|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.
|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
Yesterday’s storm brought a few inches of snow to Girdwood and Turnagain Pass. Portage Valley near the lake got 8-10″. The winds died down in the early morning but the strong easterly winds from Monday night should not be forgotten today. We have been talking about the January 21st buried surface hoar layer for a couple weeks now. This layer has been responsible for the scattered avalanche activity over the past week and a half (including a large avalanche that occurred on Saturday on Twin Peaks). Slopes that got more wind effect/loading may now have a stiffer and more reactive slab over the buried surface hoar. Leeward slopes in the Alpine are the most suspect. The new snow may be may have covered up the surface signs of wind effect. It will be important to pay attention to where the snow feels stiff, looks pillowed or sounds hollow and watch for shooting cracks. Before committing to steep terrain, identify terrain traps like gullies, cliffs or rocks below and consider the consequences if even a small slab is released. The new snow also fell on a fresh crop of surface hoar that developed last week. In Portage due to more new snow, even on lower elevation slopes, this February 5th surface hoar layer could be the layer of concern.
*Deep Persistent Slab: Weak snow can still be found near the ground at the upper most elevations in our forecast area, 3,000′ – 5,000′. Although triggering a Deep Persistent Slab is very unlikely, it is worth keeping in mind that poor structure does exist at the high elevations.
The January 21st buried surface hoar found in a snow pit yesterday under some stiffer wind-affected snow. Photo: Sam Galoob
One of the lower piles of debris from the Twin Peaks avalanche that occurred on February 3rd.
The February 5th buried surface hoar layer under a couple of inches of new snow at Turnagain Pass. Photo: Sam Galoob
Loose Snow Avalanches, ‘sluffs’: In most places the snow is very loose and ’sluffs’ easily on the steeper slopes. The new snow will add volume to these. Watch your ‘sluff’ and be aware of the consequences below you.
Cornices: Cornices are unpredictable and can break further back along a ridge than expected. Give these features plenty of space.
Yesterday was mostly cloudy and there were snow showers throughout the day. Temperatures were in the 30Fs at sea level and 20Fs at upper elevations. Winds were easterly and became light in the afternoon. Snow stopped in the evening and temperatures were in the low 20Fs.
Cloud cover should diminish this morning and skies will become clear and sunny. There is the potential for some valley fog. Temperatures will be in the 20Fs and winds will be northerly 5-15 mph. Tonight temperatures drop into the teens and winds remain light and northerly.
Tomorrow and Friday should be clear and sunny with temperatures in the low 20Fs and light variable winds. There is snow in the forecast for the weekend but the details are pretty uncertain. Stay tuned!
PRECIPITATION 24-hour data (6am – 6am)
|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: Seattle Ridge
|John Sykes Forecaster
|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