797 
 WTNT42 KNHC 161451
 TCDAT2
 
 TROPICAL STORM KARL DISCUSSION NUMBER   9
 NWS NATIONAL HURRICANE CENTER MIAMI FL       AL122016
 1100 AM AST FRI SEP 16 2016
 
 Karl remains a sheared tropical cyclone this morning with all
 of its deep convection in the northeastern quadrant due to shear
 related to its interaction with a mid- to upper-level trough.  The
 initial wind speed is kept at 40 kt for this advisory, a compromise
 between lower Dvorak estimates and higher, but noisy, scatterometer
 values.   Vertical shear is expected to decrease in about 36 hours,
 and, despite a somewhat dry environment, warming sea surface
 temperatures should allow for at least gradual strengthening.  The
 intensity models continue to trend higher at the end of the
 forecast period, and the official forecast follows this trend.  This
 forecast is remains close to the SHIPS and LGEM models.
 
 The center of Karl has become a little distorted due to the shear
 and convection, but it still seems to be moving about 280/11.
 Karl is forecast to turn more to the west and south-of-west this
 weekend as the subtropical ridge strengthens to the north of the
 cyclone. However, the current interaction of Karl with the mid- to
 upper-level trough has not been well forecast, and Karl probably
 will not get as far to the south as expected yesterday. In a few
 days, the storm should move to the west-northwest and eventually
 more to northwest around day 5 as it reaches the edge of the ridge.
 The new forecast is close to a blend of the ECMWF and GFS, plus
 their respective ensemble means, ending up a little north of the
 previous NHC prediction at long range.
 
 
 FORECAST POSITIONS AND MAX WINDS
 
 INIT  16/1500Z 18.4N  34.3W   40 KT  45 MPH
  12H  17/0000Z 18.5N  36.2W   40 KT  45 MPH
  24H  17/1200Z 18.4N  38.8W   40 KT  45 MPH
  36H  18/0000Z 17.9N  41.5W   40 KT  45 MPH
  48H  18/1200Z 17.7N  44.0W   45 KT  50 MPH
  72H  19/1200Z 18.3N  49.0W   50 KT  60 MPH
  96H  20/1200Z 20.0N  54.0W   60 KT  70 MPH
 120H  21/1200Z 22.5N  58.5W   70 KT  80 MPH
 
 $$
 Forecaster Blake