Avalanche Forecast
Issued: Mar 25th, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs.
JSmith,
Avalanche Canada
Small wind slabs below ridgetops are currently the primary concern.
Summary
Confidence
Weather Forecast
WEDNESDAY NIGHT: Mostly clear, light southwest winds, alpine low -10 C, freezing level valley bottom.
THURSDAY: Increasing cloudiness, light southwest winds, alpine high 0 C, freezing level 1300 m.
FRIDAY: Cloudy with possible flurries; 0-3 cm, light southwest winds, alpine high 1 C, freezing level 1500 m.
SATURDAY: Cloudy with flurries; 3-5 cm, moderate southwest winds, alpine high 2 C, freezing level 1700 m.
Avalanche Summary
Over the past week, avalanche activity was reported as natural loose wet avalanches (size 1-2) running in steep, sun-exposed terrain. Cornices were also observed failing naturally, primarily on north, northeast, and east aspects. Cornice falls have been as big as size 2.5.
Slab avalanches releasing on buried surface hoar layers were also reported. Several were attributed to peak warming on solar aspects. These avalanches occurred between 1700 m and 2300 m and were breaking 40-100 cm deep. See this MIN report for a helpful illustration.
Snowpack Summary
1 to 5 cm of new snow fell across the region Sunday. Most wind was light and variable, but high elevation stations have showed some moderate wind out of the south which may build wind slabs on lee features.
The recent snow sits on a variety of snow surfaces, consisting of sun crusts, hard wind-affected snow, and soft faceted snow. There have also been reports of surface hoar forming on sheltered, shady slopes. See this MIN for a helpful illustration from nearby Glacier National Park. It will be important to track the depth, cohesiveness, and bond of the new snow to these various old snow surfaces across aspects and elevations where you're travelling.
Cornices are large and looming. Two layers of buried surface hoar can be found buried 20-40 cm deep (March 10) and 60-120 cm deep (February 22). Though there is a low likelihood of triggering an avalanche on these layers, the consequences of doing so would be high.
Terrain and Travel
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Pay attention to cornices and give them a wide berth when traveling on or below ridges.
- Make observations and assess conditions continually as you travel.
- Be alert to conditions that change with aspect and elevation.
Problems
Wind Slabs
Recent winds may have formed reactive slabs on lee features below ridgetops.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Mar 26th, 2020 5:00PM
