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HURRICANE LILI DISCUSSION NUMBER  36
NATIONAL WEATHER SERVICE MIAMI FL
11 AM EDT MON SEP 30 2002
 
ALTHOUGH FLIGHT-LEVEL WINDS DO NOT QUITE SUPPORT HURRICANE 
INTENSITY...AS THE PEAK 850 MB WIND REPORTED BY THE RECONNAISSANCE 
AIRCRAFT WAS 75 KT...OF WHICH 80 PERCENT IS 60 KT...A GPS DROPSONDE 
IN THE NORTHEAST EYEWALL SUPPORTS UPGRADING LILI TO A HURRICANE.  
THIS DROP HAD 81 KT AT 14 METERS ELEVATION...AND A LOW-LAYER MEAN 
WIND OF 90 KT...WHICH ADJUSTS TO ABOUT 73 KT AT THE SURFACE.  THE 
ADVISORY INTENSITY IS SET TO 65 KT...AND IS A COMPROMISE BETWEEN THE 
ADJUSTED VALUES FROM THE AIRCRAFT AND DROPSONDE. 
 
THE INITIAL MOTION IS 300/9.  THIS HEADING HAS BEEN QUITE CONSTANT
FOR THE LAST 12 HOURS OR SO ALTHOUGH THE FORWARD SPEED HAS BEEN
INCREASING.  THE BASIC STEERING FLOW FOR LILI WILL BE PROVIDED BY A
DEEP-LAYER ANTICYCLONE THAT IS EXPECTED TO REMAIN NEARLY STATIONARY
OVER FLORIDA AND THE SOUTHEASTERN UNITED STATES THROUGH THE
THREE-DAY FORECAST PERIOD.  THIS ANTICYCLONE SHOULD MAINTAIN LILI ON
A RELATIVELY STEADY WEST-NORTHWEST TO NORTHWESTWARD TRACK FOR THE
NEXT COUPLE OF DAYS...AND FOCUSES THE ULTIMATE THREAT TO THE
NORTHWESTERN GULF OF MEXICO.  MODEL GUIDANCE REMAINS WELL CLUSTERED.
THE OFFICIAL FORECAST HAS BEEN SHIFTED ONLY SLIGHTLY TO THE LEFT OF 
THE PREVIOUS ADVISORY.

LILI APPEARS POISED FOR SOME FAIRLY SIGNIFICANT STRENGTHENING.  THE
WATERS IN THE NORTHWESTERN GULF ARE HIGH-OCTANE...AND THERE IS A
GOOD INNER CORE STRUCTURE.  ALL FIVE RAPID INTENSIFICATION
PARAMETERS FROM THE SHIPS MODEL ARE SATISFIED.  THE ONLY NEGATIVE I
CAN SEE IS A LIMITED OUTFLOW PATTERN TO THE NORTH.  THE OFFICIAL
FORECAST HAS BEEN ADJUSTED UPWARD FROM THE PREVIOUS ADVISORY...AND
IS IN GOOD AGREEMENT WITH THE EXPERIMENTAL SHIPS MODEL THAT INCLUDES
THE EFFECT OF TOTAL OCEAN HEAT CONTENT.  LILI WILL HAVE FAVORABLE
WATERS FOR ABOUT 48 HOURS...AFTER WHICH THE HEAT CONTENT IN THE
NORTHERN GULF IS A LITTLE LESS.  HOWEVER...LILI SHOULD BE MOVING
FAST ENOUGH NOT TO BE AFFECTED BY THE SHALLOWER WARM LAYER THERE.
IN ADDITION...AN UPPER-LEVEL LOW CURRENTLY IN THE WESTERN GULF IS
EXPECTED TO CONTINUE NORTHWESTWARD OVER THE NEXT 48 HOURS...AND
LEAVE A FAVORABLE UPPER-LEVEL ANTYCYCLONIC FLOW OVER THE ENTIRE
GULF.  BOTTOM LINE IS THAT WE SHOULD HAVE A MAJOR HURRICANE NEARING
THE GULF COASTLINE IN THREE DAYS TIME.

FORECASTER FRANKLIN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     30/1500Z 19.8N  80.0W    65 KTS
12HR VT     01/0000Z 20.6N  81.5W    75 KTS
24HR VT     01/1200Z 21.7N  83.5W    85 KTS
36HR VT     02/0000Z 23.0N  86.1W    90 KTS
48HR VT     02/1200Z 24.5N  88.5W   100 KTS
72HR VT     03/1200Z 28.0N  92.5W   105 KTS
 
 
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