343 
 WTPA42 PHFO 210857
 TCDCP2
  
 Hurricane Lane Discussion Number  26
 NWS Central Pacific Hurricane Center Honolulu HI   EP142018
 1100 PM HST Mon Aug 20 2018
  
 
 Lane has quite an impressive satellite signature this evening, with 
 a solid ring of very cold cloud tops surrounding a warming eye. 
 Aircraft from NOAA and the 53rd Weather Reconnaissance Squadron
 have been flying through lane at 8 to 10 thousand feet respectively
 this evening, and are confirming that Lane is a powerful hurricane
 that has intensified since their last visit this morning. The
 central pressure has dropped roughly 10 mb, peak SFMR winds were 140
 kt with max flight level winds near 128 kt, and an eyewall
 dropsonde recorded winds near 139 kt. Based on a blend of the
 aircraft data, the initial intensity for this advisory is increased 
 to 130 kt, maintaining Lane as a powerful category 4 hurricane. 
 
 The initial motion for this advisory is 280/10 kt, with Lane 
 continuing to be steered by a mid-level ridge centered to the
 north. Over the next couple of days, Lane is expected to reach the
 western periphery of the ridge, allowing the cyclone to gain
 latitude. Some increase in the clustering of the track model
 guidance has occurred this cycle, with the ECMWF no longer on the
 left hand side of the envelope. All of the reliable model guidance
 now indicates that Lane will begin to make a gradual turn to the
 west-northwest by Wednesday, with a gradual slowing in forward
 speed. A more decided turn toward the northwest is expected
 Thursday, with relatively slow-moving Lane now forecast to move
 dangerously close to the main Hawaiian Islands. A turn toward the
 west is expected in the later forecast periods, with forecast models
 indicating a weakened Lane increasingly being steered by the
 low-level trade wind flow. The updated track forecast lies between
 the previous official forecast and the HCCA.
 
 The weakening in the latter forecast periods appears to be related 
 to an increase in vertical wind shear, but it also appears that 
 forecast models are expecting interaction with island terrain to 
 interrupt the low-level wind flow into Lane. Water temperatures 
 along the forecast track will be sufficiently warm to support a 
 major hurricane, and thus any significant weakening before Lane 
 draws closer to the Hawaiian Islands will likely be due to shear.
 With shear expected to be minimal in the short term, subtle
 intensity fluctuations associated with inner-core dynamics will
 likely lead to little overall change in intensity. The later
 forecast periods anticipate an increase in shear as Lane will lie
 between the ridge to the east and trough aloft to the northwest of
 the main Hawaiian Islands, and the updated intensity forecast has
 been nudged upward in the short term due to recent trends and
 follows the previous official forecast in the latter forecast
 periods, close to the IVCN consensus. 
 
 The uncertainty in the track forecast necessitates that interests in
 the Hawaiian Islands continue to closely monitor Lane the next
 couple of days. It is important to not focus on the exact forecast
 track, as impacts from Lane extend well away from its center. 
  
  
 FORECAST POSITIONS AND MAX WINDS
  
 INIT  21/0900Z 14.0N 151.2W  130 KT 150 MPH
  12H  21/1800Z 14.3N 152.4W  130 KT 150 MPH
  24H  22/0600Z 14.7N 153.9W  120 KT 140 MPH
  36H  22/1800Z 15.4N 155.1W  115 KT 130 MPH
  48H  23/0600Z 16.4N 156.0W  110 KT 125 MPH
  72H  24/0600Z 18.9N 157.3W   95 KT 110 MPH
  96H  25/0600Z 20.7N 159.0W   75 KT  85 MPH
 120H  26/0600Z 21.0N 161.5W   60 KT  70 MPH
  
 $$
 Forecaster Birchard