Avalanche Forecast
Regions: Cascades - North East.
Watch for and avoid lingering wind slabs near and above treeline, possible on easterly facing slopes below ridges. Watch for melting and weakening surface snow on steep sun exposed slopes where loose wet avalanches will be possible. Caution travelling on steep slopes with a slick crust.
Detailed Forecast
Sunshine or filtered sunshine through high clouds is expected Sunday with significant warming. Â
Watch for recent new wind slabs at higher elevations, especially below ridges in easterly facing terrain. Watch for any wind deposited snow, however, such as cross loaded slopes or specific terrain features.Â
Sunshine and warm temperatures Sunday should make loose wet avalanches possible on steep southerly slopes facing the sun.  Â
Some slopes exposed to recent winds or where less new snow was received after rain changed to snow, may have a very slick crust. Be cautious of uncontrolled falls if traveling on steep slopes with slick crust.Â
Recent observations have been limited along the east slopes of the Cascades, increasing the amount of uncertainty in the forecast.Â
Potential persistent slab layers should have received a good test during this storm cycle. We will wait for more information regarding PWL sensitivity and distribution in areas with a shallower snowpack and in the Washington Pass area before re-listing persistent slab.  Â
Snowpack Discussion
Weather and Snowpack
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A strong storm cycle Friday, 2/3 through Monday 2/6 deposited 2-3 feet of snow along the east slopes of the Cascades with lesser amounts at lower elevations and in the Mission Ridge/Blewett area.Â
The great snow didn't last long as a strong SSW storm brought heavy snow to the east slopes of the Cascades Wednesday night.  A mix of snow, sleet, freezing rain, and rain fell Thursday in the central-east and southeast Cascades, with the northeast zone remained mostly snow with a warming trend. A strong cold frontal passage swept through the Cascades mid-day Thursday with bands of light to moderate showers in SW flow.
A switch to westerly flow brought a rise in temperatures in the Cascade Passes Thursday afternoon and night bringing a peak in temperatures. Â
Friday was windy with a slow cooling trend during the day. Light snow showers Friday afternoon and night deposited up to a few inches of new snow by Saturday.
Recent Observations
North
A 5 cm layer of facets roughly 10 cm below the 1/17 crust may still be found in the Washington Pass zone and in areas further east. This reactive PWL has only been found in isolated locations in cold non-wind affected north facing terrain. No avalanche activity has been observed on this layer.Â
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Central
A large avalanche off of Dirty Face Peak knocked in a garage door of a house on the north shore of L. Wenatchee around 1130 am Thursday.Â
NWAC's Tom Curtis travelled in the Icicle Creek area near Cashmere Mountain Saturday. Tom did not get far as there was only a dusting of recent snow over a slick, firm crust. The greatest danger in this area was from uncontrolled falls on the slick crust as opposed to avalanches. Observations were not made in higher elevation terrain where wind slabs may have formed.
South
No recent observations since Tuesday.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, South.
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