The March sun packs a punch and can quickly destabilize the snowpack. Avoid sunny slopes or overhead hazards like cornices during the heat of the day.Wind slabs may be primed for human triggering at upper elevations.
Moderate to strong southwest winds and 40 cm of recent storm snow have formed reactive wind slabs on lee slopes at treeline and above.
There are several crusts in the mid-snowpack. Their depth ranges from 50-150+ cm. A large trigger, such as a cornice fall or a smaller avalanche in motion, could trigger a very large avalanche on one of these deeply buried weak layers.
Glide slabs are unpredictable and may release during the warming.
Strong solar radiation and rising freezing levels will weaken the surface snow creating wet loose avalanches on all aspects up to 1600 m and to ridgetop on steep solar slopes.
No new reports on Wednesday.
On Tuesday, a natural size 2 wind slab and size 3 glide slab were reported both around 1300 m to 1500 m. A skier-triggered storm slab was also reported on Zoa. The slab was a size 1.5 and was triggered near the top of the slope with no involvement. It was 40 cm deep and slid clean on the underlying old snow surface. Check out the MIN HERE. Thanks for the report and happy to hear everyone was ok.
A natural persistent slab size 3 was reported on Tuesday but it's suspected that it failed Monday during the storm. This avalanche happened on a shady aspect at 1800 m, with the failure plane unknown but suspect an early March interface.
Natural and human-triggered avalanche activity may occur through the weekend with rising freezing levels and solar radiation.
Daytime warming and solar radiation will promote moist snow surfaces, destabilizing the upper snowpack on all aspects up to 1600 m and to ridgetop on solar slopes. Strong southwest winds may have formed reactive wind slabs at higher elevations and cornices loom over ridgelines.
The recent 40 cm of storm snow overlies a variety of old snow surfaces, including a sun crust on solar aspects, a melt-freeze crust at lower elevations and a spotty surface hoar in sheltered locations. Reports indicate that the slab may poor bond to the underlying crust, especially around 1500 to 1800 m.
Additionally several crusts in the mid/lower snowpack. Their depth ranges from 150 to 250 cm. The mid and lower pack is generally settled and bonded in thicker snowpack areas, with a lingering concern for these deeper buried interfaces in shallower snowpack areas.
Thursday Night
Clear with some cloudy periods. Alpine temperatures near -2. Wind southeast 20 km/hr and freezing level valley bottom.
Friday
A mix of sun. Alpine temperatures near +4. Winds south 15-30 km/hr. Freezing level 1800 m.
Saturday
A mix of sun and cloud. Alpine temperatures near +5. Wind southeast 10-30 km/hr. Freezing level 1800 m.
Sunday
Cloudy. Winds 10-20 km/hr from the southeast. Alpine temperatures near +6 with freezing levels 2000 m.
More details can be found in the Mountain Weather Forecast.
