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Hurricane Lane Discussion Number  28
NWS Central Pacific Hurricane Center Honolulu HI   EP142018
1100 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. Morning visible satellite imagery also depicts a well-defined
eye. The Hurricane Hunter aircraft from the 53rd Weather 
Reconnaissance Squadron is flying through Lane again this morning,
and confirms that the hurricane has intensified further since
their previous visit on Monday evening. The central pressure
has dropped around 10 mb during the past 12 hours, with the most
recent dropsonde in the eye finding 941 mb. Peak SFMR winds measured
so far have been 134 kt, and max flight level winds are 143 kt.
Subjective Dvorak current intensity estimates range from 6.5/127 kt
to 7.0/140 kt, with the latest ADT current intensity at 6.4/125 kt.
Based primarily on the aircraft data, the intial intensity for this
advisory is increased to 135 kt, which makes Lane a high-end
Category 4 hurricane. 

Lane is moving a bit slower this morning and appears to have wobbled
slightly to the WNW during the last few hours, and the initial
motion for this advisory is 280/8 kt. Lane has been moving westward
to the south of a mid-level ridge during the past several days.
However, this will be changing soon, as Lane begins to round the
western periphery of this ridge and moves into an area of
relatively light steering flow. This is expected to allow the
cyclone to gain latitude as its forward speed diminishes. The
hurricane is forecast to turn gradually to the west-northwest 
through tonight, then to the northwest Wednesday through Thursday,
as it moves between the mid-level ridge to the east and a developing
upper-level trough to the northwest of Hawaii. After this point, the
track and intensity forecasts remain highly uncertain, as the
majority of the reliable model guidance brings Lane very close to
the islands with potential interaction between Lane and the 
mountainous terrain of the islands. This interaction combined with
increasing vertical wind shear leads to a weakened Lane being
steered to the west by the low-level trade wind flow. The new track
forecast has been nudged slightly to the north or closer to the
islands from 36 through 72 hours, into better agreement with 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 increasing wind shear. In the short-term through
the next 24 hours or so, shear is expected to remain light, and
expect only slow weakening as the cyclone moves over slightly 
cooler SSTs and may be impacted by eyewall replacement cycles.
At 72 hours and beyond, the forecast anticipates a sharp increase
in shear as Lane moves closer to the large upper trough to the
northwest of the main Hawaiian Islands. The new intensity
forecast is close to the previous forecast, and although it 
remains on the high end of the guidance envelope, it generally
follows the trends presented by the multi-model consensus IVCN and
HCCA.
 
In addition to continued storm penetrations by the Hurricane Hunters
of the 53rd Weather Reconnaissance Squadron, the NOAA G-IV will once
again be sampling the larger scale environment today to help with
initialization of the forecast models.
 
 
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. A Hurricane Watch
remains in effect for Hawaii and Maui counties, and additional
Tropical Storm or Hurricane Watches may be required this afternoon
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 during the next few days.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  21/2100Z 14.3N 153.2W  135 KT 155 MPH
 12H  22/0600Z 14.7N 154.2W  130 KT 150 MPH
 24H  22/1800Z 15.6N 155.3W  120 KT 140 MPH
 36H  23/0600Z 16.6N 156.2W  110 KT 125 MPH
 48H  23/1800Z 17.9N 156.9W  100 KT 115 MPH
 72H  24/1800Z 20.6N 158.2W   80 KT  90 MPH
 96H  25/1800Z 21.7N 160.5W   55 KT  65 MPH
120H  26/1800Z 21.5N 164.0W   40 KT  45 MPH
 
$$
Forecaster Jacobson
 
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