Avalanche Forecast

Issued: Mar 24th, 2018 4:26PM

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

mgrist, Avalanche Canada

South Columbia.

The best and safest snow conditions are near sheltered tree line elevations. Expect any appearance from the late March sun to quickly destabilize wind slabs and loose snow at the surface.

Summary

Confidence

Moderate - Timing or intensity of solar radiation is uncertain on Sunday

Weather Forecast

Cloudy with sunny breaks on Sunday before light snow fall on Monday-Tuesday. SUNDAY: Mainly cloudy, sunny breaks possible with isolated flurries and a trace of new snow, increasing overnight. Moderate southwest winds 20-35 Km/hr. Freezing level to 1200 metres with alpine high temperatures around -4.MONDAY: Cloudy with continuing flurries bringing 5-10 cm of new snow, increasing overnight. Moderate southwest winds. Freezing level to 1400 metres with alpine high temperatures of -3.TUESDAY: Snow (5-15cm). Moderate to strong west winds, Freezing level 1500 metres with alpine high temperatures around -1.

Avalanche Summary

On Saturday, a size 1.5 natural cornice fall was reported on a north west ridge line near 2400m, pulling out a small soft slab below.On Friday we received widespread reports of several size 1-2 wind slab and storm slab releases. These were skier triggered, ski cut, and explosives triggered. They occurred on primarily north/east aspects at treeline and above.Looking forward, newly formed wind slabs are likely to remain reactive to human triggering over the near term. Watch for intervals of solar exposure to destabilize slabs as well as promote loose wet avalanche conditions on steeper, sun-exposed slopes.

Snowpack Summary

Convective snowfall coupled with strong to extreme southerly winds brought a wind-affected 15-25 cm of new snow since Thursday night. The new snow has buried a couple of recent layers of storm snow that are separated by temperature and sun crusts at lower elevations and on south aspects. Surface hoar layers have been reported between these storm snow layers on shaded aspects at higher elevations and can likely now be found at approximately 30 and 50 cm below the surface. Some potential exists for shallower slab avalanches to 'step down' to these deeper layers.New snow amounts taper with elevation and below 1900 m, reduced accumulations have buried a supportive crust on all aspects. Deeper persistent weak layers from January and December are generally considered dormant, but could wake up with a surface avalanche stepping down, large cornice fall, or a human trigger in a shallow or variable-depth snowpack area. These layers consist of sun crust, surface hoar and/or facets.

Problems

Wind Slabs

Strong winds created wind slabs at higher elevations and they could remain reactive to human triggering on Sunday. High north aspects are a particular concern due to surface hoar that could lead to easier triggering and deeper releases.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.Be especially careful with wind loaded pockets near ridge crests and roll-overs.Give cornices a wide berth when travelling on or below ridges.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Loose Wet

The sun's direct effect could rapidly destabilize the snowpack. It's best to stick to north facing terrain if the sun comes out in full force.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.Use caution above cliffs where small avalanches may have severe consequences.Watch for clues, like sluffing off of cliffs, that the snowpack is warming up.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Mar 25th, 2018 2:00PM