987 
 WTPA42 PHFO 200306
 TCDCP2
  
 Hurricane Lane Discussion Number  21
 NWS Central Pacific Hurricane Center Honolulu HI   EP142018
 500 PM HST Sun Aug 19 2018
  
 Lane's satellite presentation has not changed much since late this
 morning. The main features include a murky cloud-filled eye
 surrounded by a symmetric convective ring. Outflow is best to the
 north through northeast, but remains somewhat constricted elsewhere
 in the face of 17 kt of UW-CIMSS-derived southwest vertical shear.
 The coldest cloud tops, -75 to -80 degrees C, are within the north
 quadrant of the convective ring. The latest subjective Dvorak
 intensity estimates range from 5.0/90 kt (SAB) to 6.0/115 kt
 (PHFO). JTWC estimated 5.5/102 kt while UW-CIMSS estimated 5.0/90
 kt. The initial intensity for this package is set at 105 kt,
 representing a slight adjustment downward using a blend of
 estimates.
 
 Initial motion is a steady 280/12 kt as Lane continues tracking
 westward along the southern flank of a large subtropical ridge.
 There is still quite a bit of spread in track guidance beyond day 2
 as individual models handle the erosion of the western portion of
 this ridge differently, thanks to the forecast intrusion of a weak
 frontal band far northwest of the main Hawaiian Islands. GFS and
 HWRF represent the northern edge of the guidance envelope, while
 ECMWF lies along the southern edge. The current forecast track lies
 within the southern third of the guidance envelope, closely
 following FSSE and TVCX consensus through 96 hours, then bending
 left at 120 hours and beyond between TVCX and ECMWF guidance. The
 only noticeable change from the previous track is a slight bump to
 the right beyond day 4 to account for an overall guidance envelope
 shift to the right at days 4 and 5. The NOAA G-IV aircraft has
 completed its initial synoptic sweep around Lane and the main
 Hawaiian Islands, and the NOAA P-3 aircraft is about to start its
 mission as of this writing. Air Force Reserve WC-130J aircraft will
 begin their sampling missions through Lane this evening. The
 valuable data collected during these missions will be used to
 better initialize the guidance models and, hopefully, reduce the
 guidance envelope spread.
 
 The intensity forecast follows the logic of the previous one, only
 with a slightly lower initial intensity. Lane will remain over
 27-28 degree C waters through the forecast period, with 10 to 20 kt
 of vertical shear through most of its track, at least according to
 the ECMWF-derived SHIPS run. Gradual weakening is forecast through
 the forecast period, closely following the shape of the DSHIP and
 FSSE intensity curves but staying above the IVCN intensity curve. 
  
 Lane is forecast to pass south of the main Hawaiian Islands
 Wednesday and Thursday, potentially causing local impacts as it
 tracks west-northwestward. Interests in these islands should watch
 the progress of Lane closely, since long-range track and intensity
 forecast errors can be large.
  
  
 FORECAST POSITIONS AND MAX WINDS
  
 INIT  20/0300Z 13.8N 145.8W  105 KT 120 MPH
  12H  20/1200Z 14.1N 147.5W  100 KT 115 MPH
  24H  21/0000Z 14.4N 149.6W  100 KT 115 MPH
  36H  21/1200Z 14.6N 151.2W   95 KT 110 MPH
  48H  22/0000Z 14.9N 152.9W   90 KT 105 MPH
  72H  23/0000Z 15.6N 156.2W   80 KT  90 MPH
  96H  24/0000Z 17.0N 159.3W   70 KT  80 MPH
 120H  25/0000Z 19.1N 161.8W   60 KT  70 MPH
  
 $$
 Forecaster Powell