Avalanche Forecast

Issued: Mar 19th, 2016 9:23AM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Wind Slabs, Cornices and Deep Persistent Slabs.

jlammers, Avalanche Canada

Northwest Inland.

Lurking persistent weaknesses and mild spring-like weather make me reluctant to drop avalanche danger any lower. Continue to approach large alpine slopes with caution, especially with cornices perched above.

Summary

Confidence

Moderate

Weather Forecast

Light flurries and moderate southerly winds are forecast for Sunday and Monday. A mix and sun and cloud and light winds are expected on Tuesday. Freezing levels should sit at about 1300m for the forecast period.

Avalanche Summary

On Thursday there were reports of loose wet sluffs up to size 1.5 on solar aspects in the afternoon. A larger loose wet cycle with wind slab activity (to size 2.5) was observed in the previous 24 hours. In the far north of the region, natural cornice falls continue to trigger size 2-3.5 persistent slab avalanches, primarily on north-facing alpine slopes.

Snowpack Summary

In sheltered areas at higher elevations, 20-30cm of low density facetting snow can be found. Recent southerly winds have redistributed the surface snow in exposed terrain formed wind slabs and cornices in leeward terrain. South facing slopes could be capped by a sun crust or moist snow, depending on the time of day. A layer of surface hoar from early March can be found down 60-80cm but only seems to be a problem for the northern half of the region. Professional operators are still tracking two deep weak layers from early-January and early-February which can be found down about 1m or more. These layers have been dormant for a couple weeks but could wake up with heavy storm loading, substantial warming, or a heavy trigger like a cornice fall. In the far north of the region, there is an isolated weakness at the base of the snowpack that has been responsible for some very large and destructive avalanches.

Problems

Wind Slabs

Wind slabs may still be lurking on a variety of aspects in exposed terrain. Also, watch for pockets of wind slab in cross-loaded gullies.

Use ridges or ribs to avoid pockets of wind loaded snow.>Be cautious as you transition into wind affected terrain.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Cornices

Natural cornice releases are more likely during periods of sun exposure and warming. A falling cornice chunk could trigger a large slab on the slope below.

Extra caution needed around cornices with current conditions.>Cornices become weak with daytime heating. >

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

2 - 5

Deep Persistent Slabs

Three buried weaknesses remain a concern, mainly in the north of the region (see snowpack discussion for details). Isolated very large avalanches remain a possibility, especially with a heavy trigger like a falling cornice.

Be aware of the potential for full depth avalanches due to deeply buried weak layers. >Be aware of thin areas that may propagate to deeper instabilities. >

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 6

Valid until: Mar 20th, 2016 2:00PM