Wind loaded areas will be the first to reveal how new snow is bonding to the variety of pre-storm surfaces. Use small features to investigate conditions and calibrate your exposure.
Rounds of flurries with strong to extreme winds are forming new wind slabs that will likely be reactive to human triggering.
A weak layer of facets may be found a variable 70 to 200 cm deep. In shallower inland areas, weak depth hoar exists to ground. If you don't find a supportive crust under our new snow, these layers may be triggerable.
No avalanches have been reported since before January 16, but we should see a sharp uptick in avalanche conditions with the ongoing snowfall and high winds.
Be sure to post your observations to the MIN if you are out in the mountains!
Up to about 20 cm of new snow should be accumulated on the old surface by Wednesday morning. This snow fell under strong to extreme winds and should favour the US/Canada border area.
It buries a mix of heavily wind-affected surfaces in most areas, but in sheltered terrain below 1300 m and on south facing slopes, it now covers a crust (up to 10 cm thick) that has surface hoar preserved on it. Not a good combo! The same surface hoar is likely preserved in leeward alpine.
A weak layer of facets is buried 70 to 200 cm deep and continues to produce hard but sudden test results. This is a concern at higher elevations where the crust is thin or absent. In shallow areas, the bottom half of the snowpack is composed of weak depth hoar.
Tuesday Night
Mostly cloudy with light flurries bringing 2 to 5 cm of new snow. 30 km/h south ridgetop wind, increasing. Treeline temperature -2 °C.
Wednesday
A mix of sun and cloud with isolated flurries. 20 to 40 km/h south ridgetop wind. Treeline temperature -3 °C.
Thursday
Mostly cloudy with intermittent flurries bringing around 5 cm of new snow, including overnight. 20 to 40 km/h southeast ridgetop wind. Treeline temperature -5 °C.
Friday
Mostly cloudy with scattered flurries and around 2 cm of new snow. 20 to 40 km/h northeast ridgetop wind. Treeline temperature -7 °C.
More details can be found in the Mountain Weather Forecast.
