Avalanche Forecast

Issued: Feb 23rd, 2018 4:03PM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is low. Known problems include Storm Slabs and Cornices.

Avalanche Canada mconlan, Avalanche Canada

New snowfall likely won't bond well to underlying snow surfaces. Expect old and new slabs on all aspects at higher elevations, loose dry snow in sheltered areas, and looming cornices on ridgelines. Use caution on solar slopes when the sun is out.

Summary

Confidence

Moderate - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

FRIDAY NIGHT: Cloudy with snowfall, accumulation 5 to 15 cm with the most in the south of the region, moderate to strong southwesterly winds, alpine temperature -13 C, freezing level below valley bottom.SATURDAY: Mostly sunny in the north of the region and cloudy with intermittent snowfall in the south of the region, accumulation 2 to 5 cm, light northwesterly winds, alpine temperature -12 C, freezing level near 500 m.SUNDAY: Cloudy with early-morning snowfall, accumulation 5 to 20 cm with the most in the south of the region, moderate to strong westerly winds, alpine temperature -7 C, freezing level near 700 m.MONDAY: Partly cloudy, light westerly winds, alpine temperature -10 C, freezing level 700 m.

Avalanche Summary

No new avalanche observations were noted on Wednesday or Thursday.  On Tuesday, several natural loose dry avalanches up to size 1 were reported from steep south facing rocky terrain.Expect natural and human-triggered avalanche activity to increase with the incoming storms followed by warming sunshine.

Snowpack Summary

Around 10 to 20 cm of storm snow fell with strong westerly winds, producing storm slabs on all aspects with deeper deposits found in lee features.  This snow fell on previously wind-affected surfaces. The new snow may not bond well to these surfaces and could be reactive to both natural and human triggers.In the snowpack in southern parts of the region, a widespread crust exists around 30 to 50 cm deep.  Below the crust, well-consolidated snow exists.Avalanche professionals are still monitoring the mid-January crust and are avoiding shallow rocky slopes where triggering this layer is most likely. This layer is now 80-150 cm deep, but a heavy trigger (such as a cornice fall) or the next major storm (loading and/or warming) could wake this layer up.Also make note of cornices at ridgeline.  Variable winds in the past month have produced cornices on all aspects.  They will become touchier as they grow in size, as temperatures rise, and as the sun packs a strong punch on clear days.  Stand well back of them and avoid them from below!

Problems

Storm Slabs

An icon showing Storm Slabs
Storm slabs have formed with new snow and strong westerly winds. Expect deeper slabs in lee features and loose snow in sheltered areas. These sit above previous wind slabs. Watch out for natural avalanches on solar slopes when the sun is out.
Use caution above cliffs and terrain traps where small avalanches may have severe consequences.Approach lee and cross-loaded slopes with caution.Watch for signs of instability, such as avalanche activity, whumpfs, and shooting cracks.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2.5

Cornices

An icon showing Cornices
Large cornices have formed along ridgelines. Cornices are inherently unstable, unpredictable, and demand respect, especially if the sun is shining.
Give cornices a wide berth when travelling on or below ridges.Watch out for overhead hazards, such as cornices, which could easily trigger slabs on slopes below.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 3

Valid until: Feb 24th, 2018 2:00PM