Avalanche forecast

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Northwest Avalanche Center
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Avalanche danger

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

You may still be able to trigger large avalanches at middle and upper elevations where you find a variable and sometimes shallow snowpack. The best way to manage this risk is to avoid large, steep slopes where the problem exists, and especially where you see rocks and shallower snow cover. If you see recent avalanches or experience whumpfing collapses and cracks shooting through the snow, put a large buffer of terrain between you and slopes over 35 degrees.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–2.5

    While it's getting harder to trigger avalanches, the snowpack structure remains complex. The most dangerous area will be where the recent snow has gained stiffness from wind-drifting or sluffing at the base of cliffs, and where the overall snowpack is shallow, variable, and you see exposed rocks. You should be suspect of this anywhere you find snow of 4 Finger hardness or greater over weak, sugar-like facets (or surface hoar). If you see signs of instability, like avalanches, whupfing collapses, or shooting cracks, avoid steep slopes and put a large margin around complex terrain and large avalanche paths. Within the distribution shown above, there are two main snowpack structures of concern: 

    • Snow from the past week over the January Drought Layer (JDL or 1/31) facets and surface hoar.
      • 1.5-2 feet below the surface.
      • All reported avalanches have been at the base of cliffs. 
      • Light wind transport on 2/8-9 could add to slabs at upper elevations
    • Facets under older wind-drifted slabs (2-3 feet below the surface) can be found in isolated areas above 6,500ft.
      • Especially problematic in shallow and variably wind-affected areas.

    (2/2/2025)

    A skier triggered avalanche (D2) that ran on an old weak layer of facets from mid-December. 

    Snagtooth Ridge, NE, 6,600ft

    Photo: Adam Butterfield

Avalanche Discussion

For Sunday, expect continued cold temperatures and clearing skies. While winds may be just strong enough for subtle drifting at upper elevations. There's lots of light snow that could be easily transported. On Friday, observers investigated a number of slopes at middle and upper elevations. Near Cutthroat Lake, (NNW, 6,780ft) they found small and large column test results (CTM(SC), PST 38/100 END) about 1.5 feet (50cm) below the surface consistent with impressive shooting cracks reported by a party the day prior. They also reported a couple large natural slab avalanches at the base of cliffs, and some small point releases in the surface snow.

A strong storm brought significant precipitation on the 31st-2nd with light accumulation continuing into the 6th. The snow from the past week is very light and totals up to 2 feet. Snow totals vary with exposure to the wind and location east and west in the range. Winds transported snow on the 1st, but have been lighter since then. Observers reported reactive avalanche conditions with the onset of snow on the 31-1st, but then limited signs of avalanches in the days following . At second weekend in February, the snow has settled and observers ventured further afield. Reports of avalanches and signs of instability have once again increasing.

There's a lot of variability and complexity in layers that formed in the mid and upper snowpack since early December. The simple solution to this uncertainty is to choose more conservative terrain and to avoid slopes suspect for persistent slab avalanches. Consider their potential and consequences at middle and upper elevations, especially where facets formed and were preserved on northerly aspects. You can dig snowpits and use sudden or propagating test to identify the problematic structure.

We have good evidence of the problematic snowpack structure from recent observations near Cutthroat Lake, a skier triggered avalanche in Cedar Creek, and a cornice triggered avalanche above the Blue Lake trail. While the JDL weak layer is widespread and present most elevations. At lower elevations, we don't have evidence showing that it's an issue for triggered persistent slab avalanches in there. In many places the overlying snow lacks cohesion or "slab" characteristics. This structure may become more problematic with future storms or as the recent snow gains cohesion. Deeper layers of facets buried by older wind-drifted slabs during mid-December through mid-January have also become problematic for triggering, This distribution is more cryptic and complex, but has been observed between 6,500-7,500ft in moderately wind-exposed terrain. Observations of cracking from Cutthroat Lake on 2/6 and a 2/1 triggered avalanche near Cedar Creek/ Snagtooth Ridge show the mid-December facets Are examples of where the facets were preserved and buried. There are slopes within this range where you won't find the facets as they were melted or capped by a crust (high elevation rain event on Dec 7th) or blown away. See more below. 

 On February 2nd, NWAC observers investigated an avalanche near the Snagtooth Ridge that was triggered in an old weak layer up to 3ft deep. (See video and photos below) The avalanche was triggered at 6,600ft on a northeast aspect from a shallow spot in very steep, rocky terrain. The weak layer was into the lower half of the snowpack and was 1-2mm faceted grains. It's believed that these facets were buried on December 17th. On Monday, an NWAC Forecaster found a similar snowpack structure on northerly aspects adjacent to Silver Star Creek. There, the weak layer wasn't problematic for triggering slab avalanches, as the overlying snow was not cohesive. 

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