Avalanche Forecast

Issued: Feb 27th, 2018 4:39PM

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

jmcbride, Avalanche Canada

Northwest Coastal.

New snow and wind continue to overload the snowpack. Wednesday is expected to bring another bout of significant snowfall. Natural avalanches are likely. Choose conservative terrain and avoid overhead hazard.

Summary

Confidence

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

Weather Forecast

TUESDAY NIGHT: Flurries. Accumulation up to 5 m. Ridge wind strong, west. Temperature near -5. Freezing level 500 m.WEDNESDAY: Snow. Accumulation 10-20 cm. Ridge wind moderate to strong southeast. Temperature near 0. Freezing level 700 m.THURSDAY & FRIDAY: mix of sun and cloud, light flurries. Accumulation about 5 cm on Thursday. Ridge wind moderate, east. Temperature near -5. Freezing level 400 m lowering to valley bottom.

Avalanche Summary

Tuesday we received a report of a very large (size 4-4.5) natural avalanche on a south aspect west of Terrace near Snowbound Creek. Also evidence of a widespread natural cycle up to size 3 was reported from Sunday and Monday. And explosive control work on Monday produced numerous size 2.5 - 3 storm slabs on southeast through southwest aspects at all elevations.Skiers in the Shames area on Sunday reported reactive storm slabs up to size 2 on south and west aspects. Read the MIN report here.In the north (colder & drier inland area) near Ningunsaw there was a remotely triggered size 2.5 avalanche on Sunday with a hard slab releasing near the ground in shallow snowpack area with a gentle start zone.

Snowpack Summary

Recent storm snow accumulations of 40-80 cm have been affected by ongoing moderate to strong winds from the south-west through north-west at alpine and treeline elevations. Recent storms are burying older hard wind slabs and scoured surfaces in wind-exposed areas. In wind-sheltered terrain, sun crusts or dry facets sit below the recent storm snow.In the upper pack about 50-70 cm deep is an interface of sun crusts, facets and spotty surface hoar (which is most prevalent in sheltered treed locations) that was buried mid-February. Deeper in the snowpack, around 150-200 cm down, you'll find a crust/surface hoar layer which still has the chance to surprise you and could be triggered from a thin snowpack spot, or with a large trigger like cornice fall. Basal facets may be found near the bottom of the snowpack in colder / drier parts of the region.

Problems

Storm Slabs

Snow and wind continue to build fresh storm slabs, which have failed both naturally and with the weight of a person in recent days. Avoid steep or convex terrain, as well as wind-loaded areas on the lee side of ridges and cross-loaded slopes.

The new snow will require several days to settle and stabilize.Use conservative route selection. Choose moderate angled and supported terrain with low consequence.Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 3

Loose Wet

Watch for moist or wet snow at lower elevations as freezing levels and temperatures are expected to rise during Wednesday's storm.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Feb 28th, 2018 2:00PM