286 
 WTNT42 KNHC 301450
 TCDAT2
 HURRICANE EARL DISCUSSION NUMBER  21
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL072010
 1100 AM AST MON AUG 30 2010
  
 THE EYE OF EARL HAS BECOME BETTER DEFINED IN VISIBLE SATELLITE
 IMAGERY THIS MORNING AND IS WELL-DEFINED IN RADAR IMAGERY FROM BOTH
 SAN JUAN AND ST. MAARTEN. AN AIR FORCE HURRICANE HUNTER AIRCRAFT
 MEASURED 700 MB FLIGHT-LEVEL WINDS OF 111 KT IN THE NORTHEAST
 EYEWALL AROUND 1200 UTC. THE AIRCRAFT HAS NOT SAMPLED THE
 NORTHEASTERN QUADRANT AGAIN...BUT FOUND 90 KT SFMR WINDS IN THE
 NORTHWEST EYEWALL AND A MINIMUM PRESSURE OF 960 MB. THIS SUPPORTS
 INCREASING THE INITIAL INTENSITY TO 105 KT...CATEGORY THREE ON THE
 SAFFIR-SIMPSON HURRICANE WIND SCALE. THE LOW SHEAR AND WARM WATER
 ENVIRONMENT AHEAD OF EARL APPEARS CONDUCIVE FOR ADDITIONAL
 STRENGTHENING DURING THE NEXT FEW DAYS.  THIS SUPPORTS KEEPING EARL
 AT MAJOR HURRICANE STRENGTH DURING THAT TIME...ALTHOUGH EYEWALL
 CYCLES COULD INDUCE SOME FLUCTUATIONS IN INTENSITY.  THE OFFICIAL
 FORECAST IS AT THE UPPER END OF THE INTENSITY GUIDANCE. LATE IN THE
 FORECAST PERIOD INCREASING SHEAR AND COOLER SSTS SHOULD INDUCE
 WEAKENING.
  
 THE INITIAL MOTION REMAINS 285/13.  EARL IS EXPECTED TO TURN TOWARD
 THE NORTHWEST WITHIN THE NEXT DAY OR SO AS IT MOVES AROUND THE
 WESTERN PERIPHERY OF THE SUBTROPICAL RIDGE DURING THE NEXT COUPLE OF
 DAYS. AFTER THAT TIME...EARL IS FORECAST TO TURN NORTHWARD...THEN
 NORTHEASTWARD AHEAD OF A MID-LATITUDE TROUGH THAT MOVES ACROSS THE
 GREAT LAKES AND INTO THE NORTHEAST UNITED STATES IN 4-5 DAYS.  THE
 TRACK GUIDANCE HAS SHIFTED WESTWARD AGAIN AND THE OFFICIAL FORECAST
 HAS BEEN ADJUSTED IN THAT DIRECTION.  THE UPDATED TRACK FORECAST IS
 NEAR THE MIDDLE OF THE TIGHTLY CLUSTERED GUIDANCE.
  
 THIS IS A GOOD TIME TO REMIND EVERYONE THAT NHC AVERAGE TRACK
 FORECAST ERRORS ARE 200 TO 300 MILES AT DAYS 4 AND 5.  GIVEN THIS
 UNCERTAINTY...IT IS TOO SOON TO DETERMINE WHAT PORTION OF THE U.S.
 EAST COAST MIGHT SEE DIRECT IMPACTS FROM EARL.
  
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      30/1500Z 18.7N  63.6W   105 KT
  12HR VT     31/0000Z 19.5N  65.1W   115 KT
  24HR VT     31/1200Z 21.0N  67.0W   125 KT
  36HR VT     01/0000Z 22.8N  68.7W   125 KT
  48HR VT     01/1200Z 25.2N  70.6W   120 KT
  72HR VT     02/1200Z 31.0N  73.5W   110 KT
  96HR VT     03/1200Z 37.5N  71.5W   100 KT
 120HR VT     04/1200Z 45.5N  63.0W    75 KT...INLAND
  
 $$
 FORECASTER BROWN/BERG