Danger is expected to increase with forecast snow and wind. As always, and especially when forecast confidence is low, it's important to supplement this forecast with your own observations. Please post your obs to the MIN.
Confidence
Low - Due to the number of field observations
Weather Forecast
Snowfall starting overnight Tuesday is expected to continue throughout Wednesday with 10-15cm of fresh snow by Wednesday evening. Strong southerly ridgetop winds are expected at the onset of the storm before shifting to light to moderate southwesterlies for Wednesday. Another moderate system is expected to impact the area on Thursday, with a stronger system expected on Friday. Daytime high freezing levels are expected to hover around 1400 m throughout the forecast period.
Avalanche Summary
Reports from Monday include a remotely-triggered, 20-40 cm thick, Size 2 wind slab avalanche on a SE facing alpine slope in Rogers Pass. Check the Glacier National Park Avalanche Forecast for more details.
Snowpack Summary
Recent reports suggest snowpack depth is 150-200cm in the alpine and 100-170cm at treeline. The snowpack below treeline remains below threshold for avalanches, but watch out for early season hazards such as hidden rocks, stumps, and open creeks. 40-70cm of recent storm snow is settling into a cohesive slab over a hard crust. This crust is the primary weakness of concern and is expected to become increasingly reactive as the slab above settles and stiffens. Southerly winds have also formed very touchy wind slabs on lee features below ridetops in exposed terrain. Although conditions have been reported as being quite good, remember that an early season snowpack is inherently weak and requires thorough investigation before stepping out into bigger terrain.
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.