Archived

Avalanche Forecast

Dec 31st, 2015–Jan 1st, 2016

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

1: Low

The avalanche danger rating in the alpine will be low

Treeline

1: Low

The avalanche danger rating at treeline will be low

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Regions: Kootenay Boundary.

There's a lot of uncertainty around what affect warming alpine temperatures will have. Widespread cornice failure and loose snow avalanches are likely, wind slabs may become more sensitive to triggering too. A cautious approach will serve you well.

Confidence

Low - Freezing levels are uncertain

Weather Forecast

The recent stormy pattern that December begat is history, and we enter a new meteorological regime marked by remarkable stability and a strong temperature inversion with an almost complete void of storminess over B.C for the next week. FRIDAY: No precipitation, freezing level at valley bottom with above freezing temperatures between 1800 and 3000 m, light SE winds. SATURDAY: No precipitation, freezing level at valley bottom with above freezing temperatures between 1800 and 2900 m, light SE winds. SUNDAY: No precipitation, freezing level at valley bottom, light SW winds. For a more detailed look at mountain weather visit avalanche.ca/weather

Avalanche Summary

On Tuesday and Wednesday quite of a bit of slufing/loose dry activity was reported to size 1. These small natural avalanches were running in the upper 10cm of the snowpack. There is a great deal of variability across the region. The southern Monashees reported 40 cm deep soft slabs on Monday that were easy to trigger and entrained loose dry snow in avalanche tracks and runouts. One ski cut stepped down to a weak layer buried about 100cm deep according to a MIN report. (https://bit.ly/1Sn9Do7) 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 40cm in depth 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.

Avalanche Problems

Wind Slabs

Pockets of wind slab may not be well bonded to the old surface. Forecast warming may increase the sensitivity of wind slabs to triggering.

Avoid exposure to terrain traps like gulleys and creek bottoms where the consequences of an avalanche will be the most serious.>Avoid freshly wind loaded features by using ridges and ribs to sneak around these problem areas.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood: Possible - Likely

Expected Size: 1 - 3

Loose Wet

Loose moist or wet snow may release naturally on solar aspects or be easily triggered by light loads. Warming temperatures may cause cornices to fail naturally too.

Avoid steep sun exposed terrain like rocky cliffs and cut banks when the solar radiation is strong, especially if snow is moist or wet.>Be alert to conditions that change with elevation, time of day and aspect.>Extra caution needed around cornices with current conditions.>Watch for clues, like sluffing off of cliffs, that the snowpack is warming up. >

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

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 2