Avalanche Forecast

Issued: Dec 29th, 2015 7:37AM

The alpine rating is moderate, the treeline rating is low, and the below treeline rating is low. Known problems include Wind Slabs.

Avalanche Canada triley, Avalanche Canada

Some pockets of wind slab may continue to be poorly bonded due to the cold temperatures during and since the storm. Gradual warming may help settle the recent storm snow.

Summary

Confidence

Moderate - Timing or intensity of solar radiation is uncertain

Weather Forecast

Cloud and scattered flurries continuing overnight with very little accumulation expected. Gradual clearing on Wednesday with valley cloud remaining below about 2000 metres. Alpine temperatures around -15 overnight and rising up to about -10 during the day with light northerly winds. Clear overnight Wednesday with continued valley cloud on Thursday. Alpine temperatures gradually warming, but at this time look like they will remain around -5 on Thursday with light westerly winds. The inversion should be well developed by Friday, with clear skies above 1500 metres and alpine temperatures slightly below freezing.

Avalanche Summary

No new avalanches reported. There is a great deal of variability across the region. The southern Monashees have reported 40 cm deep soft slabs on Monday that are easy to trigger and likely to entrain loose dry snow in avalanche tracks and runouts. One ski cut stepped down to a weak layer buried about 100 cm according to a MIN report. As you move east across the region the storm slab depths become less, with about 20 cm in the Rossland range, and closer to 10 cm of recent snow 40-50 cm of overall storm snow in the Kootenay pass.

Snowpack Summary

The southern Monashees around Big White have reported recent storm slabs up to 40 cms that are easy to trigger. Another 5-10 cm of new snow fell on Sunday in the Kootenays, making the weekend total about 10-20 cm of dry cold snow. This snow fell on a variety of old surfaces including small grain facets, surface hoar up to 14mm in size and a sun crust on steep south and southwest facing features. In the last week the region received 40 to 60cm of storm snow that remains largely unconsolidated. Below this snow you will find the mid-December crust. It has not been problematic anywhere yet, but in Kootenay Pass there is a spotty surface hoar layer on or just above this crust. This interface is down around 60cm and the surface hoar is most prevalent on north facing features between 1800 and 2000m. At treeline the early December crust is down around 70 to 120cm. This thick and supportive crust is likely capping any deeper weaknesses in most places. There have been reports of facets on this crust in the Nelson area, so we'll want to keep our eye on it as we move into the New Year. The lower snowpack is thought to be well settled.

Problems

Wind Slabs

An icon showing Wind Slabs
Pockets of wind slab may continue to be poorly bonded to the old surface or a mid-storm weakness. Wind slabs are most likely in the alpine and may be slow to settle and bond due to the continued cold temperatures.
Extra caution needed around cornices with current conditions.>Exercise extra caution around recently wind loaded features and use ridges/ribs to sneak around these problem areas.>

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Valid until: Dec 30th, 2015 2:00PM

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