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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
 
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