Avalanche: Turnagain

Location: Pastoral SE Bowl

Date:
Observer:
Route & General Observations

On 12/23/2015 we parked in the Magnum parking lot, took the Sunburst approach, then followed Taylor Creek to Taylor Pass. Winds were calm until we reached Taylor Pass. After Taylor Pass the wind stayed strong until we returned thru there later in the day. From Taylor Pass we crossed Pastoral Glacier. At the terminus of the glacier we observed significant, sustained, long distance wind transport of snow from the westerly winds. Then we dropped north down the tight chute just west of Fat Santa Claus Chute towards Lyon Creek. No wind loading or signs of instability were observed in the chute itself though there was fast and high volume sloughing. The third skier down the apron actually triggered a small slab avalanche. It ran 200 vertical feet and was approximately 50 feet wide and about a foot deep. It was hard to tell the exact size due to all the sloughing before and after it. From there we booted up the Fat Santa Clause Chute. Even in the basin the was ongoing and noticeable wind. No wind loading was observed in the chute. Reaching the ridge we were again in the strong wind. From the high point (Bad Santa) we dropped south into the SE bowl of Pastoral. I ski cut the top convexity, produced no results, then skied the upper half of the bowl. There was some, though not a lot of sloughing. As the rest of the group descended, two natural avalanches released from the SE face of Pastoral. One started below us as a point release from a group of rocks and slid the remaining 500 vertical feet to the valley floor. It was approximately 50 feet wide. The second one released above us, the starting zone was not completely visible, but we could see part of a crown about 12″ thick. It ran out of sight below us. That was enough, we ditched our plans to ski to the valley floor and returned to the top of Santa Claus Chute. Next we descended Santa Claus Chute, where essentially the entire thing sloughed. From there we booted back up the first north facing chute of the day to the top of Pastoral Glacier. At the top the strong west winds were transporting snow hundreds of feet off of Pastoral. We then skied down Pastoral Glacier, crossed Taylor Pass, ascended Sunburst and skied to the car. The winds immediately decreased upon crossing east to west thru Taylor Pass. Significant surface hoar and faceting were visible everywhere.

Contact, Location & General Observations
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Forecaster Comments

Upon further follow up the reporting party noted that the slabs were big enough to bury a person if there was a terrain trap below. They weren't sure if the naturals could have been triggered by ridge top winds from above or a possible remote trigger while skier was on slope.

"Its possible that the two slides in the SE bowl of Pastoral were remote triggered. The first initiated about 1,000 feet away from us, and below us as a point release that entrained more snow as it descended to the valley floor. It did start while one of us was skiing. We were skiing a S aspect, it occurred on a SE aspect. None of our slough touched the point where it initiated. It could have buried a skier."

Avalanche Details
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Trigger NaturalAvalanche Type0
Aspect SoutheastElevation 4000ft
Slope Angle 37degCrown Depth 12in
WidthunknownVertical Rununknown
Avalanche Details

2 naturals on SE aspect, 1 human triggered on a N aspect. All at about 4,000 ASL.

Red Flags
Red flags are simple visual clues that are a sign of potential avalanche danger. Please record any sign of red flags below.
Obvious signs of instability
Recent Avalanches?Yes
Collapsing (Whumphing)?No
Cracking (Shooting cracks)?No
Observer Comments

significant ongoing wind loading

Weather & Snow Characteristics
Please provide details to help us determine the weather and snowpack during the time this observation took place.
Weather

cold, windy, wind channeled by local terrain

Snow surface

surface hoar, flattened where affected by wind