Lawinenlagebericht

West Slopes South

Northwest Avalanche Center
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Lawinengefahr

Sat
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
2 · Mässig
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Kernpunkte

A complex winter storm will create dangerous avalanche conditions in the West South zone on Friday. Actively blowing snow, new cornice development, and large drifts can help indicate where you're more likely to trigger an avalanche. Slabs could develop in atypical locations such as further down the slope or on different aspects than you're used to. When in doubt, avoid slopes over 35 degrees.

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    1–2

    Winds are forecast in the strong range throughout the West South zone on Friday. As a result, we're likely to see a new crop of wind slabs on leeward slopes. Since the wind direction will predominantly be from the southeast, these slabs may form on different aspects than you typically see them. East wind events often result in more cross-loading or mid-slope loading than normal. Add it all up and these slabs could exist in unusual locations, so don't get caught off guard.

    Luckily, the clues and tricks are largely the same. Look for actively blowing snow, new cornices, or fresh drifts behind objects to help identify wind-loaded aspects to avoid. Slabs will be more common near ridgelines, convex slopes, rocky chutes, or the base of cliffs.

    (1/2/2025)

    Obvious signs of wind transport can help you identify wind-loaded slopes to avoid on Friday.

    Photo: Dallas Glass

Avalanche Discussion

After a few days off, Friday's storm is going to pack a bit of a punch, reminiscent of last week's storm parade. There's a lot to unpack with this one and the nuance will change depending on where you are in the zone.

We mentioned the wind above. That's what we have more confidence in. Our uncertainty mostly surrounds the warming trend and how it will play out spatially across the zone. A few things to consider:

  • We could end up with "upside-down" snow and a storm slab problem. If you see cracking of the surface or blocks are failing in your tests, watch out! Similar to the wind slab problem, you're going to want to avoid slopes over 35 degrees. This may be more likely on Mt. Rainier where more snow accumulates than near the crest.
  • At lower elevations or further south in the zone we could see more warming and thus, more rain. If rain starts falling on dry snow, you'll need to put wet avalanches on your radar. Areas further away from the east side cold pool such as Mount St. Helens may warm more significantly. 
  • Freezing rain is another possibility for the day, particularly at White Pass. Although not commonly associated with avalanches, it can become a travel hazard or may help kick off a few small slides.
  • If you're further south in the zone, such as on Mount St. Helens or Mt. Adams, consider reading the Hood forecast.

On Thursday, observations from NWAC forecasters and avalanche professionals along the crest indicated that the snowpack was already getting grumpy and shedding snow from the early stages of this storm. Older interfaces were found to be reactive in small column tests at White Pass and could come into play over the next few days. Although weak surfaces are less common than they were a few days ago, you could see avalanches break widely or in surprising ways in isolated locations. 

We just took a semi-deep dive into the if/then statements of weather and avalanches, but we can boil it down by saying that Friday will be a dangerous day in the mountains. When in doubt, avoid locations where avalanches are more likely such as wind-loaded terrain and slopes over 35 degrees. 

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