Tropical Storm LESTER

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TROPICAL STORM LESTER DISCUSSION NUMBER   7
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2 AM PDT WED OCT 13 2004
 
RADAR IMAGERY FROM ACAPULCO MEXICO INDICATES THAT LESTER RETAINS A
SMALL BUT WELL-ORGANIZED CIRCULATION...WHILE SATELLITE IMAGERY
SHOWS CONVECTION WITH TOPS COLDER THAN -80C JUST EAST OF THE
CENTER.  SATELLITE INTENSITY ESTIMATES ARE 55 KT FROM TAFB...AND 45
KT FROM SAB AND AFWA.  THE INITIAL INTENSITY IS INCREASED TO 45 KT
FOR THIS ADVISORY.

THE INITIAL MOTION IS A SOMEWHAT UNCERTAIN 300/7.  LESTER IS MOVING
ALONG THE SOUTH SIDE OF A NARROW MID/UPPER-LEVEL RIDGE ALONG 20N-
21N...AND IS NORTHEAST OF A LARGE BUT POORLY ORGANIZED AREA OF
DISTURBED WEATHER.  LARGE-SCALE MODELS FORECAST THE RIDGE TO HOLD
FOR 24-48 HR...THEN STRENGTHEN WITH AN ANTICYCLONE DEVELOPING NEAR
THE SOUTHERN GULF OF CALIFORNIA.  THIS PATTERN SHOULD KEEP LESTER
ON A WEST-NORTHWESTWARD TO WESTWARD TRACK FOR 24-48 HR...FOLLOWED
BY A WESTWARD MOTION FROM 48-96 HR.  AFTER 96 HR...LESTER MAY
APPROACH THE WESTERN END OF THE RIDGE...WHICH WOULD AGAIN ALLOW A
MORE NORTHWARD MOTION.  WHILE DYNAMICAL MODELS AGREE ON THE GENERAL
MOTION...THERE ARE DIFFERENCES IN JUST HOW FAR NORTH LESTER WILL
TRACK BEFORE TURNING WESTWARD DUE TO HOW THEY HANDLE INTERACTION
BETWEEN LESTER AND THE DISTURBANCE.  THE NEW FORECAST TRACK IS
NUDGED A LITTLE NORTH OF THE PREVIOUS TRACK IN AGREEMENT WITH THE
NOGAPS AND THE CONU CONSENSUS MODEL.  THE TRACK KEEPS THE CENTER
MOVING PARALLEL TO THE MEXICAN COAST FOR ABOUT 24 HR BEFORE IT
GRADUALLY GETS FARTHER AWAY.  HOWEVER...ANY MOTION NORTH OF THE
FORECAST TRACK COULD BRING THE CENTER ONSHORE.
 
LESTER IS EXPERIENCING LIGHT-MODERATE SOUTHERLY SHEAR.  LARGE-SCALE
MODELS NOW SUGGEST THAT SOUTHERLY/SOUTHWESTERLY SHEAR MAY PERSIST
FOR 48 HR BEFORE DECREASING.  SINCE LESTER HAS STRENGTHENED DESPITE
THE SHEAR...THE INTENSITY FORECAST CALLS FOR SLOW STRENGTHENING FOR
48 HR...WITH THE CYCLONE REACHING HURRICANE STRENGTH AS THE SHEAR
DIMINISHES.  THIS BASICALLY FOLLOWS THE SHIPS MODEL.  LESTER WILL
LIKELY REMAIN A SMALLER THAN AVERAGE TROPICAL CYCLONE AND THUS IT
WILL BE SUSCEPTIBLE TO RAPID FLUCTUATIONS IN STRENGTH...INCLUDING
THE POSSIBILITY IT COULD GET STRONGER THAN FORECAST IN THE 72-120
HR TIMEFRAME WHEN THE SHEAR IS FORECAST TO BE LIGHT.
 
FORECASTER BEVEN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      13/0900Z 16.8N 100.6W    45 KT
 12HR VT     13/1800Z 17.1N 101.4W    50 KT
 24HR VT     14/0600Z 17.2N 102.2W    55 KT
 36HR VT     14/1800Z 17.2N 103.0W    60 KT
 48HR VT     15/0600Z 17.2N 104.1W    65 KT
 72HR VT     16/0600Z 17.5N 106.5W    70 KT
 96HR VT     17/0600Z 18.0N 108.5W    70 KT
120HR VT     18/0600Z 19.0N 110.5W    65 KT
 
 
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