Forecast precipitation and wind will drive the avalanche danger to High in the alpine on Monday. Due to a very limited number of information sources at this time of year, this report is based off of weather forecast information only.
New snow accompanied by moderate to strong southerly winds Sunday night and Monday will promote storm and wind slab formation. Snow amounts may increase rapidly with elevation as the freezing level fluctuates during the storm.
Rain at lower elevations will weaken the surface snow layers and increase the likelihood of sluffing in steep terrain where there is still enough snow to avalanche i.e. treeline and the upper end of the below treeline elevation band.
SUNDAY Night: Snow at upper elevations, accumulation 10-20 cm / moderate to strong south wind / alpine temperature -2 C, freezing level 1000 m
MONDAY: Snow at upper elevations, accumulation 10-15 cm / moderate to strong southwest wind / alpine high temperature 0 C / freezing level 1200 m
TUESDAY: Mainly cloudy with scattered flurries and sunny breaks / moderate southwest wind / alpine high temperature -4 C / freezing level 800 m
WEDNESDAY: Cloudy with sunny periods / light to moderate west wind / alpine high temperature -3 / freezing level 900 m
No new avalanches have been reported in the region. Expect to see an increase in storm slab activity with snowfall and wind at upper elevations along with increased wet loose avalanche activity at lower elevations associated with rainfall there. Please submit your observations to the Mountain Information Network.
Expect to see an additional 10-20 cm of new snow in the alpine on Monday morning to add to the 20-40 cm of snow that fell through the last week at upper elevations. More precipitation will accumulate throughout the day on Monday. Moderate to strong southwest winds are expected to have formed reactive wind slabs. This new snow sits on a melt freeze crust except for high elevation north aspects. It is likely that the most recent precipitation is falling as rain 1000 m and below.
A crust that formed in early April is down 30 to 100 cm on high elevation north facing slopes. Surface hoar and facets were previously observed on this crust and it recently produced sudden results in snowpack tests. At lower elevations, ongoing warm weather has been promoting isothermal snowpack conditions and melting the snowpack away.
