CPAC: LANE - Post-Tropical

[Ntxw]

That NHC forecast yields roughly ~15 additional units to the ~3 already in place

[ncapps]

Interesting, the GFS is really weakening Lane by Hour 90, yet still trends NW with movement. I don't think the GFS has had a good handle on this storm at all. See if it can start to improve its 5 Day solution with fresh data later today.

The QPF that has been modeled by it has been very suspect as well.

[Kingarabian]

Interesting, the GFS is really weakening Lane by Hour 90, yet still trends NW with movement. I don't think the GFS has had a good handle on this storm at all. See if it can start to improve its 5 Day solution with fresh data later today.

The QPF that has been modeled by it has been very suspect as well.

06z GFS shifted closer to Kauai.

[ncapps]

Interesting, the GFS is really weakening Lane by Hour 90, yet still trends NW with movement. I don't think the GFS has had a good handle on this storm at all. See if it can start to improve its 5 Day solution with fresh data later today.

The QPF that has been modeled by it has been very suspect as well.

06z GFS shifted closer to Kauai.

It did, but 12z looks a little closer to the 0Z. Too many run to run shifts for my liking unlike the Euro. What is prevalent in this run is rapid weakening, something intensity forecasts are also picking up on in the same time frame. The NHC discussion also alludes to a less conductive environment being encountered. This would allow the ridge too steer this a little quicker and further west.

One thing that probably needs to start being looked at is the QPF forecasts. Taken at face value the Big Island would have severe flooding with GFSs modeling. However, not sure I buy the amount of precipitation that is being advertised, especially the duration.

[Kingarabian]

12z UKMET shifts north and is slower through hour 144.

[Kingarabian]

12z Euro still initializing Lane as a 996mb TS.

[ncapps]

12z Euro still initializing Lane as a 996mb TS.

Correct me if I'm wrong because I haven't paid much attention to initialization strength and how affects the entire model run, but I'd think that's fairly common to under estimate it when using data that is lagging behind the most recent pressure estimate? The large scale synoptic pattern is really what were after when looking at the GFS/EURO, correct? More precise Hurricane models should be used for a better idea on intensity?

[Kingarabian]

12z Euro still initializing Lane as a 996mb TS.

Correct me if I'm wrong because I haven't paid much attention to initialization strength and how affects the entire model run, but I'd think that's fairly common to under estimate it when using data that is lagging behind the most recent pressure estimate? The large scale synoptic pattern is really what were after when looking at the GFS/EURO, correct? More precise Hurricane models should be used for a better idea on intensity?

While global models are not hurricane models, they're still supposed to initialize storms very close to their current strengths. They don't initialize based on the latest BT intensity, but by satellite data so regardless when the model is run, it should have the correct intensity. Initializing correctly is very important, and what's more important is getting its forecast strength correct. Initializing and forecasting a system as a modest TS can affect the track in a large way, because a TS is likely to be influenced by a different steering level (likely the low level flow which keeps systems moving to the west) vs. a hurricane which its track is influenced by much more complex systems in troughs/cut off lows/a ridges strength etc.

Hurricane models are better for the correct intensity and an idea of how strong can a system get but they can also be very erroneous.

[ncapps]

12z Euro still initializing Lane as a 996mb TS.

Correct me if I'm wrong because I haven't paid much attention to initialization strength and how affects the entire model run, but I'd think that's fairly common to under estimate it when using data that is lagging behind the most recent pressure estimate? The large scale synoptic pattern is really what were after when looking at the GFS/EURO, correct? More precise Hurricane models should be used for a better idea on intensity?

While global models are not hurricane models, they're still supposed to initialize storms very close to their current strengths. They don't initialize based on the latest BT intensity, but by satellite data so regardless when the model is run, it should have the correct intensity. Initializing correctly is very important, and what's more important is getting its forecast strength correct. Initializing and forecasting a system as a modest TS can affect the track in a large way, because a TS is likely to be influenced by a different steering level (likely the low level flow which keeps systems moving to the west) vs. a hurricane which its track is influenced by much more complex systems in troughs/cut off lows/a ridges strength etc.

Hurricane models are better for the correct intensity and an idea of how strong can a system get but they can also be very erroneous.

