387 
 WTPZ42 KNHC 272032
 TCDEP2
 
 TROPICAL STORM FRANK DISCUSSION NUMBER  25
 NWS NATIONAL HURRICANE CENTER MIAMI FL       EP072016
 200 PM PDT WED JUL 27 2016
 
 Frank has continued its weakening trend with only a small area of
 convection now displaced to the northwest of the low-level center.
 Although subjective and objective satellite intensity estimates
 support an intensity of about 60 kt, the initial intensity has been
 lowered to 50 kt based on a partial ASCAT-B scatterometer pass
 that showed winds of only about 40 kt in the eastern semicircle.
 Even though the western half of the cyclone was not sampled, it is
 assumed that some stronger winds exist in that part of the
 circulation, but not as strong as the satellite estimates due to the
 cooler waters creating a more stable boundary layer.
 
 The initial motion estimate is now 295/09 kt. Frank should move
 west-northwestward for the next 24 hours or so before turning
 westward by 36 hours after the cyclone degenerates into a shallow
 remnant low, which will be steered by the low-level easterly trade
 wind flow. The new NHC model guidance is in good agreement on this
 track scenario, although there is significant cross-track spread in
 the models after 48 hours. The official forecast track is similar
 to the previous advisory track and lies a little south of the
 consensus track model TVCN.
 
 Microwave imagery indicates that Frank's circulation has a
 northwestward tilt due to some southeasterly mid-level wind shear.
 The cyclone is also moving over sub-24C SSTs at this time, and
 cooler waters lie ahead of Frank. The combination of increasing
 shear, decreasing water temperatures, and a drier and more stable
 airmass should result in rapid weakening during the next 24 hours.
 Therefore, Frank is forecast to degenerate into a remnant low on
 Thursday and dissipate on Saturday. The official intensity forecast
 follows the intensity consensus model IVCN.
 
 FORECAST POSITIONS AND MAX WINDS
 
 INIT  27/2100Z 23.1N 121.8W   50 KT  60 MPH
  12H  28/0600Z 23.8N 122.9W   40 KT  45 MPH
  24H  28/1800Z 24.5N 124.1W   30 KT  35 MPH...POST-TROP/REMNT LOW
  36H  29/0600Z 24.9N 125.1W   25 KT  30 MPH...POST-TROP/REMNT LOW
  48H  29/1800Z 24.9N 126.1W   20 KT  25 MPH...POST-TROP/REMNT LOW
  72H  30/1800Z 24.4N 128.0W   15 KT  15 MPH...POST-TROP/REMNT LOW
  96H  31/1800Z...DISSIPATED
 
 $$
 Forecaster Stewart