Avalanche Forecast

Moderate

The North Rockies field team observed a small (size 1) natural wind slab release on an east aspect at 2070 m in the Lucille area on Friday. Its crown was up to 70 cm thick, almost 3 times the height of new snow. With stormy conditions otherwise limiting observations, it's good evidence of an active wind slab problem in areas with greater new snow amounts.

A variable 5 to 25 cm of snow from this week has formed new wind slabs in exposed alpine and treeline terrain. On solar aspects, at treeline, and especially below, the new snow overlies a variety of crusts from recent warming, sun, and rain. A good bond should form where rain transitioned to snowfall in the last storm.

The uppermost crust (varies by location) is the main failure plane of concern in the region, however we continue to track early January and early December surface hoar and crust layers down 30 to 50 cm and down 80 to 130 cm, respectively. Both are considered unlikely to trigger, with limited concern for higher elevations where the capping effect of recent crusts is absent.

Friday Night

Clearing with easing isolated flurries. 10 to 20 km/h northeast ridgetop winds. Treeline overnight low around -16 °C.

Saturday

Mainly sunny before clouding over in the afternoon. 20 to 50 km/h west ridgetop wind, increasing. Treeline high temperature around -13 °C.

Sunday

Mainly sunny. 20 to 40 km/h north ridgetop wind. Treeline high temperature around -12 °C.

Monday

Mainly sunny. 50 to 80 km/h southwest ridgetop wind. Treeline high temperature -9 °C with a possible above freezing layer around 2500 m.

More details can be found in the Mountain Weather Forecast.

• Watch for newly formed and reactive wind slabs as you transition into wind-affected terrain.
• Recent wind has varied in direction, so watch for wind slabs on all aspects.
• Avalanche activity is unlikely when a thick melt-freeze crust is present on the snow surface.