Avalanche Forecast

A very large natural avalanche cycle, size 2.5-3.5 was observed over the week, with the most recent occurrence near Ningunsaw on Friday. A combination of wind slabs and persistent slabs failing on buried weak layers, most were triggered in alpine start zones, entrained wet snow and ran far, many to valley bottom.

By Friday, most avalanche activity was trending smaller; size 1 rider-triggered wind slabs on north to east aspects in the alpine.

A moist upper snowpack up to 1800 m is refreezing into a crust. In the alpine, overlying dry wind slabs may slow the refreeze.

Various layers formed in January are now buried 50-100 cm deep. Up to 1600 m this presents as a thick crust, and at higher elevations, facets, sometimes in combination with surface hoar. Large avalanches ran on these layers during the height of the recent warm, wet storm. It is expected that they will strengthen as temperatures drop.

Below treeline, the previously rain-soaked snowpack is starting to refreeze from the top down. It diminishes rapidly to dirt below 500 m.

Saturday night

Mostly cloudy with a trace of snow. West ridgetop wind 40 km/h. Treeline temperature around -12°C.

Sunday

A mix of sun and cloud. West ridgetop wind tapering to <20 km/h and switching east. Treeline temperature around -9 °C.

Monday

Sunny. East ridgetop wind 20-30 km/h. Treeline temperature around -10 °C.

Tuesday

Sunny. Northeast ridgetop wind <20 km/h. Treeline temperature around -11 °C.

More details can be found in the Mountain Weather Forecast.

• Be careful with wind slabs, especially in steep, unsupported and/or convex terrain features.
• Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.
• When a thick, melt-freeze surface crust is present, avalanche activity is unlikely.