|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.
Over the last three days 4″ of water fell in the form of rain at lower elevations in Turnagain Pass. Rain/snow line fluctuated between 1800’ and 2500’ leaving the snow saturated with water. Several large wet avalanches were observed along the Seward Highway and Portage Valley over the last two days. Warm temperatures will persist today making it possible to trigger a wet avalanche on steep terrain features. Avoid this hazard by choosing low angle terrain away from large slopes and terrain traps.
*If temperatures drop below freezing this concern will stabilize quickly as water drains and the slab strengthens in the mid elevation zone.
Debris from a wet avalanche in Portage Valley. This avalanche likely released on the morning of Nov.27th.
Strong Northeast winds topped out at 109 mph on Sunburst weather station yesterday morning. Windslabs over 4’ thick on leeward aspects and crossloaded terrain features are a concern for today in the upper elevation zone. Avoid smooth pillow shaped snow on steep slopes and convexities. Even small features if steep enough could break well above you and have plenty of volume to bury a person. Obvious clues like shooting cracks and whumpfing sounds may not be present today making this avalanche problem difficult to identify.
In the upper Alpine above 2500’ weak faceted snow that formed during a cold snap has been covered up by 4’ of heavy snow creating an upside down snowpack. Last week observations showed a large variation in the distribution of this weaker snow below. It is likely that Northern aspects will harbor the bulk of this problem, but until more information is gathered much uncertainty exists as to how well this new snow has bonded with the older less stable snow below it. This is just one more high consequence reason to avoid steep terrain today.
A very wet and warm storm passed through Southcentral Alaska leaving the region with above freezing temperatures and high-sustained winds for multiple days. In Turnagain Pass rain/snow line reached 2500′, Easterly ridgetop winds maxed out above 100mph and 4 € of water fell over a three-day period.
Showery weather in the form of mixed rain and snow is expected today and into the weekend with rain/snow line moving to 1000′. Temperatures will hover just above freezing (32F) and begin to cool slightly by this evening. Easterly ridgetop winds 20-30mph are also expected to depreciate by early evening. This pattern will continue through the weekend with patches of clear sky at times.
*Seattle Wx Station wind data is currently not available.
|Temp Avg (F)
|Snow Depth (in)
|Center Ridge (1880′)
|Summit Lake (1400′)
|Alyeska Mid (1700′)
|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