Avalanche Forecast

Issued: Mar 9th, 2014 9:31AM

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

Avalanche Canada jcoulter, Avalanche Canada

Sun hitting slopes for the first time after a storm may increase the probability of natural and human triggered avalanches.

Summary

Confidence

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

Weather Forecast

The pacific frontal system produced significant moisture Saturday night and into Sunday over the south of the region. There is a chance of moderate precipitation overnight Sunday into Monday in the extreme south corner of the South Rockies. The exact track of the storm is tough to pin down so there could be significant amounts of precipitation or nothing at all. Less eventful weather for Monday and Tuesday with slightly lower freezing levels is expected.Sun Ovn: 70% chance of snow or rain, moderate accumulations possible (Flathead and Elk Valley South) if the storm makes it above the 49th parallel. Light to moderate wind out of the West. Freezing levels 1300-1600mMonday: Trace possible. Light to moderate winds from the west, freezing levels around 1400-1600m.Tuesday: Cloudy with sunny periods, light west winds with moderate gusts. Freezing levels 1400-1600m.

Avalanche Summary

There was a report that the Morrisey slidepaths near Fernie  ran to nearly full path on Sunday.  Also on Sunday, near neighbors in the Lizard Range report storm slabs and loose wet avalanches to size 2.5.There is concern for an ongoing natural and human triggered avalanche cycle on Monday with more snow in the south, and solar radiation hitting the slopes where we get some blue skies. Cornices have gotten large and tender and may trigger slabs if they fail.Avalanches in the region have the potential to run full path as dryer storm slabs from the alpine entrain moist snow as the descend. Avalanches in clearcuts, road banks, lower angle terrain and non obvious avalanche paths continue to surprise backcountry enthusiasts throughout the region, so consider them carefully in your travel plans through the forecast period.

Snowpack Summary

Various storm slabs continue to build on top of the March 2nd weak layer made up of facets, surface hoar or crusts, depending on your elevation and aspect. There is now 70-100cm of snow on this layer in the bigger snow zones in the south of our region (Flathead and around Fernie).The mid pack contains the February 10th persistent weak layer. In the deeper snowpack areas it could be up to 2 meters deep now, but in the shallower snowpack zones, it is likely about a meter deep. It is becoming a more isolated problem and likely only trigger-able by large loads like cornices or storm slabs in motion in areas that have not previously run on the February 10th layer... and those areas are getting harder to find.In the lower elevations (below 1600m) in the south of the region, expect the snowpack to be rain soaked and loosing cohesion. Below treeline terrain is likely close to isothermal in the high rain affected zones, and at least moist everywhere else.

Problems

Storm Slabs

An icon showing Storm Slabs
Sun hitting the slopes for the first time since the storm may trigger storm slabs or cornice failures. New snow and continued warm temperatures will add to the storm slab problem in the south of the region.
Caution required around loaded road banks, cutblocks and other non obvious avalanche terrain>Avoid freshly wind loaded features.>The new snow will require several days to settle and stabilize.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 5

Wet Slabs

An icon showing Wet Slabs
Wet slabs are a concern on slopes with rain soaked snow sitting over weak layers. Wet loose avalanches are also expected where rain soaked snow has lost its cohesion.
Avoid steep unsupported terrain below treeline especially if the snow is moist or wet.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

Deep Persistent Slabs

An icon showing Deep Persistent Slabs
Large loads like cornices and storm slabs in motion have the potential to trigger a persistent weak layer buried in mid February. It may also be easier to trigger in shallow snowpack areas in the north of the forecast region.
Consider the consequences of the terrain if an avalanche steps down to a persistent weakness.>Use conservative route selection, resist venturing out into complex terrain even if you observe no obvious signs of unstable snow.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

3 - 6

Valid until: Mar 10th, 2014 2:00PM