Avalanche Forecast
Issued: Mar 12th, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Persistent Slabs.
wlewis,
Avalanche Canada
Storms slabs may remain reactive to human triggers, especially in wind loaded terrain features.
Choose simple terrain, and use small slopes with low consequence to test the bond of the storm snow.
Summary
Confidence
Weather Forecast
SATURDAY NIGHT: Mainly cloudy, isolated flurries. Light and variable winds are expected. Freezing levels drop to valley bottom.
SUNDAY: A mix of sun and cloud. Isolated flurries possible. Light southerly winds becoming strong in the afternoon. Freezing level around 1000m. Alpine high -2.
MONDAY: Snowfall begins overnight, around 10 cm by morning and another 10-20 cm possible over the day. Freezing levels around 1000 m. Alpine high -3. Strong southwest winds.
TUESDAY: Light snowfall continues, up to 10 cm possible. Moderate southwest winds. Freezing levels around 1000 m, alpine high of -2.
Avalanche Summary
On Friday, as storm totals increased skier and naturally triggered slabs were reported to size 1.5. Increased reactivity was noted where storm snow overlies a crust.
Natural wet avalanches occurred in steep terrain features below treeline to size 1.5 as freezing levels rose.
Over the last 10 days, a few size 1-2 persistent slabs have been triggered on the buried weak layers described in the snowpack summary section. Avalanches were mainly triggered on North through East aspects, between 1200 and 1800 m. Recent activity suggests they are becoming less reactive with the last reported avalanche on Sunday the 6th.
Snowpack Summary
Storm totals have reached 20-40 cm. In exposed terrain, west-southwest winds may have redistributed this into wind loaded pockets.
Storm snow sits over a crust on south facing slopes and on hard wind pressed surfaces in most other terrain. A layer of surface hoar may sit below the storm snow in very isolated and sheltered terrain features.
Low elevations have seen 5-15 cm of wet snow that sits over a widespread crust on all aspects below 1000 m.
Several weak layers sit in the upper/mid snowpack that have been recently reactive. A spotty layer of surface hoar buried early March is down 20-40 cm, with another surface hoar layer from late February is buried 35-60 cm deep, and is most prominent at treeline elevations. A thick crust from mid-February is buried 70-110 cm. The snowpack below is well consolidated.
Terrain and Travel
- Continue to make conservative terrain choices while the storm snow settles and stabilizes.
- Avoid freshly wind loaded terrain features.
- Storm slabs in motion may step down to deeper layers resulting in large avalanches.
- Minimize exposure to sun-exposed slopes when the solar radiation is strong.
Problems
Storm Slabs
Storm slabs may sit over several different surfaces, expect varying reactivity. Slabs will be most reactive where it overlies a smooth crust, and/or surface hoar.
Expect strong west/southwest winds to have built larger slabs in east facing terrain features.
Lower elevations have seen wet snow that sits on a widespread crust. Wet avalanches may be possible in steep terrain
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
Large triggers such as storm slabs in motion or cornice falls may trigger large avalanches on these persistent weak layers.
- Two layers of weak surface hoar are buried in the top 60cm of the snowpack, mostly likely to be found in treeline and low alpine features sheltered from the wind and sun.
- A widespread, thick crust is buried 60-100 cm deep.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 13th, 2022 4:00PM
