Avalanche Forecast
Regions: Glacier.
We are now back into an active weather pattern with significant new snow and winds forecasted this week. It is a good time to take a step back in terrain selection, and be patient for the Hazard to decrease.
Weather Forecast
A mix of sun and cloud today, strong to extreme winds from the SW, and the freezing level will rise to valley bottom. Tonight will bring around 15cm of new snow as a cold front passes over Rogers Pass from the NW. A break in precipitation on Wednesday, but still very windy, then another 20cm could fall between Thursday morning and Friday Morning!
Snowpack Summary
Strong to Extreme SW winds have built windslabs in open terrain features at all elevations. The February 22nd persistent weak layer is now buried down 60-70cm, and consists of 3-7mm surface hoar on all aspects up to 2450m, and a crust on solar aspects. No other layers are currently active in the mid and lower snowpack.
Avalanche Summary
In the last 24 hours we observed nearly 20 avalanches in the Highway Corridor up to size 3. These avalanches were primarily triggered from Extreme wind loading, and moderate amounts of new snow. There were numerous reports of skier triggered slab avalanches over the weekend up to size 2, failing on the Feb 22nd Surface Hoar layer.
Confidence
Due to the number of field observations
Avalanche Problems
Wind Slabs
Strong- Extreme winds have built windslabs in open terrain features on all aspects in the Alpine and exposed areas of TL and BTL. If triggered these wind slabs could step down to the Feb 22nd surface hoar layer.
- If triggered the wind slabs may step down to deeper layers resulting in large avalanches.
- Be aware of the potential for wide propagations due to the presence of hard windslabs.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Likely
Expected Size: 1 - 3
Persistent Slabs
The Feb 22nd SH is now buried 60+cm deep, which is a likely depth for skier triggering, especially in shallower snow pack areas. Steep solar aspects harbor a crust under the surface hoar layer, which can increase the sensitivity of triggering.
- Avoid open slopes and convex rolls at treeline where buried surface hoar may be preserved.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Likely
Expected Size: 1.5 - 3