The region remains in a lower probability/high consequence avalanche pattern with a snowpack structure that is atypical for this time of year. Conservative terrain selection remains critical.
Summary
Confidence
Fair
Weather Forecast
Monday Night: Convective precipitation amounts are hard to pin down. The region could see 10cm to as much as 25cm above 1000m with very little wind.Tuesday: Scattered convective flurries. Freezing level rising to 1500m in the late afternoon. Very little wind.Wednesday: Winds out of the SW begin to pick up as warm air floods into the region. Look for light SW winds at treeline, potentially strong SW winds at ridgetop. Freezing level should climb to 2000m by late afternoon. 2 to 4mm of rain possible.Thursday: 1 to 5mm of rain. Light SW winds at treeline, strong W/SW winds at ridgetop. Freezing level starting the day at 2000m, climbing to 3000m by the afternoon.
Avalanche Summary
Over the past week, isolated slab avalanches to size 2.5 have been running on the mid-March persistent weak layer. In a few cases, avalanches failed with light inputs such as remote triggers. Recent heavy snowfall and wind prior to the weekend resulted in widespread storm slab avalanche activity to size 2, but it has also added load to these deeper, more destructive layers. On Sunday, numerous large slab avalanches were observed in the Spearhead Range and on Ipsoot Mtn. The mid-March interface was the suspected culprit in most of these events. See this observation for a good visual: http://bit.ly/1CS2Nld http://bit.ly/1CS2Nld
Snowpack Summary
Deep and dense new storm slabs have formed in response to steady wind, snowfall and warm temperatures prior to the weekend. At lower elevations, rain has saturated the snowpack. Cornices may also be fragile. The mid-March persistent weakness has become a serious player. It consists of a variably reactive crust/facet interface that is buried about 100cm below the snow surface. The mid and lower snowpack are generally well-settled and strong.
ghelgeson,
Avalanche Canada
