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Hurricane Lane Discussion Number  33
NWS Central Pacific Hurricane Center Honolulu HI   EP142018
1100 AM HST Wed Aug 22 2018
 
Lane continues to be a very impressive hurricane. As of the
1800 UTC analysis time, the cloud pattern had improved over the last
several hours with clearing and warming in the eye, and convection
becoming more symmetric around the eyewall. Satellite intensity
estimates from PHFO, JTWC, and SAB were unanimous at 6.5, and
CIMSS-ADT had 6.3. A 1613z SSMIS pass showed the inner core remains
very well defined, and there has been a considerable amount of
lightning in the eyewall over the past several hours. In deference
to the recent trends, we elected to maintain Lane at 135 kt for this
advisory. Since the analysis time, the eye has cooled again somewhat
and deep convection around the center has become a little more
asymmetric.

The initial motion has slowed a bit and is now 295/7. Lane
continues to be steered toward the west-northwest by a deep layer
ridge to the northeast of the tropical cyclone. By 36 hours, the
ridge is expected begin building to the southeast and south of Lane,
which will begin to impart a more northward motion through at least
48 hours. By 72 hours, the track guidance begins to show a leftward 
turn, as the low level circulation of Lane decouples in the face of 
35 to 40 kt of shear. Exactly when this critical turn will happen
is very difficult to forecast, so confidence in this portion of the 
track is unfortunately rather low. However, our most reliable
global models, the ECMWF and GFS, suggest this may happen a little
later than previously forecast. Thus, the track forecast has been
shifted to the northeast between 48 and 72 hours to be in better
agreement with the global models. 

The UW-CIMSS shear analysis shows that Lane is located within an 
area of moderate southwesterly shear. The tropical cyclone is 
expected to begin moving under increasing shear in the coming days 
which is expected to start a long-awaited weakenening trend. Around 
72 hours or so, the shear is expected to weaken the core of the 
tropical cyclone enough to initiate more rapid weakening that is 
shown for the remainder of the forecast period. Our intensity 
forecast is at the high end of the guidance, in best agreement with 
the ECMWF. 
 
 
KEY MESSAGES:
 
1. Lane is forecast to move dangerously close to the main Hawaiian
Islands as a hurricane tomorrow through Saturday, potentially
bringing damaging winds. As Lane will be slow-moving as it nears
the islands, prolonged heavy rainfall and life-threatening flash
flooding will be possible. Large and damaging surf can be
expected along exposed shorelines, along with localized storm surge.
 
2. As Lane approaches the islands from the southeast, initial
impacts will be felt on the Big Island and Maui County, where a
Hurricane Warning is in effect. Impacts on Kauai County and Oahu
are also possible, and a Hurricane Watch is in effect there.
 
3. Do not focus on the exact forecast track or intensity for Lane,
and be prepared for adjustments to the forecast. Life threatening
impacts can extend well away from the center of a hurricane.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  22/2100Z 15.5N 155.9W  135 KT 155 MPH
 12H  23/0600Z 16.2N 156.7W  125 KT 145 MPH
 24H  23/1800Z 17.6N 157.1W  115 KT 130 MPH
 36H  24/0600Z 18.9N 157.5W  100 KT 115 MPH
 48H  24/1800Z 19.9N 157.8W   85 KT 100 MPH
 72H  25/1800Z 20.8N 158.7W   65 KT  75 MPH
 96H  26/1800Z 21.0N 162.1W   50 KT  60 MPH
120H  27/1800Z 20.9N 165.0W   40 KT  45 MPH
 
$$
Forecaster R Ballard
 
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