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TROPICAL STORM LILI DISCUSSION NUMBER 33
NATIONAL WEATHER SERVICE MIAMI FL
5 PM EDT SUN SEP 29 2002
AIRCRAFT FIXES OVER THE PAST 12 HOURS CONTINUE TO SHOW A SLOW
WESTWARD MOTION JUST OFFSHORE THE NORTH COAST OF JAMAICA. LILI HAS A
TIGHT INNER-CORE CIRCULATION WITH A WELL-DEFINED EYE THIS IS ONLY 8
TO 10 NMI IN DIAMETER. DEEP CONVECTION HAS CONTINUED TO DEVELOP
AROUND THE LOW-LEVEL CENTER AND OUTER BANDING FEATURES HAVE ALSO
IMPROVED DURING THE DAY. THE HIGHEST 850 MB FLIGHT-LEVEL WIND
REPORTED THIS AFTERNOON WAS 66 KT...EQUAL TO ABOUT 53 KT AT
THE SURFACE...AND A MINIMUM PRESSURE OF 995 MB. UPPER-LEVEL OUTFLOW
REMAINS GOOD IN ALL QUADRANTS AND IT TOO CONTINUES TO IMPROVE.
THE INITIAL MOTION ESTIMATE IS 270/04. LILI HAS STEADILY WOBBLED
SLOWLY WESTWARD JUST OFFSHORE THE NORTH COAST OF JAMAICA TODAY. BUT
AS MENTIONED IN THE PREVIOUS DISCUSSION...A GOOD SOUTHWESTERLY SURGE
LOCATED SOUTH OF JAMAICA WILL PROBABLY JOG LILI NORTHWARD A LITTLE
ONCE THE CYCLONE CLEARS THE WESTERN END OF JAMAICA IN ABOUT 12
HOURS. BEYOND THAT...THERE IS NO SIGINIFICANT CHANGE TO THE PREVIOUS
FORECAST TRACK OR REASONING. LILI IS EXPECTED TO MOVE
WEST-NORTHWESTWARD AROUND THE SOUTHERN PERIPHERY OF A STRENGTHENING
SUBTROPICAL HIGH THAT IS EXPECTED TO EXTEND WESTWARD ACROSS FLORIDA
AND THE SOUTHEAST U.S...AND BY 72 HOURS...INTO THE EASTERN GULF OF
MEXICO. THE NHC MODEL GUIDANCE HAS BECOME MORE CONVERGENT AND IS IN
EXCELLENT AGREEMENT ON TAKING LILI ACROSS WESTERN CUBA IN 36 TO 48
HOURS. THE UKMET AND NOGAPS MODELS REMAIN ON THE FAR LEFT SIDE OF
THE MODEL SUITE...WHILE THE AVN/GFS AND AVN/GFS ENSEMBLE MODELS ARE
ON THE FAR RIGHT SIDE OF THE GUIDANCE ENVELOPE. THE GFDL HAS
ACTUALLY DONE THE BEST WITH THE OVERALL TRACK AND DIRECTION OF
LILI...ALBEIT TOO FAST. THE OFFICIAL FORECAST TRACK IS JUST AN
EXTENSION OF THE PREVIOUS TRACK AND IS AGAIN SIMILAR TO THE GFDL IN
DIRECTION...BUT SLOWER LIKE THE AVN/GFS MODEL.
THE INTENSITY FORECAST REMAINS PROBLEMATIC SINCE LILI HAS MAINTAINED
A SMALL DIAMETER EYE ALL DAY. USUALLY...RAPID INTENSIFICATION OCCURS
WITH SUCH SYSTEMS...AND THE LATEST SHIPS INTENSITY MODEL IS
INDICATING THAT ALL FIVE 24-HOUR RAPID INTENSIFICATION CRITERIA HAVE
BEEN FOR THE FIRST TIME. HOWEVER...THE CLOSE PROXIMITY TO JAMAICA
WILL LIKELY PREVENT RAPID INTENSIFICATION FROM OCCURING FOR AT LEAST
THE NEXT 12 HOURS OR SO. HOWEVER...UPPER-LEVEL CONDITIONS ARE
EXPECTED TO BE VERY FAVORABLE FOR SIGNIFICANT STRENGTHENING TO OCCUR
IN THE 24 TO 36 HOURS TIME FRAME...AND RAPID INTENSIFICATION COULD
CERTAINLY OCCUR AT THAT TIME. THE OFFICIAL INTENSITY FORECAST
REMAINS BELOW THE SHIPS INTENSITY MODEL...BUT ONLY BECAUSE OF THE
POSSIBILITY OF AN EYEWALL REPLACEMENT CYCLE BEGINNING AS ALLUDED TO
BY THE RECON FLIGHT CREW DURING THEIR LAST PASS THROUGH THE CENTER.
THE SHIPS MODEL BRINGS LILI TO 94 KT IN 72 HOURS...WHILE THE GFDL
MODEL STRENGTHENS LILI TO 102 KT IN 60 HOURS. IT IS ALSO NOTEWORTHY
TO MENTION THAT THE EXPERIMENTAL SHIPS UPPER-OCEAN HEAT CONTENT
INTENSITY FORECAST...WHICH DID QUITE WELL WITH ISIDORE...BRINGS LILI
UP TO 111 KT IN 72 HOURS.
FORECASTER STEWART
FORECAST POSITIONS AND MAX WINDS
INITIAL 29/2100Z 18.7N 77.8W 50 KTS
12HR VT 30/0600Z 19.5N 78.9W 55 KTS
24HR VT 30/1800Z 20.5N 80.6W 60 KTS
36HR VT 01/0600Z 21.7N 82.5W 70 KTS
48HR VT 01/1800Z 22.8N 84.7W 80 KTS
72HR VT 02/1800Z 25.4N 88.7W 90 KTS
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