|Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
|Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
|Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding, and conservative decision-making essential.
|Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.
|Extraordinarily dangerous avalanche conditions. Avoid all avalanche terrain.
|Likelihood of Avalanches
|Natural and human-triggered avalanches unlikely.
|Natural avalanches unlikely; human-triggered avalanches possible.
|Natural avalanches possible; human-triggered avalanches likely.
|Natural avalanches likely; human-triggered avalanches very likely.
|Natural and human-triggered avalanches certain.
|Avalanche Size and Distribution
|Small avalanches in isolated areas or extreme terrain.
|Small avalanches in specific areas; or large avalanches in isolated areas.
|Small avalanches in many areas; or large avalanches in specific areas; or very large avalanches in isolated areas.
|Large avalanches in many areas; or very large avalanches in specific areas.
|Very large avalanches in many areas.
Skookum Valley: A skier remotely triggered an avalanche 150’ wide and 3’ deep that ran 200 vertical feet on a NE aspect at 800’ elevation. Nobody was caught or carried. (more details)
Grandview: A skier remotely triggered a small but deep wind slab on a convex rollover at around 1500’ elevation on a west aspect. The pocket that released was about 40’ wide and 1.5-3’ deep, running for about 40 vertical feet. The slab failed on a weak layer of buried surface hoar on top of a melt-freeze crust. (more details)
|Size (D scale)
|Unlikely to bury a person
|Can bury a person
|Can destroy a house
|4 & 5
|Can destroy part or all of a village
Moderate avalanche danger covers a wide range of avalanche conditions, and today’s avalanche problem should not be taken lightly. The midweek storm brought 1-2’ of snow, burying a weak layer of faceted snow and surface hoar. Subsequent winds on Thursday and Friday have drifted this snow into stiff wind slabs up to 3’ thick or thicker, and we have seen multiple skier-triggered avalanches as a result (details here and here). Today’s combination of weather and snowpack is the exact situation where most avalanche accidents occur. A sunny weekend day with conditionally unstable snow (ready to avalanche on some slopes and stable on others) will make it easy to get lulled into a false sense of security. Here are a few things to think about to keep you out of trouble today:
Just like we saw last month, these persistent weak layers will need some time to gain enough strength to be trusted. For now, the safe bet is to recognize the increased hazard and take a step back in your terrain use.
Sluffs: Steep slopes that have been sheltered from the wind have around a foot or more of loose snow sitting on top of firm surfaces. It will be easy to trigger dry loose avalanches today, and they can pick up enough volume and speed to carry a person. While it is unlikely they will be big enough to bury you, they can be dangerous if they drag you into terrain traps like cliffs, trees, rocks, or gullies.
Yesterday: We had plenty of sunshine yesterday, with clear skies and cool temperatures. High temperatures were in the single digits to upper teens F, with overnight lows down to -12 F near Summit Lake to just barely above 0 F in Girdwood and on Turnagain pass. Westerly ridgetop winds were sustained at 5-15 mph, with gusts to around 20 mph.
Today: Another day of clear skies and chilly temperatures is on tap today before active weather returns tomorrow. Highs are expected in the single digits to upper teens F, with lows in the single digits above and below 0 F. Westerly winds are expected to gradually decrease during the day, blowing 5-15 mph at ridgetops this morning.
Tomorrow: Cloud cover will increase early tomorrow morning, with the highest chance of precipitation late afternoon Sunday to early Monday morning. Winds will shift back to the southeast at 10-15 mph with gusts to 25 mph, and high temperatures are expected in the mid to upper teens F. Total snowfall is looking a bit more modest than our last storm, with around 6” expected by Monday morning. Stay tuned for updates!
PRECIPITATION 24-hour data (6am – 6am)
|Temp Avg (F)
|Snow Depth (in)
|Center Ridge (1880′)
|Summit Lake (1400′)
|Alyeska Mid (1700′)
RIDGETOP 24-hour data (6am – 6am)
|Temp Avg (F)
|Wind Avg (mph)
|Wind Gust (mph)
|Seattle Ridge (2400′)
|Observation: Kickstep NE Bowl
|Observation: TinCan Backdoor/ Center Ridge
|AAS L1 Turnagain
|Avalanche: Lynx Creek
|Observation: Turnagain, Seattle, Mt Ascension
|Silverton Mountain Guides
|Observation: Tincan Trees
|Dalpes/Thamm/ Schauer Forecaster
|Observation: Seward Highway across from Johnson Pass TH
|Avalanche: Base of Seattle Ridge
|Troy Tempel, Thomas Lees, .Josh Bollaert, Damian Naquin
|Observation: Lynx creek