491 
 WTPA42 PHFO 210310
 TCDCP2
  
 Hurricane Lane Discussion Number  25...Corrected
 NWS Central Pacific Hurricane Center Honolulu HI   EP142018
 500 PM HST Mon Aug 20 2018
  
 Visible satellite imagery this afternoon shows an impressive,
 distinct eye on Hurricane Lane, though the convection surrounding
 the core looks more ragged on the last few infrared images. A 2258Z
 AMSR2 pass indicated that Lane had a concentric eyewall structure.
 Satellite intensity estimates ranged from 5.5 from SAB and JTWC to
 6.0 from PHFO. CIMSS ADT had 5.5 at 0000Z but has since risen to
 6.0. Based on these estimates and the earlier reconnaisance data,
 we have maintained a 115 kt intensity for this advisory. Another
 aircraft reconnaisance mission will investigate Lane this evening.
  
 The initial motion estimate continues to be 280/10. A subtropical
 ridge to the north of Lane continues to steer the system westward.
 However, changes in the steering pattern are expected relatively
 soon, as the ridge weakens ane leaves a weakness to the north of
 Lane. This will allow the tropical cyclone to begin gaining
 latitude a little more quickly by 48 hours. 
 
 The models are struggling with a couple of factors that make the
 track forecast beyond 48 hours very challenging. One is the
 evolution of a new ridge which develops to the east and southeast of
 Lane, and the other is the effect of gradually increasing shear. The
 ECMWF is stronger with the ridge, and starts shearing the system
 sooner, so the track is on the left side of the guidance envelope.
 The GFS and NAVGEM are quite a bit weaker with the ridge, and keep
 Lane away from the westerly shear longer. There do not appear to be
 any clear signals at this point to suggest which track to favor,
 and so we continue to follow the consensus guidance which is down
 the middle of an uncomfortably large guidance envelope. A turn more
 toward the west is expected toward the end of the period as Lane is
 expected to be decoupled and move as a shallower system in the
 trades. The rather large uncertainty in the track forecast
 necessitates close attention by interests in the Hawaiian Islands
 over the next couple of days. It is important to not focus your
 attention on the exact forecast track, and be prepared for changes
 to the forecast. 
 
 Weak to moderate southwesterly shear and sea surface temperatures
 near 28C are sufficient to allow Lane to maintain intensity for the
 next 24 hours or so. Some fluctuations in intensity are possible
 due to difficult to forecast eyewall replacement cycles. As
 mentioned before, increasing shear will lead to a gradual weakening
 trend at first, with more rapid weakening expected beyond 72 hours
 as Lane approaches stronger winds aloft from a subtropical jet
 stream.
  
 The larger than normal uncertainty in the future track of Lane
 necessitates close attention by interests in the Hawaiian Islands
 over the next few days as Lane approaches the islands. It is
 important not to focus on the exact forecast track, and be prepared
 for changes to the forecast. 
  
  
 FORECAST POSITIONS AND MAX WINDS
  
 INIT  21/0300Z 13.8N 150.3W  115 KT 130 MPH
  12H  21/1200Z 14.0N 151.7W  115 KT 130 MPH
  24H  22/0000Z 14.3N 153.3W  115 KT 130 MPH
  36H  22/1200Z 14.8N 154.7W  110 KT 125 MPH
  48H  23/0000Z 15.7N 155.9W  105 KT 120 MPH
  72H  24/0000Z 17.9N 157.6W   95 KT 110 MPH
  96H  25/0000Z 20.0N 159.0W   75 KT  85 MPH
 120H  26/0000Z 20.8N 161.0W   55 KT  65 MPH
  
 $$
 Forecaster R Ballard