IN
INFRARED IMAGERY...AND THE SATELLITE INTENSITY ESTIMATES ARE 127
KT...115 KT...AND 102 KT FROM TAFB...SAB...AND AFWA RESPECTIVELY.
BASED ON THIS...THE MAXIMUM WINDS ARE INCREASED TO 110 KT ON THIS
PACKAGE.

LENNY MAY BE STARTING ITS NORTHEASTWARD TURN. THE 12 HOUR AND
ADVISORY MOTION IS 065/12...AND A SHORTER TERM MOTION IS MORE
NORTHEASTERLY. WATER VAPOR AND INFRARED IMAGERY INDICATES A RIDGE IS
STARTING TO DEVELOP EAST OF LENNY...WHICH SHOULD EVENTUALLY NUDGE
LENNY ONTO A NORTHEAST TRACK. THE BIGGEST QUESTION IS THE FORWARD
MOTION. THE ECMWF AND NOGAPS MODELS SLOW LENNY BEFORE THE STORM
REACHES THE CARIBBEAN ISLANDS. THE AVN...UKMET...AND HURRICANE
GUIDANCE ARE MORE PROGRESSIVE...SLOWING THE STORM AFTER IT MOVES
INTO THE OPEN ATLANTIC. THE OFFICIAL FORECAST FOLLOWS THE LATTER
SOLUTION...AS THERE IS NO OBVIOUS REASON LENNY SHOULD STALL BEFORE
REACHING THE ISLANDS.
 
LENNY CONTINUES TO HAVE GOOD OUTFLOW IN ALL QUADRANTS EXCEPT THE
WEST...ALONG WITH VERY COLD CLOUD TOPS. SOME FURTHER STRENGTHENING
IS POSSIBLE TODAY. AFTER THE HURRICANE PASSES THROUGH THE
ISLANDS...A COMBINATION OF COOLER WATER AND INCREASING VERTICAL
SHEAR SHOULD CAUSE CONSIDERABLE WEAKENING.
 
BECAUSE OF THE SIZE OF THE HURRICANE AND THE TRACK FORECAST
UNCERTAINTIES...ONE MUST NOT FOCUS ON THE EXACT FORECAST TRACK.
 
BEVEN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     17/0900Z 16.7N  66.0W   110 KTS
12HR VT     17/1800Z 17.7N  64.4W   115 KTS
24HR VT     18/0600Z 19.2N  62.5W   110 KTS
36HR VT     18/1800Z 20.6N  60.8W   100 KTS
48HR VT     19/0600Z 21.5N  59.5W    85 KTS
72HR VT     20/0600Z 23.5N  57.5W    65 KTS
 
 
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