Avalanche Forecast

Issued: Jan 5th, 2015 9:48AM

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

jlammers, Avalanche Canada

South Rockies.

Monday night's forecast snowfall amounts are uncertain. Pay close attention to how much snow falls (and how hard the wind blows) as wind slabs are the primary concern.

Summary

Confidence

Fair - Intensity of incoming weather systems is uncertain on Tuesday

Weather Forecast

On Tuesday, expect light snowfall, moderate westerly ridgetop winds and freezing levels at valley bottom. On Wednesday and Thursday, the region will be under the influence of a dry ridge where we can expect a mix of sun and cloud, generally light northwest winds, and temperature inversions. With the temperature inversions, alpine temperatures may reach 5 degrees celcius, while valley temperatures should remain below freezing.

Avalanche Summary

Some surface sluffing was reported to have occurred in sheltered treeline areas on Monday. At higher elevations generally small wind slabs were also reported. With light snow and wind in the forecast, I would expect similar avalanche activity on Tuesday.

Snowpack Summary

Up to 15cm of recent snowfall has been shifted into wind slabs in upper elevation terrain by moderate to strong westerly winds. These new accumulations overlie hard wind slabs in exposed terrain, and low density faceted snow in sheltered areas. Up to 70 cm below the surface you will likely find a hard, thick crust which formed mid-December. This crust has overlying facets and surface hoar (up to 10 mm in sheltered locations at treeline and below). This layer seems variably reactive throughout the region. In areas where the overlying slab is thick and cohesive, large avalanches are possible at this interface. A crust/facet combo which formed in November seems to have gone dormant for the time being.

Problems

Wind Slabs

New snow and wind on Monday night will form fresh and reactive wind slabs. Watch for triggering in the lee of ridge crests and terrain breaks.

Use ridges or ribs to avoid pockets of wind loaded snow.>Be cautious as you transition into wind affected terrain.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Persistent Slabs

A crust which formed in December should remain on your radar as it has the potential to produce large avalanches. Dig down and test weak layers before committing to a line.

Make observations and assess conditions continually as you travel.>Stick to well supported terrain and be aware of what is above you at all times.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 4

Valid until: Jan 6th, 2015 2:00PM