Avalanche Forecast

Issued: Mar 27th, 2018 4:07PM

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

Avalanche Canada mbender, Avalanche Canada

Storm and wind slabs have formed with recent new snow and southwest wind. These will take a few days to settle and bond.

Summary

Confidence

High -

Weather Forecast

WEDNESDAY: Cloudy with isolated flurries / Light to moderate west wind / Alpine temperature -7 / Freezing level 1300 m. THURSDAY: Flurries, accumulation 5-10cm / Moderate to strong southwest wind / Alpine temperature -4 / Freezing level 1500 m. FRIDAY: Cloudy with sunny periods / Light west wind / Alpine temperature -2 / Freezing level 1500m

Avalanche Summary

On Sunday there was a report of a skier-triggered cornice failure (size 2) on a northwest aspect at 2100 m, as well as skier and sledder triggered storm slabs (size 1.5) on east and north aspects in the alpine. Explosive control work also produced cornice failures, size 2-3 with little effect on the slopes below.Saturday we received reports of a natural avalanche cycle from size 2-3 that occurred during the storm in wind loaded and cross-loaded alpine terrain, as well as numerous reports of large (size 2) skier and sled triggered storm slabs including several size 1-2.5's remotely triggered from a distance. These avalanches are suspected to have failed on the recently buried (March 21st) surface hoar/crust layer. Read details of a personal account here.

Snowpack Summary

Another 5-10 cm of storm snow with strong southerly wind Sunday night adds to last week's storm which delivered 20 to 50 cm of snow accompanied by strong to extreme wind out of the southwest, south and southeast. This storm snow rests on the March 21st interface, a mix of moist grains at low elevations, crusts on solar aspects at all elevations and surface hoar/facets on north/east facing features at treeline and alpine elevations. Some west facing features may have surface hoar on top of a crust. Deeper in the snowpack, 80 to 140 cm below the surface is a combination of facets, surface hoar, and/or crust known as the mid-February layer. This interface has not been active recently.The mid and lower snowpack are strong and well settled.

Problems

Storm Slabs

An icon showing Storm Slabs
New snow and strong winds have formed storm and wind slabs. This adds to recent storm snow which sits above a weak layer consisting of crusts, surface hoar and facets that has been most reactive at treeline and above.
Give cornices a wide berth when travelling on or below ridges.Whumpfing, shooting cracks and recent avalanches are all strong indicators of unstable snowpack.Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Mar 28th, 2018 2:00PM