CPAC: LANE - Post-Tropical

[supercane]

WTPA42 PHFO 231502
TCDCP2

Hurricane Lane Discussion Number 36
NWS Central Pacific Hurricane Center Honolulu HI EP142018
500 AM HST Thu Aug 23 2018


Lane's satellite appearance has degraded somewhat since the previous
advisory as southwesterly shear impacts the vertical integrity of
the cyclone. However, the eye is still evident in traditional
infrared imagery and remains surrounded by a solid ring of cold
cloud tops. Water vapor imagery shows Lane's circulation
becoming elongated, with outflow severely restricted in the
southwest semicircle. The subjective Dvorak current intensity
estimates from GTW/TAFB/HFO/SAB ranged from 6.0/115 kt to 6.5/127 kt
for this advisory, while data-T numbers were as low as 5.5/105 kt.
Using a blend, the initial intensity for this advisory is set at 115
kt.

Lane is currently moving toward the northwest into an increasingly
hostile environment between a deep-layer ridge to the east, and a
trough aloft to the northwest. The initial motion for this advisory
is 320/6 kt, with southwesterly shear estimated to be around
25 kt by UW-CIMSS.

The track and intensity forecast are extremely dependent on one
another in the current forecast scenario, with Lane expected to
move generally toward the north while it remains a hurricane, and
generally toward the west once it weakens. Confidence in the
forecast is reduced because it is uncertain how Lane's core will be
impacted by its potential interaction with island terrain, and the
subsequent rate of weakening. Regardless of whether Lane's center
moves over one of the Hawaiian Islands, an increasing amount of
southwesterly shear along the forecast track will lead to
significant weakening. If Lane's core were to move over one of the
islands as has been consistently depicted by GFS/HWRF, then the
cyclone would weaken even more rapidly. EMX2 is on the left side of
the guidance and indicates less interaction with island terrain,
and therefore a slightly slower rate of weakening.

Based on a preponderance of evidence presented by the guidance, the
updated forecast indicates a faster rate of weakening than
indicated earlier, especially on days 2 and 3. The expectation is
that Lane will weaken due to the combined and cumulative effects of
debilitating shear and the interruption of the circulation due to
proximity to the high mountains of Maui and the Big Island. The
official intensity forecast now closely follows IVCN, SHIPS and the
ECMWF-based SHIPS. The track forecast anticipates this weakening,
with Lane turning sharply toward the west on day 3. Until then, the
forecast track is shifted slightly to the right of the previous
forecast through Friday, bringing Lane northward and very close to
the Big Island and Maui County. This is similar to the multi-model
consensus HCCA, which includes GFS and HWRF as weighted members. A
slow forward speed is expected as this occurs, with Lane then moving
more quickly toward west as it becomes shallow and carried by the
low-level trade wind flow.

NOAA Buoy 51002 to the southwest of the islands is in the path of
Lane, and recently reported a wind gust to 56 kt and significant
wave heights near 23 ft. Associated data were used to refine wind
and seas radii in the northwest quadrant.


KEY MESSAGES:

1. Lane will pass dangerously close to the main Hawaiian Islands as
a hurricane today 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 23/1500Z 16.9N 157.4W 115 KT 130 MPH
12H 24/0000Z 17.9N 157.5W 105 KT 120 MPH
24H 24/1200Z 19.1N 157.6W 95 KT 110 MPH
36H 25/0000Z 20.0N 157.8W 75 KT 85 MPH
48H 25/1200Z 20.3N 158.6W 60 KT 70 MPH
72H 26/1200Z 20.0N 161.3W 45 KT 50 MPH
96H 27/1200Z 20.0N 164.0W 40 KT 45 MPH
120H 28/1200Z 21.5N 166.0W 40 KT 45 MPH

$$
Forecaster Birchard

[wxman57]

Lane is looking more like a Cat 2 hurricane than a 3 or 4 this morning. Eye just barely visible now. Cat 3s usually have a cleared-out eye. My track is closer to the consensus than CPHC's, taking the center about 75 miles SW of Maui before the west turn. This is about 80 miles south of Honolulu, putting Honolulu in 35-45 mph winds. I saw that Mark Sudduth is heading to Honolulu to chase Lane. Might see a little more action on Maui than Oahu. Surf will definitely be up on the south shore of Oahu tomorrow. Rain still looks like the greatest threat to all of the islands.

[supercane4867]

Deeper system = more eastward track. The EC ensembles have a left bias since most of them are too weak with Lane. GFS/HWRF solution is looking more likely as long as Lane keep defying shear.

[Kingarabian]

12z GFS going to be big island/Maui landfall again.

[Yellow Evan]

Lane is looking more like a Cat 2 hurricane than a 3 or 4 this morning. Eye just barely visible now. Cat 3s usually have a cleared-out eye. My track is closer to the consensus than CPHC's, taking the center about 75 miles SW of Maui before the west turn. This is about 80 miles south of Honolulu, putting Honolulu in 35-45 mph winds. I saw that Mark Sudduth is heading to Honolulu to chase Lane. Might see a little more action on Maui than Oahu. Surf will definitely be up on the south shore of Oahu tomorrow. Rain still looks like the greatest threat to all of the islands.

