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Hurricane Lane Discussion Number  27
NWS Central Pacific Hurricane Center Honolulu HI   EP142018
500 AM HST Tue Aug 21 2018
 
 
Lane remains a powerful hurricane this morning, with a well-
developed warm eye completely surrounded by persistent cold cloud 
tops. Subjective Dvorak current intensity estimates were a
unanimous 6.5/127 kt while ADT was in relative agreement. The
initial intensity for this advisory remains at 130 kt as Lane's
satellite signature has changed little since last sampled by
Hurricane Hunters and the NOAA P-3 Monday evening. 

The initial motion for this advisory is 275/10 kt, with Lane 
continuing to be steered by a mid-level ridge to the north. Over
the next day or two, Lane is expected to reach the western periphery
of the ridge, and into an area of relatively light steering flow.
This is expected to allow the cyclone to gain latitude as its
forward speed diminishes. In this scenario, Lane will begin to make
a gradual turn to the west-northwest on Wednesday, with a more
decided turn toward the northwest on Thursday. After this point, the
track and intensity forecast become increasingly uncertain, as a
bulk of the model guidance is depicting interaction between Lane and
the terrain of the islands. This interaction then leads to a
weakened Lane increasingly being steered by the low-level trade wind
flow. The updated track forecast is essentially an update of the
previous official forecast, and lies very close to the multi-model
consensus HCCA.

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. In the short-term, shear is expected to
remain light, and subtle intensity fluctuations associated with 
inner-core dynamics will likely lead to little overall change in 
intensity. By 72 hours, the forecast anticipates an increase in 
shear as Lane lies between the ridge to the east and a trough 
aloft to the northwest of the main Hawaiian Islands. The updated 
intensity forecast is close to the previous, and although it is on
the higher end of the guidance envelope, it closely follows
the trends presented by the multi-model consensus IVCN. 

In addition to an increasing number of storm penetrations by the 
Hurricane Hunters of the 53rd Weather Reconnaissance, the NOAA G-IV 
will once again be sampling the larger scale environment to help 
forecast models better initialize. The NOAA P-3 mission slated for 
this morning has been scrapped as the aircraft needs to be examined 
after encountering strong turbulence last night. 


KEY MESSAGES:

1. Lane is forecast to move dangerously close to the main Hawaiian 
Islands as a hurricane later this week, potentially bringing 
damaging winds and life-threatening flash flooding from heavy 
rainfall. As Lane is expected to be slow-moving as it nears the 
islands, it will produce large and damaging surf, mainly along 
exposed south and west facing shores. A Hurricane Watch has been 
issued for Hawaii and Maui counties, and additional Tropical
Storm or Hurricane Watches may be required later today or tonight. 

2. It is much too early to confidently determine which, if any, of 
the main Hawaiian Islands will be directly impacted by Lane. Even
if the center of Lane were to remain offshore, it is important to 
remember that impacts from a hurricane can extend well away from
the center. Interests throughout Hawaii are urged to closely
monitor the progress of Lane the next couple of days. 
 

FORECAST POSITIONS AND MAX WINDS
 
INIT  21/1500Z 14.1N 152.3W  130 KT 150 MPH
 12H  22/0000Z 14.4N 153.4W  125 KT 145 MPH
 24H  22/1200Z 15.0N 154.6W  120 KT 140 MPH
 36H  23/0000Z 15.9N 155.6W  110 KT 125 MPH
 48H  23/1200Z 17.0N 156.5W  100 KT 115 MPH
 72H  24/1200Z 19.7N 157.6W   85 KT 100 MPH
 96H  25/1200Z 21.5N 159.5W   65 KT  75 MPH
120H  26/1200Z 21.5N 163.0W   50 KT  60 MPH
 
$$
Forecaster Birchard
 
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