Avalanche Forecast

Issued: Apr 18th, 2018 4:25PM

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

jmcbride, Avalanche Canada

Kootenay Boundary.

Sun and warming on Thursday and Friday will increase the likelihood of avalanches. Be particularly cautious on south-facing slopes when it is sunny and avoid exposure to large slopes above you.

Summary

Confidence

Moderate - Due to the number and quality of field observations

Weather Forecast

TONIGHT: Mostly clear. Ridge wind light, southeast. Alpine temperature -3. Freezing level 1600 m.THURSDAY: Mostly clear. Ridge wind light, east. Alpine temperature near 0. Freezing level 2200 m.FRIDAY: Mostly sunny, increasing cloud in the afternoon. Rain changing to snow overnight. Precipitation 2-8 mm. Ridge wind light, southwest. Alpine temperature near +1. Freezing level 2300 m.SATURDAY: Cloudy, flurries. Accumulation 5-10 cm. Ridge wind strong, southwest. Alpine temperature near -2. Freezing level 1700 m.

Avalanche Summary

On Tuesday there was a report of a skier-triggered storm slab size 1.5 on a north aspect at treeline north of Rossland that failed on a crust. Read MIN report here.On Monday, loose wet avalanches were triggered naturally and by explosives. They were large (size 2 to 2.5) and on all aspects between 1700 m and 2100 m.

Snowpack Summary

An additional 20 to 35 cm of snow fell Tuesday into Wednesday, for storm snow totals of 35 to 60 cm since Monday morning. The snow fell on a melt-freeze crust produced from rain and warm temperatures on Sunday. Numerous other melt-freeze crusts exist in the upper snowpack from rain, sun, and warming during the spring season. The mid and lower snowpack are generally well-settled and strong.At lower elevations below treeline, a spring snowpack exists.

Problems

Storm Slabs

Up to 50 cm of snow fell recently, which may not bond well to an underlying crust. Slabs may be more reactive in wind-loaded terrain and with solar and daytime warming. Watch your overhead exposure, as cornices could trigger slabs on slopes below.

Use extra caution on steep slopes if the snow is moist or wet.Be careful in wind loaded terrain, especially near ridge crests and roll-overs.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2.5

Loose Wet

Sunny skies and warming air temperatures will rapidly weaken the snow surface and increase the likelihood of triggering loose wet avalanches. Expect natural avalanches on steep slopes, particularly on south aspects under sunny skies.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.If triggered the loose wet sluffs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2.5

Valid until: Apr 19th, 2018 2:00PM