Avalanche Forecast

Issued: Dec 6th, 2015 8:58AM

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

jsmith, Avalanche Canada

South Columbia.

A widespread natural avalanche cycle is expected to begin Monday and climax on Tuesday. Conservative terrain choices will be critical in the days to come.

Summary

Confidence

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

Weather Forecast

Stormy weather forecasted though Tuesday. 5-15cm of snow throughout the day and overnight on Sunday with strong-extreme southwest winds. Another 10-15cm of snow throughout the day on Monday with moderate southwest winds and 1500m freezing levels. Tuesday is the big day with 15-25cm of snow throughout the day, extreme west winds, and freezing levels spiking to 2000m. The storm tapers on Wednesday with light winds, flurries, and lowering freezing levels. Expect actual snow amounts to vary throughout the region with generally lower amounts in the south.

Avalanche Summary

On Saturday, several natural avalanches were reported up to size two, at treeline and below, on all aspects. Natural avalanching likely occurred in the alpine, but was not observed.

Snowpack Summary

10-20cm of new snow Sunday morning brings recent storm snow totals to 40-60cm. This storm slab sits over a variety of old surfaces, including wind-stripped north aspects, hard wind slabs, facets, sun crusts and/or large-sized surface hoar. The weakest of these interfaces is a layer of surface hoar which can be found below approximately 1800m on all aspects. The mid and lower snowpack is generally well settled. However, 120-150cm down, a surface hoar interface that was formed in November has been dormant but still may wake up with heavy loading or smaller avalanches stepping down.

Problems

Storm Slabs

Storm slabs are building over a crust on solar aspects and a touchy weak layer of surface hoar on all aspects below approximately 1800m. Strong to extreme SW winds are creating thick wind slabs in places not normally expected.

Avoid all avalanche terrain during periods of heavy loading from new snow and wind. >Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.>Avoid open slopes and convex rolls below treeline where buried surface hoar may be well preserved. >Avoid freshly wind loaded features and open areas at treeline.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 5

Valid until: Dec 7th, 2015 2:00PM