Hurricane IRENE

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HURRICANE IRENE DISCUSSION NUMBER  19
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL092011
1100 PM EDT WED AUG 24 2011
 
AN AIR FORCE RECONNAISSANCE PLANE ESTIMATED A MINIMUM PRESSURE OF
952 MB...BUT THE MAXIMUM WIND REPORTED SO FAR WAS 99 KNOTS AT
FLIGHT LEVEL. THE OVERALL CLOUD PATTERN HAS NOT CHANGED
SIGNIFICANTLY DURING THE PAST FEW HOURS AND SATELLITE INTENSITY
ESTIMATES STILL SUPPORT 105 KNOTS. I WILL WAIT FOR THE PLANE TO
FINISH SAMPLING THE HURRICANE BEFORE REDUCING THE WINDS A LITTLE
BIT...IF NECESSARY. BY INSPECTING AN EARLIER TRMM PASS FROM 2216
UTC...AND AND SSMIS AT 0024 UTC...ONE CAN OBSERVE CONCENTRIC
CONVECTIVE RINGS SUGGESTING THAT AN EYEWALL REPLACEMENT CYCLE IS
OCCURRING. THESE TWO EYEWALLS WERE ALSO REPORTED BY THE AIR FORCE
RECONNAISSANCE PLANE. THIS EYEWALL CYCLE WILL LIKELY RESULT IN SOME
FLUCTUATIONS IN INTENSITY DURING THE NEXT FEW HOURS...BUT THE TREND
IS FOR IRENE TO INTENSIFY A LITTLE MORE DURING THE NEXT 24 HOURS.
IN 2 TO 3 DAYS....IRENE SHOULD BEGIN TO GRADUALLY WEAKEN AS THE
HURRICANE ENCOUNTERS INCREASING SOUTHWESTERLY SHEAR AND COOLER
SSTS. IRENE IS EXPECTED TO REMAIN A LARGE AND POWERFUL HURRICANE...
OR EVEN GROW IN SIZE...AS IT MOVES NEAR THE NORTHEASTERN UNITED
STATES.
 
THE EYE OF THE HURRICANE HAS BEEN MOVING NEAR OR OVER SOME OF THE
BAHAMAS RESULTING IS SOME WOBBLING. THE BEST ESTIMATE OF THE
INITIAL MOTION IS TOWARD THE NORTHWEST OR 310 DEGREES AT 10 KNOTS.
THE DEVELOPMENT OF THE LARGE TROUGH ALONG THE EAST COAST OF THE
UNITED STATES IS MATERIALIZING AS PREDICTED BY THE GLOBAL MODELS. 
THIS STEERING PATTERN WILL FORCE IRENE TO TURN TOWARD THE
NORTH-NORTHWEST AND THE NORTH WITH A SLIGHT INCREASE IN FORWARD
SPEED OVER THE NEXT FEW DAYS. THE LATEST GUIDANCE HAS CHANGED VERY
LITTLE...AND PERHAPS THE ONLY DIFFERENCE IS THAT THE GFS SHIFTED 30
N MI TO THE WEST...TOWARD THE ECMWF SOLUTION DURING THE LAST
PORTION OF THE FORECAST. THIS DOES NOT RESULT IN A SIGNIFICANT
CHANGE OF THE OFFICIAL FORECAST TRACK FROM THE PREVIOUS ONE.
 
BECAUSE IRENE IS A LARGE CYCLONE...TROPICAL STORM AND HURRICANE
WATCHES WILL LIKELY BE REQUIRED FOR A PORTION OF THE COAST OF THE
CAROLINAS EARLY THURSDAY.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  25/0300Z 23.8N  75.4W  105 KT 120 MPH
 12H  25/1200Z 25.5N  76.5W  110 KT 125 MPH
 24H  26/0000Z 27.5N  77.3W  115 KT 135 MPH
 36H  26/1200Z 29.5N  77.4W  110 KT 125 MPH
 48H  27/0000Z 31.5N  77.0W  105 KT 120 MPH
 72H  28/0000Z 36.0N  75.2W   90 KT 105 MPH
 96H  29/0000Z 42.5N  72.0W   75 KT  85 MPH
120H  30/0000Z 50.0N  67.0W   45 KT  50 MPH...POST-TROP/EXTRATROP
 
$$
FORECASTER AVILA
 
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