222 
 WTPZ44 KNHC 302032
 TCDEP4
 
 TROPICAL STORM GUILLERMO DISCUSSION NUMBER   4
 NWS NATIONAL HURRICANE CENTER MIAMI FL       EP092015
 200 PM PDT THU JUL 30 2015
 
 Guillermo is quickly becoming better organized, and both microwave
 and visible imagery suggest that the cyclone is developing a ring
 of inner core convection.  Dvorak classifications at 1800 UTC were
 T3.0/45 kt from both TAFB and SAB, but given the quickly improving
 convective structure, the advisory intensity is set at 50 kt.  This
 is close to the latest UW-CIMSS ADT estimate of T3.4/53 kt.
 
 The upper-level outflow of Guillermo continues to expand, and the
 storm is over very warm waters of around 29 degrees Celsius.  Global
 model guidance indicates that Guillermo should remain in a
 light-shear environment for at least another 3 days, while also
 remaining over warm water and in a moisture-laden atmosphere.
 Therefore, continued strengthening is likely for the next 48 hours,
 and Guillermo could become a hurricane within the next 12-24 hours.
 Gradual weakening is forecast from day 3 through 5 due to stronger
 upper-level westerly winds which could affect the cyclone.  The
 statistical-dynamical guidance continues to show only modest
 strengthening--barely taking Guillermo to hurricane status--but
 this scenario seems low given the seemingly favorable environment.
 The NHC official intensity forecast remains closer to the higher
 dynamical guidance and is largely unchanged from the previous
 forecast.
 
 The subtropical ridge is steering Guillermo west-northwestward, or
 295/12 kt.  The ridge is forecast to strengthen slightly, causing
 Guillermo to accelerate during the next 36 hours.  After that time,
 a mid- to upper-level low well west of California is expected to
 produce a break in the ridge, which should cause the cyclone to
 slow down and turn northwestward by day 5.  The latest track
 guidance ended up lying to the west of the previous official
 forecast track, and the updated NHC track has therefore been
 shifted a bit to the left, especially after 48 hours.
 
 FORECAST POSITIONS AND MAX WINDS
 
 INIT  30/2100Z  9.8N 128.4W   50 KT  60 MPH
  12H  31/0600Z 10.6N 130.6W   60 KT  70 MPH
  24H  31/1800Z 11.5N 133.7W   70 KT  80 MPH
  36H  01/0600Z 12.4N 136.8W   75 KT  85 MPH
  48H  01/1800Z 13.2N 139.4W   80 KT  90 MPH
  72H  02/1800Z 14.9N 143.3W   75 KT  85 MPH
  96H  03/1800Z 16.5N 146.0W   65 KT  75 MPH
 120H  04/1800Z 18.0N 148.5W   55 KT  65 MPH
 
 $$
 Forecaster Berg