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TROPICAL STORM IRWIN DISCUSSION NUMBER   6
NATIONAL WEATHER SERVICE MIAMI FL
8 PM PDT SAT OCT 09 1999

SATELLITE IMAGES INDICATE THAT THE CLOUD PATTERN ASSOCIATED WITH
IRWIN HAS NOT CHANGED SIGNIFICANTLY DURING THE PAST FEW HOURS. IT
CONTINUES TO HAVE INTERMITTENT DEEP CONVECTION NEAR THE CENTER AND A
WELL DEFINED OUTFLOW TO THE WEST.  INITIAL INTENSITY CONTINUES AT 50
KNOTS. IRWIN ONLY HAS A DAY OR SO TO STRENGTHEN BEFORE BEGINS TO
MOVE OVER COOLER WATER. 

IRWIN IS ALREADY BEING STEERED BY A DEEP-LAYER MEAN EASTERLY FLOW
PRODUCED BY A HIGH OVER THE SOUTHWESTERN UNITED STATES AND NORTHERN
MEXICO.  CONSEQUENTLY...MODELS MOVE IRWIN ON A GENERAL WESTWARD
TRACK AND AWAY FROM MEXICO FOR THE NEXT FEW DAYS.  TRACK
MODELS...MAINLY THOSE WHICH DEPEND ON THE AVN MODEL FORECAST
FIELD...CAPTURED REMARKABLY WELL THE WESTWARD TURN WHEN IRWIN WAS
MOVING NORTHWARD 24 HOUR AGO. THE OFFICIAL FORECAST IS IN THE MIDDLE
OF THE ENSEMBLE.   

AVILA 

FORECAST POSITIONS AND MAX WINDS
 
INITIAL     10/0300Z 19.0N 108.4W    50 KTS
12HR VT     10/1200Z 19.1N 109.5W    50 KTS
24HR VT     11/0000Z 19.3N 111.0W    50 KTS
36HR VT     11/1200Z 19.5N 112.5W    50 KTS
48HR VT     12/0000Z 19.5N 114.5W    45 KTS
72HR VT     13/0000Z 19.5N 118.0W    35 KTS
 
 
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