180 
 WTNT43 KNHC 232046
 TCDAT3
 TROPICAL DEPRESSION LISA DISCUSSION NUMBER  18
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
 5 PM EDT THU SEP 23 2004
  
 VISIBLE SATELLITE IMAGERY SHOWS THAT NORTHERLY SHEAR HAS BLOWN AWAY
 THE DEEP CONVECTION AND EXPOSED A LOW LEVEL CLOUD CENTER TO THE
 NORTHEAST OF WHERE A CENTER LOCATION WAS ESTIMATED ON THE PREVIOUS
 ADVISORY.  THIS REQUIRES A RELOCATION OF THE CENTER AND IMPLIES
 THAT THE CENTER HAS MOVED IN A CYCLONIC OOP OVER THE PAST 24 HOURS
 AND IS NOW MOVING ABOUT 300/05.  THE GLOBAL TRACK MODELS ARE IN
 GOOD AGREEMENT ABOUT A SLOW MOSTLY NORTH-NORTHWESTWARD MOTION
 TOWARD A WEAKNESS IN THE SUBTROPICAL RIDGE TO THE NORTH OF LISA. 
 THE OFFICIAL TRACK FORECAST FOLLOWS A CONSENSUS OF THE GUIDANCE AND
 IS ADJUSTED TO THE RIGHT OF THE PREVIOUS ADVISORY DUE TO THE
 RELOCATION.
 
 THE ABSENCE OF ANY DEEP CONVECTION NEAR THE CENTER IS GROUNDS FOR
 DOWNGRADING LISA TO A TROPICAL DEPRESSION.  THE SHIPS MODEL
 INDICATES THAT THE VERTICAL SHEAR WILL WEAKEN SOME OVER THE NEXT 72
 HOURS AND THE OFFICIAL FORECAST IS FOR MODEST INTENSIFICATION
 THROUGH 72 HOURS...A LITTLE MORE THAN SHIPS BUT NOT NEARLY AS
 AGGRESSIVE AS THE GFDL MODEL.
 
 FORECASTER LAWRENCE
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      23/2100Z 14.3N  40.7W    30 KT
  12HR VT     24/0600Z 14.4N  41.0W    30 KT
  24HR VT     24/1800Z 14.9N  41.9W    30 KT
  36HR VT     25/0600Z 16.0N  43.1W    35 KT
  48HR VT     25/1800Z 17.3N  44.1W    45 KT
  72HR VT     26/1800Z 20.2N  45.2W    55 KT
  96HR VT     27/1800Z 23.0N  46.0W    55 KT
 120HR VT     28/1800Z 27.0N  47.0W    55 KT
  
  
 $$