Dec 31, 2014, Clara Lakes Avalanche
12/31/14
WA Cascades East Slopes Central
22578
3
I have two pieces of info to report about skiing in the bowls around Mission Ridge:
First, the snow is excellent and there is enough of it to make great skiing. However, there isn't enough to make safe skiing. There are nasty basalt daggers hiding just under the surface, showing no signs, and not protected at all by the cold fluff.
Second, the wind we got last weekend deposited snow in unusual areas creating avalanche hazards that are different from what we are used to seeing. The scour and deposit areas are somewhat similar to typical areas, but the wind direction was just about opposite of normal and so the deposits came from the "wrong" direction. Interesting to have familiar terrain covered backwards. Jamie and I remotely triggered a significant avalanche. TAY wouldn't let him post his write up (timed out), so here it is:
from jtack:
Just a quick note, full report to follow. Mike and I took a tour into Clara Lake Basin just to get out and about. After watching the results of the Avy controls inside Mission we were not really expecting that much. As we made our way up through the basin we were experiencing settling all the way, upping our concern, but still a little casual. We discussed lines we might ski, most of what we talked about was avoiding the thin snow. We kept to a low angle route, still seeing the settling. when we stopped for lunch we dug a pit and found the weak layer, A deposit of large crystals on the rain crust, with the new snow topping that. After lunch we decided to travel a little further up slope, and start our ski down. At the top of our climb we were feeling very uncomfortable with any steep skiing. We had thought we would ski a steeper south facing line on the way down, but because of our uneasiness with the snow we decided to keep to a low angle line. At the top of the steeper line, I suggested we "just go have a look" so we started over but the access was not all that great so we bagged that idea and resumed our planned line. As we came around the corner and looked at the steeper line it had all slid. We were at least 10 meters from the slope at our nearest. It was a south facing slope 140 degree true 6500 feet and at the top 35 degrees (un measured) failed on the faceted layer, cross loaded from the north wind we had the two days before. It took the whole slope, probably 30 or 40 meters wide, and ran to the bottom of the slope 200/250 vert. Crown 76 cm/100cm.
Unfortunately, neither of us brought a proper camera on this tour, so all these are phone photos, but they tell the story:
Snowpack movement with whoomps. Snowpack would actually drop and translate about a quarter of an inch:
We decided to look for the weak layer, and sure enough, there it was, on top of a crust layer:
Avalanche photos:
I wanted to see how deep the crown was, and you always see photos of snow professionals standing next to and under the crown, but really, I thought this was the dumbest thing I did all day.
Here are the crystals, all layed over like dominos after the slab slid over them.
Debris blocks
Wow:
overview:
before and after:
First, the snow is excellent and there is enough of it to make great skiing. However, there isn't enough to make safe skiing. There are nasty basalt daggers hiding just under the surface, showing no signs, and not protected at all by the cold fluff.
Second, the wind we got last weekend deposited snow in unusual areas creating avalanche hazards that are different from what we are used to seeing. The scour and deposit areas are somewhat similar to typical areas, but the wind direction was just about opposite of normal and so the deposits came from the "wrong" direction. Interesting to have familiar terrain covered backwards. Jamie and I remotely triggered a significant avalanche. TAY wouldn't let him post his write up (timed out), so here it is:
from jtack:
Just a quick note, full report to follow. Mike and I took a tour into Clara Lake Basin just to get out and about. After watching the results of the Avy controls inside Mission we were not really expecting that much. As we made our way up through the basin we were experiencing settling all the way, upping our concern, but still a little casual. We discussed lines we might ski, most of what we talked about was avoiding the thin snow. We kept to a low angle route, still seeing the settling. when we stopped for lunch we dug a pit and found the weak layer, A deposit of large crystals on the rain crust, with the new snow topping that. After lunch we decided to travel a little further up slope, and start our ski down. At the top of our climb we were feeling very uncomfortable with any steep skiing. We had thought we would ski a steeper south facing line on the way down, but because of our uneasiness with the snow we decided to keep to a low angle line. At the top of the steeper line, I suggested we "just go have a look" so we started over but the access was not all that great so we bagged that idea and resumed our planned line. As we came around the corner and looked at the steeper line it had all slid. We were at least 10 meters from the slope at our nearest. It was a south facing slope 140 degree true 6500 feet and at the top 35 degrees (un measured) failed on the faceted layer, cross loaded from the north wind we had the two days before. It took the whole slope, probably 30 or 40 meters wide, and ran to the bottom of the slope 200/250 vert. Crown 76 cm/100cm.
Unfortunately, neither of us brought a proper camera on this tour, so all these are phone photos, but they tell the story:
Snowpack movement with whoomps. Snowpack would actually drop and translate about a quarter of an inch:
We decided to look for the weak layer, and sure enough, there it was, on top of a crust layer:
Avalanche photos:
I wanted to see how deep the crown was, and you always see photos of snow professionals standing next to and under the crown, but really, I thought this was the dumbest thing I did all day.
Here are the crystals, all layed over like dominos after the slab slid over them.
Debris blocks
Wow:
overview:
before and after:
update 2 days later, 1-2-15, on a completely different aspect a friend triggered a slide in bounds at Mission Ridge. The slide occurred in a small clearing in the trees about 6000' on a 34 degree slope which faces 20 degrees (NNE). It was about 14" crown, soft slab (no wind affect perceived by me). It was about 40 feet across, and ran about 50' on that same layer of crystals over crust. What is similar about these is that neither involved wind slab. The slab is so soft that I could ski through the debris.
Photos of in bounds slide at Mish:
the glade: (lower skier is standing below the crown)
debris
crown:
and the crystal layer:
Photos of in bounds slide at Mish:
the glade: (lower skier is standing below the crown)
debris
crown:
and the crystal layer:
Great report, thanks for taking the time to write up the details.
Seems this is an expected PWL (I saw the discussion here: http://www.nwac.us/avalanche-forecast/current/cascade-east-central/)
Seems this is an expected PWL (I saw the discussion here: http://www.nwac.us/avalanche-forecast/current/cascade-east-central/)
Thanks for yet another great report as always, Mike. This is exactly why I haven't liked this year's snowpack at all. Those facets and slab are quite something. Much more important than little snow is what persistent cold temps, shallow pack and then wind slab on top of it does. I can only imagine how bad it has been over your way. Hard to have fun being a "recreationista." If I wanted to be intimidated and dumbfounded by buried surface hoar, depth hoar, and wind slab all on the typical tour I would've moved back to the Rockies. Here's hoping the latest "hydrologic event" coming resets things deeply - I hope over East for y'all as well - and is followed by more normal climate pattern behavior for us. That picture standing in the hang fire is even hard to look at.
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