CPAC: LANE - Post-Tropical

[AutoPenalti]

Where do we go from here? There has to be a solution?

The solution is to just hunker down and prepare for what’s coming no matter what the models say.

[Aric Dunn]

just eyeballing it. .. but it looks like from the forward speed and generalized forecast track. The maximum "suction" from the big island before the wind direction changes will be in about 12 hours... by which time it could be heading due north or nne..

[Mauistorms]

just eyeballing it. .. but it looks like from the forward speed and generalized forecast track. The maximum "suction" from the big island before the wind direction changes will be in about 12 hours... by which time it could be heading due north or nne..

My apologies, but for the lay person in hawaii that is looking for some answers...what does that mean for us?

[Aric Dunn]

just eyeballing it. .. but it looks like from the forward speed and generalized forecast track. The maximum "suction" from the big island before the wind direction changes will be in about 12 hours... by which time it could be heading due north or nne..

My apologies, but for the lay person in hawaii that is looking for some answers...what does that mean for us?

no more than any of the current model runs and the CPHC .. think of it as the divide in the models...the point where shear ( as AJC3 pointed out) and localized dynamics are causing the models to diverge..

[Kingarabian]

just eyeballing it. .. but it looks like from the forward speed and generalized forecast track. The maximum "suction" from the big island before the wind direction changes will be in about 12 hours... by which time it could be heading due north or nne..

That wouldn't be good for Maui.

[Mauistorms]

just eyeballing it. .. but it looks like from the forward speed and generalized forecast track. The maximum "suction" from the big island before the wind direction changes will be in about 12 hours... by which time it could be heading due north or nne..

That wouldn't be good for Maui.

yikes!

[euro6208]

Going to be very close...

[OahuWahine]

Mauistorms, what are the conditions like currently?

[Mauistorms]

Mauistorms, what are the conditions like currently?

the usual rain and breezy...

[mrbagyo]

Looks like the south quad is being affected by SW shear

[Kingarabian]

 https://twitter.com/DOTHawaii/status/1032527702031364097

[bob rulz]

If there is a lot of divergence in the models, I would stick with the one that has been more accurate so far, which is the GFS. The GFS was the first and for a time only model to forecast a threat to Hawaii. We all thought it was completely broken at the time, but it never budged from that and look where we are now.

[Kingarabian]

23/0530 UTC 16.0N 156.7W T6.5/6.5 LANE -- Central Pacific

[NotoSans]

Eye appears to be cooling now, typical for a system which is affected by shear.

[cjrciadt]

Final T# Adj T# Raw T#
6.2 6.3 6.3

Estimated radius of max. wind based on IR :N/A km

Center Temp : -48.4C Cloud Region Temp : -72.4C

Scene Type : EYE

Subtropical Adjustment : OFF

Extratropical Adjustment : OFF

Positioning Method : ARCHER POSITIONING

Ocean Basin : EAST PACIFIC
Dvorak CI > MSLP Conversion Used : CKZ Method

Tno/CI Rules : Constraint Limits : NO LIMIT
Weakening Flag : OFF
Rapid Dissipation Flag : OFF

C/K/Z MSLP Estimate Inputs :
- Average 34 knot radii : 105km
- Environmental MSLP : 1011mb

Satellite Name : GOES15
Satellite Viewing Angle : 31.4 degrees

[Kingarabian]

 https://twitter.com/darealgreglopez/status/1032544339635789824

[Kingarabian]

They ignored the Euro. Here is the updated forecast track from the CPHC:



Show it still a hurricane moving west after its closest approach to Oahu. However, if it's going to move west, it won't be as a hurricane...

[Kingarabian]

If the GFS is gonna shift towards the Euro the best chance it does so is within 30 minutes on the 06z run. Likely the last chance @ 12z, but by that time the track differences will become apparent regardless.

[Kingarabian]

000
WTPA42 PHFO 230857
TCDCP2

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

[Kingarabian]

Eye continues to cool. However while of course shear is affecting it, you can practically see the storm be yanked north in the last couple of frames: