CPAC: LANE - Post-Tropical

[Kingarabian]

Still needs about 6 more hours before the core starts to build. Latest frames shows shear (mid level?) blowing over the CDO.

[Chris90]

I'm going to go with my more bullish feeling and guess 130kts for peak.
This current burst of activity is definitely reminding me of '94s outbreak of major EPAC-CPAC crossers which had Emilia, Gilma, John.

Also, hats off to everyone who was predicting more potential threats to Hawaii this year. 130w-150w is definitely looking like a sweet spot overall for systems this year. Hopefully Lane follows in Hector's footsteps and avoids land impacts.

[cycloneye]

Tropical Storm Lane Discussion Number 4
NWS National Hurricane Center Miami FL EP142018
200 PM PDT Wed Aug 15 2018

Satellite images indicate that Lane is strengthening. The central
dense overcast continues to grow, with a large banding feature in
the western semicircle and expanding outflow in most quadrants.
ASCAT data recently showed maximum winds of about 40 kt, so that
will be the initial wind speed, which is also near a blend of the
latest Dvorak estimates from TAFB and SAB.

While the latest microwave data indicate that the inner core of Lane
remains loosely organized, the large-scale environment appears to be
favorable for intensification. Low shear, warm waters of 27.5-28C,
and moderate levels of mid-level moisture all support strengthening
at a higher rate than climatology. However, since the inner core is
not well established yet, the intensity forecast will be held just
below rapid strengthening (30 kt in 24 h) for day 1. There is still
a strong signal for that threshold to be met in the day 2-3 period
from the DTOPS rapid intensification index, so the forecast will
remain for a major hurricane to form during that time. This forecast
is close to a blend of the latest NOAA-HCCA and FSSE corrected
consensus models.

The storm continues to move just south of due west, now at about 11
kt. The synoptic pattern is well established with a subtropical
ridge expected to only slightly weaken in the medium-range period,
causing a slight west-northwestward turn in the central Pacific.
While the overall spread has increased in the 1200 UTC guidance, the
latest model consensus has barely budged since the previous
advisory, although it does fit the recent westward trend. The
latest official track forecast is again adjusted in that direction,
close to the eastern Pacific track model consensus TVCE.


FORECAST POSITIONS AND MAX WINDS

INIT 15/2100Z 10.6N 124.5W 40 KT 45 MPH
12H 16/0600Z 10.5N 126.2W 50 KT 60 MPH
24H 16/1800Z 10.7N 128.4W 65 KT 75 MPH
36H 17/0600Z 11.1N 130.9W 80 KT 90 MPH
48H 17/1800Z 11.6N 133.6W 95 KT 110 MPH
72H 18/1800Z 12.6N 138.7W 105 KT 120 MPH
96H 19/1800Z 14.0N 143.6W 110 KT 125 MPH
120H 20/1800Z 15.2N 148.2W 105 KT 120 MPH

$$
Forecaster Blake

[Cyclenall]

Path and behavior is similar to Hector it seems. So could be a Hector redux

I hope not, what a waste that storm was.

Two points:

1. The NHC mentioned continually in their 3rd discussion...what exactly are they talking about? Why don't they continue showing Lane going past 105 knots at the 96 and 120 hour times?

2. So far this TC is off to a good start, just south of due west and not too fast . If the models continue to show SW shifts then we might have something delicious if not than that would be another tease. Maybe Lane can become smaller and shed some of that banding.

[Kingarabian]

18z GFS much stronger through 72 hours:

[Alyono]

slightly weaker near Hawaii though

[Kingarabian]

CI# /Pressure/ Vmax
3.5 / 996.9mb/ 55.0kt


Final T# Adj T# Raw T#
3.5 3.6 3.6

[Kingarabian]

Considerable spread between the operational Euro and GFS:

[ncapps]

slightly weaker near Hawaii though

Smidge faster as well. Quicker to encounter shear perhaps?

[Kingarabian]

slightly weaker near Hawaii though

Smidge faster as well. Quicker to encounter shear perhaps?

Still a major hurricane south of the Big Island. Likely very little shear and just the model trying to incorporate less than ideal thermodynamics:

[img]https://i.imgur.com/Pi6VqL5.png[img]

Ridge builds back in and shunts it away from Kauai/Oahu:

[Kingarabian]

For the HWRF are we supposed to look at 850mb wind or 10m wind?

850mb wind:


Vs.

10m wind:

[NotSparta]

For the HWRF are we supposed to look at 850mb wind or 10m wind?

850mb wind:
[img]https://i.imgur.com/HpkrGRM.png[/imlg]

Vs.

10m wind:
[img]https://i.imgur.com/O29OINC.png[/imlg]

10m, since that's sfc wind. 850mb is gusts

[ncapps]

Not sure how well regarded it is at this point, but the FV3-GFS really keeps Lane far south and of no impact to Hawaii. High pressure is very pronounced is this run and no break in the ridge exists. Again, no idea of this models track record as it's in its infancy.

[Chris90]

For the HWRF are we supposed to look at 850mb wind or 10m wind?

850mb wind:
[img]https://i.imgur.com/HpkrGRM.png[/imlg]

Vs.

10m wind:
[img]https://i.imgur.com/O29OINC.png[/imlg]

10m, since that's sfc wind. 850mb is gusts

That isn't always the case. I'm fairly positive last year the modeled 850mb winds were closer to what ended up verifying at the surface for both Irma and Maria. So maybe the more intense the storm gets, the more accurate 850mb winds are to 10m winds for that model?

Considering the modeled pressures though, 105kts is much, much more believable than 145kts.

[Ntxw]

The NHC forecast, assuming conservative, gives Lane at least ~10 ACE units. Long way to go still before Hawaii with lots of shifting guidance beyond 7+ days.

[NotSparta]

For the HWRF are we supposed to look at 850mb wind or 10m wind?

850mb wind:
[img]https://i.imgur.com/HpkrGRM.png[/imlg]

Vs.

10m wind:
[img]https://i.imgur.com/O29OINC.png[/imlg]

10m, since that's sfc wind. 850mb is gusts

That isn't always the case. I'm fairly positive last year the modeled 850mb winds were closer to what ended up verifying at the surface for both Irma and Maria. So maybe the more intense the storm gets, the more accurate 850mb winds are to 10m winds for that model?

Considering the modeled pressures though, 105kts is much, much more believable than 145kts.

Yes, because the model solutions were too weak, & those storms became strong enough to make those gusts sustained. If a model solution verifies, 850mb tends to be the gusts, w/ 10m being the sustained winds

[Kingarabian]

The NHC forecast, assuming conservative, gives Lane at least ~10 ACE units. Long way to go still before Hawaii with lots of shifting guidance beyond 7+ days.

Yeah, for long range forecasts the operational models and their ensembles are susceptible to large errors.

[SconnieCane]

Looks like each forecast package has shifted the track to the left which lessens the threat to Hawaii, although extrapolating the 5-day cone to the WNW/NW still raises my eyebrows a bit. Not likely this will be the long-awaited/feared Iniki redux but too soon to say never.

[cycloneye]

Tropical Storm Lane Discussion Number 5
NWS National Hurricane Center Miami FL EP142018
800 PM PDT Wed Aug 15 2018

Overall, Lane's cloud pattern has become a little better organized
this evening. Modest east-northeasterly shear, however, along with
some drier air, appears to be undercutting the diffluent outflow
above 300 mb and is impinging the north through northeast portion
of the cyclone. An outer deep convective curved band, on the other
hand, is now developing over most of the eastern half of the system.
The surface center is also located a bit further in the northern
edge of an expanding, colder, central dense overcast. The initial
intensity is increased to 45 kt, and is based on a compromise of the
TAFB and SAB subjective Dvorak satellite intensity estimates (T3.0),
and a 2205 UTC SATCON analysis (51 kt).

Little change has been made to the previous intensity forecast, and
it still shows a rapid increase of nearly 55 kt in 48 hours based on
the Deterministic to Probabilistic Statistical Rapid Intensification
Index (DTOPS) which indicates a 67 percent chance of RI occuring
during this particular period. The NHC forecast is weighed heavily
on a blend of the COAMPS-TC and the HFIP Corrected Consensus
Approach model (HCCA), and indicates Lane intensifying into a
category 3 hurricane in 3 days.

Lane's motion is estimated to be westward, or 265/11 kt, a little
to the left of due west, and is being steered by a broad mid-level
ridge to its north-northwest. The large-scale models continue to
show the ridge weakening in 2 days in response to a southwestward
and westward retrograding cut-off mid-level low currently located
southwest of the Baja California coast. At that time, the cyclone
should gradually turn west-northwestward and continue in this
general direction through the remaining period of the forecast.
The official forecast is very close to the previous one, with only
minor along-track adjustments, and sides with the HCCA and TVCN
consensus models.

FORECAST POSITIONS AND MAX WINDS

INIT 16/0300Z 10.4N 125.6W 45 KT 50 MPH
12H 16/1200Z 10.4N 127.4W 60 KT 70 MPH
24H 17/0000Z 10.7N 129.8W 75 KT 85 MPH
36H 17/1200Z 11.1N 132.5W 85 KT 100 MPH
48H 18/0000Z 11.6N 135.2W 95 KT 110 MPH
72H 19/0000Z 12.9N 140.6W 105 KT 120 MPH
96H 20/0000Z 14.3N 145.4W 110 KT 125 MPH
120H 21/0000Z 15.2N 149.3W 105 KT 120 MPH

$$
Forecaster Roberts

[TheStormExpert]

Slightly off topic but Hawaii would be prone to more hurricane hits had the island chain been oriented more north to south as opposed to east to west like it is. They’ve REALLY lucked out over the years.