Light snowfall amounts are expected Saturday night, with enhanced amounts in the eastern upslope areas. If you see more than 10 cm of fresh snow by Sunday, increase the danger to MODERATE, and be cautious around developing wind slabs on alpine slopes.
Recent reverse loading associated with easterly winds has created small wind slabs in exposed terrain features and immediate lee of ridges. Solar aspects are features of concern where slabs are poorly bonded to the previous surface due to weak faceted grains that have developed over a thick and supportive melt-freeze crust.
Cornices have grown large recently but are generally not expected to fail naturally with the current and forecasted conditions. However, human-triggered cornices are possible so give them a wide berth when travelling on ridges and watch for signs that they may be weakening if they are exposed to extended periods of sun.
A surface low tracking across Montana is currently spilling over the region with favoured upslope flow. By Sunday, a ridge of high pressure will build over, bringing a drier day. Warmer and closer to seasonal temperatures are expected early next week.
SATURDAY NIGHT : Light snow (2-4 cm) with favoured upslope (up to 10 cm) in eastern areas / easterly wind increasing to 20-40 km/h / treeline low around -10 C / freezing level at valley bottom.
SUNDAY: Partially cloudy / localized snow accumulations (2-4 cm) / moderate southwest wind gusting at 40 km/h/ treeline high around -2 C / freezing level rising to 1600 m and back at valley bottom at night.
MONDAY: Increasing cloudiness / light to moderate southerly wind / treeline high around 0C / freezing level rising to 1800 m and remaining elevated at night.
TUESDAY: Snow at high elevation 5-15 cm / moderate southwesterly wind gusting 50 km / treeeline high around +2 C / freezing level at 1800 m.
Observations are very limited this time of year. On Friday, small loose wet avalanches (size 1) were observed on steep rocky terrain features near Crowsnest due to strong solar input.
Check out the South Rockies field team's MIN from Friday for pictures of current conditions !
Last week, eastern upslope areas of the region received light snow flurries accumulation each day (up to 20 cm). Recent periods of strong wind from the northeast through southeast have redistributed the recent snow in exposed high elevation terrain forming small pockets of wind slabs. A widespread and supportive melt-freeze crust, formed on April 8, is found under the recent snow and / or wind slabs. The middle and lower snowpacks are currently well settled and strong.
