Avalanche Forecast
Issued: Dec 28th, 2024 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs.
Avalanche Canada,
Avalanche Canada
Information on lingering storm instabilities is still in short supply, so bring an assessment mindset with you on Sunday. Wind slab sitting on near-surface crust is the most likely problem.
Summary
Confidence
Moderate
Avalanche Summary
No new avalanches were reported on Friday.
Explosives control in the Mount Washington area produced several more size 1.5 - 2 wind slabs in west-facing terrain Thursday.
Numerous size 1 - 1.5 slabs were seen throughout north-facing terrain in the same area Wednesday as well as a size 2 storm slab triggered accidentally by a skier walking along a ridgeline. An island-wide large avalanche cycle took place during the height of the Christmas storm.
Snowpack Summary
Warm temperatures or rain should create a surface crust below about 1400 m and otherwise aid in the rapid settlement of 50 - 80 cm of new snow since Dec 24; 10 - 30 cm of this came Friday night through Saturday. In exposed areas, strong winds have led to a wide-ranging 0 - 200 cm sitting on the pre-storm crust!
Drier snow at higher elevations has likely remained more available for wind transport and should be investigated carefully for the presence and reactivity of wind slabs.
Below the new snow, the snowpack is thoroughly settled and bonded.
Snowpack depths at treeline are now about 130 -180 cm on the north and south island, closer to 250 to 300 cm on the central island.
Weather Summary
Saturday night
Diminishing cloud and easing flurries with minimal accumulations. 20 to 50 km/h southwest ridgetop wind shifting southeast and easing. Freezing level 1000 m.
Sunday
Mainly cloudy with scattered flurries bringing up to 5 cm of new snow in the afternoon/evening. 20 to 40 km/h southeast ridgetop wind shifting southwest and increasing. Freezing level falling from 1100 m to 800 m in the afternoon.
Monday
Mainly cloudy with isolated flurries after less than 5 cm accumulation overnight. 10 to 30 km/h southwest ridgetop wind. Freezing level 800 m to 1000 m.
Tuesday
Cloudy with flurries bringing up to 10 cm of new snow. 40 to 60 km/h southeast ridgetop wind, increasing. Freezing level 700 m to 900 m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Be alert to conditions that change with elevation, aspect, and exposure to wind.
- Watch for newly formed and reactive wind slabs as you transition into wind-affected terrain.
- Avalanche activity is unlikely when a thick melt-freeze crust is present on the snow surface.
Problems
Wind Slabs
Strong southwest winds have been moving dry snow at higher elevations into wind slabs that may still react to a human trigger on Sunday.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 29th, 2024 4:00PM
