Avalanche Forecast

Issued: Feb 18th, 2014 9:57AM

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

ghelgeson, Avalanche Canada

Purcells.

Stick to simple, well supported terrain that is free of overhead hazard. Don't let your lust for deep powder lure you into anything more committing.

Summary

Confidence

Fair - Timing, track, or intensity of incoming weather system is uncertain on Tuesday

Weather Forecast

Synopsis: Another pacific frontal system passes over the region Tuesday evening accompanied by strong SW winds. Expect isolated convective flurries to linger in the wake of the front Wednesday.Tuesday Night: Freezing Level: Valley Bottom; Precip: 5/7mm - 7/11 cm; Wind: Mod SW | Strong/Extreme SW at ridgetopWednesday: Freezing Level: Valley Bottom; Precip: Trace; Wind: Light, West | Strong West at ridgetopThursday: Freezing Level: Valley Bottom; Precip: 2/5mm - 3/8 cm; Wind: Light, SW | Mod SW at ridgetop.Friday: Freezing Level: Valley Bottom; Precip: Trace; Wind: Light, NW | Mod NW at ridgetop

Avalanche Summary

An ongoing avalanche cycle continues to produce natural avalanches to size 3.5 with control work inducing similar results. Skiers and sledders are triggering avalanches to size 1.5. We received one report of an avalanche being remote triggered from flat terrain 200m away from the slope yesterday. This activity continues to occur on all aspects and elevations, however, most of the activity is happening at and above treeline.

Snowpack Summary

The never ending storm has produced 60 - 120 cm of total snowfall across the region which is settling into a cohesive slab that averages a 40 - 90 cm in depth. This slab rests on a nasty persistent weak layer (Late Jan/Early Feb.) surface hoar/facet/crust combo that was formed during the month of cold clear weather. Field observations continue to report easily triggered sudden planar failures on this interface in snowpack tests. Large settlements / "whoomphs" have been reported at all elevations. Large natural avalanches have been widespread and destructive. The persistent weak layer under all the storm snow is incredibly pervasive in the region. I expect touchy conditions to remain in place longer than we're normally accustomed to. Ongoing strong winds out of the SW and W have loaded lee aspects and damaged snow at all elevations, but the effect is most prevalent at and above treeline. More strong winds in the forecast are expected only to add to this problem.Weak basal facets exist in some areas, but triggering has now become unlikely. For the most part, the mid and lower snowpack are strong and well consolidated.

Problems

Storm Slabs

A cohesive slab averaging 75 cm in depth rests on a weak layer that remains very sensitive to human triggering. This problem is widespread, even below treeline. Fresh wind slabs are forming in open terrain at and above treeline too.

Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>Avoid all avalanche terrain during periods of heavy loading from new snow or wind>Use very conservative route selection, stick to simple well supported terrain that is low consequence and free of overhead hazard.>Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

2 - 6

Valid until: Feb 19th, 2014 2:00PM