Freezing levels are expected to climb to 2900m today. Warm temperatures will weaken the snowpack and increase avalanche hazard at all elevations.
Weather Forecast
Cloudy and dry conditions today with a stationary warm air mass over the area. Freezing levels are expected to climb to 2900m this afternoon. Precipitation begins this evening with 6mm of rain for the overnight period. Daytime temperatures remain warm over the weekend with modest cooling at night and strong SW winds. 14 cm of snow for Sunday.
Snowpack Summary
Overnight winds have created wind slabs on high elevation northerly aspects. Warm temperatures prevented an overnight re-freeze leading to moist surface snow below 2100m. Above TL, up to 70cm of snow sits over several persistent week layers in the form of crusts, surface hoar and facetted layers which are reactive to light loads such as skiers.
Avalanche Summary
Yesterday a field team on Mt Abbott observed several loose snow avalanches up to size 2.0, running in steep alpine terrain during the warmest part of the day. Two size 2.0 moist avalanches were observed in the highway corridor running on Mt MacDonald, on the east side of Rogers Pass.
Confidence
Freezing levels are uncertain
Problems
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.
Loose Wet
Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.