Avalanche Forecast

Archived

Jan 16th, 2018–Jan 17th, 2018

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches possible, human triggered probable.

Regions

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Moderate precipitation and winds along with significant warming will combine to create wind and storm slabs Wednesday. Avoid wind-loaded terrain, particularly at higher elevations where sensitive wind slabs may become large. Keep slope angles down and avoid roll-overs to avoid sensitive shallow storm slabs initially found at all elevations. Anticipate loose wet avalanches later in the day as rain wets the new snow.

Detailed Forecast

This forecast only applies to the Cascade West-North zone which includes Mt. Baker.

Rain and snow showers are ending Tuesday evening. After a break in the action Tuesday night, rain and snow will return and will be of moderate intensity in the North Cascades during the morning hours on Wednesday. The first round of precipitation will come with moderate SE winds and a slow warming trend during the morning hours. Further warming will push rain near or above crest level by late in the afternoon, becoming moderate to heavy along with strong winds.

Southeasterly winds anticipated Wednesday will transport additional snow, forming shallow to moderately deep wind slab near and above treeline. These slabs will be touchy on Wednesday as winds, moderate snowfall rates, and warming help slab formation, particularly near and above treeline. Avoid wind-loaded slopes on Wednesday. Particularly watch for wind slabs on W-N-E lee aspects, which have been and will continue to be favored for loading.

Shallow storm slabs will also develop above approximately 4000 feet. Storm slabs should become increasingly touchy as the day progresses.

Loose wet avalanches will become likely below treeline by mid-day and at all elevations by late in the day with continued warming. Avoid avalanche terrain if you find rain falling on significant new snow.

Snowpack Discussion

Across the west slopes of the Cascades, many locations near and above treeline received 2-4" of higher density snow Wednesday. Locally higher amounts were seen near Mt. Baker, especially above treeline. Moderate winds, with strong gusts, are locally transporting this shallow new snow around on Wednesday afternoon, most notably at Mt. Baker.

Recent snowfall sits on a firm crust at higher elevations and refreezing or still wet snow at lower elevations.

After 3 extraordinarily warm days of high pressure (Saturday-Monday), the snow from late last week is well consolidated and sits on a thin crust (Jan. 9) which may be found in the near treeline elevation band in most areas. A more supportable and thicker crust (Jan. 5) from rain or freezing rain is easily identifiable in the upper snowpack.

Below the 1/5 crust, observations continue to indicate a strong snowpack with no notable layers of concern.

Observations

North

Large natural and skier-triggered loose wet avalanches were reported on Sunday in the Twin Lakes area by Baker Pro Patrol and Hidden Lake Peak area via our public observations page.

Central

No recent observations

South

No recent observations

Problems

Wind Slabs

Wind Slab avalanches are the 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.

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). 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.

Loose Wet

Loose Wet avalanches are the 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. 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.