A warm and wet storm is developing. Strong winds, a heavy storm load, and rising temperatures are increasing the avalanche danger.
Confidence
Fair - Forecast snowfall amounts are uncertain on Tuesday
Weather Forecast
Overnight and Tuesday: A warm front is forecast to move into the interior overnight bringing cloud and strong Southwest winds. Moderate snow fall amounts are expected to begin by early morning. Freezing levels are expected to rise to about 1000 metres.Wednesday: Continued moderate precipitation overnight becoming heavy during the day combined with strong Southwest winds as the cold arctic air to the North collides with the warm front.Thursday: Unsettled weather with continued light to moderate precipitation and moderate Westerly winds.
Avalanche Summary
One natural cornice fall was reported that released size 2.0 from a Northeast aspect in the alpine.
Snowpack Summary
There is a thin layer of new snow and wind transported snow that is covering a widespread layer of surface hoar that developed during the recent clear weather. Sun crusts also developed during the clear weather on solar aspects up to about 2000 metres. Some areas had strong winds before the surface hoar was buried, so the distribution may be specific to sheltered and shaded terrain features. There is still concern for the buried weak layer of surface hoar from February 12th that is now down more than a metre in most places. The forecast new load of snow and wind may overload this deeply buried weak layer in areas that did not slide after the last storm.
Problems
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.
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.