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 10th, 2016–Feb 11th, 2016

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

Regions

.

The avalanche danger is expected to be limited for most of daylight hours on Thursday. Change your plans if the next system arrives sooner than expected and you see significant layers of new snow starting to build at higher elevations or significant wet snow deeper than boot top at lower elevations.

Detailed Forecast

A relative break between systems with little change in snow levels and temperatures should be seen most of the daylight hours on Thursday.

Continue to watch for loose wet avalanche potential above terrain traps such as above cliffs, near gullies or where avalanche debris would deeply accumulate. These are the types of places that even small wet avalanches can have serious unintended consequences.

Avoid cornices along ridges and slopes below cornices since cornices may still be weaker due to the warm weather.

Rain and snow from a warm front should start to move into the Northwest Thursday late afternoon. Be prepared to change your plans if this system arrives sooner than expected and you see significant layers of new snow starting to build at higher elevations or significant wet snow deeper than boot top at lower elevations.

Snowpack Discussion

Weather and Snowpack

Two fair weather periods in January allowed surface hoar and near surface faceting to occur. These persistent weak layers were buried intact on Jan 3rd and 11th, but are no longer considered a persistent slab threat after several warm and wet systems tested this layer and it has been unreactive where it can still be identified in recent snowpit tests.

A large upper ridge and warm air mass aloft has been over the US west coast the past 3 days. Temperatures at NWAC stations along the east slopes reached the 40 to 50 degree F range near and above treeline with cooler temperatures in the below treeline which is the warmest weather so far this season. The very warm temperatures and solar effects caused loose wet avalanches, consolidation and night-to-morning surface crusts. This will have further stabilized the lower and mid snow pack and turned recent storm snow into moist to wet snow especially on solar aspects.

An initial weak front is moving over the Northwest today. Areas at higher elevations may see a little light rain with a lowering of high snow levels. This should not greatly change snow conditions.  

Recent Observations

Extensive observations in the Washington Pass area over the past few days indicated an active loose-wet avalanche cycle occurred mainly Monday afternoon.

NWAC pro-observer Jeff Ward was in the Washington Pass area in the 6-7600 foot range on Tuesday and saw several size 1 natural loose wet avalanches on steep solar slopes.

NWAC pro-observer Tom Curtis in the Blewett Pass area in the 4-5900 foot range Tuesday and also saw several small to large wet loose avalanches on solar slopes near and above tree line.

Problems

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.

Cornices

Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.