Avalanche forecast

East Slopes Central

Northwest Avalanche Center
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Avalanche danger

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

7:30am Update: Increased the avalanche danger at mid-elevations to account for increased precipitation totals for the Wenatchee MountainsA storm favoring the Wenatchees and Blewett Pass area may bring a few inches of new snow overnight and into Monday. You could trigger small avalanches in wind-drifted snow below corniced ridgelines or the base of cliffs in these locations, especially where they form over weak or slick surfaces. Steer around steep slopes where you identify deeper drifts.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    Visual clues such as actively drifting snow, textured surfaces, corniced ridges, and drift formations around rocks or trees can all point you to likely spots to trigger a wind slab. Lee slopes below ridgelines and the base of cliffs are common locations for wind slabs to form. You can use small test slopes to identify instability. Shooting cracks or mini avalanches on test slopes are bullseye signs of instability. Where you find these deeper drifts of snow on steep slopes, simply steer around them on lower angle terrain. Winds and snow totals are not impressive with this storm, but it will be enough to form shallow wind slabs. Travel cautiously in extreme terrain where small avalanches can have significant consequences. In addition, these slabs may form over weak snow surfaces and slick crusts and be easy to trigger. Areas further north and west in the zone will receive significantly less snow, and wind slabs may be less likely.

    (12/26/2020) 

    You could trigger small wind slabs like in this example in wind exposed terrain where you find more than 4-5 inches of new snow on Monday.

    Photo: Anthony Lubetski

Avalanche Discussion

The Wenatchee mountains and Blewett Pass are the favored areas for this incoming storm Sunday night into Monday. We may see 5-7 inches of new snow in these areas, with significantly less elsewhere. Travel conditions may improve slightly, but planning for difficult travel on slick crusts is best until a more significant storm impacts our mountains. Open creeks, avalanche debris, and low snow cover will all still add complexity to your travel plans.

An observer reported wet, slushy snow below 3500ft in Icicle Creek on Sunday, and there still may be a few spots waiting on a solid re-freeze. with rain expected below 3500ft on Monday, wet avalanches could become more likely. If you are sinking deeply into wet, heavy snow, you might want to stick to lower-angle slopes to avoid wet avalanche problems. 

On Sunday, I was out in the lower elevations of the Salmon La Sac area. The new Early February Crust is 6-7 inches thick and supportable even at very low elevations. We expect this crust to act as our new "ground" going forward. There was some surface hoar over the crust in shady spots, but it had melted away on most of the westerly aspects I traveled. In the Teanaway drainage on Friday, we found widespread surface hoar and near surface facets above the Early February Crust. These weak surfaces make for good sliding surfaces, and wind slabs or very small storm slabs may be touchy. Use test slopes and quick hand pits to observe how the new snow reacts. If it slides easily, avalanches are more likely. 

The avalanche cycle from January 21st through February 1st was impressive and long-lived. We are still looking for old crowns and avalanche debris to understand the full extent of this warm, wet storm. On January 28-30th, many natural and skier-triggered, very large avalanches (D2.5-3) were reported throughout the zone and in neighboring zones. Slides on Big Chiwaukum Mtn and Tumwater Canyon ran to the ground (see photos below). Forecasters at the Holden Mine reported natural wet slab and wet loose avalanches to size D3 on the 27th and 28th. Control at Stevens Pass ski area triggered very large (D3) avalanches that ran on the Solstice Crust 3ft deep. On Sunday, a skier triggered a 2.5ft deep and 200ft wide wet slab that ran on weak layers near the ground at Mission Ridge. One skier was caught, carried, and lost their skis, but luckily reported only a knee injury. If you find evidence of a large or very large avalanche that we haven't logged in our avalanche observations, take a photo and let us know by submitting a public observation!

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