Avalanche Forecast

Issued: Feb 28th, 2018 5:33PM

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

Avalanche Canada ghelgeson, Avalanche Canada

This forecast is based on 1 to 10 cm of snow Wednesday night and an additional 2 to 10 cm on Thursday. Both pulses feature strong southerly winds. Seek out wind sheltered terrain to avoid the wind slab problem and find the best riding!

Summary

Confidence

Moderate - Timing, track, or intensity of incoming weather system is uncertain on Thursday

Weather Forecast

After much uncertainty, the models have converged on a solution that is more of a glancing blow than direct hit, but the Inland should still see a bit of snow and wind Wednesday night though Thursday.  It looks like we will be entering a high and dry period after this system passes through.  WEDNESDAY NIGHT: Freezing level around 500 m, 1 to 10 cm of snow, strong to extreme south/southwest wind. THURSDAY: Broken cloud cover, freezing level rising to around 1100 m, moderate to strong southeast wind, 2 to 10 cm of snow possible.              FRIDAY: Clear skies in the morning, cloud building throughout the day, freezing level around 900 m, light variable wind, no precipitation expected.SATURDAY: Broken cloud cover, freezing level around 1200 m, light variable wind, no precipitation expected.

Avalanche Summary

Several small wind slab avalanches 15 to 25 cm in depth were susceptible to ski cutting Tuesday on north, northeast and east facing features between 1800 and 2000 m.On Monday natural wind slabs in lee terrain were observed near ridgeline to size 2. Isolated sluffing was also observed. On Sunday wind slabs up to size 2 were sensitive to skier triggering on northeast, north and northwest facing features between 1950 and 2100 m. Small wind slabs failed naturally and were human triggered Saturday to size 1 on south and southeast facing features between 1750 and 1900 m.

Snowpack Summary

20 to 50 cm of new snow fell over the weekend accompanied by strong winds that were predominantly out of the south, southwest and west. Wind out of the southwest and west picked up again on Monday forming very soft wind slabs that were reactive to skier traffic. These two wind events have formed widespread wind slabs that likely extend down into treeline elevations. You may find the odd wind slab in open features below treeline too. The new storm and wind slabs rests on the February 23 weak layer that consists of wind hardened snow, facets, a sun crust on solar aspects and surface hoar that is present at and below treeline. Compression tests preformed Monday continue to show resistent planar results at this interface. In the southern portion of the region a widespread crust is down 40 to 80 cm below the surface. Well-consolidated snow exists below the crust.Variable winds in the past month have created cornices on many an alpine ridgeline. They will become touchier as they grow in size, as temperatures rise, and as the strong late-winter sun shines down upon them on clear days.

Problems

Wind Slabs

An icon showing Wind Slabs
Strong wind and snowfall over the last 72 hours has formed slabs that may remain sensitive to human triggering. Continued strong south wind and 5 to 20 cm of new snow Wednesday night into Thursday will likely fuel fresh storm slab formation.
Avoid wind loaded terrain features, especially during periods of active loading.Seek out wind sheltered terrain below treeline.Watch for signs of instability like whumphing, hollow sounds, shooting cracks or recent avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Mar 1st, 2018 2:00PM

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