Snowslide and Doyle Fracture line profile

Routes, debrief, pictures.
Kaptain Safe T
Posts: 315
Joined: October 30th, 2010, 8:57 am

Snowslide and Doyle Fracture line profile

Postby Kaptain Safe T » February 3rd, 2017, 11:31 am

Finally had a chance to make it over to paradise in the IB....booted out the high traverse in the bowl after consulting with patrol on surface conditions out there. Once on the ridge got a good view of the Snowslide Spring and Doyle avalanche paths and the recent activity around inauguration day.....Quite impressive fracture across most of the South Cirque connecting the thin rocky and steeper terrain. Skied carefully one at a time on the old bed surface on Snowslide to the ridge that divides Doyle from Snowslide.....Dug a pit and repeated several tests near the Crown of the slide, 11800' NE facing, 32 degree slope.....First a shovel shear tests which were consistently STV....also Q1....the compression test results were CT 15 @20 cms to CT 23 @ 53cms from surface Q1 as well.....Extended column test was ECTX no propagation....overall the slide seems to have been all the wind transported snow running on a faceted layer of .5 ml size grains...the wind had made most xtl ID difficult at best. The avalanches both ran 1500 or more feet down into the lower parts of Snowslide taking out a few 10inch diameter trees and leaving well defined flanks for over 700 feet. Quite a bit of debris in the tow of the slide with significant deposition...We opted to ski on the ridge line separating Doyle and Snowslide then onto the old bed surface of snowslide itself. Nice wind buff surface and good powder skiing once in the trees and lower altitudes.....out thru the hippie trees and into the cinder pit short cut where there was signs of rapid warming and snow snail abundant....A great tour and very enlightening as to what does actually happen when the wind blows and transports such large quantities of snow.....I would give it a Rating of HS-N-D3-R4-I...Wind deposit on old snow surface....

raisingarizona
Posts: 172
Joined: November 28th, 2010, 8:01 am

Re: Snowslide and Doyle Fracture line profile

Postby raisingarizona » February 3rd, 2017, 6:22 pm

Cool!

I know the winds have probably made it hard to see the fracture lines clearly but how deep do you think the original crown was?

We spotted it from Core ridge last week and thought it looked somewhere in the ball park of around 6 feet but it was hard to say from where we saw it.

Kaptain Safe T
Posts: 315
Joined: October 30th, 2010, 8:57 am

Re: Snowslide and Doyle Fracture line profile

Postby Kaptain Safe T » February 4th, 2017, 6:32 am

Crown height was variable across the cirque....2 foot at the flanks to 6 plus in the steeper sections....ripped thru rock gardens and larger talus features.....must have been an impressive show

splitboarder
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Joined: November 9th, 2010, 9:07 pm
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Re: Snowslide and Doyle Fracture line profile

Postby splitboarder » February 6th, 2017, 11:16 am

Some pictures of this avalanche, from BJ Boyle and Carlos Danel. Subsequent winds and snow have obscured the evidence of this avalanche, however crown/flank lines and debris piles are evident.
BJ_Snowslide02Feb2017Crown.jpg

BJ_Snowslide02Feb2017.jpg

CarlosDanel_SnowslideAvalanche01Feb2017.jpg

amos68
Posts: 3
Joined: February 3rd, 2017, 12:25 pm

Re: Snowslide and Doyle Fracture line profile

Postby amos68 » February 7th, 2017, 8:57 am

Do you have an educated guess on when the avalanches happened? Is around 200 PM on January 24 a very good guess?

Kaptain Safe T
Posts: 315
Joined: October 30th, 2010, 8:57 am

Re: Snowslide and Doyle Fracture line profile

Postby Kaptain Safe T » February 7th, 2017, 9:38 am

Exact time of event is unknown but you may be able to extrapolate from your wind data? It seems to be related to the loading from W and SW winds during that storm cycle.....Carlos are you out there? Chime in if you can help nail down time of event.

splitboarder
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Re: Snowslide and Doyle Fracture line profile

Postby splitboarder » February 7th, 2017, 9:40 am

amos68 wrote:Do you have an educated guess on when the avalanches happened? Is around 200 PM on January 24 a very good guess?


I think it happened sometime between January 20th and the 23rd, during the POTUS inauguration storms.
Unless you have some evidence, I don't think January 24th is a very good guess.... Unless maybe you are thinking of some winds that may have been happening that day??? Agassiz station was rimed up so wind data there is no good.... Dang we sure could use a better weather station...
Troy Marino is a splitboarder and on the KPAC board of directors.
KPAC Snow Summary.
Future Guidebook?!

amos68
Posts: 3
Joined: February 3rd, 2017, 12:25 pm

Re: Snowslide and Doyle Fracture line profile

Postby amos68 » February 7th, 2017, 10:05 am

It didn't look like it snowed much on the break in upper Snowslide Canyon...so I was thinking it happened after almost all of the snowfall. Maybe the 23rd would be more reasonable. There were only a few inches that fell after mid afternoon on the 23rd.

splitboarder
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Joined: November 9th, 2010, 9:07 pm
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Re: Snowslide and Doyle Fracture line profile

Postby splitboarder » February 7th, 2017, 10:40 am

Here is the Snowslide Canyon Snowtel data during the storm. All values from 11PM.

Date | Snow Depth Inches | SWE | Max temp last 24 hours F. | Min temp last 24 hours F.
Thursday Jan 19 | 62 | 18.9 | 35 | 12
Friday Jan 20 | 74 | 20.8 | 32 | 21
Saturday Jan 21 | 80 | 21.8 | 25 | 20
Sunday Jan 22 | 78 | 22.1 | 24 | 15
Monday Jan 23 | 90 | 24.8 | 36 | 13
Tuesday Jan 24 | 91 | 25.2 | 26 | 17

I think the avalanche happened on Monday the 23rd, during the last storm that was a bit warmer and added ~2.7" of snow water equivalent (SWE) to the snowpack. Also, if the avalanche had happened early on in the weekend, it would have been much more obscured by the last storm on January 23rd....

Thanks for the discussion!
Troy Marino is a splitboarder and on the KPAC board of directors.
KPAC Snow Summary.
Future Guidebook?!


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