Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

Sun
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

Rising freezing levels could combine with sunshine to produce Wet Loose avalanches on Saturday. Expect more widespread avalanche activity in areas where it is warmer and sunnier, such as the southern parts of the zone. In areas with more cloud cover, you may be more likely to trigger an avalanche in wind-loaded terrain as you ascend in elevation.

Avalanche problems

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    Saturday should be the warmest day of the week and the clouds should be thinner than the past few days, increasing the potential for Wet Loose avalanches. The more sun in the area you are traveling, the higher the potential for these avalanches to occur. A warm and sticky snow surface combined with rollerballs, pinwheels, or snow shedding from trees and rocks will be your first indication that these avalanches are possible. Don't rule out the possibility that the highest peaks could be sticking out of the lower level clouds, basking in the sunshine, and possibly producing avalanches on the slopes above you. Wet Loose avalanches often start at a point and can entrain snow, fan-out, or even trigger slabs as they descend downhill. You can minimize your exposure to these avalanches by heading toward lower angled or shaded slopes and ensuring that the slopes above you are not in the sunshine.

    (3/25/2021) Wet Loose activity, such as rollerballs and small avalanches, were observed at Mount St. Helens on Thursday. A skier triggered these rollerballs on a steep convexity. [Photo: John Darmody]

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    We continue to get reports of shallow human-triggered Wind Slabs around the zone and you need to keep these on your radar for Saturday. You should use test slopes, uptrack tests, or visual clues such as freshly built cornices or textured snow surfaces to help you determine the existence and reactivity of potential Wind Slabs. Convex rollovers, terrain features over 35 degrees, or rocky terrain including confined gullies or the base of cliffs are the more likely locations for you to trigger one of these slabs. If you find a poor bond during your testing or notice cracking in the recent snow as you travel, look to avoid these features.

    (3/26/2021) Shallow Wind Slabs were triggered by skiers in the White Pass backcountry on Friday (3/26). [NE 6200']

Avalanche Discussion

Freezing levels are forecasted to jump up to 7000 feet in the zone on Saturday and areas further to the south such as Mount St. Helens and Mt. Adams could see them reach even higher, possibly reaching 10,000 feet. No matter where in the zone you are, Saturday should be the warmest day of the week and although we are forecasted for mostly cloudy skies, there should be more sun breaks than the past few days or even full sun in those areas further to the south. 

On Friday, shallow Wind Slabs were triggered in the backcountry around both White Pass and Crystal Mountain. These slabs developed during the most recent storm on Wednesday that created the 3/24 interface. On slopes that see direct sunshine, this interface along with the deeper 3/18 interface should be easily identifiable. On slopes with a more northerly tilt, you should be able to still find them, but they could be a bit more subtle. We believe that all avalanche activity should occur above the 3/18 interface, with most focused above the 3/24. 

Some areas of the zone may have freshly built cornices that may be sensitive to humans or rising freezing levels. Be sure to give cornices a wide berth by not traveling on or below them.

During the ongoing Covid-19 pandemic, continue to follow the latest guidance from local, state, and federal health officials. Avoid unnecessary risks that could impact first responders and stress medical resources.  Wear a mask when appropriate, practice social distancing, and consider recreating closer to home.

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