963 
 WTPZ42 KNHC 242044
 TCDEP2
 
 TROPICAL STORM FRANK DISCUSSION NUMBER  13
 NWS NATIONAL HURRICANE CENTER MIAMI FL       EP072016
 300 PM MDT SUN JUL 24 2016
 
 Some impressive changes have occurred with Frank in the last several
 hours.  The cloud structure has evolved from a sheared pattern into
 a more banded central dense overcast configuration.  A 1911Z GPM
 microwave pass shows the development of a sharp hooking feature,
 indicative of a notable increase in organization.  ASCAT data caught
 the eastern side of the circulation, with 55-kt maximum winds.  Due
 to the low bias of the instrument at that intensity and the
 increasing inner-core structure, the initial wind speed is set to
 60 kt, near the TAFB classification.
 
 The shear appears to have abated enough to allow Frank to intensify,
 and Frank is now forecast to become a hurricane before reaching more
 marginal water temperatures.  The bulk of the guidance is also
 showing a similar solution, although the COAMPS-TC and the GFDL do
 not show any further strengthening.  Frank is expected to become a
 remnant low in 3 to 4 days while it moves over cool 23 deg C waters.
 The latest NHC intensity forecast is raised from the previous one,
 close to a blend of the SHIPS and LGEM models, with a bit more
 weight on the latter model.
 
 Frank has slowed down and turned westward recently according to the
 microwave data, although a longer term motion is still
 west-northwestward at about 5 kt.  While a ridge to the north of the
 storm should steer Frank generally westward to west-northwestward
 for the next few days, there is a big difference emerging in the
 latest guidance on what happens thereafter.  It seems like the track
 forecast is closely related to the depth and intensity of the
 cyclone, with a stronger storm probably more likely to take a
 west-northwest or northwest track at long range like the new ECMWF
 model. Conversely, a weaker system would likely turn to the
 west-southwest, as shown by the GFS and its ensemble.  Few changes
 are made to the forecast on this cycle since the model consensus has
 not moved much, but it would not be surprising to see a northward
 trend in the forecast if Frank becomes a stronger and deeper
 cyclone.
 
 FORECAST POSITIONS AND MAX WINDS
 
 INIT  24/2100Z 20.0N 112.8W   60 KT  70 MPH
  12H  25/0600Z 20.2N 113.5W   65 KT  75 MPH
  24H  25/1800Z 20.5N 114.6W   60 KT  70 MPH
  36H  26/0600Z 20.7N 115.7W   55 KT  65 MPH
  48H  26/1800Z 21.0N 117.1W   50 KT  60 MPH
  72H  27/1800Z 22.1N 120.1W   40 KT  45 MPH
  96H  28/1800Z 22.8N 122.7W   30 KT  35 MPH...POST-TROP/REMNT LOW
 120H  29/1800Z 23.0N 125.0W   20 KT  25 MPH...POST-TROP/REMNT LOW
 
 $$
 Forecaster Blake