Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 2–3
Recent Avalanches: We continue to see glide avalanches release from Girdwood to Seward. On Saturday, there were three remotely triggered avalanches in the upper Seattle Creek area in Turangain Pass, but similar conditions could exist in Summit Lake. The last known avalanches that weren't glide-related were two skier-triggered avalanches on Tenderfoot Ridge over two weeks ago.
We have a couple of different types of weak layers in the upper snowpack right now that could cause human-triggered avalanches 1 to 3' deep. These include a layer of faceted snow that was buried by the recent wind loading on Friday and Saturday, which could still be reactive to the weight of a skier or rider. This is likely the type of avalanche that was triggered in Seattle Creek on Saturday. You can keep an eye out for recently wind-loaded slopes to identify where these weak layers could be concerning and test how sensitive they are using small test slopes or hand pits.
The second type of weak layer we are dealing with is three different generations of buried surface hoar from November. These are buried up to 3' deep and based on our recent observations, have become less sensitive to human triggering during this long cold spell. Despite the lack of recent concerning test results on these layers, it is still possible they could cause an avalanche. It takes a long time for layers like this to gain strength, and often they can linger in thin spots in the snowpack or on slopes that have not seen any traffic. You can always stick to simple, low-angle terrain and avoid terrain traps to hedge your bets.
Wind slabs: Some areas within the forecast zones will see higher winds today, like along Turnagain Arm, the higher alpine peaks around Girdwood, and near Seward. These areas could see fresh wind slabs up to 1'+ deep forming today. Keep an eye out for active wind loading to identify where these fresh wind slabs could cause natural or human-triggered avalanches.
