Tropical Storm LISA

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TROPICAL STORM LISA DISCUSSION NUMBER  34
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 PM EDT MON SEP 27 2004

LATEST SATELLITE IMAGERY CONTINUES TO DEPICT A SHEARED SYSTEM...WITH
THE LOW-LEVEL CENTER EXPOSED TO THE SOUTHWEST OF THE MAIN AREA OF
DEEP CONVECTION.  THERE IS NO REASON TO EXPECT THIS SHEAR TO RELAX
SOON...SO THE INTENSITY FORECAST SHOWS LITTLE CHANGE IN STRENGTH
FOR THE NEXT 1-2 DAYS.  LATER IN THE FORECAST PERIOD...AN
UPPER-LEVEL LOW TO THE WEST OF LISA IS FORECAST TO BREAK UP AND
THIS MAY ALLOW FOR A MORE FAVORABLE UPPER-LEVEL ENVIRONMENT.  THE
CURRENT NHC WIND SPEED FORECAST SHOWS A LITTLE LESS STRENGTHENING
THAN THE PREVIOUS ONES AND IS IN REASONABLE AGREEMENT WITH THE
LATEST SHIPS GUIDANCE.  THE CURRENT GFDL RUN SHOWS MORE
STRENGTHENING...BUT THAT MODEL HAS BEEN EXHIBITING A POSITIVE BIAS
FOR THIS STORM THUS FAR.

LATEST FIXES SHOW A SLIGHTLY FASTER MOTION TO THE NNW...340/7.  LISA
IS BEING STEERED BY THE FLOW ON THE SOUTHWESTERN SIDE OF A MID-LEVEL
SUBTROPICAL ANTICYCLONE.  TRACK GUIDANCE NOW SUGGESTS MORE OF A
NORTHEASTWARD TURN LATER IN THE PERIOD DUE TO A WEAK APPROACHING
SHORTWAVE IN THE WESTERLIES.  WE HAVE NOT ENTIRELY BOUGHT INTO THIS
CHANGE...BUT HAVE SHIFTED THE TRACK SOMEWHAT TO THE EAST...TO BE AT
LEAST PARTIALLY CONSISTENT WITH THE NEW GUIDANCE.  IT SHOULD BE
NOTED THAT THE DYNAMICAL MODEL CONSENSUS IS EVEN FARTHER TO THE
NORTHEAST OF THE OFFICIAL FORECAST.

FORECASTER PASCH/SISKO
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      27/2100Z 21.5N  46.5W    35 KT
 12HR VT     28/0600Z 22.5N  47.1W    35 KT
 24HR VT     28/1800Z 24.0N  47.9W    35 KT
 36HR VT     29/0600Z 25.5N  48.3W    35 KT
 48HR VT     29/1800Z 27.0N  48.5W    40 KT
 72HR VT     30/1800Z 30.5N  49.0W    50 KT
 96HR VT     01/1800Z 33.0N  49.0W    60 KT
120HR VT     02/1800Z 35.0N  48.0W    60 KT
 
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