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TROPICAL STORM IRWIN DISCUSSION NUMBER   7
NATIONAL WEATHER SERVICE MIAMI FL
2 AM PDT SUN OCT 10 1999
 
INFRARED SATELLITE ANIMATION SHOWS SIGNIFICANT WARMING IN THE CDO OF
IRWIN DURING THE PAST SEVERAL HOURS.  T-NUMBERS ARE NOW 3.0 AND 2.5
AND AN EARLIER SSMI PASS INDICATED ONLY A SMALL AREA OF 35 KNOT
WINDS.  THE INITIAL INTENSITY IS REDUCED TO 45 KNOTS.  THE LATEST
SHIPS MODEL FORECASTS A SLOW WEAKENING TO 40 KNOTS IN 72 HOURS. 
HOWEVER...WITH THE INCREASE IN FORWARD SPEED THE SYSTEM WILL BEGIN
ENCOUNTERING COOLER WATERS IN 12 HOURS OR SO AND CONTINUE TO WEAKEN
AS INDICATED IN THE OFFICIAL FORECAST.
 
IRWIN CONTINUES TO BE STEERED BY A DEEP-LAYER MEAN EASTERLY FLOW
PRODUCED BY A HIGH OVER THE SOUTHWESTERN UNITED STATES AND NORTHERN
MEXICO.  THE INITIAL MOTION IS NOW 275/9.  THE TRACK MODELS ARE IN
GENERAL AGREEMENT WITH A STRONG WESTWARD COMPONENT IN THEIR
RESPECTIVE FORECASTS.  THE OFFICIAL FORECAST IS SIMILAR TO THE
PREVIOUS ONE BUT SLIGHTLY FASTER DUE TO THE FASTER INITIAL MOTION.
 
JARVINEN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     10/0900Z 19.2N 109.5W    45 KTS
12HR VT     10/1800Z 19.4N 111.0W    40 KTS
24HR VT     11/0600Z 19.5N 112.8W    30 KTS
36HR VT     11/1800Z 19.6N 114.6W    25 KTS
48HR VT     12/0600Z 19.7N 116.4W    20 KTS...DISSIPATING
72HR VT     13/0600Z 20.0N 120.0W    DISSIPATED
 
 
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