Avalanche forecast

Snoqualmie Pass

Northwest Avalanche Center
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Avalanche danger

Mon
Alpine
4 · High
Treeline
4 · High
Below
3 · Considerable
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Out of date — this forecast expired 5 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Those who have been waiting for a return to winter should get their wish on Sunday. Try to keep your expectations and excitement in check as this storm runs its course by sticking to slopes under 35 degrees. Avalanches will be more likely during periods of heavy precipitation or wind and have the potential to break in surprising ways. 

6:30am Update: Upgraded to HIGH avalanche danger based on overnight snow totals and convergence bringing continued heavy snow during the daylight hours. See Discussion.

Avalanche problems

  • Storm Slabs

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

    Sunday is going to be a stormy day at Snoqualmie Pass. The highest precipitation rates should be first thing in the morning, but snow will continue to fall throughout the day. We are expecting over a foot of new snow to accumulate during the forecast period and build Storm Slabs at all elevations. Significant winds will accompany this storm and of course, Wind Slabs will also develop in wind-prone areas. You can look for blowing snow, fresh cornices, or large pillow-like piles to help you identify where these thicker and possibly stiffer slabs have developed. We are lumping these together because the core message is that it will be a stormy day and your terrain management should be similar between the two problems.

    Throughout your travels, be sure you are digging down to the Valentine’s Day Crust with your hand or shovel to check the bonding of all of the new snow. At the base of the storm snow you may find a thin melt-freeze crust in some locations. Using small test slopes is an excellent way to see how the new snow is reacting to your weight. If you notice that the snow is failing in blocks (slabs) during your tests or that there are shooting cracks as you travel, dial back your terrain choices to avoid slopes over 35 degrees where avalanches are more likely. 

    (2/19/2022)

    The Alpental Pro Patrol found that weak snow near the Valentine's Day Crust was failing during small column tests on 2/19. Be sure to investigate all of the snow above this crust as this storm rolls through.

    Photo: Alpental Pro Patrol

Avalanche Discussion

6:30 Update: Most of the original forecast continues to hold true, but at this point, we are expecting to see more widespread large avalanches and naturals are more likely than originally thought. Travel in avalanche terrain is not recommended during periods of HIGH avalanche danger. The convergence zone will deliver high precipitation rates for the morning hours and a second convergence zone may develop this afternoon to again produce periods of high-intensity snow and wind.

This drastic pattern change should have you easing into terrain slowly and collecting information. There are plenty of questions that need to be answered and it could take a few days until we collectively wrap our heads around the true conditions. We do know that the new snow and strong winds will be building slabs over a variety of existing surfaces, which could mean that the bonding is different from slope to slope. Recent reports from avalanche professionals confirm that weak snow still exists around both the Valentine’s Day and Late January Crusts, further complicating matters. Although we don’t expect widespread avalanches on either of these layers on Sunday, it's certainly in the realm of possibility, so you should be suspicious of all the snow above the Valentine’s Day Crust. As of Saturday, this layer was about 6” below the surface. Keep an eye out for avalanches failing at these interfaces or that are breaking widely and connecting terrain features. If you notice these persistent-type slides occurring, step your terrain choices way back. 

Another observation that should make you think twice about your terrain choices is if you see widespread natural avalanche activity. This may be more likely during periods of heavy precipitation. If more natural avalanches are occurring around you than expected, obviously avalanche hazard has inched toward HIGH and you should choose travel routes that minimize your exposure to avalanche terrain.

Unfortunately, the recent warm and sunny weather did a number on our snowpack and helped expose many hazards such as rocks, stumps, and streams that are normally buried this time of year. The new snow should help to reestablish our mid-winter snowpack, but these objects may be lurking just under the surface. Take care while traveling not to get tripped up by one of these hidden obstacles. 

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