Avalanche Forecast

Issued: Jan 25th, 2019 4:02PM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is moderate. Known problems include Persistent Slabs.

mconlan, Avalanche Canada

Kootenay Boundary.

There is wide variability in the weather forecast for air temperature and cloud cover on Saturday. The forecast herein is assuming warm, above-freezing air temperature at high elevations.

Summary

Confidence

Moderate - Freezing levels are uncertain

Weather Forecast

FRIDAY NIGHT: Increasing clouds, freezing level 800 m.SATURDAY: Cloudy, light northwest winds, alpine temperature variable between -1 C and 5 C, freezing level rising to 2000 m with inversion conditions possible.SUNDAY: Cloudy with trace snowfall, moderate to strong northwest winds, alpine temperature near 0 C, freezing level dropping from 2000 m to below valley bottom.MONDAY: Mostly clear skies, light northwest winds, alpine temperature -9 C, freezing level below valley bottom.

Avalanche Summary

On Thursday, a couple 15 cm thick slab avalanches were triggered by skiers on south to east aspects. The avalanches likely released on the surface hoar layer described in the Snowpack Summary.Looking towards the weekend, the likelihood of triggering the layers discussed in the Snowpack Summary may increase. Also expect loose wet avalanches if the air temperatures reach as warm as the weather forecast predicts.

Snowpack Summary

Warm air temperatures may moisten the snow surface on all aspects, with the most pronounced warming expected on southerly aspects. Below this, a rain crust exists about 10 to 20 cm beneath the surface. At depths of around 20 to 50 cm, expect to find a sun crust on south aspects and feathery surface hoar crystals in sheltered and shaded areas. The surface hoar may be most pronounced at treeline elevations.The remainder of the snowpack is generally reported as well-settled.

Problems

Persistent Slabs

Around 20 to 50 cm of snow sits above variable crusts and a weak layer of surface hoar. Warm air may make it more likely to initiate an avalanche on these layers. Treating this snow with caution is advised.

Avoid steep slopes on warm or sunny days, particularly on south aspects with clear skies.Watch for signs of instability such as whumpfing, cracking, or recent avalanches.Watch for clues that the snowpack is warming up, like moist snow or sluffing off of cliffs.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Jan 26th, 2019 2:00PM