Avalanche Forecast

Issued: Mar 30th, 2018 4:49PM

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

mgrist, Avalanche Canada

Kootenay Boundary.

Recent new snow and moderate to strong northwest / southwest winds have created wind slabs at upper elevations. These may be most reactive on shady aspects. Reduce your exposure to sunny slopes if the sun makes an appearance.

Summary

Confidence

Moderate - Timing or intensity of solar radiation is uncertain on Saturday

Weather Forecast

There may be some significant periods of sunny weather on Saturday before a weak system comes through on Sunday. Temperatures are staying cool for this time of year. SATURDAY: A mix of sun and cloud / Light to moderate west wind / Alpine temperature -4 / Freezing level 1500m SUNDAY: A mix of sun and cloud with some flurries (5-10 cm possible) / Light to moderate south west wind / Alpine temperature -5 / Freezing level decreasing to 1300m MONDAY: Mix of sun and cloud and some lingering flurries / Light to moderate northwest wind / Alpine temperature -7 / Freezing level 1000m

Avalanche Summary

On Friday, cornice control work resulted in triggering a size 2 wind slab below, on an east aspect near 2200m. Slab depth averaged 20cm. Tuesday's reports focus on a few natural storm slab avalanches size 1.5-2 on northeast and northwest aspects at 2200m. On Monday there were reports of numerous explosives and naturally triggered storm slab avalanches size 1.5-2 on all aspects in the alpine and tree line.

Snowpack Summary

30-60 cm of recent snow sits on a crust at all elevations on solar aspects and all aspects below 1900 m elevation. Winds were moderate to strong from the north west on Wednesday (switching to southwest by Friday) , creating fresh wind slabs on down wind (lee) aspects at higher elevations. On northerly aspects at and above tree line the storm snow is burying a mix of large surface hoar and surface facets. Two other weak layers are present in the upper snowpack. A layer buried mid March is down 30 to 60cm is crust on solar aspects and surface hoar on high elevation north. A layer buried early March is 50 to 80cm below the surface and is similar in composition to those just described.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.

Problems

Wind Slabs

Northwest then southwest wind combined with recent snowfall have formed fresh wind slabs which could be most reactive on shady aspects, where they may be sitting on weak surface hoar or facets.

Extra caution needed around cornices with current conditions.Use ridges or ribs to avoid pockets of wind loaded snow.

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Loose Wet

The sun really packs a punch this time of year - it's no April Fool's joke! Be prepared to adjust your terrain use accordingly if the sun comes out in full force.

Avoid exposure to sunny slopes.Watch for clues, like sluffing off cliffs and pinwheeling, that the snowpack is warming up.Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.

Aspects: North, North East, East, South East.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Mar 31st, 2018 2:00PM