Watch for reactive storm slabs building through the day at treeline and above. Strong south winds will load leeward slopes (north-east), building deeper slabs.
Weak layers can become reactive when loaded due to snow/rain or wind
A weak layer from early March is now 100 to 150 cm deep with January and February layers buried 200 to 300 cm. These remain a concern, especially in northerly alpine terrain.
15 to 30 cm of new storm snow may accumulate at treeline and above by Thursday afternoon. Expect to find deeper deposits on north- and east-facing slopes, where the wind will load lee slopes.
On Tuesday, numerous natural and explosive triggered wet slab avalanches were reported up to size 3.
Natural avalanche activity may decrease with cooling temperatures, but rider-triggered storm slabs will likely be reactive on Thursday.
Rain and warming to mountaintop has saturated the upper snowpack from 40 to 70 cm deep on all aspects and elevations, except high north-facing alpine slopes. As freezing levels fall Thursday, a widespread crust will form. New snow accompanied by strong south wind will likely build storm slabs at upper elevations. Expect deeper and more reactive deposits on north—and east-facing slopes.
Persistent weak layers from January, February and March can be found 100 to 160 cm and 200 to 300 cm deep. These layers were reactive in the recent warming event.
Below this, the snowpack is well-settled and strong.
Wednesday Night
Cloudy rain 15 to 20 mm transitioning to snow above 1200 m by 4 am. 35 to 65 km/h south ridgetop winds. Treeline temperature 2 °C. Freezing level dropping to 1500 m.
Thursday
Mostly cloudy with 5 to 15 cm above 1200 m. 20 gusting to 35 km/h southeast ridgetop winds. Treeline temperature -1 °C. Freezing level 1500 m.
Friday
Mostly cloudy with snow 10 to 15 cm above 1200 m. 15 to 35 km/h southeast ridgetop winds. Treeline temperature -2 °C. Freezing level 1500 m.
Saturday
Cloudy with scattered flurries up to 5 cm. 15 to 30 km/h southwest ridgetop winds. Treeline temperature -3 °C. Freezing level 1200 m.
More details can be found in the Mountain Weather Forecast.
