An upslope (NE flow) storm starts tonight giving us a 10-15 cm refresh of snow by Monday afternoon with a cooling trend. Expect smallish fresh windslabs that trigger easily and note the date (Jan 30), because a new weak layer is getting buried now.
These are new windslabs formed overnight on Sun and associated with the new snow. We expect them to be thin (ie: < 25 cm) but very sensitive to triggers as they bury a new weak layer. This is different from the windslabs described in previous days.
This problem represents both the Dec. 2nd crust/ facet layer (treeline and below) and the late December facet layer. Lots of variation in the sensitivity ranging from reactive sudden collapse to no results depending on location, aspect and elevation.
Winds shift to a NE upslope flow overnight on Sunday with 10 cm expected by Monday morning under cooling temperatures as a cold front crosses the area making for blustery conditions. This should clear out by the end of Monday, leaving a maximum of 15 cm of snow in its wake. Temperatures continue to drop until Wednesday morning.
10cm of new snow under an upslope flow will produce small, fresh windslabs and surface instabilities that bond poorly to the underlying surface of crust and facets (hint: new weak layer getting buried). Expect easy triggering of thin slabs. This storm is unlikely to wake up the deep facets, but they continue to lurk anywhere from 100-150 cm deep.
No new avalanches observed or reported on Sunday. Over the past week we have received reports and observed a few avalanche to size 3 on the persistent weak layer. All of these avalanches were triggered by large loads (cornice).
