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HURRICANE LENNY DISCUSSION NUMBER  17
NATIONAL WEATHER SERVICE MIAMI FL
10 AM EST WED NOV 17 1999
 
LENNY IS NOW A DANGEROUS CATEGORY FOUR HURRICANE ON THE SAFFIR
/SIMPSON HURRICANE SCALE...THE FIFTH OF THE SEASON.  THIS IS
BASED ON A DROPSONDE IN THE EYEWALL WHICH MEASURED MEAN BOUNDARY
LAYER WINDS OF 118 KNOTS...REPORTS FROM A PLANE OF A MAXIMUM WIND OF
134 KNOTS AT 700 MB AND A MINIMUM MEASURED PRESSURE OF 948 MB AND A
LATER EXTRAPOLATED 942 MB.  SUBJECTIVE T-NUMBERS ARE BETWEEN 6.0 AND
6.5 ON THE DVORAK SCALE WITH A PEAK 7.0 RAW OBJECTIVE T-NUMBER. 
SOME FLUCTUATIONS IN INTENSITY ARE LIKELY DURING THE NEXT 24 TO 36
HOURS.  THEREAFTER...A GRADUAL WEAKENING IS EXPECTED AS LENNY MOVES
INTO A LESS FAVORABLE UPPER-LEVEL ENVIRONMENT.
 
LENNY HAS SLOWED DOWN A LITTLE AND THE BEST ESTIMATE OF THE INITIAL
MOTION IS 055/10.  WITH THE EXCEPTION OF THE UNLIKELY SOLUTION OF
NOGAPS...WHICH TURNS LENNY NORTHWARD TODAY...THE REMAINDER OF THE
MODELS AND THE OFFICIAL FORECAST ARE IN GOOD AGREEMENT...TAKING
LENNY SLOWLY TOWARD THE NORTHEAST OVER THE NORTHEASTERN CARIBBEAN
ISLANDS.  THIS MOTION WAS EXPECTED BECAUSE GLOBAL MODELS HAVE BEEN
DEVELOPING A RIDGE TO THE EAST OF THE LENNY.  IN SUMMARY...THERE HAS
BEEN NO CHANGES IN THE STEERING PATTERN CONTROLLING THE PATH OF THE
HURRICANE. 
 
BECAUSE OF THE SIZE OF THE HURRICANE AND THE TRACK FORECAST
UNCERTAINTIES...ONE MUST NOT FOCUS ON THE EXACT FORECAST TRACK.  
 
IF THE NORTHEASTWARD TREND CONTINUES DURING THE NEXT FEW HOURS AND
THERE ARE NO SIGNS OF A MORE NORTHERLY TRACK...THE WARNINGS FOR
MAINLAND PUERTO RICO..BUT NOT FOR CULEBRA AND VIEQUES WILL LIKELY BE
DOWNGRADED.

AVILA
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     17/1500Z 17.1N  65.1W   115 KTS
12HR VT     18/0000Z 17.8N  64.0W   115 KTS
24HR VT     18/1200Z 19.0N  62.5W   110 KTS
36HR VT     19/0000Z 20.3N  61.0W   100 KTS
48HR VT     19/1200Z 22.0N  59.5W    85 KTS
72HR VT     20/1200Z 24.5N  57.5W    65 KTS
 
 
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