Expect to see sunny breaks over the next few days. Brief periods of solar radiation could be enough to trigger stubborn persistent slabs or cause cornice failures. Conservative route selection remains crucial at this time.
Summary
Confidence
Fair
Weather Forecast
Light flurries Sunday morning are expected to taper off early in the day. A weak ridge of high pressure will build Sunday night and should persist for most of Monday. Some weak disturbance may bring light flurries for Monday night but Tuesday is expected to be mainly dry. The next organized system is expected Tuesday night or Wednesday morning. Freezing levels during the forecast period are expected to be higher in the southern part of the region.Sunday: Mostly cloudy, flurries 0-2cm, freezing level am: surface pm: 800-1200m, ridgetop wind: light NWMonday: Mostly sunny, freezing level am: surface pm: 700-1000m, ridgetop wind: light variableMon. Night/Tuesday: Flurries overnight 3-6cm, freezing level am: 600m pm: 1800m, ridgetop wind: light SW
Avalanche Summary
Reports from Friday include natural storm slab activity up to size 2 on south facing slopes triggered during the afternoon sun. Several human-triggered and explosive-triggered storm slabs up to size 2 were also reported. These avalanches were typically releasing 15-30cm deep within the storm snow. In the North Columbia region, several avalanches were stepping down to deeper layers.Generally, we are still seeing relatively small inputs, like periods of strong winds or brief sunny breaks, trigger deeper persistent slab avalanches. Many of these events have occurred on southerly aspects from slopes in the alpine or at treeline. Extra caution is advised when the sun is out.
Snowpack Summary
Recent storm snow has settled into a 40-60cm slab that sits on the mid-March interface, which is commonly described as a sun crust/surface hoar sandwich. Recent snowpack tests suggest that the reactivity of this layer is becoming more isolated but many areas still have the potential for human-triggering. Periods of gusty SW-NW winds have redistributed some of the new snow forming soft wind slabs in exposed lee terrain.The early March persistent weak layer, which is a crust mixed with facets or surface hoar in places, is now down around 80-120 cm. This layer has been most reactive on southerly aspects. The mid-February crust/facet/surface hoar layer is widespread throughout the region, but the depth varies significantly. It still producing sudden "pops or drops" results in snowpack tests where it is less than 150 cm deep. The biggest concern with this interface is being able to trigger it where it is less deep and having it propagate into thick snowpack areas producing very deep and large avalanches. Cornices are also large and fragile at this time and could pop off during sunny breaks.
rbuhler,
Avalanche Canada
