Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Very Likely
- Size
- 1.5–2.5
Recent Avalanches: Several avalanches were triggered remotely in Lynx Creek on Tuesday and two were triggered on Seattle Ridge. These all very likely failed on the layer of surface hoar that has been observed across our advisory area. Several other skier triggered avalanches were reported on Sunday.
The storm is finishing early this morning, but we are anticipating very dangerous avalanche conditions today. It is very unusual that we would issue a high danger rating during a day with quiet weather like we are expecting today, but we are dealing with an unusually dangerous snowpack. We've seen multiple human-triggered avalanches failing on the layer of surface hoar that was buried two weeks ago, and we've just experienced the largest 24-hour loading event that layer has seen so far. This is adding a lot of stress to a problematic snowpack, and it is very likely a person will trigger an avalanche. We have seen multiple avalanches triggered remotely from low angle terrain connected to steeper slopes, which means it may be possible to trigger an avalanche in steep overhead terrain even if you are on a relatively mellow slope.
Conditions will become more dangerous if the sun comes out this afternoon. Now that we're into early March the sun is packing a punch once again, and this will likely heat the new snow, triggering loose snow avalanches in the afternoon. There is a good chance even a smaller avalanche failing within this new snow will create a much bigger avalanche failing on that layer of buried surface hoar.
Don't be caught off guard by the fair weather expected today. Conditions will be very dangerous, and we recommend avoiding avalanche terrain while this snow settles down. Surface conditions should be really good, but this is the kind of day where we're hoping everyone stays out of trouble and enjoys the new snow in low-angle terrain.
Storm totals below are since early Wednesday morning, just over 24 hours:
- Girdwood: 12-18" snow (1.25-1.75" Snow Water Equivalent (SWE)
- Turnagain Pass: 10-12" snow (1.0" SWE)
- Summit Lake: 1-2" snow (0.1" SWE)
- Seward/Lost Lake: 12-15" snow (1.2" SWE)
The chances of cornice falls will increase as temperatures rise this afternoon. These may fail naturally, so it's important to limit any time traveling below them. They may also be triggered from ridgelines, and they often break much further back from the edge that we'd expect. Give them plenty of space if you find yourself traveling along ridgelines today.
Glide Avalanches: The glide cracks across the area are still on the move, some of which are still releasing into large avalanches. These are very big and completely unpredictable. The only way to manage this problem is to avoid traveling below open glide cracks. Look closely; these will likely be harder to recognize under the recent snowfall.
Very low visibility storm day on Tincan yesterday. This new snow will make problems today.
Photo: John Sykes
