[NCEP Logo] HOME ARCHIVES FORECASTS IMAGERY ABOUT TPC RECONNAISSANCE

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TROPICAL STORM LILI DISCUSSION NUMBER  31
NATIONAL WEATHER SERVICE MIAMI FL
5 AM EDT SUN SEP 29 2002
 
AIRCRAFT FIXES FROM 0152Z...0338Z...AND 0505Z INDICATED A DUE
WESTWARD MOTION HOWEVER MORE RECENT SATELLITE IMAGES...AFTER THE
ECLIPSE BLACKOUT...SUGGESTED A MORE NORTHWARD POSITION.  BLENDING
THE FIXES GIVES ROUGHLY A WEST-NORTHWEST HEADING...290/6.  ALTHOUGH
SOME MORE ERRATIC MOTION MAY OCCUR TODAY...IT IS PRUDENT TO MAINTAIN
GOOD CONTINUITY WITH THE PREVIOUS FORECAST TRACKS.  THE TRACK
FORECAST REASONING IS BASICALLY UNCHANGED.  GLOBAL MODELS SHOW A
MID-TROPOSPHERIC RIDGE TO THE NORTH OF LILI FOR THE NEXT FEW
DAYS...WHICH WOULD MAINTAIN A WEST-NORTHWEST OR NORTHWESTWARD MOTION
THROUGH THE FORECAST PERIOD.  IT IS INTERESTING TO NOTE THAT THE
NCEP GLOBAL MODEL...THE GFS...SHOWS SOME STAIR-STEPPED
MOVEMENT...MORE NORTH...THEN MORE WEST...MORE NORTH...ETC...OVER THE
NEXT COUPLE OF DAYS WHILE MAINTAINING AN OVERALL WEST-NORTHWESTWARD
HEADING.  AS NOTED IN THE PREVIOUS DISCUSSION...FAIRLY SUBTLE
CHANGES IN HEADING COULD MAKE THE DIFFERENCE IN LILI STAYING SOUTH
OF CUBA...MOVING OVER CUBA...OR EVEN ENTERING THE STRAITS OF
FLORIDA.  THE OFFICIAL FORECAST IS ON THE NORTH SIDE OF THE GUIDANCE
ENVELOPE.  IN ANY EVENT...BY 3 DAYS THE TROPICAL CYCLONE SHOULD HAVE
MOVED INTO THE EASTERN GULF OF MEXICO.

THE EARLIER AIRCRAFT RECONNAISSANCE OBSERVATIONS INDICATED AN
EYEWALL STRUCTURE...ALBEIT OPEN TO THE SOUTHWEST ON THE LAST REPORT.
EVEN SO...THE IR SATELLITE PRESENTATION IS STILL NOT THAT
IMPRESSIVE...WITH LITTLE EVIDENCE OF BANDING FEATURES AT THIS
TIME.  HOWEVER THE IMAGES ALSO SHOW A PERSISTENT BALL OF DEEP
CONVECTION NEAR THE ESTIMATED CENTER.  THERE IS A LARGE UPPER-LEVEL
ANTICYCLONE OVER LILI AND VERTICAL SHEAR IS...AND SHOULD
REMAIN...WEAK.  THEREFORE STRENGTHENING IS FORECAST...BUT AT A SLOW
RATE SINCE THE SYSTEM STILL DOES NOT LOOK THAT WELL ORGANIZED.
AFTER LILI MOVES INTO THE GULF...IT CERTAINLY HAS THE POTENTIAL TO
BECOME A SIGNIFICANT HURRICANE.

FORECASTER PASCH
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     29/0900Z 19.1N  77.1W    40 KTS
12HR VT     29/1800Z 19.6N  77.9W    45 KTS
24HR VT     30/0600Z 20.6N  79.3W    50 KTS
36HR VT     30/1800Z 21.6N  80.7W    55 KTS
48HR VT     01/0600Z 22.4N  82.3W    60 KTS
72HR VT     02/0600Z 24.0N  85.5W    70 KTS
 
 
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