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Tropical Storm OPHELIA (Text)

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TROPICAL STORM OPHELIA DISCUSSION NUMBER  28
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL162011
1100 AM AST THU SEP 29 2011
 
THE CLOUD PATTERN HAS DEFINITELY BECOME BETTER ORGANIZED SINCE
YESTERDAY...AND NOW IT IS VERY SYMMETRIC WITH A WELL-DEFINED
CONVECTIVE BAND WRAPPING AROUND THE CENTER. I EVEN SUSPECT THAT AN
EYE FEATURE COULD BE FORMING. THE OUTFLOW IS TRYING TO EXPAND
WESTWARD...BUT UPPER-LEVEL HOSTILE WINDS JUST WEST OF THE CYCLONE
ARE DISRUPTING IT AT THIS TIME. T-NUMBERS FROM TAFB AND SAB HAVE
INCREASED TO 3.5 AND 4.0 ON THE DVORAK SCALE. ON THAT BASIS..THE
INITIAL INTENSITY HAS BEEN INCREASED TO 60 KNOTS. THE UPPER-LEVEL
ENVIRONMENT IS FORECAST TO REMAIN UNFAVORABLE BUT NOT HOSTILE
ENOUGH TO PREVENT OPHELIA FROM BECOMING A HURRICANE BY THE END OF
THE DAY...AS INDICATED BY MOST OF THE GUIDANCE. THE OFFICIAL
FORECAST IS VERY SIMILAR TO THE STATISTICAL LGEM. BEYOND 72 HOURS
THE SHEAR IS FORECAST TO INCREASE SIGNIFICANTLY...AND THE SEA
SURFACE TEMPERATURES WILL DECREASE. THIS SHOULD RESULT IN
WEAKENING...AND MOST LIKELY OPHELIA WILL BECOME POST-TROPICAL BY 96
HOURS.
 
THE BEST ESTIMATE OF THE INITIAL MOTION IS 335 DEGREES AT 7 KNOTS.
THE STEERING PATTERN HAS NOT CHANGED...AND I FACT...IT IS VERY
SIMILAR TO THE ONE THAT HAS PREVAILED THIS SEASON SO FAR. THE
COMBINATION OF A TROUGH ALONG THE EASTERN UNITED STATES AND THE
SUBTROPICAL RIDGE OVER THE ATLANTIC CALLS FOR A GENERAL NORTHWARD
TRACK FOR THE NEXT TWO DAYS. THEREAFTER...A TURN TO THE
NORTH-NORTHEAST WITH INCREASING FORWARD SPEED IS FORECAST AS
OPHELIA BECOMES EMBEDDED WITHIN THE MID-LATITUDE FLOW. THE
TRACK...AT LEAST FOR THE NEXT 2 TO 3 DAYS IS CENTERED WITHIN THE
GUIDANCE ENVELOPE AND BETWEEN THE GFS AND THE ECMWF. AT THIS
TIME...THE WESTERN EDGE OF THE GUIDANCE ENVELOPE...ALTHOUGH VERY
CLOSE...DOES NOT REACH BERMUDA.
 
BASED ON DATA FROM NOAA BUOY 41044 THE TROPICAL STORM FORCE WIND
RADII HAVE BEEN EXPANDED IN THE NORTHEAST QUADRANT. ONCE AGAIN THESE
BUOYS ARE PROVING TO BE VERY VALUABLE IN TRACKING TROPICAL CYCLONE. 
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  29/1500Z 20.9N  61.8W   60 KT  70 MPH
 12H  30/0000Z 22.1N  62.3W   65 KT  75 MPH
 24H  30/1200Z 24.0N  63.0W   70 KT  80 MPH
 36H  01/0000Z 26.5N  63.5W   75 KT  85 MPH
 48H  01/1200Z 29.5N  63.5W   75 KT  85 MPH
 72H  02/1200Z 38.5N  60.0W   70 KT  80 MPH
 96H  03/1200Z 50.0N  52.5W   40 KT  45 MPH...POST-TROP/EXTRATROP
120H  04/1200Z 55.0N  40.0W   30 KT  35 MPH...POST-TROP/EXTRATROP
 
$$
FORECASTER AVILA
 
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