401 
 WTNT44 KNHC 272057
 TCDAT4
  
 HURRICANE IRENE DISCUSSION NUMBER  30
 NWS NATIONAL HURRICANE CENTER MIAMI FL       AL092011
 500 PM EDT SAT AUG 27 2011
  
 THE CENTER OF IRENE HAS BEEN MOVING ACROSS EASTERN NORTH CAROLINA
 THIS AFTERNOON...AND THE RADAR PRESENTATION OF THE INNER CORE
 ACTUALLY IMPROVED FOR A FEW HOURS.  SINCE THAT TIME...THE RAGGED
 EYE HAS FILLED IN BUT THE CENTER REMAINS WELL DEFINED ON
 RADAR...WHICH WARRANTS A RETURN TO TWO-HOURLY INTERMEDIATE
 ADVISORIES.  AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT
 REPORTED PEAK FLIGHT-LEVEL WINDS OF 85-90 KT TO THE EAST OF THE
 CENTER DURING THE PAST FEW HOURS...AND A VERY RECENT CENTER DROP
 MEASURED A MINIMUM PRESSURE OF 950 MB.  THERE HAVE NOT BEEN ANY
 RECENT SFMR DATA...BUT BASED ON THE EARLIER SHARP DISCREPANCY
 BETWEEN THE FLIGHT-LEVEL AND SURFACE WINDS...THE INITIAL INTENSITY
 IS REDUCED TO 70 KT.  A SLOW WEAKENING IS EXPECTED AS IRENE MOVES
 ALONG THE COAST OF THE MID-ATLANTIC STATES DUE TO LAND
 INTERACTION...COLDER WATERS...DRY AIR ENTRAINMENT...AND INCREASING
 SOUTHWESTERLY SHEAR.  BECAUSE THE LARGE WIND FIELD WILL TAKE TIME
 TO SPIN DOWN...HOWEVER...IRENE IS STILL EXPECTED TO REACH THE NEW
 YORK AREA AT OR NEAR HURRICANE STRENGTH.
 
 MORE SO THAN WITH MOST STORMS...THE WINDS WITH IRENE INCREASE
 SHARPLY WITH HEIGHT ABOVE THE SURFACE.  AS IRENE MOVES THROUGH
 AREAS WITH HIGH-RISE STRUCTURES...THESE STRUCTURES WILL EXPERIENCE
 WINDS SIGNIFICANTLY STRONGER THAN INDICATED BY THE ADVISORY
 INTENSITY.  WINDS AT THE 30-STORY LEVEL WILL LIKELY BE 20 PERCENT
 HIGHER THAN AT THE SURFACE...AND WINDS 80-100 STORIES UP COULD BE
 ABOUT 30 PERCENT HIGHER THAN AT THE SURFACE.
  
 THE CENTER CONTINUED NORTHWARD FOR A SHORT PERIOD OF TIME AFTER THE
 RELEASE OF THE PREVIOUS ADVISORY BUT HAS RESUMED A NORTHEASTWARD
 MOTION OF ABOUT 015/11. IRENE IS FORECAST TO MOVE NORTH-
 NORTHEASTWARD ALONG THE MID-ATLANTIC COAST TONIGHT AND OVER NEW
 ENGLAND ON SUNDAY. AFTER THE CYCLONE BECOMES EXTRATROPICAL IN 36-48
 HOURS IT SHOULD TURN NORTHEASTWARD THEN EAST-NORTHEASTWARD IN THE
 MID-LATITUDE WESTERLIES. THE NEW TRACK FORECAST IS UNCHANGED FROM
 THE PREVIOUS ADVISORY. 
 
 NOTE THAT ESTIMATES OF STORM TOTAL RAINFALL HAVE BEEN INCREASED WITH
 THIS ADVISORY...TO 20 INCHES.
  
  
 FORECAST POSITIONS AND MAX WINDS
  
 INIT  27/2100Z 36.2N  76.0W   70 KT  80 MPH
  12H  28/0600Z 38.1N  75.1W   65 KT  75 MPH
  24H  28/1800Z 41.7N  73.2W   60 KT  70 MPH...INLAND
  36H  29/0600Z 46.2N  70.2W   45 KT  50 MPH...POST-TROP/EXTRATROP
  48H  29/1800Z 50.7N  66.3W   45 KT  50 MPH...POST-TROP/EXTRATROP
  72H  30/1800Z 56.5N  53.5W   40 KT  45 MPH...POST-TROP/EXTRATROP
  96H  31/1800Z 59.0N  37.0W   35 KT  40 MPH...POST-TROP/EXTRATROP
 120H  01/1800Z 61.0N  26.0W   35 KT  40 MPH...POST-TROP/EXTRATROP
  
 $$
 FORECASTER BROWN/FRANKLIN