Significant uncertainty surrounds snowfall amounts on Wednesday-Thursday. If you see more than 25cm fresh snow, danger ratings will be CONSIDERABLE. Limit your exposure to cornices when it's cloudy and completely avoid them when it's sunny.
Confidence
Low - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
There's significant uncertainty surrounding precipitation on Wednesday-Thursday (wide range given), and then some clearing for Friday. WEDNESDAY: Flurries late morning into the afternoon (5-10cm). Moderate southerly ridgetop winds. Freezing level around 1700 m.THURSDAY: Snow continues Wednesday overnight with 5-20cm possible by Thursday afternoon. Moderate southwest ridgetop winds. Freezing level around 1900 m.FRIDAY: Clearing Thursday overnight and then cloudy by Friday afternoon. Strong southwest ridgetop winds. Freezing level around 1800 m.
Avalanche Summary
On Tuesday, two recent storm slab avalanches (35cm crown, Size 2) were observed in steep north facing terrain near Elkford at 2400m elevation.
Snowpack Summary
Over the past few days, 15-30cm of new snow fell above treeline with southerly winds. The sun on Monday & Tuesday made snow surfaces moist and unstable during the day, but it should stabilize quickly after an overnight refreeze (in most areas forming a crust on all aspects up to 2300m).Cornices remain large, looming, and are best avoided.The mid snowpack is well settled and continues to transition into a spring snowpack, becoming isothermal at treeline in some areas and below treeline in most areas.The bottom third of the snowpack is composed of weak facets, but this deep persistent weakness has not been reactive for several weeks. That said, a large trigger like a cornice, or rapid warming of the snowpack could potentially trigger this layer.
Problems
Cornices
Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.
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.