Confidence
Fair - Freezing levels are uncertain on Wednesday
Weather Forecast
Synopsis: Northwesterly flow will bring a series of low-intensity pulses of precipitation interspersed with short-lived periods of clear weather to the region through the forecast period. Temperatures will start out fairly cool but become mild on Wednesday.Tuesday: Mainly dry during the day. Temperatures around -10C. Northwesterly winds, gusting to 30km/h at ridgetop.Wednesday: Light snowfall, up to 5cm. Treeline temperatures rising to around -1C. Northwesterly winds gusting to 50km/h at ridgetop.Thursday: Dry and bright. Temperatures rising through the day with the possibility of above zero temperatures at treeline in the afternoon. Generally light northwesterly winds.
Avalanche Summary
Explosive avalanche control on Monday produced loose avalanches that ran on the upper surface hoar layer and deeper slab avalanches (up to 100 cm deep) that ran on basal facets on very steep north-facing alpine slopes. There have been no natural avalanches reported since the small cycle (up to size 1.5) on Thursday and Friday last week.
Snowpack Summary
Recent storm snow amounts over the past few days are 30 to 40 cm with as much as 60cm reported. Over the weekend, this low density storm snow started to settle into more of a cohesive slab, although little activity was reported through the weekend. Below the new snow is a suncrust on steep southerly facing slopes and a surface hoar layer at treeline and lower elevations (but it has a patchy distribution). Early January surface hoar is now around 60 - 80 cm deep and is reported to be patchy. It is most likely to be preserved on shady slopes below treeline.
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.