Wind slabs may be more reactive to human triggers where they sit above a buried weak layer. If you've been out, please post your observations to the Mountain Information Network.
Summary
Confidence
Moderate - Due to the number of field observations
Weather Forecast
The weather trend will start to stabilize as a high pressure system sets up, allowing dryer and cooler conditions. Clouds will linger through the weekend.FRIDAY: Mostly cloudy with sunny periods and scattered flurries/ alpine temperatures near -7/ generally light winds from the SSW/ freezing level 1100 mSATURDAY: Cloudy/ alpine temperatures near -9/ ridgetop winds light from the North/ freezing levels 1100 mSUNDAY: Cloudy with sunny periods and a trace of new snow/ alpine temperatures -11/ ridgetop winds light from the East/ freezing levels near 700 m
Avalanche Summary
On Wednesday, a few loose dry avalanches up to size 1 were reported from steep rocky terrain features. With little avalanche observations and low confidence of the surface hoar distribution, I suspect that human triggered avalanches remain possible, especially where deeper deposits of storm snow or wind slabs sit above the buried weak layer.Last Saturday, a large human triggered avalanche was reported in the South Columbia forecast region. The size 3 avalanche occurred on a steep, north aspect in the alpine and failed to ground, likely on the October crust. This avalanche is notable for the Purcells where we have a similar, but shallower snowpack than in the South Columbia, resulting in a higher possibility of impacting a weak layer near the ground. Check out the
MIN report here.
Snowpack Summary
The early season snowpack is highly variable in this region. Approximately 20 cm of recent snow fell earlier this week which may have been blown into wind slabs on exposed northerly and northeasterly slopes. Expect loose dry, unconsolidated snow sluffing from steeper, rocky terrain features. In most places, there are two layers of feathery surface hoar being reported, one around 20 cm below the surface and one down 35 cm. One or both of these may be associated with a crust on south aspects. The most likely places to trigger one of these layers is in deeper snow areas in shady spots on smooth slopes. A prominent feature of the snowpack is a combination of a crust and underlying sugary, faceted snow found near the base of the snowpack. It may still be possible to release an avalanche on smooth slopes in the alpine.
swerner,
Avalanche Canada
