Avalanche Forecast

A large (size 2) loose wet avalanche triggered a slab about 50 cm deep on Tuesday at 1700 m. It is possible that it triggered the weak layer described in the snowpack summary.

Otherwise, the most recent persistent slab activity was a week ago. Although likelihood is decreasing, it remains possible for humans to trigger this buried weak layer.

Also expect sun-exposed slopes to become unstable with daytime warming, possibly triggering wet avalanches or releasing cornices.

Dry, settled snow is found on shaded aspects in the alpine. A hard melt-freeze crust exists on the snow surface on sun-exposed slopes to the mountain tops and on all aspects below treeline. The crust will transition to wet snow with daytime warming and re-freeze at night.

50 to 100 cm of snow overlies a hard melt-freeze crust from early April. The overlying snow is slow to bond to the crust where pockets of weak surface hoar or faceted grains rest on the crust, which is most likely on northerly aspects at treeline and alpine elevations.

Thursday night

Clear skies. 20 km/h east ridgetop wind. Treeline temperature around +1 °C. Freezing level rising to 1800 m.

Friday

Clear skies. 20 to 30 km/h east ridgetop wind, increasing. Treeline temperature 0 °C. Freezing level to 1500 m.

Saturday

Clear skies with cloud invading late afternoon. 20 to 30 km/h southeast ridgetop wind. Treeline temperature 0 °C. Freezing level to 1500 m.

Sunday

Increasing cloud with isolated flurries in the afternoon. 10 - 15 km/h southwest ridgetop wind. Treeline temperature 0 °C. Freezing level to 1500 m.

More details can be found in the Mountain Weather Forecast.

• Be aware of the potential for surprisingly large avalanches due to deeply buried weak layers.
• Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.
• Pay attention to cornices and give them a wide berth when traveling on or below ridges.
• Back off slopes as the surface becomes moist or wet with rising temperatures.