Avalanche Forecast

Issued: Mar 9th, 2016 7:16AM

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

Avalanche Canada pmarshall, Avalanche Canada

An intense weather system slamming the South Coast will also give the Northwest a solid smack. Winds will be the main story. Expect rapid wind loading throughout the day on Thursday.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain on Thursday

Weather Forecast

THURSDAY: Periods of snow 15-25 cm. The freezing level peaks near 1400 m but gradually lowers to 500-700 m. Winds are strong from the W-SW. FRIDAY: Cloudy with sunny breaks. The freezing level is around 1200 m and winds are light to moderate from the SE. SATURDAY: Cloudy with sunny breaks. The freezing level is around 1000-1200 m and winds are light from the SE.

Avalanche Summary

Observations on Monday and Tuesday were limited due to poor visibility; however, there were a few reports of natural slab avalanches up to size 2 from immediate lee slopes in the alpine. on Monday There was also a report of a size 3 avalanche that initiated on a north aspect in the alpine, and a large natural cornice fall. Expect wind slabs to remain sensitive to rider triggering in steep exposed terrain.

Snowpack Summary

Over the past few days we've seen snowfall accumulations of 5-15 cm each day, and storm snow totals of around 40-60 cm. Strong to extreme ridgetop winds have shifted the new snow into hard or soft wind slabs at treeline and in the alpine, adding to an ongoing wind slab problem. Some areas are reporting a weak surface hoar layer near the base of the most recent storm snow. An old crust buried in early February can now be found around 80-120 cm below the surface. This crust, which may coexist with small facets or decomposing surface hoar, recently produced sudden planar ("pops") results in snowpack tests. Although no recent avalanches were reported to have failed at this interface, I'd remain suspicious of this layer in steep, unsupported terrain at treeline and in the alpine.

Problems

Storm Slabs

An icon showing Storm Slabs
Forecast snowfall and very strong winds will combine to create deep and dense wind slabs on a variety of aspects well below ridge crests. This new loading could overload weaknesses in the upper snowpack creating large slabs.
Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>Be cautious as you transition into wind affected terrain.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

2 - 5

Cornices

An icon showing Cornices
Large weak cornices could pop off with additional growth during the next intense weather system. 
Give cornices a wide berth when travelling on or below ridges.>Extra caution needed around cornices with current conditions.>

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

2 - 5

Valid until: Mar 10th, 2016 2:00PM