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Archived

Avalanche Forecast

Apr 19th, 2018–Apr 20th, 2018
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low

Regions: Kootenay Boundary.

High overnight freezing levels combined with continued warm temperatures and sunny skies on Friday will increase the likelihood of loose, wet avalanche activity.  These releases can start small and gain mass quickly becoming a big problem.

Confidence

-

Weather Forecast

TONIGHT: Mostly clear. Ridge wind light, southwest. Alpine temperature near +1. Freezing level 2200 m.FRIDAY: Mostly sunny. Increasing cloud and rain overnight. Precipitation up to 5 mm. Ridge wind light southwest. Alpine temperature near +2. Freezing level 2200 m.SATURDAY: Cloudy, flurries. Accumulation 5-10 cm. Ridge wind moderate to strong, southwest. Alpine temperature near -2. Freezing level 1700 m.SUNDAY: Mix of sun and cloud. Ridge wind light, northwest. Alpine temperature near 0. Freezing level 2000 m.

Avalanche Summary

Wednesday numerous natural loose, wet avalanches (size 1-1.5) were observed on solar (southeast, south, and west) aspects in the southeastern part of the region.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

Snow and warm temperatures on Thursday have likely moistened the 35 to 60 cm of storm snow that fell earlier in the week.  This snow sits on a melt-freeze crust that formed following 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.

Avalanche Problems

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 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.Use caution above cliffs and terrain traps where small avalanches may have severe consequences.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 2.5