Dashboard Regions Weather Stations Radar Alerts Glossary
Contact About
Log In

Register for an account and never miss a forecast again!

Register

Avalanche Forecast

Archived

Feb 9th, 2015–Feb 10th, 2015

Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.

Regions

.

A transition from the recent wet warm weather to dry warm weather will begin on Tuesday. You will need to watch for a variety of snow and avalanche conditions on Tuesday.

Detailed Forecast

The upper ridge will begin to rebuild over the west US on Tuesday. This should cause light west winds with light showers mainly west of the crest decreasing Tuesday morning and ending Tuesday afternoon.

Wind slab from the past couple days may linger mainly on steep N to SE slopes near and above treeline. Watch for firmer wind transported snow especially in the above treeline of the south p[art.

New storm slab would be mainly in the south part from Monday where there is more than a few inches of snowfall in areas with light wind. This problem should be limited elsewhere due to limited new snow.

Any cooling will be limited Tuesday morning and temperatures will be on the rise again by Tuesday afternoon. More mostly small loose wet avalanches may be seen again below treeline Tuesday afternoon on steep mainly solar slopes.

As a result of the unseasonably low snowpack, especially at lower elevations, watch for terrain hazards such as open creeks, partially covered rocks and vegetation.

Snowpack Discussion

A series of fronts in an atmospheric river has been crossing the Northwest. The west slopes will have seen anywhere from about 3-14 inches of WE mostly as rain from about February 5th-10th with the most at Mt Baker. This caused another period of bad weather, instability, avalanches and poor skiing west of the crest. About 7-20 inches of melting, consolidation and stabilizing of the snowpack was also seen west of the crest.

At least some snow finally started accumulating above about 4500 feet in the north and 5500 feet in the south on Saturday.

NWAC pro-observer Jeff Hambelton was near the Mt Baker ski area Sunday and reported 7-10 inches of new snow near Artist Point about 5100 feet. Pit tests indicated the new snow was fairly well attached to the moist old snow surface. Of note were the numerous loose-wet avalanches releasing on most solar aspects entraining most of the new snow.

NWAC pro-observer Dallas Glass was at Stevens on Sunday and found 4-10 inches of moist or wet snow over the old snow surface. Recent snow was overall cohesive and well bonded. He triggered one small loose wet avalanche on a test slope.

NWAC pro-observer Jeremy Allyn was at Paradise on Sunday and reported a moist or wet stable upper snowpack.

A report via Turns All Year for Paradise on Sunday also indicated 1-3 inches of recent snow and pinwheels and natural point releases on solar slopes.

A filling low pressure system is crossing  mainly the south Cascades and Mt Hood area on Monday. This caused the most wind and rain or snow in the far south Cascades and at Mt Hood on Monday and Monday night. Lighter west winds and mostly light rain or snow showers were seen over the rest of the west slopes Monday night. A brief minor drop in snow levels should be seen mainly in the south Cascades and at Mt Hood Tuesday morning.

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.

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.