760 
 WTNT44 KNHC 252032
 TCDAT4
 TROPICAL STORM LISA DISCUSSION NUMBER  21
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL142010
 500 PM AST SAT SEP 25 2010
  
 CONVENTIONAL AND MICROWAVE SATELLITE IMAGERY INDICATE WESTERLY SHEAR
 IS TAKING ITS TOLL ON LISA WITH ITS UPPER-LEVEL ANTICYCLONE NOW
 DISPLACED MORE THAN 100 NMI TO THE EAST OF THE LOW-LEVEL CENTER. AS
 A RESULT...SATELLITE INTENSITY ESTIMATES HAVE BEEN RAPIDLY
 DECREASING DURING THE PAST 6 HOURS. THE INITIAL INTENSITY OF 45 KT
 IS BASED ON A BLEND OF SATELLITE INTENSITY ESTIMATES T3.5/55 KT
 FROM TAFB...T1.5/25 KT FROM SAB...AND AN ADT VALUE OF T3.0/45 KT
 FROM UW-CIMSS.
  
 THE INITIAL MOTION ESTIMATE IS 350/10. LISA REMAINS ON TRACK AND THE
 CYCLONE IS EXPECTED TO TURN TOWARD THE NORTH-NORTHWEST DURING THE
 NEXT 12 HOURS OR SO...AND CONTINUE THAT MOTION FOR THE REMAINDER OF
 THE FORECAST PERIOD. THE NHC MODEL GUIDANCE IS MUCH MORE CONVERGENT
 NOW...AND THE OFFICIAL FORECAST TRACK IS SIMILAR TO THE PREVIOUS
 ADVISORY TRACK AND IS A LITTLE TO THE RIGHT OF THE MODEL CONSENSUS.
  
 WESTERLY TO SOUTHWESTERLY VERTICAL SHEAR IS FORECAST TO INCREASE TO
 MORE THAN 30 KT BY 24 HOURS...WHICH COULD HASTEN THE ONGOING
 WEAKENING TREND. THE GFS-BASED SHIPS MODEL INDICATES DISSIPATION BY
 48 HOURS...BUT THE OFFICIAL FORECAST DELAYS DISSIPATION DUE TO
 INTERMITTENT BURSTS OF DEEP CONVECTION POSSIBLY KEEPING THE
 CIRCULATION ALIVE A LITTLE BIT LONGER...WHICH IS SIMILAR TO THE
 LGEM...HWRF...AND GFDL SOLUTIONS. THE OFFICIAL INTENSITY FORECAST
 IS SIMILAR TO THE PREVIOUS ADVISORY AND IS A BLEND OF THE NHC
 OBJECTIVE INTENSITY GUIDANCE.
  
 
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      25/2100Z 23.7N  28.4W    45 KT
  12HR VT     26/0600Z 24.7N  28.6W    40 KT
  24HR VT     26/1800Z 26.1N  28.8W    35 KT
  36HR VT     27/0600Z 27.4N  29.0W    30 KT
  48HR VT     27/1800Z 28.6N  29.3W    30 KT
  72HR VT     28/1800Z 30.7N  30.0W    25 KT...POST-TROP/REMNT LOW
  96HR VT     29/1800Z 32.5N  30.5W    25 KT...POST-TROP/REMNT LOW
 120HR VT     30/1800Z...DISSIPATED
  
 $$
 FORECASTER STEWART