Avalanche Forecast
Regions: Cascades - East.
Watch for fresh shallow wind slabs, mainly near ridges or cross loaded features near and above treeline. Fast moving loose-dry avalanches continue to be a problem in many areas, especially in steep terrain of consequence.
Detailed Forecast
A break between disturbances is expected during the day Tuesday before the next weather system arrives Tuesday afternoon. Cold temperatures, light winds and increasing light snow showers by late Tuesday afternoon, should not appreciably change the current avalanche danger.Â
Watch for fresh, generally shallow wind slabs on lee aspects and cross loaded features. Any recently formed wind slabs should mainly be confined to the terrain above treeline, but in some areas wind slabs may have formed in the upper elevations of the below treeline, so evaluate the snow and terrain carefully Tuesday. Be cautious for shallow new snow to mask earlier formed wind slabs in exposed terrain.
Watch for loose dry avalanches on steeper slopes in non-wind affected terrain. Be especially wary of fast running loose dry avalanches near terrain traps.Â
Give cornices a wide berth when traveling along ridgelines and avoid lingering on slopes below cornices as they may fail at any time.
Snowpack Discussion
Weather and Snowpack
The most recent warm and wet SW storm arrived on Valentines Day 2/14 and formed the uppermost strong rain crust in our snowpack in the Central-East and Southeast Cascades while only a thin freezing rain crust was observed in the Washington Pass area.Â
A slightly unstable weather pattern last week caused a mix of sun and light snow showers with sun crusts forming on solar aspects.
A period of increasing westerly ridgetop winds Saturday afternoon was noted at the Mission Ridge and Dirty Face Peak weather stations and by guides in the Washington Pass area. Light snow showers over the past two days has deposited about 2-6 inches of low density snowfall along the east slopes of the Cascades from Sunday through Monday afternoon, with generally light winds and cold temperatures.Â
Recent Observations
North
Recent reports around the Washington Pass area from NCH and NCMG over the past few days continue to indicate excellent quality snow conditions. The primary avalanche problem noted, were shallow wind slabs formed late Saturday in isolated areas above treeline due to moderate W-NW alpine winds.
A public observation received via the NWAC observation page Saturday indicated a small natural loose dry avalanche, possibly cornice triggered, that hit a skier on the Silver Star glacier.   Â
Central
No recent observations. Â
South
No recent observations.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 Dry
Release of dry unconsolidated snow. These avalanches typically occur within layers of soft snow near the surface of the snowpack. Loose Dry avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs. Loose Dry avalanches can trigger slab avalanches that break into deeper snow layers.
Loose Dry avalanches are usually relatively harmless to people. They can be hazardous if you are caught and carried into or over a terrain trap (e.g. gully, rocks, dense timber, cliff, crevasse) or down a long slope. Avoid traveling in or above terrain traps when Loose Dry avalanches are likely.
Loose Dry avalanche with the characteristic point initiation and fan shape.
Loose dry avalanches exist throughout the terrain, release at or below the trigger point, and can run in densely-treed areas. Avoid very steep slopes and terrain traps such as cliffs, gullies, or tree wells.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Possible
Expected Size: 1 - 1