Avalanche Forecast
Regions: Stevens Pass.
Expect possible recent wind and storm slab layers on Saturday as well as possible small wet loose avalanches on direct sun exposed slopes, especially in local areas that received the most significant recent snow this week.
Detailed Forecast
Increasing mid and high clouds with sun and filtered sun are expected Saturday along with continued cool temperatures and light winds. This should allow for slow stabilization of any recent wind and storm slabs that will be most likely found on lee north to east slopes near and above treeline. Watch for cracking or firmer wind transported snow in steep exposed terrain.
Most shorter lived storm slab concerns should have mostly stabilized by Saturday, but continue to watch for such instabilities being possible on a wider variety of slopes mainly near and above treeline.Â
The equinox has passed and we've officially moved into spring,  so despite the cool temperatures and low snow levels wet loose avalanches may be possible on Sun exposed terrain, especially mid and lower elevations. Watch for wet surface snow deeper than a few inches, pinwheels, and natural wet loose releases that usually precede more major wet loose snow avalanches.
Increasing and lowering clouds late Saturday may bring a few showers in the north part, with the Mt Baker area most likely, however little accumulation is expected.
Snowpack Discussion
Recent Weather and Avalanches
We are shifting avalanche concerns to more recent storm related layers and moving away from deeper snowpack concerns, at least for the near term.
A stalled and wet frontal boundary extended mainly over the Olympics and the north Cascades Saturday afternoon before finally sagging south on Sunday, with rain generally changing to snow in a north to south fashion across the area.  A favorable temperature trend with a gradual cooling occurred with this storm. NWAC sites along the west slopes picked up 5-20 inches of snow late Saturday through Monday with more likely at higher elevations that cooled sooner. Some storm and wind slab avalanches were seen following the last front, for example at Mt Baker.
A natural stone slab on a west aspect near treeline at Mt Baker on 17 March by NWAC observer Jeff Hambelton.
But areas of without extensive instability were also seen due to the cooling trend, favorable profiles and short lived storm layers. The new snow was generally reported to be over wet snow in the upper snow pack.
Little avalanche activity was reported in the Cascades on Tuesday, mainly small wet loose avalanches, such as from NWAC observer Dallas Glass at Stevens and the Alpental ski patrol.
The latest cold front crossed the Northwest late Wednesday. This caused increasing winds, rain and snow and a cooling trend on Wednesday and deposited mainly 6 to 16 inches of new snow by Thursday morning.  Temperatures remained cool Thursday with a few showers adding small additional new snow amounts as of Thursday afternoon.Â
Reports from pro patrol Thursday at Alpental indicated new shallow soft storm slabs were easily released from both ski cuts as well as explosives. Â There had been a limited, but noted natural avalanche cycle Wednesday night. Â By Thursday midday some shallow daytime warming effects were creating slightly increased surface slab like character as low density surface snow began consolidating.
NWAC received a report about an accident that occurred early Thursday afternoon.  The second skier entering a steep chute triggered a soft slab within the recent storm snow in a chute called Fluer de Lis in the Mill Valley area of Stevens Pass.  The first skier was in a safe area and the person who triggered the slab was caught and carried, lost gear, but fortunately was uninjured, ending on the debris surface.  The crown released near the chute entrance at the top at roughly 5000 feet on a mainly NNW aspect. An accident report will be written with more details and we'll post that and link to it when completed.Â
Observer, Dallas Glass above Paradise Thursday at Mt Rainier saw evidence of recent wind affects producing wind slab on some exposed lee NE-E aspects near treeline, which were avoided.  Snow tests indicated storm weak layers of large stellar crystals from last Sunday/Monday's storm remained buried about 1 foot but no recent avalanches were noted on this temporary layer.
Cool, partly cloudy weather Friday has allowed for continued slow settlement of storm weak layers and caused a slow decrease in danger. Â
Avalanche Problems
Wind Slabs
Release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
Wind Slabs form in specific areas, and are confined to lee and cross-loaded terrain features. They can be avoided by sticking to sheltered or wind-scoured areas..
Wind Slab avalanche. Winds blew from left to right. The area above the ridge has been scoured, and the snow drifted into a wind slab on the slope below.
Wind slabs can take up to a week to stabilize. They are confined to lee and cross-loaded terrain features and can be avoided by sticking to sheltered or wind scoured areas.
Aspects: North, North East, East, South East.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1 - 1
Storm Slabs
Release of a soft cohesive layer (a slab) of new snow that breaks within the storm snow or on the old snow surface. Storm-slab problems typically last between a few hours and few days. Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
You can reduce your risk from Storm Slabs by waiting a day or two after a storm before venturing into steep terrain. Storm slabs are most dangerous on slopes with terrain traps, such as timber, gullies, over cliffs, or terrain features that make it difficult for a rider to escape off the side.
Storm slabs usually stabilize within a few days, and release at or below the trigger point. They exist throughout the terrain, and can be avoided by waiting for the storm snow to stabilize.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1 - 1
Loose Wet
Release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. They generally move slowly, but can contain enough mass to cause significant damage to trees, cars or buildings. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.
Travel when the snow surface is colder and stronger. Plan your trips to avoid crossing on or under very steep slopes in the afternoon. Move to colder, shadier slopes once the snow surface turns slushly. Avoid steep, sunlit slopes above terrain traps, cliffs areas and long sustained steep pitches.
Several loose wet avalanches, and lots of pinwheels and roller balls.
Loose wet avalanches occur where water is running through the snowpack, and release at or below the trigger point. Avoid terrain traps such as cliffs, gullies, or tree wells. Exit avalanche terrain when you see pinwheels, roller balls, a slushy surface, or during rain-on-snow events.
Elevations: Treeline, Below Treeline.
Likelihood: Possible
Expected Size: 1 - 1