This advisory expires in 24 hours
Considerable avalanche hazard on southerly aspects at all elevations, on slopes 35 degrees and steeper, and anywhere in the run-out of these slopes. Likelihood of avalanches: Human triggered avalanches likely, natural avalanches possible.
Avalanche size and distribution: Small avalanches in many areas or large avalanches in specific areas or very large avalanches in isolated areas.
Travel advice: Dangerous conditions. Careful snowpack evaluation, cautious route finding and conservative decision making are essential.
Moderate avalanche hazard on northerly aspects at upper (above 3500′)elevation for wind slabs up to 10″ thick in very specific locations.
Likelihood of avalanches: Human triggered avalanches possible, natural avalanches unlikely.
Avalanche size and distribution: Small avalanches in specific areas; or large avalanches in isolated areas.
Travel advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
Low hazard at mid (2500′-3500′)and low (below 2500′) elevations.
Likelihood of avalanches: Natural and human triggered avalanches unlikely.
Avalanche size and distribution: Small avalanches in isolated areas, or extreme terrain.
Travel advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
RECENT ACTIVITY and CONDITIONS
The last few days brought unseasonably warm weather with highs reaching the mid-forties and two nights with above freezing temps on Marmot.
A variety of conditions currently exist. Slide for life conditions still exist on northerly aspects where the wind hardened surfaces make travel up and down challenging. South aspects range from soft in the afternoon to punchy all the way to the ground.
AVALANCHE CONCERN #1
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- Several wet-loose avalanches released naturally on 2/26-2/28 on south, southeast, and southwest aspects. Although small to medium in size, these avalanches are running faster than you can say “avalanche”. The significant amount of facets in the snowpack are contributing to the speed of these avalanches. The sudden increase in temperature, and lack of freezing at night has quickly transformed our winter snowpack into an isothermal snowpack on southerly aspects. Fortunately, buried crusts from earlier in the season are keeping avalanches from running larger. It is just time before we see huge wet-loose avalanches where weak facets are waiting to fail as the sun’s rays penetrate deeper. Check out the pits page to revisit what lies in the depths of the snowpack (mostly facets) and is available to be entrained in a wet-loose avalanche if the cycle continues.
- Travel protocol and good route finding skills are absolutely critical for avoiding wet-loose avalanches right now. These avalanches are large enough to bury, injure, or throw you off a cliff. Avoid ski cutting and traversing across these slopes as the speed of the wet snow moving on a bed of facets is faster than you can move. Stay out of and away from terrain traps that could compound the consequences.
AVALANCHE CONCERN #2
Wind slabs from Feb.14-18 still exist and are reactive to human triggers on northerly aspects at mid to upper elevation. These wind slabs are failing easily in stability tests and sit atop weak faceted melt-freeze grains that resemble champagne glasses. The distribution of these wind slabs is specific. Instability exists in portions of terrain, although evidence is not always obvious. Wind slabs exist in specific portions of terrain including: leeward aspects (north, northwest, west), starting zones, gullies, and rideglines. Remember that strong winds formed slabs well down slope and on crossloaded features.
A simple hand shear, pole test, or stability test will confirm the presence of these wind slabs. A human trigger, cornice collapse, or continued warming will cause the wind slab to fail on the facets and has the potential to step down and awaken our deep persistent weak layers from earlier in the season, compounding the risk and size of the avalanche.
The weather forecast predicts slightly cooler temperatures in the low to mid thirties through the weekend. A freeze/thaw cycle will help stabilize the conditions. Temperatures above freezing will continue to weaken bonds. If we do not see freezing temps, the avalanche danger will increase and weaken cornices.
If you are out and about HP and see an avalanche or have a snow observation, please share it with us by clicking on these links or under the observations tab in the menu bar or email us at email@example.com. We would like to hear from you!