You realize that latest Dvorak estimates are T5.5 with a CI of T6.0 from JTWC and estimates not too long ago at T6.0/T6.5 from SAB, right? Yes, the eye has slowly been cooling but the CDO is still quite cold, and there have plenty of Cat 3's with such presentation (although not all, some have warmer CDO's with warmer eyes near 10C). And given that recon found 110-115 knots with a similar presentation a few days back on August 20 as well as the fact there's some lag time with weakening systems, it's not unreasonable for this to still be a Cat 4 IMO.

Also, why are you so confident in a westward turn given how much this has defied forecasts in intensity for days along with the fact that for several days the runs have gradually been shifting east (to the surprise of many here myself included)? The only way this turns west at this point is if this decopuples soon, which to be fair is still plausible but it's far from a done deal.

[Alyono]

GFS all in on a Maui/Big Island landfall

[supercane4867]

12z GFS going to be big island/Maui landfall again.

I‘m not sure about the rapid NE movement though. It seems GFS is overdone a bit.

[Kingarabian]

12z GFS going to be big island/Maui landfall again.

I‘m not sure about the rapid NE movement though. It seems GFS is overdone a bit.

UKMET shows this type of movement too. Let's see what the 12z shows.

[supercane4867]

GFS has mid-level steerings shifting from S-N to SW-NE due to ridge building south of Lane. Also that short wave feature to its north is also hooking Lane into Maui.

[Kingarabian]

Lane is looking more like a Cat 2 hurricane than a 3 or 4 this morning. Eye just barely visible now. Cat 3s usually have a cleared-out eye. My track is closer to the consensus than CPHC's, taking the center about 75 miles SW of Maui before the west turn. This is about 80 miles south of Honolulu, putting Honolulu in 35-45 mph winds. I saw that Mark Sudduth is heading to Honolulu to chase Lane. Might see a little more action on Maui than Oahu. Surf will definitely be up on the south shore of Oahu tomorrow. Rain still looks like the greatest threat to all of the islands.

You realize that latest Dvorak estimates are T5.5 with a CI of T6.0 from JTWC and estimates not too long ago at T6.0/T6.5 from SAB, right? Yes, the eye has slowly been cooling but the CDO is still quite cold, and there have plenty of Cat 3's with such presentation (although not all, some have warmer CDO's with warmer eyes near 10C). And given that recon found 110-115 knots with a similar presentation a few days back on August 20 as well as the fact there's some lag time with weakening systems, it's not unreasonable for this to still be a Cat 4 IMO.

Also, why are you so confident in a westward turn given how much this has defied forecasts in intensity for days along with the fact that for several days the runs have gradually been shifting east (to the surprise of many here myself included)? The only way this turns west at this point is if this decopuples soon, which to be fair is still plausible but it's far from a done deal.

Also when Lane looked worse than this, let's not forget that recon found this to be a 130mph hurricane after it recovered from its first bout with shear.

[Yellow Evan]

Near CMG ring with LG eye still.

[Kingarabian]

 https://twitter.com/TropicalTidbits/status/1032630903690985473

[Kingarabian]

Anyone got the plotted UKMET?

[NotSparta]

I'm guessing right now the winds are so strong that the convection can get rotated upshear & still not be sheared away. As Lane weakens, shear may really begin to get at it imo

[Alyono]

WTNT82 EGRR 231607

MET OFFICE TROPICAL CYCLONE GUIDANCE FOR NORTH-EAST PACIFIC AND ATLANTIC

GLOBAL MODEL DATA TIME 1200UTC 23.08.2018

HURRICANE LANE ANALYSED POSITION : 16.9N 156.7W

ATCF IDENTIFIER : EP142018

LEAD CENTRAL MAXIMUM WIND
VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS)
-------------- ---- -------- ------------- -------------
1200UTC 23.08.2018 0 16.9N 156.7W 957 80
0000UTC 24.08.2018 12 18.1N 157.3W 965 75
1200UTC 24.08.2018 24 19.2N 157.3W 977 70
0000UTC 25.08.2018 36 20.2N 156.9W 999 45
1200UTC 25.08.2018 48 20.5N 158.6W 1007 31
0000UTC 26.08.2018 60 19.8N 160.8W 1008 29
1200UTC 26.08.2018 72 19.4N 162.2W 1008 27
0000UTC 27.08.2018 84 19.4N 163.6W 1008 26
1200UTC 27.08.2018 96 19.3N 165.5W 1008 24
0000UTC 28.08.2018 108 19.0N 166.0W 1007 24
1200UTC 28.08.2018 120 19.5N 166.1W 1008 24

[Alyono]

big time right shift for CMC

[supercane4867]

UK is similar to GFS doing a right hook toward Maui. But it has Lane sheared out before hitting the island.

[bjackrian]

This buoy about 20 miles to the NE of the center is reporting 45 kt sustained/66 kt gusts with 24 foot waves. Compact wind field, especially on the NE side, but that'll bring some big waves to the islands.

https://www.ndbc.noaa.gov/station_page.php?station=51002

[hawaiigirl]

I don’t know how to attach a photo here but I was wondering if you can tell me if we should worry about what looks like another system forming next to Lane, did she create a baby? People are talking about it on Instagram. Mahalo!

[Alyono]

This buoy about 20 miles to the NE of the center is reporting 45 kt sustained/66 kt gusts with 24 foot waves. Compact wind field, especially on the NE side, but that'll bring some big waves to the islands.

https://www.ndbc.noaa.gov/station_page.php?station=51002

or this is quite a bit weaker than we are estimating. That pressure is quite high given that it is only 20 miles NE of the center