Turnagain Pass Avalanche Forecast

Cold temperatures and moderate to strong northwest winds are expected today from 20-25+mph and will be capable of transporting surface snow.  With all this fresh snow, we can expect to find new touchy wind slabs around 1-2′ thick. In areas seeing snow pluming off the peaks and ridges, natural wind slab avalanches are possible. This is most likely south and north of Turnagain Pass in areas such as Summit Lake, Lost Lake and Girdwood.  Additionally, there still could be older wind slabs or storm slabs lingering from last week’s storm.  If a wind slab or other slab releases in the top few feet of the snowpack, it could ‘step down’ and trigger a much larger slide that breaks in deep weak layers; more on that below.

Cornices:  These have grown substantially over the past week and could easily be triggered. If making it to the ridgelines, be sure to give these features a very wide berth.

3-5 feet of new snow accumulated from 2/18-20 and has added to forming a thick deep slab over weak faceted snow from January.  The storm cycle this week naturally triggered many steeper slopes to avalanche.  Many steep slopes didn’t avalanche, and may not take much load to initiate.  If todays clear skies draw us into the mountains, it’s easiest to avoid these issues by remaining in the flats or on slopes 30 degrees or less with nothing steeper above.

The natural cycle we had a glimpse of Thursday afternoon proves that the snowpack isn’t stable. Many of the avalanches had crowns 5-8′ thick, were rated ‘very large’ and stepped down into buried weak snow. In shallower snowpack zones such as Lynx Creek or Summit Lake, it could be much easier to initiate a large slab. Yesterday a party felt many large whumpfs in Summit Lake.

If you are headed out into avalanche terrain today, things to remember:

• Between 3-7′ below your snowmachine or feet sits various layers of weak sugary faceted snow
• Very large avalanches could be triggered that take out the entire slope
• Yes, many slopes have already slid, but these could have portions still intact and waiting for a trigger
• There is no way to know how close a slope is to avalanching. It could be the first person or the 15th person that hits the trigger point.
• Remote triggering is possible (initiating a collapse in the weak layer from the top, side or bottom on the slope resulting in an avalanche)

This slab avalanche was naturally triggered sometime in the range of 2/18-20 on a southwest facing aspect of Sunburst.   This slope is frequented by skiers.  What will it take to initiate the adjacent slopes?  2/22/2020 . Photo:  Kellie Okonek

Pictured here is one slab of many naturally triggered avalanches that occurred earlier in the week. Many steep areas that haven’t avalanched could still be near the tipping point.  2/22/2020 . Photo: E. Roberts