Avalanche Forecast

Issued: Feb 21st, 2018 4:11PM

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

Avalanche Canada swerner, Avalanche Canada

Natural avalanche activity has tapered but wind slabs continue to be reactive to human triggering. Pay attention to overhead hazards like cornices, especially when the sun is out.

Summary

Confidence

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

Weather Forecast

New snow amounts on Friday will vary through the region. The Coquihalla (southern areas) could see 5-15 cm of new snow, while the Duffy (northern areas) may only receive 3-8 cm of new snow. Thursday: Mostly sunny with alpine temperatures near -7 and freezing levels 500 m. Ridgetop winds moderate from the North.Friday: Overcast with new snow amounts 5-15 cm. Alpine temperatures near -5 and ridgetop wind strong from the southwest. Saturday: Mix of sun and cloud in the North and overcast in the South. Snow amounts 5-10 cm with less in the North. Alpine temperatures near -5 with freezing levels 600 m. Light to moderate winds from the West.

Avalanche Summary

On Tuesday, reports of several natural loose dry avalanches up to size 1 from steep south facing rocky terrain. Wind slabs are becoming  more stubborn to human triggers but remain the primary avalanche concern for the region. Respect overhead hazards like cornices, especially if Thursday is sunny. A large trigger (like cornice fall) could initiate a large slab avalanche from the slope below.

Snowpack Summary

Extensive wind effect exists at treeline and above. In exposed terrain, strong north and east winds have scoured windward slopes and loaded lee slopes. You can still find low density snow from last Saturday's storm stashed in sheltered trees at treeline and below. The cold temperatures are promoting settlement and surface facetting in the recent storm snow. In southern parts of the region, the new snow (40-50 cm) sits above a widespread crust with well settled snow below the crust. In northern parts of the region up to 30 cm of recent storm 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 (cornice?) or the next major storm (warming and loading) could potentially wake up this layer.

Problems

Wind Slabs

An icon showing Wind Slabs
Strong winds from various directions (primarily north and east) have blown recent snow into reactive slabs at higher elevations.
Approach steep lee and cross-loaded slopes with caution.Use ridges or ribs to avoid pockets of wind loaded snow.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Cornices

An icon showing Cornices
Large cornices linger along ridgelines. They are unstable, unpredictable and demand respect, especially when the sun is shining.
Give cornices a wide berth when travelling on or below ridges.Pay attention to overhead hazards like cornices which could easily trigger slabs from slopes below.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 2.5

Valid until: Feb 22nd, 2018 2:00PM