494 
 WTPA42 PHFO 202115
 TCDCP2
  
 Hurricane Lane Discussion Number  24
 NWS Central Pacific Hurricane Center Honolulu HI   EP142018
 1100 AM HST Mon Aug 20 2018
  
 Air Force Reserve Hurricane Hunters found a maximum flight level
 wind of 121 kt, and the NOAA Hurricane Hunters found maximum SFMR
 wind of 113 kt earlier on the northwest quadrant. The 15 to 20 nm
 diameter eye had also temporarily become more distinct over the past
 6 to 8 hours, and this was the justifiation for raising the current
 intensity slightly to 115 kt. This is somewhat higher than the 18z
 satellite based estimates were showing. The eye has since started
 to become less distinct once again in satellite imagery.
 
 The initial motion is 280/10, slightly slower than the previous
 advisory. Lane is marching toward the west on the southern flank
 of a large subtropical ridge. In the near term, the track guidance
 is in excellent agreement. This motion is expected to gradually turn
 more toward the west-northwest, and then finally northwest over the
 next few days as the ridge weakens and erodes. Beyond 48 hours, the
 forecast becomes quite challenging. The guidance shows increasing
 spread due to noteworthy differences in the handling of the strength
 of the ridge to the east and southeast of the cyclone. The GFS
 remains on the far right side of the guidance with a harder right
 turn starting around 72 hours, and the ECMWF shows a more gentle
 curve. The consensus guidance remains split down the middle of these
 two camps and did not change much from the previous advisory. The
 forecast track at 96 hours was nudged slightly eastward to better
 agree with the consensus guidance, but it should be noted that in
 this situation, forecast confidence is lower than normal. A turn
 back toward the west-northwest is expected toward the end of the
 forecast period as strong wind shear begins to impact Lane, but this
 is also a rather low confidence scenario. 
  
 Lane is expected to remain over 28C sea surface temperatures in the
 short term in a weak to moderate shear environment that should allow
 the hurricane to maintain intensity. After a day or two, the models
 show increasing shear beginning to work on the circulation and
 weaken the system. However, there are some differences as to when
 that will begin. The intensity forecast shows a slow weakening
 trend beginning in the 24 to 36 hour time frame in good agreement
 with the intensity consensus guidance. Once shear increases in the
 48 to 72 hour time frame, a somewhat faster weakening trend is
 anticipated which should continue through the rest of the forecast
 period.
 
 Interests in the main Hawaiian Islands, as well as the northwestern
 Hawaiian Islands, should continue to monitor the progress of Lane
 this week. With such a complex forecast scenario, it is especially
 important not to focus on the exact forecast track and intensity
 and be ready for changes to both.
  
  
 FORECAST POSITIONS AND MAX WINDS
  
 INIT  20/2100Z 13.6N 149.1W  115 KT 130 MPH
  12H  21/0600Z 13.7N 150.6W  115 KT 130 MPH
  24H  21/1800Z 13.9N 152.3W  115 KT 130 MPH
  36H  22/0600Z 14.3N 153.9W  110 KT 125 MPH
  48H  22/1800Z 14.9N 155.3W  105 KT 120 MPH
  72H  23/1800Z 16.9N 157.2W   95 KT 110 MPH
  96H  24/1800Z 19.4N 158.8W   75 KT  85 MPH
 120H  25/1800Z 20.6N 160.4W   55 KT  65 MPH
  
 $$
 Forecaster R Ballard