Avalanche Forecast

Issued: Mar 18th, 2018 3:54PM

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

mgrist, Avalanche Canada

Northwest Coastal.

Low danger does not mean no danger. Normal caution applies: Be alert for lingering wind slabs at high elevations and wet loose / glide avalanches at lower elevations.

Summary

Confidence

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

Weather Forecast

We're looking at increasing cloud and small amounts of precipitation over the next three days.MONDAY: Cloudy with isolated flurries / Light to moderate north westerly winds / Alpine temperature near 0 degrees C / Freezing level 1200 m.TUESDAY: Scattered flurries (5-10 cm possible) / Moderate south westerly winds / Alpine temperature near 0 degrees C / Freezing level 700 m.WEDNESDAY: Cloudy with isolated flurries (5-10cm possible) / Light south west winds / Alpine temperature -2 C / Freezing level 500 m.

Avalanche Summary

Over the past three days, several wet loose avalanches to size 3 were observed at tree line and below, primarily on sunny aspects. Some of these stepped down to basal facets in northern parts of the region.On Sunday we received reports of a glide avalanche near Terrace, size 3 on an east aspect near 700m elevation. On Saturday, explosives control work near Stewart produced several wet loose and wet slab avalanches to size 3. Some avalanches stepped down to the mid December ice layer. On Friday, a remote-triggered size 2 persistent slab was reported near Stewart, running on an east facing rib feature near 1600m. The slab (30-120cm thick) failed on the mid January layer, with surface hoar 4-8mm reported.

Snowpack Summary

Recent warming has melted and refrozen the snow surface on sunny aspects. Expect the snow surface to be wet or a melt-freeze crust on all aspects except for north facing slopes above 1100-1300m. Last week, strong easterly to southerly winds redistributed any available soft snow and produced variable surfaces at high elevations, including wind slabs in lee and cross-loaded features. This overlies a sun crust on solar aspects and 5 to 20 mm surface hoar on sheltered, shady aspects at all elevation bands.Beneath this, layers of crusts, facets, and isolated surface hoar buried 50 to 100 cm exist below the surface from mid- and late-February. A surface hoar and crust layer from January is buried around 150 to 200 cm.Near the bottom of the snowpack, sugary facets exist in colder and dryer parts of the region, such as the far north.

Problems

Loose Wet

A possible lack of overnight re-freeze means loose wet and glide avalanches are more likely at lower elevations. Use caution in terrain features where a small avalanche could have serious consequences. Be aware of overhead hazard near runout zones.

Avoid terrain traps such as gullies and cliffs where small avalanches can have high consequence.Watch for signs that the snow is moistening such as pin-wheeling and point-releases below cliffs.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

1 - 2.5

Wind Slabs

Isolated wind slabs may linger in lee features. These slabs overly a weak surface hoar layer in parts of the region, which have produced wide propagations and fast-moving avalanches.

Avoid steep, rocky, and wind affected areas where triggering slabs is more likely.Approach lee and cross-loaded slopes with caution.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 2.5

Valid until: Mar 19th, 2018 2:00PM