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TROPICAL DEPRESSION LILI DISCUSSION NUMBER  22
NATIONAL WEATHER SERVICE MIAMI FL
11 PM EDT THU SEP 26 2002
 
A 26/2319Z QUIKSCAT OVERPASS INDICATED THAT THE REMNANT LOW PRESSURE
SYSTEM ASSOCIATED WITH LILI HAS BECOME MUCH BETTER ORGANIZED AND
THAT A WELL-DEFINED CLOSED CIRCULATION IN THE LOW-LEVEL WIND FIELD
NOW EXISTS.  IN ADDITION...A 26/2309Z SSMI MICROWAVE OVERPASS
INDICATED A TIGHT LOW-LEVEL CIRCULATION JUST SOUTHWEST OF THE
STRONGEST CONVECTION.  CLOUD TOPS HAVE ALSO COOLED TO -80 TO -85C
DURING THE PAST 4 HOURS AND THE OVERALL CONVECTIVE PATTERN HAS
CONTINUED TO IMPROVED...EVEN THOUGH IT IS STILL SHEARED.  BASED ON
THIS INFORMATION...ADVISORIES HAVE BEEN RE-INITIATED ON TROPICAL
DEPRESSION LILI.  THE INITIAL INTENSITY OF 30 KT IS CONSERVATIVELY
BASED ON QUIKSCAT WIND DATA.  HOWEVER...  SATELLITE INTENSITY
ESTIMATES FROM TAFB AND SAB ARE 45 KT AND 35 KT...RESPECTIVELY...AND
STRONGER WINDS IN GUSTS TO TROPICAL STORM FORCE LIKELY EXIST IN THE
DEEPER CONVECTION THAT IS SHEARED TO THE NORTH AND EAST OF THE
CENTER.  AN AIR FORCE RESERVE RECONNAISSANCE AIRCRAFT WILL
INVESTIGATE THE CYCLONE FRIDAY MORNING AND WILL PROVIDE A BETTER
ASSESSMENT OF THE LOCATION AND INTENSITY.

THE INITIAL MOTION ESTIMATE IS 300/05...WITH EMPHASIS ON THE WORD 
ESTIMATE. THE NHC MODEL GUIDANCE IS IN GOOD AGREEMENT ON LILI MOVING 
WEST-NORTHWEST TO NORTHWESTWARD NEAR THE EASTERN TIP OF JAMAICA IN 
ABOUT 36 HOURS...AND THEN TURNING MORE WEST-NORTHWEST OR WESTWARD 
AFTER 48 HOURS ONCE LILI CLEARS JAMAICA. THE FORWARD SPEED OF LILI 
IS PROBLEMATIC WITH MODEL SPEEDS RANGING FROM AS LOW 5 KT BY THE 
AVN/GFS MODEL AND AS HIGH AS 12 KT BY THE NOGAPS MODEL. THE OFFICIAL 
TRACK WILL USE A MIDDLE-OF-THE-ROAD VALUE OF 7 TO 8 KT UNTIL A GOOD 
CENTER LOCATION AND INITIAL FORWARD MOTION CAN BE ESTABLISHED BY 
RECON DATA.

THE UPPER-LEVEL SHEAR THAT HAS BEEN HINDERING LILIS DEVELOPMENT THE 
PAST FEW DAYS HAS SHOWN SIGNS OF LETTING UP SOME DURING THE PAST 12 
HOURS. HOWEVER...SIGNIFICANT SHEAR STILL EXISTS AND ALL OF THE 
GLOBAL MODELS HAVE BEEN TOO QUICK IN FORECASTING THE SHEAR TO LET 
UP. BY 36 HOURS...THOUGH...ALL OF THE MODELS INDICATE THE ELONGATED 
UPPER-LEVEL TROUGH TO THE WEST OF LILI WILL WEAKEN AND MOVE RAPIDLY 
WESTWARD...WHICH WILL PLACE LILI UNDER MORE FAVORABLE EASTERLY 
UPPER-LEVEL FLOW. HOWEVER...UNTIL THE CENTER CONSOLIDATES WITHIN THE 
DEEP CONVECTION...THE OFFICIAL INTENSITY FORECAST WILL REMAIN BELOW 
THE SHIPS INTENSITY MODEL FORECAST...WHICH BRINGS LILI TO 75 KT IN 
72 HOURS.
 
FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     27/0300Z 15.7N  73.5W    30 KTS
12HR VT     27/1200Z 16.2N  74.3W    35 KTS
24HR VT     28/0000Z 17.0N  75.3W    40 KTS
36HR VT     28/1200Z 18.0N  76.3W    45 KTS
48HR VT     29/0000Z 18.9N  77.5W    50 KTS
72HR VT     30/0000Z 20.5N  80.5W    60 KTS
 
 
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