Avalanche Forecast

Issued: Mar 19th, 2019 4:40PM

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

cgarritty, Avalanche Canada

Northwest Inland.

Another day of strong sun and warm temperatures will maintain very dangerous avalanche conditions on Wednesday. Travel in avalanche terrain is not recommended.

Summary

Confidence

Moderate -

Weather Forecast

Tuesday night: Clear. Light south winds. Freezing levels remaining near 2800 metres. Wednesday: Sunny. Light southeast winds. Alpine high temperatures around +7 with freezing levels around 2900 metres, dropping a bit overnight.Thursday: Mainly sunny. Light south winds. Alpine high temperatures around +5 with freezing levels lowering to 2400 metres over the day, steadying overnight.Friday: A mix of sun and cloud with cloud increasing over the day. Moderate east winds. Alpine high temperatures around +4 with freezing levels around 2500 metres, dropping to 1700 metres by mid-morning Saturday.

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 the current heightened avalanche activity to continue, potentially expand to all aspects, and intensify 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. This snow rests on previously wind affected surfaces, sun crusts (on solar aspects) and weak, sugary facets. The prolonged period of cold temperatures in February has 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

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 overhead hazards and avoid exposure to avalanche runout zones.Be aware of loose wet avalanche problems expanding to shaded aspects as warm temperatures persist.Minimize 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.

Likelihood

Likely - Very Likely

Expected Size

1 - 3

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.

The chance of persistent slab avalanches will increase as warm temperatures persist.If triggered, storm/wind slabs may step down to deeper layers and result in even larger avalanches.Remote triggering is a concern, watch out for adjacent slopes.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1.5 - 3

Valid until: Mar 20th, 2019 2:00PM