Avalanche: Summit

Location: Manitoba

Date:
Observer:
Route & General Observations

We toured up to 3,600’ on Manitoba on a sunny day to check out the snowpack on different aspects throughout the day. The sun was already warming the snow at the parking lot despite the 15 F low overnight. The recipe for an avalanche existed in all locations that I dug in the snow with a weak layer beneath a slab, but the snow was most reactive in a hand pit at 2,000’ which failed easily on what I think might have been surface hoar about 5” down and a thick layer of facets about 1’ down. There was dry powder on the upper elevation north facing slopes, but anything E-S-W had some kind of crust. There are a variety of weak layers in the Summit Pass snowpack at different elevations, we recommend assessing the snowpack on the aspect you intend to ride at this time of year when the sun is affecting each aspect a little differently.

 

Avalanche Details
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Trigger NaturalRemote Trigger Unknown
Avalanche Type UnknownAspect Southwest
Elevation 3000ftSlope Angleunknown
Crown DepthunknownWidthunknown
Vertical Rununknown  
Avalanche Details

We watched a loose wet avalanche come down on a southwest slope off the west ridge of Silvertip at about 5:30pm.

Red Flags
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Observer Comments

Recent wet loose avalanches

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

Amazing partly sunny spring day, 38 F when we started at 11:30, temps reached 41 F in the afternoon for several hours at the Summit Creek snotel. There were some high clouds that were in and out throughout the day.

Snow surface

The shaded surfaces were frozen with a 3” crust at the parking lot with moist snow underneath. At 2,000’ facing southwest there was a 3” crust that was starting to soften. At 2,500’ facing west the crust was 2” thick. There was dry settled powder on the north facing slopes at 3,500’ and there was widespread surface hoar everywhere. In the lower elevations it was melting with the sun effect.

Snowpack

We dug several hand pits along our tour. The first at 2,000’ was the most concerning with an easy failure 5” down on what I think might have been surface hoar, but I wasn’t sure. It also failed simultaneously about 1’ down on a thick layer of facets, the slab was 1F and the facets were F+. Hand pits at 2,500' and 3,200' facing west had moderate failures 1' down on a hardness change, and a hand pit at 3,600' north aspect had a hard uneven failure 1' down on an unknown layer.

We dug a snowpit at 3,600’ on an east aspect 18 degree slope. We did not get any concerning results in the tests (CT11 down 5cm under a crust, ECTX). We did find the set up for an avalanche with a weak layer of facets below a slab. We will keep an eye on this and it will become more concerning when the snowpack gets an additional load of snow, wind, or warm. Also, a similar structure exists on other aspects E-S-W that get warmed especially on sunny days which adds weight to the slab increasing the avalanche danger the more it warms.

Photos & Video
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