Overnight freezing level change, rain and snow leaves uncertainty over how the snowpack will react.
During times of uncertainty lean on a conservative approach to terrain, cautious mindset and constantly make observations while you travel.
Cornices have grown large during the recent storms and may remain weak from warm temperatures. Falling cornices are hazardous and may trigger slabs avalanches on the slopes below.
Up to 40 mm of wet snow or rain will add to previous storm totals of 60-100 cm sitting on a reactive crust that has produced large avalanches in the last 3 days. A natural cycle is likely overnight during peak precipitation.
Storm snow is expected to be sensitive to human triggers and avalanches may involve the most recent snowfall, or the settling storm snow from the past week.
THURSDAY NIGHT: Freezing levels fall from 2500 m to around 1200 m by morning. Precipitation begins as rain and transitions to snow. 30-40 mm is forecast with strong to extreme southwest winds.
FRIDAY: Mostly cloudy with continued snowfall 10-15 cm. Freezing levels remain around 1200 m. Moderate westerly winds.
SATURDAY: Mostly cloudy with flurries of up to 5 cm. Freezing levels around 800 m. Moderate westerly winds.
SUNDAY: Clearing skies with scattered flurries possible. Freezing levels remain below 1000 m. Light westerly winds.
High freezing levels and a mix of rain and snow overnight are expected to produce a natural avalanche cycle.
On Wednesday, several natural and rider triggered storm slab avalanches were reported on all aspects to size 2. Previous natural activity from the storm was observed to size 3. Several cornice falls were also reported, some triggered slab avalanches on the slope below. Most avalanches have failed on the buried crust from late March.
On Tuesday, rider, natural and explosive triggered avalanches were reported to size 2.5. Small avalanches were also remotely triggered, indicating the sensitivity of the recent storm snow.
Up to 40 mm of precipitation overnight with falling freezing levels will create a mixed bag of conditions on Friday, as snow continues to accumulate.
High elevations can expect up to 40 cm of fresh wind affected storm snow, that will likely be redistributed into deeper deposits on north and east facing slopes over a crust or moist snow. Another widespread and supportive crust is buried 60-100 cm deep, below recent settling storm snow. This crust has recently been very reactive to human and natural triggers.
Snow will transition to mixed precipitation and rain as elevation decreases. The lowest elevations will likely hold wet surface snow or a crust from heavy overnight rainfall.
The middle and lower snowpack are generally strong and well bonded.
