Avalanche Safety Kodiak 2021

[steve]

If you have been getting out and enjoying Kodiak's backcountry snow, you have probably seen the number of new people on Pyramid enjoying our abundant snow pack.

We are lucky to have a Maritime snow pack, wet warm, and for the most part the new snow adheres to the existing snow.

This is not the same if you travel and ski on the mainland Alaska or lower 48, where colder dryer snow does not adhere to the older snow, so you have more unstable snowpack and avalanches.

Kodiak received 6 to 8 inches of new snow at Pyramids trailhead last Saturday and now today, Monday, it is blowing 20+mph from the West so this is an avalanche hazard, snow being rapidly transported by wind creating "wind loading" on Eastern slopes.

Both the North Bowl and South Bowl have some East facing slopes and this is a time when our Maritime snow pack could be Unstable.

I would like to put out a special "Thank You" to Phillip Tschersich for the great Transceiver Companion Rescue class he gave to KISAR members on Saturday. kisar.org/2021/02/22/kisar-february-avalanche-transceiver-training/

If you are new to backcountry snow travel, I highly recommend that you take an Avalanche safety class. Alaska Avalanche School and Alaska Guide Collective are two of the resources available in Alaska.

Have fun but Stay Safe out there!

Example of a classic Kodiak wind-slab avalanche after NW winds re-deposited snow on SE aspects (the X denotes where the human triggered the slide):

[ericlinscheid]

Is this in south bowl?

[Philip]

It's a pic from last year behind Bell Flats. It is just an example of what a wind slab avy can look like.

You can see that the crown face (the vertical wall of snow left behind when the snow involved in the avy moved downslope) is tallest the closer to the ridge top you get. This indicates that the most deposition occurred near the ridge top. As you move down away from the ridge the crown face tapers off, telling you that the wind slab becomes thinner as you move downslope. The wind lost it's energy after blowing over the ridge onto the lee slope, and the snow entrained in the wind quickly dropped out of the air after coming over the ridge.

This is a Pyramid South Bowl avy from a few years ago. This is looking up from the bottom of the bowl, and the summit is out of the image frame on the right. Again you can see the thickest part of the crown face is just below the ridge where most of the snow fell just as the wind coming over the ridge met the still air on the lee slope, and the crown face tapers off as you move downslope. You can see old ski tracks in the bed surface of the avy path in the small gut on the right side of the image. The rollover at the top of the South Bowl is a perfect 38 degrees. Literally the optimal slope angle for maximum avy hazard.



Here is a wind slab avy near the WWII B18-A plane crash site on Sharatin: