Avalanche Forecast

Issued: Mar 22nd, 2018 5:15PM

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

Avalanche Canada ghelgeson, Avalanche Canada

Very strong southwest wind, continued precipitation and lowering freezing levels are expected to drive fresh storm slab development through Friday. Wind slabs are likely to be found in unusual locations, welcome back to winter!

Summary

Confidence

Moderate - Intensity of incoming weather systems is uncertain

Weather Forecast

A rather complex weather pattern continues to deliver precipitation to the Kootenay Boundary. Lower freezing levels Thursday night should allow for snow at lower elevations. Convective precipitation is expected to continue through the weekend. THURSDAY NIGHT: Freezing level lowering from 1800 m down to 300 m, strong to extreme southwest wind, 5 to 15 mm of precipitation. FRIDAY: A few clouds in the early morning with cloud quickly building throughout the day to broken by the afternoon, freezing level starting at 500 m rising to 1500 m, strong to extreme southwest wind, 1 to 5 mm of precipitation expected.SATURDAY: Broken cloud cover, freezing level beginning at 400 m rising to 1500 m, light to moderate westerly wind, 2 to 8 mm of precipitation possible. SUNDAY: Scattered cloud cover, freezing level beginning near valley bottom rising to 1500 m, light west/southwest wind, a few mm of precipitation possible.

Avalanche Summary

No significant avalanche observations to report from the last few days. New snow and wind Thursday likely initiated natural avalanche activity.

Snowpack Summary

5 to 10 cm of new snow has fallen as of Thursday afternoon with moderate southeast wind. This snow sits on a mixture of weak grains including a slippery crust that is present at all elevations on solar aspects and low elevation polar aspects. On polar aspects at and above treeline the new storm snow is burying a mix of large surface hoar and surface facets.Two other weak layers are present in the upper snowpack. The mid March interface is down 10 to 15 cm and it mirrors the old surface; crust on solar, surface hoar on high elevation north.The early March interface is 25 to 40 cm below the surface and is similar in composition to those listed above.A few other persistent weak layers are buried in the mid and lower snowpack, but they have gone dormant and are unlikely to resurface until we move into consecutive warm nights later in the spring.

Problems

Storm Slabs

An icon showing Storm Slabs
Strong to extreme southwest wind combined with continued snowfall through Friday will form fresh slabs that are not expected to bond well to the mix of crusts, surface hoar and facets that they rest on. Watch for wind slabs in unusual locations.
Storm slabs are expected to be most sensitive to triggering in wind exposed terrain.Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.The new snow will likely need a day to settle and stabilize.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Valid until: Mar 23rd, 2018 2:00PM