746 
 WTNT42 KNHC 040239
 TCDAT2
 TROPICAL STORM EARL DISCUSSION NUMBER  39
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL072010
 1100 PM EDT FRI SEP 03 2010
  
 EARL HAS CONTINUED TO SLOWLY WEAKEN THIS EVENING.  WHILE THE
 CENTRAL PRESSURE REMAINS 958 MB...AIRCRAFT DATA SUGGEST THAT EARL
 IS NOW BELOW HURRICANE STRENGTH.  THE INITIAL INTENSITY OF 60 KT IS
 BASED ON A BLEND OF PEAK SFMR VALUES OF AROUND 55 KT AND A 700-MB
 FLIGHT LEVEL WIND MAXIMUM OF 67 KT JUST PRIOR TO 0000 UTC.  THE
 DEEP CONVECTION WITH EARL IS INCREASINGLY LIMITED TO THE NORTHERN
 SEMICIRCLE OF THE CIRCULATION...DUE TO SOUTHERLY WIND SHEAR OF
 15-20 KT AND DRY AIR ADVECTION SOUTH OF THE CENTER.  EARL WILL BE
 CROSSING THE NORTHERN WALL OF THE GULF STREAM SOON...AND COLD WATER
 AND INCREASING SHEAR SHOULD RESULT IN CONTINUED WEAKENING UNTIL
 EXTRATROPICAL TRANSITION BEGINS.  GLOBAL MODEL FIELDS AND PHASE
 SPACE DIAGRAMS SUGGEST THAT EARL WILL BE UNDERGOING EXTRATROPICAL
 TRANSITION BY 24 HOURS...WITH THE TRANSITION COMPLETE IN 36 HOURS.
  
 THE INITIAL MOTION ESTIMATE IS TOWARD THE NORTHEAST...OR 035 DEGREES
 AT 22 KNOTS.  EARL SHOULD CONTINUE TO ACCELERATE AHEAD OF A LARGE
 MID- TO UPPER-LEVEL TROUGH MOVING EASTWARD FROM THE GREAT LAKES
 INTO SOUTHEASTERN CANADA OVER THE NEXT COUPLE OF DAYS.  BEYOND THAT
 TIME...MUCH OF THE GLOBAL MODEL GUIDANCE NOW SUGGESTS THAT EARL WILL
 TURN NORTHWARD AND THEN NORTHWESTWARD AS A DISTINCT CYCLONE THROUGH
 72 HOURS BEFORE DISSIPATING OR BEING ABSORBED.  THE EXTRATROPICAL
 PORTION OF THE TRACK IS BASED ON COORDINATION WITH THE OCEAN
 PREDICTION CENTER.
  
 EARL REMAINS A LARGE TROPICAL CYCLONE...AND WILL BRING HIGH WINDS
 AND RAINFALL TO MUCH OF COASTAL NEW ENGLAND AND THE CANADIAN
 MARITIMES OVERNIGHT TONIGHT AND SATURDAY.
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      04/0300Z 40.0N  69.7W    60 KT
  12HR VT     04/1200Z 43.1N  66.6W    55 KT
  24HR VT     05/0000Z 48.2N  61.6W    45 KT...POST-TROPICAL
  36HR VT     05/1200Z 52.5N  56.5W    45 KT...POST-TROP/EXTRATROP
  48HR VT     06/0000Z 55.5N  54.0W    40 KT...POST-TROP/EXTRATROP
  72HR VT     07/0000Z 57.0N  57.0W    40 KT...POST-TROP/EXTRATROP
  96HR VT     08/0000Z...DISSIPATED
  
 $$
 FORECASTER BRENNAN