Avalanche Forecast

Issued: Mar 2nd, 2014 8:03AM

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

Avalanche Canada rbuhler, Avalanche Canada

Summary

Confidence

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

Weather Forecast

A series of weak systems from the coast will cross the region resulting in periods of snow and milder temperatures. There is currently some uncertainty in the weather models as to the timing, precipitation amounts, and freezing levels during the forecast period.Sunday Night: Snowfall 5-15cm, freezing level around surface, ridgetop wind 30-50 SWMonday: Snow flurries 5-15cm, freezing level 500-1000m, ridgetop wind 20-40 SWMonday Night: Snow flurries 4-8cm, ridgetop wind 20-40 SWTuesday: Snow flurries 4-8cm, freezing level 700-1200m, ridgetop wind 30-50 SWWednesday: A mix of sun and cloud, snow flurries 3-6cm

Avalanche Summary

On Saturday, two size 2 skier remote avalanches were reported.  They released down 35-40cm and were triggered from 25m away.  Also reported were two natural size 1.5 wind slab avalanches on NW aspect slopes.On Friday, a size 1.5 skier accidental avalanche was reported. It released at a depth of 30-45cm.

Snowpack Summary

The primary concern is a persistent slab (typical thickness 50-90cm) from the last series of storms that is sitting on a stubborn persistent weak layer consisting of facets, surface hoar, melt-freeze crusts, or any combination of these. This weak layer is widespread at all elevations and aspects. Recent test results are suggesting that the layer is still easy to trigger in some areas but may becoming harder to trigger in other areas. We are still receiving isolated reports of large settlements or whumpfing which suggests the layer still has the potential for large propagations. In many areas the layer has the potential to produce large, destructive avalanches. The phase we are now entering is referred to a 'low probability/high consequence' problem. Continue to use conservative terrain choices until you are sure the layer is no longer unstable in your local area. Strong forecast winds from the SW are expected to create touchy new wind slabs on leeward slopes and cross-loaded features.  As more snow accumulates we can expect a more widespread storm slab.  This slab sits on top of surface hoar up to 10mm, near-surface facets, and/or a sun crust on south facing slopes.

Problems

Persistent Slabs

An icon showing Persistent Slabs
The thick persistent slab on the early-Feb weak layer is still reactive to human triggers and has the potential to produce large, destructive avalanches.  The new snow may 'wake up' the weak layer and large natural avalanches may occur.
Avoid unsupported slopes.>Use conservative route selection and resist venturing out into complex terrain, even if you observe no obvious signs of unstable snow.>Remote triggering is a big concern, be aware of the potential for wide propagations and large, destructive avalanches at all elevations.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

3 - 6

Storm Slabs

An icon showing Storm Slabs
New snowfall will form a storm slab which overlies a variety of potentially weak surfaces.  Moderate to strong SW winds will form stiffer wind slabs in leeward and cross-loaded features which will be more sensitive to human triggers.
Avoid avalanche terrain during periods of heavy loading from new snow and wind.>Avoid freshly wind loaded features.>The new snow will require several days to settle and stabilize.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Mar 3rd, 2014 2:00PM

Login