Thanks. That's entirely logical. One thing that was become evident with most model runs today is bringing Lane into the CPAC as a TS around Day 5, this is hard for me to believe, but the trend is widespread.

[Kingarabian]

SAB came in with 4.5 again.

CIMSS ADT is currently down, so using SSD's ADT (8.2 version):

2018AUG17 173000 6.0 953.6 115.0 6.0 5.9 5.9 NO LIMIT OFF OFF -14.76 -66.14 EYE 12 IR 62.1 11.40 133.41 SPRL GOES15 13.5

[Yellow Evan]

Decently cold CDO with still a clearing eye points to an intensity in the 90 knots range.

[Kingarabian]

Decently cold CDO with still a clearing eye points to an intensity in the 90 knots range.

Maybe stronger than 90kts based on these recent microwave passes:

2 1/2 hour old GMI pass:

[Blown Away]

TABD gone wild...

[Kingarabian]

Latest EPS run not tightly clustered west, with some strong members recurving close to Kauai.



PC - Ryan Maue - www.weathermodels.com

[Kingarabian]

UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 9.0
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 17 AUG 2018 Time : 183000 UTC
Lat : 11:21:35 N Lon : 133:24:36 W


CI# /Pressure/ Vmax
5.6 / 960.3mb/104.6kt


Final T# Adj T# Raw T#
5.6 5.7 5.9

[CyclonicFury]

My guess is NHC goes with 95 kts @ 21z.

[ncapps]

Couple interesting Euro Ensemble members, but most likely can be tossed out.

[Kingarabian]

[img]https://www.weathernerds.org/tc_guidance/images/EP14_2018081712_ECENS_large.png[img]

Couple interesting Euro Ensemble members, but most likely can be tossed out.

Hope it's not the start of a trend.

[Kingarabian]

131
WTPZ44 KNHC 172033
TCDEP4

Hurricane Lane Discussion Number 12
NWS National Hurricane Center Miami FL EP142018
200 PM PDT Fri Aug 17 2018

A series of microwave overpasses and conventional visible/infrared
imagery show that Lane's inner core continues to develop rapidly.
The eye in the visible presentation has begun to clear out, and the
lower frequency microwave images show a completely enclosed, solid
inner convective ring. The subjective and objective T-numbers from
TAFB, SAB, and UW-CIMSS, respectively, support increasing the
initial intensity to 95 kt.

The intensity forecast philosophy has not changed from 6 hours ago,
and Lane is still predicted to quickly strengthen to major hurricane
intensity later tonight, and has the potential to become a category
4 hurricane in 24 hours. The environment certainly appears favorable
enough for this 24-hour trend to occur and the hurricane regional
and statistical intensity guidance reflect strengthening, but the
NHC forecast is much higher than the NOAA HCCA and the IVCN
consensus models during the first 24 hours. Beyond 36 hours, Lane
should begin to gradually weaken in response to increasing westerly
shear. The NHC forecast is similar to the previous advisory and is a
blend of HCCA and IVCN at these times.

The initial motion continues to be westward or 275/14 kt. Lane is
forecast to move south of a subtropical ridge in either a westward
or west-northwestward direction over the next 5 days. Little change
was made to the official track forecast, with only minor along-track
adjustments after 72 hours, and the NHC forecast is basically a
compromise of the various consensus models.

FORECAST POSITIONS AND MAX WINDS

INIT 17/2100Z 11.5N 134.1W 95 KT 110 MPH
12H 18/0600Z 11.7N 136.4W 110 KT 125 MPH
24H 18/1800Z 12.2N 139.3W 120 KT 140 MPH
36H 19/0600Z 12.9N 141.8W 120 KT 140 MPH
48H 19/1800Z 13.5N 144.1W 110 KT 125 MPH
72H 20/1800Z 14.4N 148.3W 95 KT 110 MPH
96H 21/1800Z 14.9N 152.3W 80 KT 90 MPH
120H 22/1800Z 15.3N 156.2W 70 KT 80 MPH

$$
Forecaster Roberts

either a westward or west-northwestward direction

What's going on here lol.

[Yellow Evan]

Have serious reservations over a recurve near Hawaii just due to the fact it'll be getting torn apart and not vertically deep to feel a 200mbar weakness. This wil likely pass well the south of the island group as a rapidly dissipating cyclone.