Avalanche Forecast
Regions: Cascades - North West.
Dangerous avalanche conditions are expected to develop west of the crest Thursday, especially above treeline in the Mt. Baker area. Backcountry travel is not recommended near and above treeline Thursday.
Detailed Forecast
Morning update for higher avalanche danger in Cascades West Mt. Baker Zone Thursday
Southwest flow will carry the first in a parade of mild wet fronts across the Northwest on Thursday. This will cause increasing winds and increasing moderate to heavy rain or snow by Thursday morning with rising snow levels. Snow levels west of the crest should rise to about 6000 feet in the north and 7000 feet in the south by Thursday afternoon.
The more widespread avalanche problem west of the crest on Thursday should be increasing loose wet snow avalanches involving snow from so far in February. The late January crust should make a good bed surface on many slopes. Small natural or triggered loose wet avalanches should be likely in many areas with some large wet loose avalanches. This problem should be most likely near and below treeline where there is more rain but may work its way into the above treeline by the end of the day due to rising snow levels.
Some new storm slab and wind slab should also build above treeline in the morning hours. The trend of rising temperature will help build upside down higher density snow over lower density snow above the snow level. New storm or wind slab of up to several inches seems possible above the snow level. Any surviving buried surface hoar from late January would act as a weak layer.
Dangerous avalanche conditions are expected on Thursday. Watch for rapidly changing snow conditions if you decide to venture into avalanche terrain.
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Snowpack Discussion
Mild weather with sunny days or minor rain or snow was seen from about January 26th to about January 31st. This caused more consolidation, stabilizing and the formation of a thick strong stable surface crust in most areas west of the crest. Surface hoar formed on shaded and north slopes in some areas in fair weather during this time.
Slightly wet weather from about February 1 through today produced about 1-4 inches of snow at NWAC sites west of the crest with more at higher elevations.
NWAC pro-observer Jeff Hambelton visited Artist Point at about 5000 feet next to the Mt Baker ski area February 2nd. Winds had redistributed the 10 inches of recent snow depending upon terrain and cross loading. He rated wind and storm slab layers as likely but an ECT did not indicate propagation.
NWAC pro-observer Jeff Ward was at Steven Pass on February 2nd where there was 4-6 inches of recent snow up to about 5800 feet. The main problem there was skier triggered wet loose avalanches on steep slopes of varied aspect.
NWAC pro-observer Dallas Glass was at Paradise today and found 2-4 inches of recent snow producing small triggered loose wet avalanches on steep slopes on the thick late January crust.
The mid and lower snowpack west of the crest should consist of layers of stable consolidated rounded grains or melt forms and crusts from multiple warm periods this winter.
Avalanche Problems
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: All aspects.
Elevations: All elevations.
Likelihood: Certain
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: Likely
Expected Size: 1 - 2
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.
Likelihood: Likely
Expected Size: 1 - 1