ZCZC MIATCDAT3 ALL
TTAA00 KNHC DDHHMM
TROPICAL STORM LILI DISCUSSION NUMBER 18
NATIONAL WEATHER SERVICE MIAMI FL
5 PM EDT WED SEP 25 2002
LILI HAS BECOME A LITTLE BETTER ORGANIZED BASED ON RECON AND
SATELLITE DATA. HOWEVER...RECON DATA EARLIER THIS AFTERNOON STILL
SHOWED A BROAD LOW-LEVEL CIRCULATION THAT IS LOCATED ALONG THE
WESTERN EDGE OF THE DEEP CONVECTION. RECON WIND DATA INDICATED A
WEAK VORTEX NEAR 14.2N 69.1W WITH A PRESSURE OF 1007 MB...BUT IT WAS
NOT STRONG ENOUGH FOR A VORTEX MESSAGE TO BE GENERATED. 1500 FT
FLIGHT-LEVEL WINDS OF 49 KT...ROUGHLY 40 KT AT THE SURFACE...WERE
INDICATED NORTH OF THE CENTER. IT APPEARS THAT THE CENTER MAY
REFORMING A LITTLE FARTHER TO THE NORTH NEAR THE STRONGER
CONVECTION...BASED ON THE 30 KT EAST WIND JUST NORTH OF THE RECON
CENTER POSITION.
THE INITIAL MOTION 290/06. THE DECREASE IN FORWARD IS PROBABLY DUE
TO THE LOW-LEVEL CENTER TRYING TO RE-DEVELOP FARTHER TO THE EAST
NEAR THE STRONGER CONVECTION. THE NHC TRACK GUIDANCE REMAINS SPLIT
INTO TWO CAMPS WITH THE GLOBAL MODELS...THE AVN/GFS 10-MEMBER
ENSEMBLE MODEL...AND THE GFDN MODEL BEING TO THE RIGHT OF THE
PREVIOUS OFFICAL FORECAST TRACKS...WHILE THE GFDL...THE BAM
MODELS...AND CLIPER MODELS ARE NEAR JAMAICA. THE GFDL MODEL HAS DONE
ITS USUAL DAILY FLIP-FLOP AND IS NOW JUST SOUTH OF JAMAICA IN 72
HOURS. WHAT IS MOST INTERESTING IS THE SHARP RIGHT TURN THAT THE
UKMET...NOGAPS ...AND THE CANADIAN MODELS TAKE AFTER 12 TO 24 HOURS.
THOSE MODELS INSIST ON DRIVING LILI NORTHWARD ACROSS HISPANIOLA INTO
A STRONG NORTHEAST-SOUTHWEST ORIENTED RIDGE...A SCENARIO THAT I
STILL CAN FIND NO PHYSICAL REASONING FOR. THE AVN/GFS MODEL HAS NOW
ABANDONED ITS PREVIOUS NORTHWARD JOG ACROSS HISPANIOLA AND IS
STRIKINGLY CLOSE TO THE CONSENSUS OF THE LAST 8 NHC OFFICIAL
FORECAST TRACKS AND NOW TAKES LILI ACROSS SOUTHEAST CUBA IN 60 TO 72
HOURS. THE SUBTROPICAL RIDGE TO THE NORTH OF THE GREATER ANTILLES
THAT SEPARATES LILI FROM KYLE AND ISIODORE IS EXPECTED TO REMAIN
INTACT AND IN THE SAME PLACE THROUGHOUT THE FORECAST PERIOD.
THEREFORE...NO SIGNIFICANT CHANGE WAS MADE TO THE PREVIOUS FORECAST
TRACK...ESPECIALLY SINCE THE GULFSTREAM-IV AIRCRAFT WILL BE MAKING A
SYNOPTIC FLIGHT TO THE NORTH OF LILI AT 00Z. THAT DATA SHOULD
PROVIDE SOME INTERESTING MODEL OUTPUT FOR THE 06Z FORECAST CYCLE.
DUE TO THE UNCERTAINTY IN THE LOCATION OF THE LOW-LEVEL...THE
OFFICIAL INTENSITY FORECAST REMAINS CONSERVATIVE AT THIS TIME. THE
SOUTHERLY UPPER-LEVEL SHEAR CURRENTLY ON THE CYCLONE IS FORECAST TO
WEAKEN TO LESS THAN 10 KT BY 36 HOURS AND LESS THAN 5 KT BY 48 HOURS
ACCORDING TO THE SHIPS MODEL. THIS WOULD IMPLY THAT AT LEAST SOME
MODEST STRENGTHENING SHOULD OCCUR.
FORECASTER STEWART
FORECAST POSITIONS AND MAX WINDS
INITIAL 25/2100Z 14.4N 69.6W 40 KTS
12HR VT 26/0600Z 15.0N 71.0W 40 KTS
24HR VT 26/1800Z 16.0N 72.7W 45 KTS
36HR VT 27/0600Z 17.3N 74.0W 50 KTS
48HR VT 27/1800Z 19.0N 74.7W 60 KTS
72HR VT 28/1800Z 21.5N 76.0W 55 KTS
NNNN
Webmaster