Dangerous avalanche conditions exist at alpine and treeline elevations. Fresh snow sits over a persistent slab problem, at a prime depth for human triggering large, consequential avalanches.
A crust that formed in early January has been bonding poorly to the overlying snow. With the recent new snow load, this crust is now buried 60 to 80 cm deep, a prime depth for human-triggering as well as large, consequential avalanches.
10 to 30 cm of new snow with strong south wind will form fresh storm slabs at treeline and alpine elevations. Storm slabs will be most reactive where wind has loaded deep deposits into leeward terrain features.
Rain and rising freezing levels will destabilize surface snow and possibly trigger wet loose avalanches in steep terrain.
No recent avalanches have been reported, but there have likely been natural avalanche cycles during the recent storms. Large human-triggered avalanches will continue to be a concern on Tuesday due to a combination of new snow, warming temperatures, and a potential weak layer and crust buried 60 to 80 cm deep.
10 to 30 cm of new snow is expected on Monday night, which will quickly settle and melt as freezing levels rise on Tuesday. Storms over the past week deposited 60 to 80 cm over a slippery crust layer above 1000 m. Rain has soaked the snowpack at lower elevations.
Snowpack depths at treeline are around 100 cm, tapering quickly with elevation to below threshold for avalanches at most elevations below treeline, except for isolated smooth features such as rock slabs and grassy slopes.
Monday night
Periods of snow with accumulations of 5 to 10 cm on the north island and 10 to 20 cm on the south island, rain below 500 m, 60 to 80 km/h southeast wind, treeline temperatures around -2 °C.
Tuesday
Cloudy with scattered flurries bringing another 5 to 10 cm of snow above 1000 m, rain below, 40 to 50 km/h southeast wind, freezing level climbs to 1600 m in the afternoon as treeline temperatures reach 0 °C.
WednesdayMix of sun and cloud in the morning then light flurries starting in the late afternoon, 50 to 60 km/h southeast wind, freezing level drops to 1000 m with treeline temperatures around -1 °C.
ThursdayStormy weather with 40 to 80 mm of precipitation, freezing level climbs from 1000 to 1800 m throughout the day, 70 to 100 km/h south wind.
More details can be found in the Mountain Weather Forecast.
