Avalanche forecast

Mount Shasta

Mount Shasta Avalanche Center
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Avalanche danger

Sat
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
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Out of date — this forecast expired 2 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Dangerous avalanche conditions will develop today. Around 10–15 inches of new snow is expected to accumulate on weakened surface snow throughout the forecast area. By late this afternoon, a widespread natural avalanche cycle is possible. If you're headed into the backcountry today, you need to be on your A game. Look for cracking, collapsing, failing test slopes, or small avalanches to assess instability. Best bet is to stay clear of steep slopes greater than 30 degrees, and let the mountains adjust to the new snow.  

Avalanche problems

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2

    Storm slab will certainly be an issue today on all aspects below and near treeline. With 10–15 inches of new snow expected, it won't take long for instability to arise. The new snow will likely be reactive to ski cut or just the weight of a standing skier. If triggered, these slabs have the potential to propagate wider than usual, and over a foot deep. Prior to this storm, surface snow had eroded and weakened in the majority of the forecast area. This weak snow underneath could make storm slabs particularly sensitive and dangerous. Make no mistake, dangerous avalanche conditions will develop today. If in doubt, avoid all slopes greater than 30 degrees. 

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2.5

    Today, this problem will develop quickly due to the strong wind and high precipitation intensity. Wind slab development will occur on N-NE-E-SE aspects, with cross loading on S and NW aspects. Peak sensitivity will be late this afternoon, where slabs could react to ski cut, or even release naturally. To intensify this issue, any wind loading will occur on top of variable, and weakened surface snow. If triggered, slabs could break up to two feet deep and over a hundred feet wide. Avalanches could certainly break large enough to bury and kill. If headed into the backcountry today, vigilant observation and conservative decision-making will be crucial. Keep your eye out for fresh wind drifts, collapsing under foot, and shooting cracks. If in doubt, stay clear of leeward (N-NE-E-SE) aspects. 

Avalanche Discussion

After 27 long days, precipitation has finally returned to Mount Shasta! 

Now it's time to pump the brakes. The forecast area has experienced a very long period of dry weather to which has had negative impacts on the snow structure. Please take a minute and read up on the current snowpack condition:Weakened Near-surface Facets: Prior to this storm, multiple field observations (Avalanche Gulch, Parks Creek, Gray Butte, Gray Rock Lakes) had reported Near-surface Facets (NSF's) in below and near treeline terrain. For the most part, these grains exist in shaded, wind protected areas on the bottom half of slopes (treed and open), and in meadows. These grains are fist hard, and lack any cohesion. This layer will certainly fail under the weight of new snow, but how much weight will it take? And if triggered, will these grains propagate across slopes? This is where uncertainty exists. These are questions to be answered in the coming days. For now, these grains could present instability in unusual locations such as terrain traps, gullies, and mid-slope. Read HERE to learn more about NSF's. 

Firm Ice: For the last few weeks, bullet-hard ice has been the primary mountain hazard for upper elevation and wind affected areas. Now with new snow falling, these firm areas will be perfect sliding surfaces for avalanches. More than likely, these bed surfaces will heighten the sensitivity of storm slab and wind slab in the next 24 hours.

Solar Sun Crust: Similar to the firm conditions in the alpine, the recent warm weather has resulted in a melt-freeze cycle on solar aspects. With temperatures dropping overnight, these surfaces have likely frozen solid. Again, this could be a perfect sliding surface for new snow avalanches, heightening sensitivity in the snowpack.

To sum it all up, our snowpack is about to experience a giant shift back into winter. Anytime there are large swings in temperature, precipitation, or weather, it's a good reason to take a step back and reassess. Today (and this weekend) will be a great time for just that. Approach the backcountry with caution and respect, following safe travel techniques, and with a partner.

This Weekend's MSAC Events:

Know Before You Go — Avalanche Awareness. February 1st, 7 pm at Deadwood Supply Co. No cost!Companion Rescue Clinic -- February 2nd, 9 am at Bunny Flat. No cost!

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