Avalanche Forecast
Issued: Mar 4th, 2020 8:00AM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
chris gooliaff,
Parks Canada
Heads up! Things are spicy today!
Extreme winds fired up a natural avalanche cycle last night. The widespread surface windslab is easily triggered by humans and is enough additional load to cause the Feb 22 surface hoar/suncrust to wake up.
Summary
Weather Forecast
A short-lived ridge builds today, then is overrun by minor disturbances Thurs/Fri.
Today: Mix of sun and cloud with isolated flurries, mod W winds gusting extreme, Alpine high of -12*C
Thurs: Flurries amounting to 10cm, mod SW winds gusting strong, Alpine high of -5*C
Fri: Flurries amounting to 5cm, light SW winds gusting strong, Alpine high of -5*C
Snowpack Summary
Continuing Strong to Extreme SW winds are building 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, many avalanches in the Highway Corridor up to size 3 were observed, primarily triggered from Extreme wind loading and moderate snowfall. There are numerous reports of skier triggered and natural slab avalanches within the park and from our nearest neighbors, many with slab depths stepping down to 50-70cm deep.
Confidence
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 have the potential to step down to the Feb 22nd surface hoar layer.
- Watch for surface cracking and stiffer surface layers of snow. Avoid wind loaded terrain.
- Be aware of the potential for wide propagations due to the presence of hard windslabs.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
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.
- If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Mar 5th, 2020 8:00AM
