Danger could be LOW below treeline in the Cascades where heavy rain saturated the snowpack and has probably refrozen into a solid crust.
Summary
Confidence
Moderate - Due to the number of field observations
Weather Forecast
Saturday: Cloudy with sunny breaks. The freezing level is around 600 m and winds are light from the W-SW. Sunday: Cloudy with sunny breaks and a chance of flurries. The freezing level is at 500 m and winds are light from the S-SW. Monday: Cloudy with sunny breaks and a chance of flurries. The freezing level remains near 500 m and winds rise to moderate from the S-SW.
Avalanche Summary
Observations were quite limited during the storm on Thursday; however, a large and widespread avalanche cycle was very likely in most places. In the Coquihalla, a widespread cycle was observed with most avalanches being size 2-2.5 at treeline and in the alpine. At least one size 3 was reported with very impressive propagation. To the north (Upper Lillooet River), a widespread cycle was reported below treeline with avalanches up to size 2.5 being observed. I suspect we will hear more about this cycle in the next day or two.
Snowpack Summary
So far, 30-50 cm of new snow has fallen since Wednesday night. The snow line may have gone up to ridge top in the south, but only 1400-1600 m in the north. Expect dense new wind and storm slabs, and fresh cornice growth at upper elevations. Heavy loading from snow and rain, and the resulting avalanche cycle, may have flushed-out the mid- and early-January surface hoar/facet layers that were initially buried 30-50 cm deep. However, don't rule these layers out right away. It may still be possible to trigger shallow slopes that did not release naturally. The mid and lower snowpack is generally strong, with the exception of shallower snowpack areas that may be more faceted.
pmarshall,
Avalanche Canada
