996 
 WTPZ41 KNHC 070301
 TCDEP1
 
 Hurricane Sergio Discussion Number  31
 NWS National Hurricane Center Miami FL       EP212018
 800 PM PDT Sat Oct 06 2018
 
 Little overall change has been noted in Sergio's satellite
 presentation the past several hours other than cloud tops have
 warmed slightly. The 30-nmi-wide eye remains quite distinct and
 outflow is still very impressive in all quadrants. However, he
 warming tops have resulted in slightly lower satellite intensity
 estimates from all agencies, so the initial intensity has been
 lowered to 105 kt for this advisory.
 
 Sergio is lumbering along toward the west, or 270/06 kt. There is no
 significant change to the previous forecast track or reasoning.
 Sergio should continue to move slowly westward around the
 southwestern periphery of a weak deep-layer ridge for the next day
 or so. By early next week, a strong trough is forecast to dig
 southward off the coasts of California and Baja California, which
 will erode the ridge and cause Sergio to make a sharp northeastward
 turn and accelerate throughout the forecast period. The latest NHC
 track guidance remains in good agreement on this developing steering
 flow pattern, and there is very little cross-track spread in the
 models. The speed differences noted in the previous discussion have
 decreased on this forecast cycle, so only minor tweaks had to be
 made to the previous advisory track. The new forecast track lies
 close the previous one and near a blend of the various consensus
 track models.
 
 Ocean temperatures beneath the cyclone are forecast to decrease over
 the next few days due to cold upwelling beneath the hurricane, so
 gradual weakening is expected for the next 3 days. After that, more
 rapid weakening is forecast due to increasing southwesterly
 vertical wind shear ahead of a a deep-layer trough. The NHC
 intensity forecast is very similar to the previous advisory and the
 IVCN consensus model.
 
 FORECAST POSITIONS AND MAX WINDS
 
 INIT  07/0300Z 14.5N 125.4W  105 KT 120 MPH
  12H  07/1200Z 14.5N 126.4W  100 KT 115 MPH
  24H  08/0000Z 14.8N 127.2W   95 KT 110 MPH
  36H  08/1200Z 15.4N 127.6W   90 KT 105 MPH
  48H  09/0000Z 16.1N 127.4W   85 KT 100 MPH
  72H  10/0000Z 18.0N 124.9W   75 KT  85 MPH
  96H  11/0000Z 20.9N 120.6W   60 KT  70 MPH
 120H  12/0000Z 25.6N 115.1W   45 KT  50 MPH
 
 $$
 Forecaster Stewart