Avalanche Forecast
Issued: Apr 7th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Cornices.
swerner,
Avalanche Canada
Fresh snow amounts are variable across the region, and may have formed reactive wind slabs on many aspects due to changing wind directions. Keep in mind that even brief periods of sun could initiate avalanche activity in the new snow.
Summary
Confidence
Moderate - Forecast snowfall amounts are uncertain.
Weather Forecast
Wednesday Night: Cloudy with snow up 5-10 cm. Ridgetop wind moderate from the West. Alpine temperatures near -9 and freezing levels 900 m.
Thursday: Mostly cloudy with some sunny periods and isolated flurries. Ridgetop wind light from the northwest. Alpine temperatures near -8 and freezing levels 1300 m.
Friday: Snow 10-15 cm. Ridgetop wind strong from the southwest. Alpine temperatures near -8 and freezing levels 900 m.
Saturday: Snow 5-10 cm. Light to moderate West wind and freezing levels 1200 m.
Avalanche Summary
On Tuesday, a natural size 3.5 wet slab was reported from an S-SW aspect at 2500 m to 1800 m along with numerous wet loose avalanches up to size 1. A skier-triggered wind slab size 1 was mentioned from a North aspect at 2500 m and a skier-triggered cornice fall size 2.5 from an alpine ridgeline in Glacier National Park.Â
New snow and strong winds shifting from the southwest to the northwest may have formed fresh and reactive wind slabs on leeward slopes at treeline and in the alpine.Â
Loose surface avalanches within the new snow may occur from steeper slopes and terrain features, especially if the sun comes out and in locations that received heavier snowfall amounts.
Snowpack Summary
New snow 5-15 cm fell across the region. Shifting wind directions from the southwest to northwest could form new wind slabs on leeward slopes and behind terrain features. The new snow sits on a series of melt-freeze crusts on all aspects below 1900 m and solar aspects to mountain top. On North aspects in the alpine, the new snow will sit on dry wintery snow surfaces and possibly surface hoar on wind-sheltered slopes.Â
At alpine and treeline elevations, a few layers of note are buried 50-100 cm deep including a layer of small surface hoar crystals on shady, wind-sheltered aspects and a series of crusts on solar aspects and below 1800 m. Overall the snow seems to be bonding well to these interfaces, although there have been a few isolated avalanches running on deeper crust layers in the past week.
Terrain and Travel
- Watch for wind-loaded pockets especially around ridgecrest and in extreme terrain.
- Use ridges or ribs to avoid areas of wind loaded snow.
- Be aware of the potential for loose avalanches in steep terrain where snow hasn't formed a slab.
- Pay attention to cornices and give them a wide berth when traveling on or below ridges.
Problems
Wind Slabs
New snow and strong southwest to northwest wind may form fresh wind slabs. They will most likely be isolated to immediate lees of ridgecrests and roll-overs at upper elevations.
Loose surface avalanches are possible from steeper slopes and terrain features, especially if the sun comes out and in locations that received higher snowfall amounts.
Aspects: North East, East, South East.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Cornices
Cornices are especially fragile this time of year. Cornice falls are dangerous in their own right and they can also trigger slabs on slopes below.
Aspects: North, North East, East, South East.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Apr 8th, 2021 4:00PM
