Baker Avalanche on Sat. April 15

Bascially we got 4 feet of fresh snow sitting ontop of the rain/ slush layrer from the prior tow weeks. This never really developed a strong bond, and that combined with some wind loading and ocasionaly, but very intense and quick thermal warming from sun breaks created the potentail for slabs, on all aspects, and wet slides on south exposures.

That's one of the biggies in the springtime. You've got not only the classic abrupt differences between adjacent layers, but it is compounded in this case by the fact that after mid-March or so, it just isn't cold enough to re-freeze a buried wet layer at an interface. This is especially so when you get a thick layer of new snow. The new snow, in this case 2-4' of it, has the effect of insulating the wet layer and actually preventing any significant re-freezing at the interface between the dissimilar layers. Any bonding that does occur is likely to be transient. So, even a slight bit of cohesiveness in the new snow, and you've got a slab....the weak layer is a given. Then the slightest warming, the slab loses a bit of it's strength and the minor bonding disappears. The later one gets into spring, the more isothermal the snowpack, the thicker the layer of new snow, the harder it is to develop a good bond. Maybe on a north slope at higher elevations with clear skies, but not at moderate elevations, and not with partially cloudy conditions.

Sorry to hear about the accidents.

Hi Garybrill,
                  I found your comments most interesting regarding the wet layers. I was an attendee at the Crystal Fest on Sunday April 30th, however my partner and I started our tour not by going up the ski area to High Campbell lodge but by skinning up into Silver Basin and climbing to the top of the King.
The point is this. We started skinning up the steep slopes of Sliver Basin and the surface was fozen and appeared firm. About 1/2 way up we changed to bootpacking because it was difficult to skin without slipping( we where also following two other skiers who where about 1,000 higher than us).
It was then that we noticed that below the firm surface film,the top 12-18" of snow was completely saturated from the previous day's cloudy, wet weather. At this point I became vey concerned as the sun was getting hotter, and I basically run up the rest of the bootpack like a scared rabbit. Once on top I discussed my worries about the slope with my partner and how I was not going to ski down it. He felt the slope was " not to bad" and was not overly worried about it.  I told him I felt like a real coward but he was very gracious. We proceeded to climb the King and ski down the ridge  and dropped into Avalanche Basin low down. We joined the Crystal Fest group and hiked up Campbell Basin and skied the Throne chutes.

On the way home that night I was feeling rather guilty that my unease with the Silver Basin slope had spoiled my partners day, and that my tendency to be cautious ( and at times I think I can be over-cautious) adn prevented us from getting in some good sking.

Who knows who was right or if there was a right or wrong ,but I find it interesting that two relatively informed people had such different risk assessments of that particular slope at that particular time.

However, both of us had no worry about the Campbell Basin slope below the Throne because lot's of people where skiing it and we believed it was more skier compacted that the Silver Basin slope. ???

The more I do this stuff, I get more conviced than ever that we make our decisions to ski a particular slope based upon those " huerisitic ( probably spelled wrong) traps" that have been recently written about.

Anyway, thanks TAY for the avenue to disuss this.
Always learning, but will never know enough.


Cheers
Scotsman

Hey Scotsman-

Perhaps you've already read this, but I am pretty impressed with it-

Secrets of the Snow: Visual Clues to Avalanche and Ski Conditions
by Edward R. Lachapelle

It's a mixture of snow photos and lengthy discussions about which details are important to pick out, allowing better assessment of snow conditions. There's quite a bit of juicy info regarding spring snowpacks and wet/slush slides.

Thanks Korup,
I will get read. Thanks

Heres a reference photo showing the crown-line of the accident slide in Stonemans chute. This was taken after another snowfall had occured...

Scotsman,
I believe any avy expert worth their salt would tell you that you did exactly the right thing by backing off when you had concerns about the safety of the slope you declined to ski. Your reference to heuristic traps was spot-on. No one every got killed or seriously injured on a slope where they assessed the situation, listened to their "gut" and passed on the opportunity to ski that slope. It takes more confidence and intelligence to say no when presented with a beautiful untracked slope, than it does to risk your life and go along for the ride, as it were. I hope I'm as smart and confident as you were the next time I'm faced w/ such a decision. Thanks for sharing you story. The life you save may be mine.
Dan