Avalanche Forecast Northwest Inland

Tuesday 12th February 2019

Avalanche Danger Ratings Tue 12th Feb 5:20PM Danger Ratings Alpine: Moderate Danger Ratings Treeline: Moderate Danger Ratings Below Treeline: Low Wind Slabs Wind Slabs

Avalanche Canada Forecaster: cgarritty

Date Issued:

Valid Until:

Winds will ease a bit on Wednesday, but recently formed wind slabs at higher elevations may remain reactive to human triggering. Sheltered lower elevations are likely to still hold the best skiing and riding conditions.

Confidence

Moderate - Due to the number of field observations

Weather Forecast

Tuesday night: Clear periods with increasing cloud. Light variable winds. Wednesday: Cloudy with sunny periods. Light northwest winds. Alpine high temperatures around -12.Thursday: Mainly cloudy with isolated flurries and a trace of new snow. Light to moderate east winds. Alpine high temperatures around -16.Friday: Mainly cloudy with isolated flurries and a trace of new snow. Light northeast winds. Alpine high temperatures around -21.

Avalanche Summary

Winds have been driving avalanche danger at higher elevations, redistributing recent snow accumulations into reactive wind slabs. Skiers reported small natural wind slab releases, whumpfing, and shooting cracks on Thursday and Friday. A small (size 1) ski cut wind slab at 2100 metres was reported on Sunday.

Snowpack Summary

In the alpine and upper treeline, the upper snowpack is composed of successive layers of aging, wind-affected storm snow layers. The most recent wind slabs are likely to exist on on southwest aspects as a result of ongoing, predominantly northeast winds. The upper snowpack has also been faceting (becoming sugary) under the influence of recent cold temperatures at all elevations.Sheltered areas at lower elevations still hold around 20-30 cm of low density snow from a couple of recent snowfall events. Below this more recent snow, another 20-40 cm of older, faceted (sugary) storm snow overlies a widespread melt-freeze crust. In the central and northern parts of the region, it may sit on feathery surface hoar crystals in sheltered terrain at all elevations. In the south of the region, the remainder of the snowpack has been reported as well-settled.Around and north of Hazelton, 50 to 100 cm of snow may overlie two weak layers of surface hoar or sugary faceted grains.

Wind Slabs Wind Slabs

Likelihood

Possible

Expected Size

1 - 2

Relentless outflow winds have been redistributing snow at higher elevations for days. There is likely a mix newer, smaller, reactive wind slabs as well as older, larger, more stubborn slabs to be found in wind-affected areas.

Watch for patterns of wind loading if you venture into wind affected terrain.Be careful around wind loaded pockets near ridge crests and roll-overs.Back off from your line if the snow has become stiff or slabby from wind.

Aspects: North, South, South West, West, North West.

Elevations: Alpine, Treeline.

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