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HURRICANE LILI DISCUSSION NUMBER  38
NATIONAL WEATHER SERVICE MIAMI FL
11 PM EDT MON SEP 30 2002
 
LILI CONTINUES TO LOOK MORE IMPRESSIVE IN SATELLITE IMAGERY WITH THE 
CENTER NOW EMBEDDED IN THE MIDDLE OF A VERY COLD-TOPPED CENTRAL 
DENSE OVERCAST FEATURE. SATELLITE INTENSITY ESTIMATES ARE T4.5...OR 
77 KT FROM BOTH TAFB AND AFWA...WHILE 3-HR OBJECTIVE DVORAK 
T-NUMBERS ARE ABOUT 80 KT...OR T4.8. HOWEVER...NONE OF THIS APPEARS 
TO BE TRANSLATING DOWN TO THE SURFACE AS AN INCREASE IN WIND SPEED. 
WHILE THE SURFACE PRESSURE OF 978 MB SUPPORTS ABOUT 78 KT...THE 
INITIAL INTENSITY WAS HELD AT 70 KT BASED ON A 700 MB FLIGHT-LEVEL 
WIND OF 77 KT AND A 934 MB DROPSONDE WIND OF 94 KT. THESE WINDS 
CORRESPOND TO APPROXIMATELY 69 KT AND 71 KT SURFACE WINDS... 
RESPECTIVELY. UPPER-LEVEL OUTFLOW IS EXCELLENT IN THE SOUTHERN 
SEMICIRCLE AND FAIR TO GOOD TO THE NORTH.
 
THE INITIAL MOTION REMAINS 300/9. LILI APPEARS TO HAVE STEADIED ON 
THIS GENERAL COURSE AND IT LOOKS LIKE THERE WILL BE LITTLE DEVIATION 
ABOUT THIS MEAN COURSE FOR THE NEXT 36 TO 48 HOURS. THE DEEP LAYER 
SUBTROPICAL RIDGE THAT EXTENDS FROM BERMUDA ACROSS THE SOUTHEAST 
UNITED STATES IS FORECAST TO REMAIN IN PLACE THROUGHOUT THE FORECAST 
PERIOD. THE 500 MB RIDGE AXIS IS FORECAST TO LIE ALONG 31-32N 
LATITUDE AND SHOULD BE THE AXIS OF RECURVATURE AT OR BEYOND 72 
HOURS. THE NHC MODEL GUIDANCE REMAINS REMARKABLY CONVERGENT ON A 
TRACK ACROSS EXTREME WESTERN CUBA IN ABOUT 18 HOURS AND THEN ENDING 
UP NEAR THE SOUTHWEST COAST OF LOUISIANA IN 72 HOURS. THE ONLY 
UNNERVING PART OF THE MODEL GUIDANCE IS THE GFS/AVN 10-MEMBER 
ENSEMBLE MODEL WHICH TAKES LILI DUE NORTH AFTER 48 HOURS TO A 
POSITION JUST SOUTH OF NEW ORLEANS. WATER VAPOR IMAGERY INDICATES 
THE DEEP MID- TO UPPER-LEVEL TROUGH OVER THE WESTERN U.S. CONTINUES 
TO DIG SOUTHWARD. MORE AMPLIFICATION OF THE TROUGH THAN THE GLOBAL 
MODELS ARE INDICATING COULD CAUSE THE SUBTROPICAL RIDGE OVER THE 
SOUTHEAST U.S. TO LIFT A LITTLE MORE NORTHWARD. THE INCREASING 
SOUTHWESTERLY MID-LEVEL FLOW AHEAD OF THE TROUGH COULD ALSO PUSH 
LILI A LITTLE MORE INTO THE WESTERN PERIPHERY OF THE RIDGE...MAKING 
THE GFS/AVN ENSEMBLE MODEL A VIABLE FORECAST. THE OFFICIAL FORECAST 
TRACK IS JUST AN EXTENSION OF THE PREVIOUS FORECAST TRACK THROUGH 48 
HOURS...WITH JUST A SLIGHT SHIFT EASTWARD AT 72 HOURS OUT OF RESPECT 
FOR THE GFS/AVN ENSEMBLE MODEL.

THE CENTRAL PRESSURE HAS DECREASED 6 MB IN THE PAST 6 HOURS...SO 
LILI MAY BE STARTING TO RAPIDLY INTENSIFY. THE SATELLITE SIGNATURES 
ALSO SUGEGST THIS...SO THE INTENSIFICATION RATE WAS INCREASED DURING 
THE NEXT 12 HOURS...AFTER WHICH LAND INTERACTION WITH CUBA SHOULD 
DISRUPT THE STRENGTHENING PROCESS. THE WATER OVER THE GULF OF MEXICO 
HAS BEEN CHURNED UP PRETTY GOOD BY FORMER HURRICANE ISIDORE...BUT 
THE WATER IS WARM ENOUGH FOR CONTINUED INTENSIFICATION AND ALSO 
SUPPORTS MAJOR HURRICANE INTENSITY. THE GFDL MODEL NOW BRINGS LILI 
TO 103 KT IN ABOUT 60 HOURS. THE FSU SUPERENSEMBLE BRINGS LILI UP TO 
148 KT IN 72 HOURS...WHICH SEEMS MUCH TOO HIGH GIVEN THE COLD 
UPWELLING THAT HAS OCCURRED IN THE WAKE OF ISIDORE.
 
FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     01/0300Z 20.7N  81.5W    70 KTS
12HR VT     01/1200Z 21.8N  83.2W    85 KTS
24HR VT     02/0000Z 23.1N  85.8W    90 KTS
36HR VT     02/1200Z 24.5N  88.3W    95 KTS
48HR VT     03/0000Z 25.8N  90.8W   100 KTS
72HR VT     04/0000Z 29.5N  93.0W   105 KTS
 
 
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