Avalanche Forecast
Regions: Cascades - North West.
On Saturday, expect a decreasing likelihood for small loose wet avalanches even on solar slopes. Wind slab should be isolated to lee aspects above treeline.
Detailed Forecast
Another sunny day is forecast Saturday for the north Cascades. The high freezing levels recently will begin to cool on Saturday.  Â
While less likely Saturday, small loose wet avalanches should still be possible in the north Cascades Saturday on steeper solar slopes. Watch for surface wet snow deeper than a few inches, initial roller balls and natural loose wet avalanches on steep solar slopes where snow may shed from rocks or cliffs.
Wind slab is expected to be less of an issue in the north Cascades than areas further south, but may still linger on N through SE aspects mainly above treeline.Â
Snowpack Discussion
A storm cycle brought 5-9 feet of snowfall along the west slopes the week ending December 24th. Light additional accumulations followed by high pressure over the past week have allowed slow but significant snowpack settlement and stabilizing. Widespread surface hoar or near surface faceting has been reported in sheltered areas during the recent stretch of high pressure. Significant snow transport from east winds has built new wind slab on a variety of aspects over the last few days primarily in the central and south Cascades, including the Cascade Passes. The north Cascades including Mt. Baker have not seen the same wind effects but have experienced warmer temperatures, likely inducing a loose snow shed cycle over the last few days.   Â
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Preliminary Granite Mountain Avalanche Fatality Information: Through preliminary interviews with SAR teams, a hiker died on Granite Mountain near Snoqualmie Pass Thursday, likely due to a wind slab avalanche on a west facing slope near treeline. The hiker was recovered by SAR on Friday morning and found on top of the avalanche debris. It is not known yet whether the slab was natural or human triggered.Â
Recent avalanche and snowpack observations:Â
Wed: NWAC pro observers Dallas Glass and Ian Nicholson were on Chair Peak at Snoqualmie and reported that wind slab was a bit more prevalent there than the past couple days. Dallas triggered a small wind slab on a 35-40 degree north slope at about 5500 feet.They saw another skier triggered wind slab on a southwest slope about 600 feet below a ridge. They felt wind slab was possible on a variety of slopes and to 1000 feet below ridges.
Thu: Moderate east transport winds were observed from Snoqualmie down to Mt. Hood.  NPS rangers from Mt. Rainier reported several D1/R1 (small) skier triggered wind slab on west aspect near treeline Thursday. Two skier triggered wind slabs were reported near Kendall peak (Snoqualmie area) on north and west aspects. Both were small but one ran a fair distance and took a skier for a ride.Â
Fri: The MRNP Paradise backcountry ranger reported two harder wind slab releases on the west aspect off of Pan Face, and at least 1 was skier triggered. In a nearby pit, the ranger determined the wind slab was about 30 cm (1 ft) deep and 1F to P hardness. He also reported a skier a small triggered wind slab release on a SW aspect in the Nisqually area.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, North West.
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.
Aspects: South East, South, South West.
Elevations: All elevations.
Likelihood: Possible
Expected Size: 1 - 1