Avalanche Forecast

Issued: Feb 1st, 2013 4:00PM

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

chris gooliaff, Parks Canada

Banff Yoho Kootenay.

Avalanche control is planned tomorrow during an afternoon warm spell. Mt's Bosworth, Stephen, Dennis, and the Vermilion Slide Paths will be affected. On this note, expect natural activity to spike on sunny slopes in the p.m.

Summary

Weather Forecast

A high pressure ridge is driving mild, dry air through the region. This, coupled with clear skies, will cause temp's to rise to near 0* Celsius in the alpine Saturday, especially in the southern portions of the region. Winds should be in the light to moderate range from the west. Sunday will be few degrees cooler with possible light flurries.

Snowpack Summary

Two main layers in the upper pack are Jan 23 and Jan 4 surface hoar/ facets or suncrust down 25 & 55. Watch for wind slabs in all open areas. These may be easily triggered in steep terrain.

Avalanche Summary

Very little activity. Minor point releases on south-facing aspects reported, all in the surface snow. Expect some natural activity from southerly aspects tomorrow afternoon.

Confidence

Problems

Wind Slabs

Isolated wind slabs in steep terrain features may be human triggered or run naturally with slight additional loading. Warmer temp's on Saturday will initially weaken the bond of these slabs to the underlying snow.

Avoid steep Southerly aspects.Finish ice climbs early in the day before the temperature rises.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Persistent Slabs

In Kootenay and Yoho there is a buried surface hoar and/or crust layer down about 50 cm. This layer may be triggered on steep terrain features where the wind may have stiffened up the overlying snow into a slab.

Be cautious as you transition into wind affected terrain.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Persistent Slabs

Hard slabs from previous high winds have been buried by recent storm snow. These slabs have been unreactive to skier triggering, but warm temp's or new wind loading may awaken them.

Minimize exposure to sun exposed slopes when the solar radiation is strong.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Valid until: Feb 2nd, 2013 4:00PM