Avalanche Forecast
Regions: Northwest Inland.
Sustained warming continues to increase the likelihood for large cornice failures and wet loose avalanches. Start early and plan to be off large slopes before the heat of the day.
Check out the latest Forecaster's Blog for more information on managing current conditions.
Confidence
Moderate - Uncertainty is due to how the snowpack will react to the forecast weather.
Weather Forecast
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WEDNESDAY NIGHT: Clear / Light, southeast ridgetop wind / alpine low temperature 4 / Freezing level 2800 m.
THURSDAY: Sunny / Light, south ridgetop wind / alpine high temperature 9 / Freezing level 2900 m.
FRIDAY: Sunny / Light, southwest ridgetop wind / alpine high temperature 9 / Freezing level 3000 m.
SATURDAY: Sunny / Light, southwest ridgetop wind / alpine high temperature 8 / Freezing level 2900 m.
Avalanche Summary
Over the last few days there were many small (size 1) wet loose avalanches on south-facing slopes at all elevations and a few size 2-2.5 cornice failures on north and east facing slopes.Â
The lower snowpack has been strong and settled over the past month, however, the dramatic warming this week could potentially wake up weak facets at the bottom of the snowpack. This is particularly a concern on steep, rocky slopes with a shallow or thin to thick snowpack. Cornice failures or a rider hitting a thin spot in the snowpack are the most likely ways to trigger these weak layers at the bottom of the snowpack.
Snowpack Summary
Sunny skies and rising freezing levels will result in melting surfaces everywhere except north-facing alpine terrain. In the alpine 5-20 cm. of snow is quickly settling and strengthening, although some wind slabs could linger on steep slopes. The recent snow has covered a variety of snow surfaces, including wind affected snow, crusts on solar aspects and at lower elevations, and soft snow on sheltered slopes at upper elevations.
The lower snowpack has been strong and settled over the past month, however the dramatic warming this week could potentially wake up weak facets at the bottom of the snowpack. This is particularly a concern on steep, rocky slopes with a shallow or thin to thick snowpack.
Cornices are large, looming, and capable of triggering large avalanches when they fail.
Terrain and Travel
- Extra caution is needed around cornices under the current conditions.
- Avoid exposure to slopes that have cornices overhead.
- As surface loses cohesion due to melting, loose wet avalanches become common in steeper terrain.
- Back off slopes as the surface becomes moist or wet with rising temperatures.
- The likelihood of deep persistent slab avalanches will increase with each day of warm weather.
Avalanche Problems
Loose Wet
Expect natural wet loose avalanches to occur on solar aspects when the sun comes out.
Aspects: East, South East, South, South West, West.
Elevations: All elevations.
Likelihood: Likely
Expected Size: 1 - 2
Cornices
Strong solar radiation and warming will likely trigger the large cornices that hang over ridgelines. Cornice falls could trigger large avalanches on the slopes below.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine.
Likelihood: Likely
Expected Size: 1.5 - 2.5
Deep Persistent Slabs
Prolonged warming could increase the sensitivity of deeply buried layers in the snowpack. While these layers have not been reactive lately, you should practice increasing caution during this period of warm weather. Steep rocky terrain with a shallow or thin to thick snowpack are most suspect.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Unlikely - Possible
Expected Size: 2.5 - 3.5