CPAC: LANE - Post-Tropical

[OahuWahine]

I don't understand why they took the islands out of the cone and downgraded the hurricane warning to a tropical storm warning for the Big Island. Weren't the models trending toward Maui? What changed?

[Kingarabian]

Probably because Lane is continuing NNW/N

[Kingarabian]

I don't understand why they took the islands out of the cone and downgraded the warning to a watch for the Big Island. Weren't the models trending toward Maui? What changed?

They've never believed the east solutions from the beginning. So we'll see how this goes.

[Alyono]

the CPHC track is a good .7 degrees southwest of the model consensus, almost a southern outlier at this point

It does have a chance to verify, however. If Lane does not turn north now

[OahuWahine]

This is probably better news for Maui than a direct hit, but what about Oahu? Better or worse?

[Kingarabian]

the CPHC track is a good .7 degrees southwest of the model consensus, almost a southern outlier at this point

It does have a chance to verify, however. If Lane does not turn north now

But if Lane remains this strong, what exactly forces this west?

[supercane4867]

I understand the downgrade of warning for Big Island, since it's unlikely to get any hurricane force winds. But I'm also confused with the west shift in track.

[Kingarabian]

I haven't seen a single model show this remain a hurricane while shifting west.

[NDG]

It does look like it has gotten better organized again during the past few hours but the buoy never reported hurricane force winds after the eye went over it, maybe it was before the southern eyewall starting filling back up.

Keep in mind that during the period of peak winds that seas were 25FT, and the buoy spent half of its time taking wind readings inside that trough. Shielding from very high waves is a well-known problem during tropical cyclone and other extreme marine windstorm events. We frequently see this just offshore Florida, particularly at buoy 41010 - Floyd was a great example of this.

https://www.nhc.noaa.gov/data/tcr/AL081999_Floyd.pdf

Floyd’s eye passed over NOAA data buoy 41010, located about 105 nmi east-northeast
of Cape Canaveral, around 0900 UTC 15 September. That buoy reported maximum
8-minute averaged winds of 72 knots at an anemometer height of 5 meters. At least
three factors would imply a higher value for the 1-minute, 10 meter wind speed from
the buoy observation:

1) going from an 8-minute to a 1-minute average;
2) going from 5 meters to 10 meters elevation; and
3) the presence of waves over 50 feet high.

The best track intensity of Floyd when it passed over the buoy is near 100 knots, as
indicated by dropsonde and aircraft flight level wind data

Good point, didn’t think about that.

[supercane]

WTPA42 PHFO 240311
TCDCP2

Hurricane Lane Discussion Number 38
NWS Central Pacific Hurricane Center Honolulu HI EP142018
500 PM HST Thu Aug 23 2018

The weakening trend is underway. Over the past several hours, the
CDO of Lane has become elliptical as strong shear, 25 to 35 kt in
the UW-CIMSS shear analysis, begins to impinge on the core of the
hurricane. Outflow has become very restricted in the southwest The
eye, while still clearly evident on radar, is becoming indistinct in
the visible and infrared satellite imagery. The satellite intensity
estimates from HFO, JTWC, TAFB and SAB were a unanimous 5.5, and the
CIMSS FT number was 5.6 with the CI being held up by constraints.
Based the current intensity of 105 kt on these estimates.

The initial motion estimate is 330/5. There is no change to the
forecast philosophy with this package. Lane continues to be steered
toward the north on 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 the
cyclone. The official forecast is similar to the previous track, and
remains a bit left of the consensus tracks. As the inner core
continues to deteriorate, Lane will come increasingly under the
influence of the low level easterlies and begin tracking westward.
However, the exact time when this will occur is still rather
uncertain, and only a small delay in this decoupling could bring
Lane farther north, with considerably worse conditions over the
islands. Even if Lane remains along the forecast track, some
significant impacts are expected.

Our intensity forecast shows 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. During the later
periods of the forecast, it is possible that Lane will not survive
the shear and may become a remnant low even sooner than forecast.


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 24/0300Z 17.8N 157.9W 105 KT 120 MPH
12H 24/1200Z 18.7N 157.9W 95 KT 110 MPH
24H 25/0000Z 19.6N 158.1W 85 KT 100 MPH
36H 25/1200Z 20.1N 158.6W 75 KT 85 MPH
48H 26/0000Z 20.3N 159.6W 65 KT 75 MPH
72H 27/0000Z 20.2N 162.4W 55 KT 65 MPH
96H 28/0000Z 20.8N 165.1W 35 KT 40 MPH
120H 29/0000Z 23.2N 167.3W 30 KT 35 MPH

$$
Forecaster R Ballard

[Mauistorms]

There is another great explanation for today’s situation for the non experts on tropicaltidbits.com

[Kingarabian]

There is another great explanation for today’s situation for the non experts on tropicaltidbits.com

Yup. Levi explains it well how the southwesterlies and trying to force Lane north east towards Maui, and the easterlies are trying to push Lane towards the northwest. The result is a net north motion. However as Lane weakens and becomes shallow, it'll feel the easterlies more than the south westerlies.

Exactly when will this happen, no one knows.

[Alyono]

dont understand the cphc shift. The shift is west despite this remaining a hurricane through 48 hours

[somethingfunny]

WTPA42 PHFO 240311
TCDCP2

Hurricane Lane Discussion Number 38
NWS Central Pacific Hurricane Center Honolulu HI EP142018
500 PM HST Thu Aug 23 2018

...... As the inner core
continues to deteriorate ...

...

I'm not sure I see it yet....

[Kingarabian]

00z GFS trend.

[floridasun78]

in new avd their expecting lane move west soon not get close islands

[Kingarabian]

00z GFS hour 18 trend.

[Kingarabian]

00z GFS looks like a molokai landfall.

[Bocadude85]

The GFS is still insistent that Lane makes landfall in the islands in 24 hours.. I guess we will just have to wait and see what happens.

[Alyono]

and the Canadian shifts back to little impact

24 hours before a potential landfall, and we have 200 mile differences. Beyond pathetic

CMC keeps it south of 19N. Yes, south of 19N