195 
 WTPZ43 KNHC 012032
 TCDEP3
 TROPICAL STORM ERICK DISCUSSION NUMBER   5
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP082007
 200 PM PDT WED AUG 01 2007
  
 VISIBLE SATELLITE IMAGERY INDICATES THAT STRONG EASTERLY SHEAR
 IS TAKING ITS TOLL ON ERICK...WITH THE LOW LEVEL CIRCULATION NOW
 ALMOST COMPLETELY EXPOSED ON THE NORTHEAST SIDE OF A WEAKENING BLOB
 OF DEEP CONVECTION.  WHILE THE SATELLITE SIGNATURE IS SUGGESTIVE OF
 A WEAKENING CYCLONE...THE INITIAL INTENSITY IS CONSERVATIVELY HELD
 AT 35 KT TO SEE IF THE CURRENT CONVECTIVE TREND PERSISTS. GIVEN THE
 CYCLONE IS CURRENTLY OVER SSTS OF ABOUT 28C...SOME STRENGTHENING
 REMAINS POSSIBLE IF THE SHEAR DECREASES.  HOWEVER...SSTS START
 APPROACHING 26C IN 48 HOURS AND THE THERMODYNAMIC ENVIRONMENT
 APPEARS MARGINAL. IT WOULD APPEAR THAT ANY STRENGTHENING THAT DOES
 OCCUR WOULD NEED TO HAPPEN SOONER RATHER THAN LATER. 
 ACCORDINGLY...THE OFFICIAL FORECAST ALLOWS FOR A LITTLE
 STRENGTHENING IN THE SHORT-TERM FOLLOWED BY SLOW WEAKENING.  
  
 BASED ON LATEST VISIBLE IMAGERY...THE LOW LEVEL CIRCULATION IS
 MOVING A LITTLE TO THE RIGHT OF THE PREVIOUS FORECAST TRACK OR
 ABOUT 285/9. ASSUMING THE SYSTEM CAN MAINTAIN SOME VERTICAL
 DEPTH...A MID-LEVEL RIDGE TO THE NORTH IS EXPECTED TO BE
 THE PRIMARY STEERING MECHANISM OVER THE NEXT SEVERAL DAYS.
 THEREFORE ERICK SHOULD CONTINUE ON A GENERAL WEST-NORTHWESTWARD
 HEADING FOR MOST OF THE FORECAST PERIOD.  TRACK GUIDANCE CONTINUES
 TO TREND NORTHWARD AND SO DOES THE OFFICIAL FORECAST. 
 
 THE 34 KT WIND RADII WERE ADJUSTED BASED ON THE LATEST QUIKSCAT DATA
 THAT INDICATES TROPICAL STORM FORCE WINDS ARE CONFINED TO THE
 SOUTHWEST QUADRANT. 
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      01/2100Z 13.6N 127.1W    35 KT
  12HR VT     02/0600Z 13.7N 128.4W    35 KT
  24HR VT     02/1800Z 13.9N 130.0W    40 KT
  36HR VT     03/0600Z 14.2N 131.5W    45 KT
  48HR VT     03/1800Z 14.4N 133.3W    45 KT
  72HR VT     04/1800Z 14.7N 136.8W    45 KT
  96HR VT     05/1800Z 15.0N 139.5W    40 KT
 120HR VT     06/1800Z 15.0N 143.0W    40 KT
  
 $$
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