Avalanche Forecast

Issued: Mar 26th, 2018 4:05PM

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

Avalanche Canada jmcbride, Avalanche Canada

More snow and wind will continue to build slabs on a touchy layer of crusts and buried surface hoar. Assess the bond between the new snow and the old surface before committing to bigger slopes.

Summary

Confidence

Moderate -

Weather Forecast

TONIGHT: Flurries. Accumulation 5-15 cm. Ridge wind moderate to strong, southwest. Alpine temperature near -5. Freezing level 1400 m.TUESDAY: Snow. Accumulation 10-15 cm. Ridge wind strong, southwest. Alpine temperature near -5. Freezing level 1600 m.WEDNESDAY: Mostly sunny. Ridge wind light to moderate, northwest. Alpine temperature near -6. Freezing level 1500 m.THURSDAY: Mostly cloudy. Ridge wind light to moderate, west. Alpine temperature near -4. Freezing level 1500 m.

Avalanche Summary

Sunday there was a report of a natural size 2 wind slab and a skier triggered size 1 wind slab release. Both of these were on northeasterly aspects above 2000 m. Also on Sunday explosive control work produced numerous size 1.5-2 storm slab results all failing in the recent storm snow (25-40 cm deep) on north and northwest aspects above 2000 m.Saturday we received reports of several remotely (from a distance) triggered and skier-triggered size 2 storm slab release that failed 40-50 cm deep on a mix of buried crusts, surface hoar and facets. Explosive control work also produced size 1.5-2 storm slab results running on a crust on southeast aspects from 1900 -2000 m. Read more here. And here.Last week on Thursday and Friday, there were reports of natural (size 1.5-2) storm slab releases on north and west aspects in the alpine that were suspected to have failed overnight during the storm, as well as size 1 skier triggered storm snow releases in steep, leeward terrain.

Snowpack Summary

Around 30 - 40 cm of recent storm sits on a mixture of weak grains including a crust that is present at all elevations on solar aspects and all aspects below 1900 m elevation. On northerly aspects at and above treeline the 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 30 to 60 cm and it resembles the old surface; crust on solar, surface hoar on high elevation north.The early March interface is 50 to 80 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 a period with consecutive above-freezing nights later in the spring.

Problems

Storm Slabs

An icon showing Storm Slabs
Southwest wind combined with recent snowfall have formed fresh storm slabs that sit on a mix of crusts, surface hoar and facets that are now buried. Continued snow and wind will increase the load and slab development on this touchy layer.
Use caution in lee areas in the alpine and treeline. Storm snow and wind have formed touchy slabs.Whumpfing, shooting cracks and recent avalanches are all strong indicators of unstable storm snow.Use caution on steep slopes and convex rolls.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Valid until: Mar 27th, 2018 2:00PM