Avalanche Forecast
Regions: Olympics.
The Bottom Line: Generally safe conditions should be seen on Monday. Use normal caution on lee shaded slopes and watch for small areas of wet snow on steep solar aspects.
Detailed Forecast
Sunny weather should continue to Monday morning. High clouds should be seen by Monday afternoon mainly in the Olympics and south Cascades. There should be little change in snow conditions.
Concerns again on Monday should be very limited. Small areas of slab layers may linger on some lee shaded slopes mainly near or above treeline. Such layers would likely require large triggers such as a fall cornice or snowmobile. Use normal caution on steep lee shaded slopes.
Wet loose avalanches also seem unlikely on Monday due to recent consolidation, past activity and increasing high clouds. But avoid steep solar aspects or gullies in the sun if you seen natural wet loose avalanches or wet surface snow deeper than a few inches.
Snowpack Discussion
The last storm cycle to impact the Northwest was long ago about 10-14 of January. This produced a storm slab avalanches cycle about 12 January and large wet loose avalanches about 14 January with avalanches ranging up to size D3. Â
But mostly sunny weather and warm temperatures have been seen the past 11 days. This has caused snow pack consolidation and stabilizing with surface crusts on most slopes in most of the area. A generally favorable mid and lower snowpack of crust layers and melt form crystals should also be seen in most of the area. The avalanche danger is especially low on many south slopes and at lower elevations where there is little snow and ample terrain and vegetation anchors. There have been no significant avalanches reported for about a week or more.
Small areas of cold slab layers are still apparently surviving on some lee shaded slopes where some faceting has been occurring in the upper snowpack.  NWAC observers at Hurricane and Nason Ridge near Stevens Pass the past several days are reporting moderate or hard test results with sudden collapse or sudden planar fractures (see photos below). But extended column tests have not indicated a tendency for propagation. These layers would also likely require large triggers such as a cornice or a snow mobile. There have been no known avalanches on these layers but we will continue to monitor them in case future changes or loading activate the layers.
Surface hoar growth has been reported this week especially east of the crest and will need to be watched in case it is buried by future snowfall.
ECTP29 SC Q1 at 67 cm due to crust and facet layers, Nason Ridge. NWAC observer Tom Curtis, 20 January.
Faceted crystals from the upper snow pack, Klahhane Ridge near Hurricane Ridge, NWAC observer Katy Reid, 20 January.
Quite a difference on north and south slopes, Klahhane Ridge, Olympics, NWAC observer Katy Reid, 18 January.
Report of the cornice/avalanche fatality on Lewis Peak on 18 January available at:
https://www.nwac.us/accidents/accident-reports/Â
Local non-avalanche hazards:  On 13 January a heavy local freezing rain event occurred in the Snoqualmie Pass area above about 4500 feet, covering the surface with about a 2-3 inch ice crust.  This crust should break down over time but a fall on a slope on this surface could result in a long and dangerous ride!
Additionally, guides in the North Cascades have noted some thin crevasse bridges on lower glaciers. Don't assume that crevasses have the usual relatively thick bridges during this so far shallow snow season.
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.
Elevations: Alpine.
Likelihood: Unlikely
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: Alpine.
Likelihood: Unlikely
Expected Size: 1 - 1