Avalanche Forecast

Moderate -

Sunday night: Cloudy with continuing flurries bringing 5 -15 cm of new snow. Winds easing to light westerly.

Monday: Mainly cloudy with isolated flurries and a trace of new snow, continuing overnight. Light northwest winds. Alpine high temperatures around -5.

Tuesday: Cloudy with increasing snowfall bringing 15-30 cm of new snow, continuing overnight. Strong to extreme south or southwest winds. Alpine high temperatures around -3.

Wednesday: Cloudy with isolated flurries and a trace of new snow, 10-20 cm from overnight. Light west winds. Alpine high temperatures around -5.

We don't yet have observations from Sunday's storm in the South of the region, however MIN reports from Thursday and again on Saturday in the Shames area paint a clear picture of recent slab reactivity in specific wind loaded features. These touchy conditions almost certainly ramped up a few notches on Sunday as heavy snowfall and high winds set up a widespread new storm slab problem.

Natural wind slab releases to size 3 (very large) were observed in the Bear Pass corridor again on Sunday morning, the latest in a string of similar morning observations in this part of the region.

Looking forward, the new snow won't have a great deal of time to stabilize before another round of snowfall on Tuesday refreshes our avalanche problems.

About 35 cm of new snow accumulated at the 740 m Shames weather station during Sunday's storm, with a bit more expected to add to this total over Sunday night. Totals are likely a bit greater at higher elevations. Strong southwest winds accompanied much of this snowfall, especially early on.

The new snow buried previously wind affected recent snow in exposed areas and settled storm snow in sheltered areas. Below 1000 metres it has introduced a new hazard but also greatly improved travel on rugged, crusty surfaces. At higher elevations where this crust tapers out, the new snow has added significant load to a couple of deeply buried weak layers that we haven't quite ruled out as problems. The nature of avalanche activity resulting from this storm and again on Tuesday should give some clarity on this uncertainty as we move forward. 

The first and most concerning is a roughly 70-100 cm-deep persistent weak layer of surface hoar buried March 12 on sheltered northerly aspects around treeline. Deeper down, around 100 to 300 cm now overlies another layer of surface hoar (and faceted snow) buried in mid-February that may still be a concern in shallower snowpack areas. Although they haven't produced recent avalanches, professionals in the region have been tracking and treating these layers with caution. If it hasn't already been occurring, there is a chance further loading during Tuesday's storm could result in some step-down activity to produce very large and destructive avalanches.

The mid and lower snowpack is well settled and strong in most areas.

• Continue to make conservative terrain choices while the storm snow settles and stabilizes.
• Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
• Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.