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Hurricane Lane Discussion Number  35
NWS Central Pacific Hurricane Center Honolulu HI   EP142018
1100 PM HST Wed Aug 22 2018
 
Lane remains resilient in the face of increasing southwesterly 
wind shear, and remains a potent category 4 hurricane this evening. 
The cloud-filled eye continues to be surrounded by a solid ring of 
cold cloud tops, with lightning bursts persisting in the northern 
eye wall for the last several hours. The subjective Dvorak current 
intensity estimates from GTW/TAFB/HFO/SAB were all 6.5/127 kt for 
this advisory, while ADT was slightly lower. The current intensity 
estimate for this advisory will remain 125 kt based on a blend of 
these data. 

Lane continues to make the long-awaited turn toward the northwest, 
and the forward speed has slowed, with the initial motion for 
this advisory estimated to be 315/6 kt. Lane has reached the
western periphery of a deep-layer ridge, with a trough aloft to the 
northwest of Hawaii. The steering flow is relatively light and out 
of the south, and Lane will move northwest and north at a
relatively slow speed through Friday in this environment. By 48 to
72 hours, most of the track guidance begins to show a sharp turn
toward the west, 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 quite low. The updated track forecast is
very close to the previous but has been shifted slightly closer to
the islands on days 2 and 3, when Lane will be making its closest
point of approach to the islands. In deference to the HCCA,
the forecast track has shifted to the right in response to the
HWFI/GFSI and other members doing so, while the EMXI lies on the
left hand side of the guidance envelope. Beyond 72 hours, the
shallow circulation of Lane is expected to be carried westward away
from the islands in the low-level trade wind flow. 

Lane is beginning to move underneath increasing shear, analyzed to 
be near 20 kt, and latest satellite pictures indicate that this may 
be finally beginning to negatively impact Lane. The shear is 
expected to remain moderate for the first 24 to 36 hours, then 
become quite strong beyond 48 hours. A gradual weakening trend is 
shown through 48 hours, with more rapid weakening beyond that time 
frame. The intensity forecast remains on the high end of the 
guidance envelope, but follows closely all of the guidance trends 
that indicate significant weakening through the forecast period. 

KEY MESSAGES: 

1. Lane will pass dangerously close to the main Hawaiian Islands as 
a hurricane Thursday and Friday, and is expected to bring damaging 
winds. These winds can be accelerated over and downslope from
elevated terrain, and will be higher in high rise buildings.

2. The slow movement of Lane also greatly increases the threat for 
prolonged heavy rainfall and extreme rainfall totals. This is 
expected to lead to life-threatening flash flooding and landslides 
over all Hawaiian Islands. 

3. Large and damaging surf can be expected along exposed
shorelines, especially along south and west facing coasts, with
localized storm surge exacerbating the impacts of a prolonged period
of damaging surf.
 
4. Do not focus on the exact forecast track or intensity of Lane, 
and be prepared for adjustments to the forecast. Although the 
official forecast does not explicitly indicate Lane's center making 
landfall over any of the islands, this could still occur. Even if 
the center of Lane remains offshore, severe impacts could still be 
realized as they extend well away from the center. 

 
FORECAST POSITIONS AND MAX WINDS
 
INIT  23/0900Z 16.3N 156.9W  125 KT 145 MPH
 12H  23/1800Z 17.2N 157.2W  120 KT 140 MPH
 24H  24/0600Z 18.4N 157.4W  115 KT 130 MPH
 36H  24/1800Z 19.5N 157.6W   95 KT 110 MPH
 48H  25/0600Z 20.2N 158.1W   75 KT  85 MPH
 72H  26/0600Z 20.4N 160.5W   65 KT  75 MPH
 96H  27/0600Z 20.0N 163.0W   50 KT  60 MPH
120H  28/0600Z 20.5N 166.5W   40 KT  45 MPH
 
$$
Forecaster Birchard
 
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