|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.
Today could be one of those days where someone could easily be caught in an avalanche: It will be our first chance for a break in cloud cover after a 4 day storm and it’s Saturday. The big concern centers around 2-3′ of new snow, which fell between Tuesday and Friday, that sits on a layer of weak older snow. This weak old snow was last weekend’s surface, which became loose and faceted along with a layer of surface hoar on top. Not only that, at the mid-elevations, between 2,000 and 3,000′, a crust exists below the weak snow (see photo below). What this all boils down to is that the new snow may not stabilize very quickly after this storm and people could trigger large and dangerous avalanches through the weekend. Things to keep in mind with this type of snowpack:
1) This unstable ‘set-up’ is one we have not seen this year
2) Triggering an avalanche remotely, from the side, top or below a slope is possible
3) The snowpack between 2,000′ and 3,000′ (where the weak snow/crust combination exists under the new snow) could be more unstable that the higher elevations. Crusts can inhibit stability and contribute to the possibility for remote triggers.
4) With little ground truth information at this point, very cautions terrain selection is required.
5) Sticking to slopes less than 30 degrees – with nothing steeper above you – to give the snowpack time to adjust is a great way to have a safe weekend in the backcountry.
The photo below shows the new snow at 2,000′. At this elevation the snow was very warm and dense; the rain snow line was just below this and lighter and deeper snow existed just above this.
The glide avalanche cycle continues…. Another glide crack released into a full-blown avalanche sometime late on Thursday or early Friday morning. These cracks are clearly still active and avalanching. Again, this is not the type of avalanche that can be triggered, but instead release spontaneously on their own. Just one more reason to avoid being under steep slopes today.
Photo: Glide avalanche on the Southeast face of Seattle Ridge, between the motorized lot and the motorized up-track.
With the warm and sticky nature of the new snow, cornices are likely to have grown even larger (they are already behemoths…) and be on the verge of collapse. These are not only hazards in themselves, but are also likely to trigger large avalanches below.
Yesterday we saw the tail end of the storm cycle move out with light snowfall adding roughly 1-3″ of new snow. 1″ fell at the Center Ridge SNOTEL at 1,900′ while 3″ fell in Girdwood Valley at the Alyeska Mid station. Winds died down as well with averages ~15mph from a generally East direction. Temperatures were warm (low 30’s at 1,000′) with a rain/snow line fluctuating between 1,000′ and 1,200′.
This morning we are seeing a quick pulse of moisture, increasing cloud cover and increasing Easterly winds move though. This should exit the region by mid-day and skies may break up if we are lucky. We may pick up another 1-3″ of snow with a rain/snow line ~500′ this morning. Winds are expected to be in the 15-25mph range from the East on the ridgetops. Temperatures look to hover in the upper 20’s at 1,000′ and near 20F at 4,000′.
For Sunday, another band of wind and snow looks to move in. We should see some breaks in this stormy pattern this week hover, so stay tuned.
|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′)
|Avalanche: Base of Seattle Ridge
|Troy Tempel, Thomas Lees, .Josh Bollaert, Damian Naquin
|Observation: Lynx creek
|Observation: Tincan Trees
|Moderow / Clayton
|Observation: Turnagain (below the uptrack)
|Alaska Avalanche School Moto Level 2
|John Sykes Forecaster
|Observation: Tincan Backdoor, Center Ridge
|AAS Level 1 / R Sullivan
|Avalanche: Tincan Trees
|Schauer/ Moderow/ Stephenson Forecaster
|Schauer/ Moderow/ Clayton Forecaster