|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.
For most folks that have been in the backcountry lately it is hard not to notice the collapsing in the snowpack. Other than a few avalanches in the past week, this has been our prominent ‘obvious clue’ as to the weak snow lying 12-18” below the surface. If you look at the two observations sent in yesterday, both highlight collapsing (or whoomphing). You can see them HERE and HERE. Other red flags are found by digging in the snow. However, a collapse trumps all and essentially means that if a slope is steep enough chances are it will avalanche.
With weak layers in the pack that are hard to assess from the surface, keeping with safe travel practices will help to hedge your bets if riding/skiing on steep slopes. These include watching your partners, exposing only one person at a time and having an escape route planned if the slope avalanches.
Below is a cross section of the snowpack at 3,200′. You can see a vertical crack in the ‘slab’ and the weak snow (lighter colored) below a crust. This if from a snow pit on Magnum, SW facing. – more details and video HERE.
We received 2-3″ of snow from Friday night that was blown into drifts on the ridgelines. Cornices grew a bit with this event and some small to medium natural cornice failures were seen yesterday. This snow has shown signs of bonding well with the surface and is now part of the ‘slab’ mentioned above.
Below treeline the slab is losing its cohesion and the pack is unsupportable. Though there is some localized collapsing in the alders, triggering an avalanche is unlikely.
During the past 24-hours we have seen a slight warm up above treeline (20-25deg) and a slight cool down at sea level (upper 30’s to low 20’sF) due to minimal cloud cover producing a weak inversion. Winds have been light from the Southeast and have switched to the Northwest overnight. We only picked up ~3 € above treeline with Friday night’s snow event.
Today we will see a weak disturbance move over us from the Gulf bringing mostly cloudy skies and continued warm temperatures. Ridgetops will be in the mid 20’sF with winds shifting back to the Southeast and picking up through the day to the 20mph range by the evening hours.
There is a possibility for precip on Tuesday into Wednesday as a warm low pressure system moves in from the South. How much will depend on the track this low takes but it is fairly warm with rain at sea level likely.
|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