Avalanche Forecast

Issued: Feb 27th, 2013 9:05AM

The alpine rating is high, the treeline rating is considerable, and the below treeline rating is moderate. Known problems include Storm Slabs and Wind Slabs.

jfloyer, Avalanche Canada

Northwest Inland.

High danger may overstate things Thursday if the expected snow amounts come through less than anticipated. However, strong winds will still increase danger rapidly in exposed areas.

Summary

Confidence

Poor - Timing, track, or intensity of incoming weather is uncertain for the entire period

Weather Forecast

Synopsis: A Pineapple Express to the south of the region will spill some moisture over into this region starting Thursday. Note, poor confidence in snowfall amounts at this time.Thursday: Moderate snowfall, with the potential for locally heavy amounts. 10-20 cm. Freezing level rising to around 1000 m in the afternoon. Winds southwest 35 km/h becoming 60 km/h in the afternoon/evening.Friday: Most likely light, but moderate snowfall possible. Southwest winds 30 km/h. Freezing level around 800 m.Saturday: Flurries. Winds becoming light. Freezing level around 600 m.

Avalanche Summary

Small (size 1) soft slab avalanches could be triggered in response to ski-cutting at treeline on Tuesday and similar activity was reported Monday from steep wind-loaded features. During the weekend there were reports of natural avalanches up to size 2.5 on north facing slopes following loading from new snow and wind.

Snowpack Summary

A new sun crust has formed on steeper solar aspects. In shady areas there is 40-60 cm of well settled storm snow. Strong southwest winds formed touchy wind slabs in exposed terrain in lee of ridges, in gullies, and behind terrain features. There are a variety of old interfaces now down 60 - 100cm which include facets, crusts and isolated pockets of surface hoar. Recent observations indicate that these weaknesses have bonded fairly well now, but I still suggest digging and testing the snowpack to confirm.A strong mid-pack currently overlies a weak base layer of facets/depth hoar. It is worth noting that the snowpack in general is quite shallow in northern and eastern parts of the region. Triggering the basal weakness may still be possible from thin spots, rocky outcrops or under the weight of larger triggers such as cornice fall.

Problems

Storm Slabs

Variable and difficult to predict storm snow amounts could bring sufficient new snow to create hazardous avalanche conditions on sufficiently steep slopes.

Assess start zones carefully and use safe travel techniques.>Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>Choose conservative lines and watch for clues of instability.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 5

Wind Slabs

The strong wind has the potential to create touchy wind slabs even in areas where less snow falls. Cornices are also well developed and could collapse with additional loading by new snow.

Avoid freshly wind loaded features.>Be aware of the potential for wide propagations due to the presence of hard windslabs.>Highmark or enter your line well below ridge crests to avoid wind loaded pillows.>

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

Elevations: Alpine, Treeline.

Likelihood

Very Likely

Expected Size

1 - 4

Valid until: Feb 28th, 2013 2:00PM