Tropical Storm IRWIN

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TROPICAL STORM IRWIN DISCUSSION NUMBER  32
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP112011
800 PM PDT THU OCT 13 2011
 
TONIGHT WE HAVE RECEIVED UNCOMMON BUT WELCOME DATA. THERE ARE 3
DIFFERENT SHIPS LOCATED NEAR AND TO THE EAST OF IRWIN THAT REPORTED
AT THE SAME TIME...AND THEY ALL MEASURED WINDS OF TROPICAL STORM
FORCE. ALTHOUGH THE CLOUD PATTERN HAS NOT BECOME ANY BETTER
ORGANIZED AND THE DVORAK T-NUMBERS REMAIN UNCHANGED...THE INITIAL
INTENSITY HAS BEEN INCREASED TO 40 KNOTS BASED ON THESE SHIP
OBSERVATIONS. SOME MODELS SUGGEST THAT IRWIN SHOULD BEGIN TO
STRENGTHEN SLIGHTLY...BUT THERE IS AN UNFAVORABLE MID-LEVEL DRY
ENVIRONMENT SURROUNDING THE CYCLONE. THE LOW SHEAR AND THE WARM
OCEAN COULD COMPENSATE FOR THE DRY AIR...SO IRWIN IS KEPT AS A 35-
TO 40-KT TROPICAL STORM THROUGH 5 DAYS IN THIS ADVISORY.
 
THE CENTER HAS BEEN MEANDERING DURING THE PAST SEVERAL HOURS...AND
LITTLE MOTION IS ANTICIPATED DURING THE NEXT 12 TO 24 HOURS.
THEREAFTER...LIGHT MID-LEVEL NORTHERLY AND NORTHEASTERLY FLOW
SHOULD DEVELOP NEAR THE CYCLONE AS SUGGESTED BY GLOBAL MODELS...AND
THIS PATTERN SHOULD FORCE IRWIN ON A VERY SLOW SOUTHWARD AND
SOUTHWESTWARD TRACK THROUGH 5 DAYS. MOST OF GUIDANCE UNANIMOUSLY
FAVOR SUCH MOTION.
 
GIVEN THE SMALL AREA OF TROPICAL STORM FORCE WINDS...THE FACT THAT
IRWIN IS BASICALLY STATIONARY...AND THAT IT IS FORECAST TO MOVE
AWAY FROM MEXICO OVER THE NEXT COUPLE OF DAYS...TROPICAL STORM
WATCHES OR WARNINGS ARE NOT REQUIRED FOR THE COAST OF MEXICO AT
THIS TIME. HOWEVER...DATA FROM THESE SHIPS INDICATE THAT THE
TROPICAL STORM FORCE WINDS ARE NOT TOO FAR FROM THE MEXICAN COAST.
 
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  14/0300Z 19.2N 106.6W   40 KT  45 MPH
 12H  14/1200Z 19.0N 106.5W   35 KT  40 MPH
 24H  15/0000Z 18.0N 106.2W   35 KT  40 MPH
 36H  15/1200Z 16.8N 106.2W   35 KT  40 MPH
 48H  16/0000Z 15.8N 107.0W   40 KT  45 MPH
 72H  17/0000Z 15.0N 108.0W   40 KT  45 MPH
 96H  18/0000Z 15.0N 109.0W   40 KT  45 MPH
120H  19/0000Z 15.0N 109.5W   40 KT  45 MPH
 
$$
FORECASTER AVILA
 
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