Avalanche Forecast

Issued: Feb 21st, 2015 8:20AM

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

jlammers, Avalanche Canada

Cariboos.

Keep an eye on the temperatures over the next few days. Solar radiation and rising freezing levels can weaken the snowpack and make destructive avalanches more likely.

Summary

Confidence

Fair - Due to the number of field observations

Weather Forecast

Mainly sunny skies will persist throughout the forecast period as the dry ridge continues to occupy our province. Daytime freezing levels should hover around 1500m for each day, although an inversion is possible on Tuesday. Winds will remain generally moderate from the northwest.

Avalanche Summary

Avalanche activity has gradually tapered off throughout the week. On Thursday there were a couple reports of natural cornice falls, but these did not trigger slabs. There was also a report of a size 1 (20 cm deep) skier controlled wind slab from an East facing slope. Wind slabs could build and remain sensitive to rider triggering throughout the weekend.

Snowpack Summary

Light amounts of recent snowfall (5-15 cm) covers the previous variable snow surface of surface hoar, crusts, dry facetted snow, or wind affected snow depending on aspect and elevation. The "Valentine's Day" crust is just below the surface and is now strong and thick in most places. New wind slabs may have formed in lee terrain from recent W-NW winds, and cornices remain large and weak. The late-Jan crust/surface hoar layer (up to 100 cm deep) and the mid-January surface hoar (80-120 cm deep) continue to give variable results in snowpack tests. Chances of triggering these weaknesses have decreased, but triggering may be possible from thin or rocky snowpack areas; or perhaps with a cornice fall, or an avalanche stepping down, especially on sun drenched slopes.

Problems

Wind Slabs

Gusty northwest winds are expected to redistribute recent accumulations into fresh wind slabs in higher elevation terrain. Due to the anomalous wind pattern, wind slabs may be found in unsuspecting locations.

Give cornices a wide berth when travelling on or below ridges.>Use ridges or ribs to avoid pockets of wind loaded snow.>Avoid travelling in areas that have been reverse loaded by winds.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Persistent Slabs

Persistent weak layers have been less reactive as of late. I'd be increasingly cautious in steep, unsupported terrain and watch my overhead hazard, especially with daytime warming.

Avoid common trigger points like steep convexities or areas with a thin or variable snowpack.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely

Expected Size

3 - 6

Valid until: Feb 22nd, 2015 2:00PM