Avalanche Forecast

Issued: Mar 20th, 2019 4:23PM

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

Avalanche Canada cgarritty, Avalanche Canada

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Slight cooling and increasing cloud may take the edge off loose wet avalanche problems on Thursday, but it's still a tricky time to be in avalanche terrain. Get an early start if you're heading out.

Summary

Confidence

Moderate -

Weather Forecast

Wednesday night: Clear. Light southeast winds. Freezing levels remaining near 3000 metres.Thursday: Sunny with cloud increasing in the evening. Light to moderate southwest winds. Alpine high temperatures around +6 with freezing levels easing from 2900 to 2500 metres over the day.Friday: Mainly cloudy with scattered rain showers or wet alpine flurries beginning in the evening. Moderate east winds. Alpine high temperatures around +4 with freezing levels to 2400 metres, dropping to 1500 metres by Saturday morning.Saturday: Cloudy with flurries bringing 5-8 cm of new snow by end of day and light rain below about 1100 metres, easing overnight. Alpine high temperatures around -3 with freezing levels to 1500 metres.

Avalanche Summary

Reports from Monday included an observation of a size 3 (very large) persistent slab running full path and within 100 metres of the viewing platform at Twin Falls. This highlights the current elevated danger in lower elevation areas threatened by large overhead avalanche paths. Please see the Northwest Coastal forecast's avalanche summary for a description of the natural avalanche cycle that is ongoing in this neighbouring region. With limited observations inland, it is advised to treat this activity as an indication of potential in our region.Natural loose wet avalanches have been widespread and reaching size 2 (large), but were confined mainly to solar aspects on Monday. Only small (size 1) loose wet avalanches have been observed on north aspects thus far.Looking forward, expect heightened avalanche activity to continue and potentially expand to all aspects as temperatures remain elevated and overnight cooling remains weak.

Snowpack Summary

Up to 50 cm of settled snow from storms last week sits on the surface. With the help of warm temperatures, this snow has either settled into a slab on shaded aspects or becomes increasingly isothermal (slushy) each day on sun-exposed aspects. Where it exists as a slab, it overlies previously wind affected surfaces, sun crusts (on solar aspects) and weak, sugary facets. The prolonged period of cold temperatures in February had an overall effect of weakening the upper and mid-snowpack, as well as the basal snowpack in thinner areas. These weaknesses are increasingly being tested under the pattern of strong warming currently affecting the region.

Problems

Loose Wet

An icon showing Loose Wet
Sunshine and warming will destabilize surface snow - especially on steep, sunny slopes. This problem may expand to include shaded aspects under sustained warming. Large loose wet avalanches can impact lower elevations with destructive debris flows.
Be aware of loose wet avalanche problems expanding to shaded aspects as warm temperatures persist.Be aware of overhead hazards and avoid exposure to avalanche runout zones.Avoid exposure to steep, sun exposed slopes when the solar radiation is strong.

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

Elevations: All elevations.

JavaScript chart by amCharts 3.20.8

Likelihood

Likely

Expected Size

1 - 3

Persistent Slabs

An icon showing Persistent Slabs
Old weaknesses may reactivate under sustained sunshine and warming. There are numerous reports of large slab avalanches in the neighbouring Northwest Coastal region, some of them remotely triggered. Expect similar potential in the Northwest Inland.
Remote triggering is a concern, watch out for adjacent slopes.Loose wet avalanches may initiate slab releases that result in even larger avalanches.

Aspects: All aspects.

Elevations: All elevations.

JavaScript chart by amCharts 3.20.8

Likelihood

Possible - Likely

Expected Size

1.5 - 3

Valid until: Mar 21st, 2019 2:00PM

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