Northwest Avalanche Center - Public Observation

Name:

Mike Rolfs

Observation Date:

February 7, 2021

Submitted:

February 7, 2021

Zone or Region:

East Central

Activity:

Skiing/Snowboarding

Location:

West of Mission Ridge

Did you observe any avalanches?

Yes

Comments:

I saw just one debris pile after touring many aspects and elevations west of Mission Ridge this weekend. This looked to me to have slid naturally as a shedding off nearly vertical surface on the north side of the bomber cliffs.

Photo:

None reported

I dug several pits at various elevations between 5500 and 6500 feet both Saturday and Sunday. Isolated columns in three locations were welded together. I was unable to cause any failure by compression. I tipped over two 150cm columns and one 200cm column right off the ground and two of those survived impact with the ground. Shovel shear tests indicated many (up to 12) crust layers, but compression could not activate these layers. In one location we found wind slab over 2 inches of grouple. This was the only reactive situation we found, but it was pretty startling how easily the slab slid over the grouple ball bearings.

Here is a video of exposing the grouple: https://youtu.be/I5V_nfQHRks
And here is a video of trying to show how the wind slab slides off the grouple as it did the first time, but we got a result we didn't expect: https://youtu.be/cWZm5q1R-_c