000
WTNT44 KNHC 260234
TCDAT4
TROPICAL STORM LISA DISCUSSION NUMBER  22
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL142010
1100 PM AST SAT SEP 25 2010
 
MICROWAVE IMAGES FROM THIS EVENING INDICATE THAT LISA HAS BEEN
MOVING MORE TOWARD THE NORTH-NORTHWEST...WITH THE CENTER BECOMING
EXPOSED TO THE SOUTHWEST OF VERY LIMITED DEEP CONVECTION. DVORAK
CLASSIFICATIONS ARE DECREASING AS FAST AS THE RULES ALLOW...AND THE
INITIAL WIND SPEED IS LOWERED TO 40 KT. COOL WATERS...DRY AIR...AND
STRONG SOUTHWESTERLY SHEAR SHOULD FINISH OFF LISA BY MONDAY UNLESS
THE CYCLONE PULLS ANOTHER SURPRISE. THE GUIDANCE IS IN GOOD
AGREEMENT ON THE WEAKENING SCENARIO...AND THE OFFICIAL FORECAST IS
BASICALLY AN UPDATE OF THE PREVIOUS ONE.
 
BASED ON SSMI/S IMAGES FROM EARLIER THE LOW-LEVEL CENTER HAS BEEN
RELOCATED FARTHER WEST...AND IS MOVING AT ABOUT 340/8. A NORTH-
NORTHWESTWARD MOTION IS EXPECTED UNTIL DISSIPATION IN A DAY OR TWO
AS THE CYCLONE MOVES BETWEEN A TROUGH OVER THE EASTERN ATLANTIC
OCEAN AND RIDGE NEAR NORTHWESTERN AFRICA. SOME MODEL GUIDANCE...
SUCH AS THE HWRF/GFDL...SHOW THE CYCLONE TAKING A TRACK TOWARD THE
NORTH OR NORTH-NORTHEAST...BUT THESE MODELS ALSO HAVE A MUCH MORE
VERTICALLY COHERENT CYCLONE. SINCE THIS STRUCTURE IS UNLIKELY TO
OCCUR...THE NHC FORECAST WILL REMAIN ON THE LEFT SIDE OF THE
GUIDANCE. THE NEW FORECAST HAS BEEN SHIFTED TO THE WEST...BUT THAT
IS MOSTLY DUE TO THE CENTER RELOCATION. THE REMNANT LOW SHOULD MOVE
VERY SLOWLY BY THE END OF THE PERIOD AS SURFACE HIGH PRESSURE
BUILDS NEAR THE AZORES.

 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      26/0300Z 24.3N  29.0W    40 KT
 12HR VT     26/1200Z 25.3N  29.3W    35 KT
 24HR VT     27/0000Z 26.5N  29.6W    30 KT
 36HR VT     27/1200Z 27.8N  30.0W    25 KT...POST-TROP/REMNT LOW
 48HR VT     28/0000Z 29.2N  30.6W    25 KT...POST-TROP/REMNT LOW
 72HR VT     29/0000Z 31.0N  31.0W    25 KT...POST-TROP/REMNT LOW
 96HR VT     30/0000Z 32.0N  31.0W    20 KT...POST-TROP/REMNT LOW
120HR VT     01/0000Z...DISSIPATED
 
$$
FORECASTER BLAKE