Avalanche Forecast

Issued: Mar 2nd, 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 Persistent Slabs.

mbender, Avalanche Canada

North Columbia.

Recent new snow and wind in the alpine and at treeline. The sun packs a punch at this time of year - steep south facing slopes are suspect right now.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain on Saturday

Weather Forecast

SATURDAY: Cloudy with isolated flurries / Light east wind / Alpine temperature -9 SUNDAY: Mix of sun, cloud and isolated flurries / Light west wind / Alpine temperature -11 MONDAY: Mix of sun, cloud and isolated flurries / Light to moderate west wind / Alpine temperature -12

Avalanche Summary

Reports of avalanche activity on Thursday include natural storm and wind slab avalanches to size 2 on northerly and easterly aspects from below tree line into the alpine. There were also a few size 1 skier triggered avalanches reported between 1400 and 2000m. These were primarily on southerly aspects.On Wednesday a size 2 remotely triggered (from a distance of 10m) persistent slab avalanche was reported to run on surface hoar sitting on a crust that was buried mid February. This was on a southwest aspect at 1800m. Other recent avalanche activity has consisted of mainly wind slabs and loose dry in the size 1-1.5 range but up to size 2. These were either naturally occurring or intentionally triggered. More interesting avalanches included a re-loaded bed surface where an avalanche previously released on the Nov crust and the "newly awoken" Feb 14 crust found on solar aspects.

Snowpack Summary

40 to 60 cm of recent storm snow has been redistributed into deeper, reactive slabs in wind-exposed terrain. Below this is a layer buried mid-February that presents as a sun crust on solar aspects, and spotty surface hoar on sheltered slopes. This layer looks most concerning on on solar aspects where it's associated with with small facets or surface hoar above.There are several deeper layers in the mid-pack that have shown signs of improving but remain on the radar as having a low probability of triggering yet a high consequence avalanche if they are triggered. We're talking about surface hoar layer buried back in December and January. Near the base of the snowpack is a November crust combined with loose sugary snow. These layers may "wake-up" with strong inputs such as sustained warming, sustained snowfall, large triggers (e.g. cornice fall, smaller avalanches coming down from above); human triggering is also possible in shallow snowpack areas with variable snow depth and convoluted terrain.

Problems

Wind Slabs

Shifting wind means there may be old buried wind slabs in places you don't expect them i.e. reverse loading, however the most recent wind has been slowing from a southerly direction.

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

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1.5 - 2.5

Persistent Slabs

An interface buried up to 70cm deep has "woken-up" with recent snow loading, and a few large avalanches have been triggered easily. Observations have been limited, but this problem seems most reactive in south-facing terrain where buried crusts exist

Make observations and assess conditions continually as you travel.Watch convoluted terrain with variable snowpack depth and multiple trigger points.

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

Elevations: All elevations.

Likelihood

Possible

Expected Size

1.5 - 2.5

Valid until: Mar 3rd, 2018 2:00PM