Thursday's danger will be driven by the amount of sun you get in your local area. When the sun is out in full strength, expect natural avalanches including the potential for large persistent slabs. Conservative terrain selection remains critical.
Summary
Confidence
Moderate - Timing or intensity of solar radiation is uncertain
Weather Forecast
Another 5-10 cm of snow is expected Wednesday overnight with strong alpine wind from the southwest and freezing levels at 1200-1500 m. A mix of sun and cloud is expected on Thursday with lingering flurries, moderate alpine wind from the southwest, and freezing levels reaching around 1500 m in the afternoon. 2-4 cm of snowfall is forecast for Friday with a chance of sunny breaks, moderate southwest wind in the alpine, and freezing levels reaching 1500 m or so in the afternoon. Similar conditions are forecast for Saturday with light snowfall, sunny breaks, moderate alpine wind, and freezing levels reaching around 1500 m in the afternoon.
Avalanche Summary
On Tuesday, a size 3 cornice released on a northeast aspect at 2800 m scrubbed down to rock. Explosives released a cornice on a north aspect which triggered a size 3.5 deep persistent slab which stepped down to the November crust and to the ground in places. Explosives also released a size 2 cornice with a small slab and a size 2.5 persistent slab on a south aspect which failed on the mid-Feb crust layer down 120 cm. On Monday, several natural cornices released on north aspects and many triggered storm slabs. One of these triggered a deep persistent slab which failed on basal facets down 100 cm. Over the weekend, several natural storm slabs up to size 3 were reported and a cornice triggered size 3.5 persistent slab avalanche which failed on the February layer down 100 cm.
Click here for photos of some recent avalanches.On Thursday, sun is expected to drive the hazard. If there is are long periods of strong sun, expect sluffing from steep sun exposed slopes, cornices will become weak, and persistent slab avalanches could fail naturally. With the recent avalanche activity and several weak layers within snowpack waking up, it is a time to be very conservative with terrain selection.
Snowpack Summary
40-60 cm of recent storm snow typically overlies the mid-March crust in the south of the region, with smaller amounts in the north. Recent strong winds from a variety of directions formed wind slabs in exposed terrain. On Wednesday, the snow surface was reported to be moist to around 1900 m. The mid-February crust/facet layer is now typically down 100-140 cm and has recently been reactive with many avalanches stepping down to it. The deep mid-December facet layer and November rain crust both still linger near the bottom of the snowpack and a few avalanches stepped down to these layers recently resulting in very large avalanches.
rbuhler,
Avalanche Canada
