4 November 2010: More Paradise climax avalanches.

Bundy Phillips was a Paradise Ranger back in the late 70's & 80's.  Super fit, one of those 1:15 to Muir types; outstanding skier also, both tele & skate. I think he recently retired as a Yellowstone District Ranger.  I was introduced to him in the Paradise lot the week he arrived & we immediately set off on a little orientation tour.  Within the hour, he had broken a tip on his Europa 99's flipping off a drift; only broken Fischer I've ever seen.       That slope was 'Bundy's Blunder' ever after for me. 

Fantastic thread.

The irregular shape of the crown / flanks is very telling. It's a sign of that the slab is being held on the slope by the tensile strength of the snow. As the slab warms, its hardness decreases, which can mean that the snow has already "failed" even if it hasn't fractured yet.

These types of situations are very dangerous because it can be incredibly easy to trigger an avalanche with, basically, almost no energy requirements. You might be able to skin past one of those starting zones and trigger an avalanche with a snowball.

NEAT!

Thanks for sharing the pictures and historic data.

We've all skied those exact lines haven't we? I know I have, more than a few times.

One warm spring day circa 2003, I set off a slow moving sludge slide (non-climax) on the line just left of the second photo. It was pretty interesting to watch as we expected it to stop quickly because it moved so slowly. But it just kept going and going until it finally petered out in the flats at the bottom of the bowl. It all seemed harmless at first. But in the end, I was glad to have decided to ski quickly out of the sliding goo in order to avoid the 4 foot high pinwheel chasing me down the slope, otherwise I may have ended up twisted up in slow motion fashion like a piece of taffy on a pulling machine.

So I am wondering if an early season climax slide indicates a high likelihood of mid-winter, non climax slides at the same locations? The slope angle and aspect played key roles in these slides, and those are fixed variables needed for winter slides. What are the other elements? How dangerous might these lines really be in winter?

Gary, I love it when you share the stories behind the names of these places! Most of us carry them around in our heads with no idea where they came from.

So I am wondering if an early season climax slide indicates a high likelihood of mid-winter, non climax slides at the same locations? The slope angle and aspect played key roles in these slides, and those are fixed variables needed for winter slides. What are the other elements? How dangerous might these lines really be in winter?

Well, early season climax avalanches are avalanches, which means it's avalanche terrain. From the perspective of backcountry avalanche forecasting, the answer to your question is no.

The likelihood of avalanche formation depends on the snowpack and weather. In the past, I have definitely been concerned about triggering soft slab avalanches in storm snow on steep slopes around Paradise.

Also, aspect is in general a *very* poor predictor of avalanche activity.

Also, aspect is in general a *very* poor predictor of avalanche activity.

I disagree. If it were a poor predictor, the "avalanche rose" would have little to no utility.

In the absence of all other relevant information, in midwinter, I'd be maximally hesitant to drop in on an NE-facing slope. If you average over the full year, then yes, I agree.

Terrain and timing are the only things you get to choose. Aspect is an important part of both decisions.

According to The Avalanche Handbook, citing research by Grimsdottir, aspect is in general a very poor predictor of avalanche activity.

From page 224:

"When the numbers of people are accounted for, research ( Grimsdottir, 2004 ) has shown that aspect becomes a weak predictor."

"However, when slope usage is taken into account ( number of people ), aspect as a predictor is too weak. If anything, the risk is slightly higher on east than west aspects, and north-south aspects form a mirror image of each other in this Canadian data set."