885 
 WTPZ41 KNHC 050232
 TCDEP1
 
 Hurricane Sergio Discussion Number  23
 NWS National Hurricane Center Miami FL       EP212018
 800 PM PDT Thu Oct 04 2018
 
 Sergio's cloud pattern has deteriorated somewhat since the previous
 advisory, with cloud tops warming and the eye becoming more ragged
 and less distinct. The initial intensity is reduced to 110 kt based
 on a blend of the latest objective and subjective Dvorak estimates.
 Sergio is expected to steadily weaken for the next 48 hours while
 moving into a drier and more stable environment. By then, most of
 the guidance suggests little change from 48-72 hours before the
 shear increases by the end of the period and SSTs cool to between
 26C and 27C, which should again result in weakening. The new NHC
 intensity forecast is lower than the previous one during the first
 48 hours to account for the observed weakening and the trend in the
 guidance, but is similar after that time. This prediction is close
 to or a bit above the latest HCCA intensity consensus aid.
 
 Sergio has turned toward the left during the past few hours, with an
 initial motion estimate now 305/07. A mid-level ridge building to
 the northwest of Sergio will steer the hurricane toward the west and
 even toward the west-southwest during the next 36 to 48 hours. After
 that time, an amplifying longwave trough over western North America
 will erode the ridge and cause Sergio to recurve, with a faster
 northeastward motion shown by day 5. The new NHC track forecast has
 been adjusted to the south of the previous one from 24 to 48 hours,
 following the trend of the latest consensus aids, which are showing
 a more equatorward motion during this time. At days 3 through 5, the
 NHC track is largely an update of the previous one, and lies between
 the faster GFS and the slower ECMWF models.
 
 FORECAST POSITIONS AND MAX WINDS
 
 INIT  05/0300Z 15.9N 120.5W  110 KT 125 MPH
  12H  05/1200Z 16.0N 121.4W  100 KT 115 MPH
  24H  06/0000Z 15.9N 122.5W   95 KT 110 MPH
  36H  06/1200Z 15.6N 123.8W   85 KT 100 MPH
  48H  07/0000Z 15.5N 125.0W   80 KT  90 MPH
  72H  08/0000Z 16.0N 127.0W   80 KT  90 MPH
  96H  09/0000Z 17.5N 127.0W   70 KT  80 MPH
 120H  10/0000Z 19.5N 124.5W   65 KT  75 MPH
 
 $$
 Forecaster Brennan