Avalanche Forecast

Issued: Jan 28th, 2013 8:40AM

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

Avalanche Canada istorm, Avalanche Canada

Summary

Confidence

Fair - Forecast snowfall amounts are uncertain

Weather Forecast

The pattern through Tuesday is a strong NW flow before shifting back to a more typical westerly flow on Wednesday & Thursday.Overnight Monday & Tuesday: Mod to strong NW  or W wind with below freezing temps above approximately 1000m. Less than 10mm water equivalent precipitation (falling as up to 10 cm of snow up high).Wednesday: Winds easing slightly from the NW, drying out so no precipitation other than flurries expected. Temperatures slightly warmer to just below freezing up in the mountains.Thursday: Dry, light SW wind, and slightly warmer than Wednesday (freezing level rising to 1800 m possible).

Avalanche Summary

No new avalanche observations reported.

Snowpack Summary

15 to 25 cm of snow fell over the past few days with light to moderate SW wind. This snow is settling and gaining strength although lingering wind slabs are possible behind ridges & ribs. This snow buried a variety of surfaces including hard old wind slabs, thin and thick crusts and large surface hoar crystals which can be found in sheltered terrain below treeline. Weather forecasts call for shifting winds to the NW or W and strong enough to transport snow - this will create a new series of wind slabs, primarily on easterly and southerly facing slopes and in cross-loaded terrain features.A surface hoar layer buried down 40-80 cm seems to be gaining strength, but still exhibits moderate, sudden results in isolated snowpack tests. Near the base of the snowpack, a crust/facet layer exists, which is now unlikely to be triggered, except perhaps by heavy triggers in unsupported, shallow, rocky terrain where more faceting has taken place.

Problems

Wind Slabs

An icon showing Wind Slabs
Pockety wind slabs will likely form behind ridges and ribs with increasing NW wind. This is a less typical pattern so east and south facing slopes as well as cross-loaded features are more suspect.
Assess start zones carefully and use safe travel techniques.>Be cautious as you transition into wind affected terrain.>Avoid freshly wind loaded features.>Watch for terrain traps where small amounts of snow will accumulate into deep deposits.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Jan 29th, 2013 2:00PM