012 
 WTNT44 KNHC 232053
 TCDAT4
  
 HURRICANE IRENE DISCUSSION NUMBER  14
 NWS NATIONAL HURRICANE CENTER MIAMI FL       AL092011
 500 PM EDT TUE AUG 23 2011
  
 THE EYE OF IRENE WAS MORE APPARENT IN VISIBLE SATELLITE IMAGERY
 EARLY THIS AFTERNOON...BUT HAS RECENTLY BECOME OBSCURED.  THE AIR
 FORCE RESERVE HURRICANE HUNTER AIRCRAFT FOUND A MAXIMUM 700 MB
 FLIGHT-LEVEL WIND OF 74 KT AND PEAK SFMR WINDS OF AROUND 75 KT. IT
 HAS BEEN NEARLY 24 HOURS SINCE THE AIRCRAFT HAS MEASURED WINDS THAT
 SUPPORT AN INTENSITY OF 85 KT.  THEREFORE...THE INITIAL INTENSITY
 HAS BEEN REDUCED TO 80 KT.  THE PRESSURE DROPPED ABOUT A MILLIBAR
 ON EACH SUCCESSIVE FIX AND WAS DOWN TO 976 MB ON THE LASS PASS
 AROUND 1830 UTC.  ANOTHER HURRICANE HUNTER AIRCRAFT WILL
 INVESTIGATE IRENE THIS EVENING.
  
 THE HURRICANE WILL BE TRAVERSING VERY WARM WATERS DURING THE NEXT
 COUPLE OF DAYS. HOWEVER...THE UPPER-LEVEL PATTERN IS NOT IDEAL FOR
 RAPID DEVELOPMENT...AND THE GLOBAL MODELS SUGGEST MODERATE WESTERLY
 SHEAR WILL CONTINUE FOR ANOTHER DAY OR TWO. THE NEW INTENSITY
 FORECAST IS SLIGHTLY BELOW THE PREVIOUS ADVISORY DURING THE FIRST
 24 HOURS DUE TO THE LOWER INITIAL INTENSITY. AFTER THAT...IT IS
 UNCHANGED FROM THE PREVIOUS FORECAST AND BRINGS IRENE TO MAJOR
 HURRICANE STATUS IN 36 HOURS. THE NEW INTENSITY FORECAST IS A BLEND
 OF THE LOWER STATISTICAL GUIDANCE AND THE MORE AGGRESSIVE GFDL/HWRF
 MODELS. 
  
 THE AIRCRAFT FIXES INDICATE THAT IRENE HAS BEEN MOVING
 WEST-NORTHWEST OR 295/8 KT...A LITTLE SLOWER THAN BEFORE. THE TRACK
 FORECAST REASONING REMAINS UNCHANGED. IRENE IS EXPECTED TO TURN
 NORTHWESTWARD THEN NORTHWARD DURING THE NEXT 2-3 DAYS AS THE
 WESTERN PORTION OF THE SUBTROPICAL RIDGE WEAKENS. THE TRACK
 GUIDANCE IS IN REMARKABLY GOOD AGREEMENT DURING THIS TIME AND THERE
 IS HIGH CONFIDENCE IN THAT PORTION OF THE FORECAST. AFTER THAT...
 IRENE IS FORECAST TO MOVE NORTHWARD TO NORTHEASTWARD AROUND THE
 ATLANTIC RIDGE. SEVERAL OF THE MODELS...INCLUDING THE
 GFS...ECMWF...HWRF...AND GFDL...SHOW A TURN BACK TOWARD THE NORTH
 NEAR THE END OF THE FORECAST PERIOD. THIS APPEARS TO BE IN RESPONSE
 TO A WEAK TROUGH THAT MOVES THROUGH THE SOUTHEASTERN UNITED STATES
 BEHIND THE HURRICANE. THE UPDATED TRACK FORECAST HAS BEEN SHIFTED
 EASTWARD AT 72 AND 96 HOURS BUT THE NEW 5-DAY POINT IS STILL ALONG
 THE LEFT SIDE OF THE GUIDANCE ENVELOPE...IN AGREEMENT WITH THE
 MODELS MENTIONED ABOVE. USERS ARE REMINDED THAT LARGE FORECAST
 ERRORS ARE POSSIBLE AT THE LONGER LEAD TIMES.  
 
  
 FORECAST POSITIONS AND MAX WINDS
  
 INIT  23/2100Z 20.9N  71.5W   80 KT  90 MPH
  12H  24/0600Z 21.5N  72.7W   85 KT 100 MPH
  24H  24/1800Z 22.7N  74.2W   95 KT 110 MPH
  36H  25/0600Z 24.2N  75.5W  105 KT 120 MPH
  48H  25/1800Z 26.1N  76.7W  110 KT 125 MPH
  72H  26/1800Z 30.0N  77.2W  110 KT 125 MPH
  96H  27/1800Z 34.0N  76.2W  100 KT 115 MPH
 120H  28/1800Z 39.0N  74.8W   75 KT  85 MPH
  
 $$
 FORECASTER BROWN