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Hurricane IRENE (Text)

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HURRICANE IRENE DISCUSSION NUMBER   8
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL092011
1100 AM AST MON AUG 22 2011
 
DATA FROM A RECONNAISSANCE PLANE...RADAR AND SATELLITE IMAGERY
INDICATE THAT IRENE HAS CONTINUED TO GRADUALLY BECOME BETTER
ORGANIZED. HOWEVER THE WINDS WINDS HAVE NOT INCREASED SIGNIFICANTLY
AND THE MINIMUM CENTRAL PRESSURE WAS AROUND 988 MB IN THE LAST
CENTER DROPSONDE. THE INITIAL INTENSITY HAS BEEN INCREASED TO 70
KNOTS IN THIS ADVISORY. SINCE THE CORE OF THE HURRICANE IS NOT
FORECAST TO MOVE DIRECTLY OVER THE HIGH TERRAIN OF HISPANIOLA...AND
THE OCEANIC AND ATMOSPHERIC CONDITIONS ARE QUITE FAVORABLE... THE
OFFICIAL FORECAST CALLS FOR INTENSIFICATION...AND MAKES IRENE A
CATEGORY 3 HURRICANE AS IT MOVES ACROSS THE CENTRAL BAHAMAS. THIS
IS CONSISTENT WITH MOST OF THE DYNAMICAL GUIDANCE AND IN
FACT...EVEN GLOBAL MODELS FORECAST A SIGNIFICANT DROP IN THE
CENTRAL PRESSURE OVER THE NEXT TWO OR THREE DAYS. IRENE IS BECOMING
A LARGE CYCLONE...AND BASED ON BUOY OBSERVATIONS THE TROPICAL STORM
FORCE WINDS EXTEND 160 N MI TO THE NORTHEAST OF THE CENTER.
 
RADAR AND RECONNAISSANCE FIXES INDICATE THAT THE HURRICANE IS MOVING
TOWARD THE WEST-NORTHWEST OR 295 DEGREES AT ABOUT 12 KNOTS. IRENE
IS CURRENTLY LOCATED SOUTH OF A NARROW SUBTROPICAL RIDGE WHICH IS
FORCING THE CYCLONE ON A WEST-NORTHWEST TRACK. HOWEVER...MOST OF
THE GLOBAL MODELS SHOW THE GRADUAL DEVELOPMENT A LARGE UPPER TROUGH
ALONG THE UNITED STATES EAST COAST. THIS PATTERN WILL INDUCE A MORE
NORTHWESTWARD AND THEN NORTHWARD TRACK THROUGH THE FORECAST PERIOD
WITH A DECREASE IN FORWARD SPEED. BASED ON THE LATEST GUIDANCE...
THE OFFICIAL TRACK FORECAST HAS BEEN SHIFTED TO THE EAST...BUT
STILL REMAINS SLIGHTLY WEST OF THE MODEL CONSENSUS. ALTHOUGH IT IS
TOO EARLY TO BE CERTAIN...THE CURRENT GUIDANCE LESSENS THE THREAT
TO SOUTH FLORIDA.
 
DO NOT TO FOCUS ON THE EXACT FORECAST TRACK...ESPECIALLY AT DAYS 4
TO 5...SINCE THE MOST RECENT 5-YEAR AVERAGE ERRORS AT THOSE
FORECAST TIMES ARE 200 AND 250 MILES...RESPECTIVELY.
 
  
FORECAST POSITIONS AND MAX WINDS
 
INIT  22/1500Z 19.2N  67.5W   70 KT  80 MPH
 12H  23/0000Z 19.9N  69.2W   75 KT  85 MPH
 24H  23/1200Z 20.5N  71.4W   80 KT  90 MPH
 36H  24/0000Z 21.2N  73.2W   85 KT 100 MPH
 48H  24/1200Z 22.0N  75.0W   90 KT 105 MPH
 72H  25/1200Z 25.0N  77.5W  100 KT 115 MPH
 96H  26/1200Z 28.5N  79.0W  100 KT 115 MPH
120H  27/1200Z 32.5N  80.0W  100 KT 115 MPH
 
$$
FORECASTER AVILA
 
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