West Slopes Central

Stay alert to general mountain hazards and areas of locally higher avalanche danger, especially in alpine terrain where wind-transported snow could form unstable new slabs. You might see rollerballs or other signs of instability related to warmer temperatures and sun on Thursday.

Active wind transport at the highest elevations was reported from the North Cascades on Wednesday. Though less of an issue for the Central Cascades, small but reactive slabs could exist where the wind is strong enough to transport abundant new snow. Look for signs of active or recent wind transport like freshly wind scoured snow surfaces, especially on northerly aspects. New wind slabs might be easier to trigger where they form over slick crusts. Even very small avalanches can have high consequences in extreme terrain or step down and trigger a larger avalanche.

You could see signs of instability like trees shedding snow, rollerballs, or even a small loose wet avalanche with rising freezing levels and sunny skies on Thursday. Solar slopes have had a few days of previous sun exposure but could still produce a small avalanche in some areas. Keep an eye on sun-exposed terrain overhead.  

The snowpack near treeline is fattening up and beginning to fill in terrain features. Wind-affected snow is commonly found above treeline but in many areas a few inches of light snow cover old, unreactive wind slabs. Low elevations still have ground cover poking up through the snowpack.

Surface hoar and facets are found at the snow surface in most shaded terrain while sun-warmed slopes are topped with a crust. 1-3’ of settled, right side up new snow from last weekend sits on a layer of buried surface hoar. However, the distribution of this layer varies greatly between neighboring zones that produce more observations. Test results are showing less reactivity. Farther south and east in the Cascades, a thinner slab sits on a more evenly distributed layer of surface hoar and has reached “problem” status.

Crust-facet layering that produced a surprising human-triggered avalanche in West North 10 days ago is well over 4’ deep in most areas - where it exists at all. Heavy loads like a smaller avalanche or landing a big air might produce a large avalanche in any of these weaker layers that still exist in the snowpack.