439 
 WTNT41 KNHC 190846
 TCDAT1
 
 TROPICAL STORM FIONA DISCUSSION NUMBER  10
 NWS NATIONAL HURRICANE CENTER MIAMI FL       AL062016
 500 AM AST FRI AUG 19 2016
 
 Fiona hasn't really changed much overall in the past several hours
 with an earlier burst of convection having dissipated and a new
 burst taking its place.  Microwave data suggest the center is near
 or south of the main area of thunderstorms, which is a sign of
 the ongoing southwesterly shear.  The initial wind speed is kept at
 40 kt for this advisory since the Dvorak estimates are the same as
 the previous cycle.  Little significant change is expected with
 Fiona's intensity today due to gradually increasing shear.  The
 storm should weaken over the weekend as the shear further increases,
 along with the likely entrainment of drier mid-level air.  While the
 environmental conditions might get less hostile at the end of the
 period, it is uncertain how much will be left of Fiona at that time
 to take advantage of that change, with some suggestion in the global
 models that Fiona could decay to a remnant low by then.  Thus,
 the new NHC intensity forecast is a bit lower than the previous one,
 near a model consensus than excludes the GFDL (which has looked
 consistently too high).
 
 A timely AMSR2 pass helped show that Fiona has sped up, and is now
 moving 300/9.  Fiona should move around the Atlantic subtropical
 ridge for the next few days.  The biggest change to the track
 guidance is that all of the models have shifted a few degrees
 westward at long range.  This appears to be due to less of a trough
 forecast over the central Atlantic and a weaker representation of
 Fiona in the global models, both of which would cause the storm to
 continue moving northwestward for a longer period of time.  The new
 NHC track forecast follows the trend of the models, but remains a
 fair distance east of the model consensus at days 4 and 5 due to
 continuity constraints.  It would not be surprising if further
 westward adjustments had to be made later today.
 
 
 FORECAST POSITIONS AND MAX WINDS
 
 INIT  19/0900Z 17.6N  42.7W   40 KT  45 MPH
  12H  19/1800Z 18.2N  44.0W   40 KT  45 MPH
  24H  20/0600Z 19.1N  46.0W   35 KT  40 MPH
  36H  20/1800Z 20.2N  48.1W   35 KT  40 MPH
  48H  21/0600Z 21.3N  50.3W   30 KT  35 MPH
  72H  22/0600Z 23.5N  54.8W   30 KT  35 MPH
  96H  23/0600Z 26.0N  57.5W   30 KT  35 MPH
 120H  24/0600Z 28.0N  59.0W   30 KT  35 MPH
 
 $$
 Forecaster Blake