258 
 WTPZ44 KNHC 011432
 TCDEP4
 
 HURRICANE GUILLERMO DISCUSSION NUMBER  11
 NWS NATIONAL HURRICANE CENTER MIAMI FL       EP092015
 800 AM PDT SAT AUG 01 2015
 
 The cloud pattern is not as impressive as it was yesterday when
 there was a hint of an eye on satellite imagery. However, Dvorak
 T-numbers from all agencies still support an initial intensity of 90
 kt. It appears that Guillermo has already peaked in intensity, and
 the hurricane is heading toward an environment no longer favorable
 for strengthening. On this basis, the NHC forecast calls for a
 steady state during the next 12 hours or so, and a gradual weakening
 thereafter. By the time Guillermo approaches the Hawaiian
 Islands, the upper-level winds are forecast to be even more
 unfavorable, and by then, Guillermo is expected to have weakened to
 a tropical storm. The NHC forecast is very close to the intensity
 consensus model ICON.
 
 The steering currents have begun to weaken, and Guillermo is slowing
 down. The best estimate of the initial motion is toward the west or
 280 degrees at 12 kt.  The hurricane is already located on the
 southwestern edge of the subtropical ridge, and there is a large
 weakness of the ridge to its northwest. This pattern should force
 the cyclone to slow down even further and turn more to the
 west-northwest. The GFS insists on a more northwesterly component
 bringing the center of Guillermo north of the Hawaiian Islands. The
 ECMWF, on the other hand, brings the cyclone south or near the
 Islands.  The NHC forecast is very similar to the previous one,
 and is basically on top of the consensus of the ECMWF and the GFS
 models.
 
 Due to uncertainties in longer-range track predictions, it is
 important for users not to focus on the exact track forecasts at 96
 and 120 hours. Given the large spread of the models beyond 72
 hours in this case, the forecast uncertainty is particularly high at
 those time periods.
 
 
 FORECAST POSITIONS AND MAX WINDS
 
 INIT  01/1500Z 13.5N 139.0W   90 KT 105 MPH
  12H  02/0000Z 13.9N 141.0W   90 KT 105 MPH
  24H  02/1200Z 14.5N 143.0W   85 KT 100 MPH
  36H  03/0000Z 15.3N 144.7W   80 KT  90 MPH
  48H  03/1200Z 16.2N 146.0W   70 KT  80 MPH
  72H  04/1200Z 17.5N 148.5W   60 KT  70 MPH
  96H  05/1200Z 19.0N 151.5W   50 KT  60 MPH
 120H  06/1200Z 20.7N 155.0W   40 KT  45 MPH
 
 $$
 Forecaster Avila