Banff Yoho Kootenay

Cornices remain fragile, limit exposure. Wind slabs persist in alpine lee terrain. Solar input is strong this time of year despite seasonally cool temperatures.

Moderate

• We are uncertain about how quickly persistent slabs are gaining strength.

Sunshine patrol reported triggering small loose dry avalanches with ski cuts. Lake Louise patrol triggered small (size 1) wind slabs with explosives. No other avalanches were observed or reported.

20-45 cm of snow fell over the last week, with moderate to strong SW winds creating wind effect in open areas, and wind slabs in lee areas. This snow fell on the Mar 20th rain crust, which exists below 2100-2300m. Above this crust on solar aspects, various buried sun crusts exist, some extending to higher elevations. Cornice growth continues.

The Jan 24th facet layer is buried 70–180 cm deep at treeline and in the alpine, with some tests still producing hard, sudden results

Seasonally cool temperatures will persist on Tuesday, with valley temperatures just below zero and ridgetop temperatures around -13. Expect a mix of sun and cloud, with no significant precipitation forecast, though localized convective showers remain possible. Light to moderate southwest wind.

• Watch for newly formed and reactive wind slabs as you transition into wind-affected terrain.
• Fresh snow rests on a problematic persistent slab, don't let good riding lure you into complacency.
• Cornice failures could trigger large and destructive avalanches.