Tropical Storm ISELLE

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TROPICAL STORM ISELLE DISCUSSION NUMBER  10
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP102008
200 PM PDT FRI AUG 15 2008
 
ISELLE'S CONVECTIVE PATTERN HAS CONTINUED TO DETERIORATE TODAY DUE
TO MODERATE TO STRONG EASTERLY UPPER-LEVEL SHEAR. HOWEVER...A
15/1316Z QUIKSCAT OVERPASS INDICATED SOME CREDIBLE 35- TO 40-KT
SURFACE WINDS IN THE SOUTHERN SEMICIRCLE. THEREFORE...THE INITIAL
INTENSITY IS BEING MAINTAINED AT 35 KT SINCE THERE IS STILL SOME
CONVECTION PRESENT IN THE SOUTHWESTERN QUADRANT. THE 34-KT WIND
RADII HAVE ALSO BEEN LIMITED TO ONLY THE SOUTHWESTERN QUADRANT
BASED ON THE QUIKSCAT WIND DATA AND CURRENT CONVECTIVE PATTERN.
 
VISIBLE SATELLITE IMAGERY SUGGESTS THAT THE MOSTLY-EXPOSED LOW-LEVEL
CIRCULATION HAS BEEN NEARLY STATIONARY FOR THE PAST 12 HOURS OR SO.
HOWEVER...ALL NHC MODEL GUIDANCE INDICATES THAT A SLOW
WEST-NORTHWEST OR WESTWARD MOTION IS EXPECTED TO RESUME DURING THE
NEXT 12 HOURS AND CONTINUE THROUGHOUT THE FORECAST PERIOD. THE
OFFICIAL FORECAST IS SIMILAR TO THE PREVIOUS FORECAST TRACK AND A
LITTLE SOUTH OF THE NHC MODEL CONSENSUS.
 
ALTHOUGH THE UPPER-LEVEL FLOW REMAINS DIFLUENT...20- TO 30-KT WINDS
OVERSPREADING THE CYCLONE HAS CREATED MODERATE TO STRONG VERTICAL
WIND SHEAR CONDITIONS. ALL AVAILABLE GUIDANCE SUGGESTS THAT THESE
UNFAVORABLE UPPER-LEVEL WINDS WILL SLOWLY INCREASE THROUGHOUT THE
FORECAST PERIOD...WHICH SHOULD INDUCE GRADUAL WEAKENING DURING THE
NEXT 12 TO 24 HOURS.

 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      15/2100Z 17.6N 111.2W    35 KT
 12HR VT     16/0600Z 17.8N 111.8W    35 KT
 24HR VT     16/1800Z 18.0N 112.4W    30 KT
 36HR VT     17/0600Z 18.1N 113.2W    30 KT
 48HR VT     17/1800Z 18.3N 114.1W    25 KT...REMNANT LOW
 72HR VT     18/1800Z 18.5N 116.0W    20 KT...REMNANT LOW
 96HR VT     19/1800Z 18.5N 118.0W    20 KT...REMNANT LOW
120HR VT     20/1800Z 18.5N 119.5W    20 KT...REMNANT LOW
 
$$
FORECASTER STEWART/BEVEN
 
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