Tropical Storm KEVIN
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TROPICAL STORM KEVIN DISCUSSION NUMBER 6
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2 PM PDT THU SEP 04 2003
A QUIKSCAT OVERPASS AT 1335Z SHOWED A LARGE AREA OF 30 KT WINDS
SURROUNDING THE CENTER OF THE CYCLONE...WITH RAIN CONTAMINATED
WINDS AS HIGH AS 55 KT IN THE SOUTHWEST QUADRANT. WHILE THIS MAY
BE TOO HIGH...THE DATA SUPPORT UPGRADING THE SYSTEM TO TROPICAL
STORM KEVIN. SATELLITE INTENSITY ESTIMATES OF 35 KT FROM SAB AND
AFWA SUPPORT ALSO SUPPORT THE UPGRADE. KEVIN CONTINUES TO HAVE A
LARGE CIRCULATION...AND MULTIPLE SWIRLS OF LOW CLOUDS APPEAR TO BE
ROTATING AROUND THE MEAN CENTER. THE INITIAL POSITION IS BASED ON
THE MEAN CENTER.
THE INITIAL MOTION IS 300/8. WATER VAPOR IMAGERY INDICATES A
MID/UPPER-LEVEL RIDGE NORTH OF KEVIN. THIS SHOULD STEER KEVIN
BASICALLY WEST-NORTHWESTWARD TOWARD A DEVELOPING WEAKNESS CAUSED BY
A TROUGH ADVANCING EASTWARD TO THE U. S. PACIFIC NORTHWEST. SINCE
KEVIN SHOULD WEAKEN OVER COOLER WATER AS IT APPROACHES THE
WEAKENESS...IT WILL LIKELY TURN MORE WESTWARD AS LOW-LEVEL STEERING
BECOMES PREDOMINANT. THIS IS THE SCENARIO OF THE OFFICIAL
FORECAST...WHICH IS IN GOOD AGREEMENT WITH THE GFS AND NOGAPS.
EVEN AS KEVIN IS BEING NAMED...IT LOOKS LIKE IT IS PEAKING AS IT
HEADS FOR COLDER WATER. THE CENTER IS BECOMING LESS INVOLVED WITH
THE CONVECTION...WHICH HAS DECREASED IN COVERAGE OVER THE PAST
SEVERAL HOURS. THE FORECAST TRACK TAKES THE STORM OVER 23C-24C SEA
SURFACE TEMPERATURES BY 72 HR...WHICH SHOULD RESULT IN STEADY
WEAKENING. KEVIN SHOULD WEAKEN TO A DEPRESSION IN 24-36 HR AND
BECOME A NON-CONVECTIVE LOW IN 72-96 HR...FOLLOWED BY DISSIPATION.
THERE IS A CHANCE THAT THE WELL-DEFINED CLOUD SWIRL NEAR 21.8N114.2W
IS THE ACTUAL CENTER AND NOT ROTATING AROUND THE MEAN CENTER. IF
THAT IS THE CASE...THE FORECAST TRACK MAY HAVE TO BE ADJUSTED
SOMEWHAT TO THE NORTH AND A FASTER WEAKENING FORECAST.
FORECASTER BEVEN
FORECAST POSITIONS AND MAX WINDS
INITIAL 04/2100Z 21.0N 114.9W 35 KT
12HR VT 05/0600Z 21.5N 116.0W 35 KT
24HR VT 05/1800Z 22.2N 117.5W 35 KT
36HR VT 06/0600Z 22.7N 119.1W 30 KT
48HR VT 06/1800Z 23.1N 120.8W 30 KT
72HR VT 07/1800Z 23.5N 124.0W 25 KT...DISSIPATING
96HR VT 08/1800Z 23.5N 127.0W 20 KT...REMNANT LOW
120HR VT 09/1800Z...DISSIPATED
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