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Hurricane Lane Discussion Number  39
NWS Central Pacific Hurricane Center Honolulu HI   EP142018
1100 PM HST Thu Aug 23 2018
 
Hurricane Lane is beginning to show some signs of slow weakening
due to wind shear of over 20 knots from the southwest according to
the SHIPS and UW-CIMSS analyses. There is no eye evident in
satellite imagery, which is likely a result of these hostile
conditions. Radar reflectivity data from the WSR-88D radars at
Molokai and Kohala show the center is becoming elongated in a north
to south direction. The latest satellite intensity estimates from
HFO, JTWC, TAFB and SAB were a unanimous T5.5/102 knots, while the
UW-CIMSS ADT was T5.7/107 knots. The current intensity is held at
105 kt based on these estimates.
 
The initial motion estimate is 350/5 knots, which shows a northward
turn has occurred this evening. Lane continues to be steered toward
the north along the western side of a mid-level ridge, which is
located to the east of Hawaii. The consensus guidance continues to
show a northward motion, or even a motion toward just east of due
north, as the ridge builds south and possibly southwest of Lane.
The latest track has shifted to the right of the previous forecast
through the next 48 hours. This more closely follows the latest
consensus track guidance. Note that on this track, Hurricane Lane
continues to approach the Main Hawaiian Islands, so there is no
reason to believe that anyone is safe in the warning area. Assuming
Lane begins to weaken, and decouple before, or after, it hits the
islands, Lane is forecast to come increasingly under the influence
of the low level easterlies and begin tracking westward. Again, the
exact time when this will occur remains highly uncertain, and only
a small delay in this decoupling could bring Lane farther north.
This will produce considerably worse conditions over the islands.
Even if Lane remains along the forecast track, significant impacts
are expected in the Hawaiian Islands.
 
Our intensity forecast shows some weakening, but continues to trend
on the high side of the intensity guidance through 72 hours owing to
how organized Lane's core has been in recent days. Note that the
CIRA analysis of Ocean Heat Content along the latest forecast track
continues to show very high values during the next 24 to 36 hours,
so this will likely help maintain the intensity longer than might
be expected with such high shear. By early next week, it is possible
that Lane will not survive the shear, and may become a remnant low
by day 5.
 
 
KEY MESSAGES:
 
1. It is vital that you do not focus on the exact forecast track or
intensity of Lane, and remain 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
remains a very real possibility. Even if the center of Lane remains
offshore, severe impacts could still be realized as they extend well
away from the center.
 
2. Lane will pass dangerously close to the main Hawaiian Islands as
a hurricane on Friday, and is expected to bring damaging winds.
Terrain effects can cause strong localized acceleration of the wind
through gaps and where winds blow downslope. These acceleration
areas will shift with time as Lane passes near or over the islands.
Winds will also be stronger at the upper floors of high rise
buildings.
 
3. The slow movement of Lane also greatly increases the threat for
prolonged heavy rainfall and extreme rainfall totals. This is
expected to lead to major, life-threatening flash flooding and
landslides over all Hawaiian Islands.
 
4. 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. This could lead to severe beach erosion.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  24/0900Z 18.2N 158.0W  105 KT 120 MPH
 12H  24/1800Z 19.0N 158.0W   95 KT 110 MPH
 24H  25/0600Z 19.9N 158.0W   80 KT  90 MPH
 36H  25/1800Z 20.4N 158.7W   70 KT  80 MPH
 48H  26/0600Z 20.3N 160.1W   65 KT  75 MPH
 72H  27/0600Z 20.3N 163.1W   55 KT  65 MPH
 96H  28/0600Z 21.0N 166.0W   35 KT  40 MPH
120H  29/0600Z 24.6N 168.4W   30 KT  35 MPH
 
$$
Forecaster Houston
 
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