Avalanche Forecast

Issued: Feb 17th, 2016 8:30AM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is moderate. Known problems include Wind Slabs, Loose Wet and Cornices.

jlammers, Avalanche Canada

South Rockies.

Precipitation and high freezing levels will be driving the avalanche danger on Thursday. Surprisingly large avalanches are possible especially if the region receives significant rainfall.

Summary

Confidence

Moderate - Freezing levels are uncertain on Thursday

Weather Forecast

WEDNESDAY NIGHT: Up to 5mm of precipitation / strong southwest winds / freezing level at about 2000m THURSDAY: 5-10mm of precipitation / strong southwest winds / freezing level falling from 2000m to about 1500m FRIDAY: light flurries / moderate southwest winds / freezing level at 1500m SATURDAY: mix of sun and cloud / light to moderate northwest winds / freezing level at 1000m

Avalanche Summary

Small loose dry and loose wet sluffs were observed in the Crowsnest Pass area on Tuesday. In addition to a small wind slab avalanche in a lee alpine feature, there was also evidence of recent natural cornice failures. Looking forward, new snow and wind on Thursday is expected to spark a round of wind slab activity at higher elevations. At elevations where precipitation falls as rain, loose wet avalanches may be likely.

Snowpack Summary

Up to 30 cm of recent storm snow sits on a melt-freeze crust on southerly aspects and lower elevation terrain, surface hoar on sheltered slopes, and older wind affected surfaces in exposed terrain. Widespread wind effect is evident in the alpine with fresh wind slabs forming in exposed lee terrain. Warming has Cornices have grown significantly recently. A layer of buried surface hoar can be found between 50 and 70cm down and remains a concern, primarily west of the Continental Divide. Below 1500-1600 m the snowpack is essentially isothermal and very spring-like. The snowpack rests on a weak crust/facet layer from early December.

Problems

Wind Slabs

New snow and wind on Thursday will form fresh and reactive wind slabs at higher elevations. Warm temperatures on Thursday could make these more sensitive to human triggers.

Be careful with wind loaded pockets on steep slopes below ridge crests.>Stay off recent wind loaded areas until the slope has had a chance to stabilize.>

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Loose Wet

Precipitation and high freezing levels on Thursday will promote loose wet avalanche activity. Loose wet avalanches can be pushy, run long distances and entrain mass quickly.

Be cautious of sluffing in steep terrain at lower elevations if it's raining.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Cornices

Large and unstable cornices continue to grow and could fail naturally. A cornice fall could also become a trigger for a larger avalanche on the slope below

Give cornices a wide berth when travelling on or below ridges.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 4

Valid until: Feb 18th, 2016 2:00PM