Avalanche Forecast

Issued: Mar 11th, 2014 9:32AM

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

bcorrigan, Avalanche Canada

Kootenay Boundary.

Solar radiation and daytime warming will be important in hazard assessment for the next few days, even on north slopes. Keep an eye out for large, mature cornices.

Summary

Confidence

Fair - Freezing levels are uncertain

Weather Forecast

Synopsis: A high pressure ridge will dominate the weather pattern for the next few days bringing warm temperatures and clear skies.Tonight: Clear with some cloudy periods, no precipitation, freezing level dropping to valley bottom. Ridge top winds light to moderate from the west.Wednesday: Sunny with cloudy periods, no precipitation in the forecast, freezing level rising to 1900m. winds from the south west, light to moderate.Thursday: Cloudy periods, possibility of flurries, freezing level around 1500m. Light to moderate ridge top winds. from the west possibly shifting north for a brief period.Friday: Cloudy with isolated flurries, trace of precipitation, freezing level around 1600m, light, locally moderate ridge top winds.

Avalanche Summary

We have reports of large natural avalanches occurring, most recently on north and north east aspects. A skier accidental size 2 around tree line yesterday indicates that even light loads may trigger a significant avalanche. Cornice failures and resulting large avalanches are being reported in the Kootenay-Boundary region and in the neighboring areas as well. Careful attention to daytime warming and aspect will be necessary to travel safely in the back country.

Snowpack Summary

Warm temperatures have promoted rapid settlement of the recent storm snow into a dense slab that sits above a variety of old surfaces. Overnight freezing will help seal up the surface from the weak layers buried below, at least until warm temperatures break down the surface crust, then all bets are off ! Rain up to 1900m has saturated the upper snowpack in some parts of the forecast area and will crust-over as the freezing level lowers at night. At elevations above the freezing level strong SW winds have have formed significant winds slabs in lee features. 3 persistent weak layers are still buried in the snowpack, A January 28th layer of surface hoar, facets and crusts, a Feb.10th layer of surface hoar, facets and crusts, and the March 2nd layer of surface hoar, facets and crusts. Of these layers, the Feb. 10th layer appears to still be problematic, with field reports still indicating easy and sudden planar shears on this layer, especially on north aspects. The most recent weak layer, March 2nd, will be on the radar for a while as we wait for it to bond.

Problems

Storm Slabs

Temperatures will rise over the next few days, Use caution on sun drenched slopes, south west winds have formed wind slabs on lee slopes at tree line and above. Storm snow on solar aspects may be on a sun crust that is touchy and quite reactive.

The new snow will require several days to settle and stabilize.>Be alert to conditions that change with elevation.>Choose conservative lines and watch for clues of instability.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Likely

Expected Size

2 - 4

Loose Wet

Rain soaked snow as well as aspects exposed to solar radiation may be touchy during this warm period.

The new snow will require several days to settle and stabilize.>Watch for terrain traps where small amounts of snow will acumulate into deep deposits.>Avoid steep, open glades in the forest.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 4

Deep Persistent Slabs

Avoid unsupported slopes.>Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

3 - 6

Valid until: Mar 12th, 2014 2:00PM