Watch for isolated pockets of wind slab at upper elevations, and minimize your exposure to cornices.
New snow and strong southwest to northwest wind may form fresh wind slabs. They will be most likely be isolated to immediate lees of ridgecrests and roll-overs at upper elevations.
Loose-dry sluffing may occur from steeper slopes and terrain features, especially if the sun comes out, and in locations that receieved higher snowfall amounts.
Cornices are especially fragile this time of year, especially when the sun is out. Cornice falls are dangerous in their own right and they can also trigger slabs on slopes below.
Wednesday Night: Cloudy with snow up 5-10 cm. Ridgetop wind moderate from the West. Alpine temperatures near -9 and freezing levels valley bottom.
Thursday: Mix of sun and cloud with isolated flurries. Ridgetop wind moderate to strong from the northwest. Alpine temperatures near -8 and freezing levels 1400 m.
Friday: Mix of sun and cloud with flurries near 5 cm. Ridgetop wind strong from the southwest. Alpine temperatures near -8 and freezing levels 1400 m.
Saturday: Mostly cloudy with some sun and 5 cm of snow. Light to moderate West wind and freezing levels 1700 m.
On Tuesday, wet loose pinwheels were reported from steep solar aspects.
The weather pattern is spring-like which can bring intense periods of solar radiation and convective power flurries. Get after it early before daytime warming kicks in and solar radiation weakens the snowpack and cornices. Loose surface avalanches within the new snow may occur from steeper slopes and terrain features, especially if the sun comes out.
Stay well back from ridgetops that are corniced and avoid slopes with overhead cornice exposure especially under the current conditions where recent rapid growth and daytime warming has made them large and fragile.
5 cm to 10 cm of new snow fell across the region. Shifting wind directions from the southwest to northwest could form isolated pockets of wind slab on leeward slopes and behind terrain features. A series of melt-freeze crusts exist on all aspects below 1900 m and solar aspects to mountain top. North aspects in the alpine hold dry wintery and wind-affected snow. The mid-pack is generally strong and consolidated.
A widespread crust layer from the mid-March warm spell can be found 30-60 cm deep, and a small surface hoar and facets have been observed at this depth on some isolated north-facing slopes. Reports suggest the snow is generally well bonded to these layers but isolated instances of large solar-triggered slab avalanches running on the crust have been observed. The early November crust is buried down 180-200 cm and has faceted crystals above and below it. This is currently dormant but something to keep in mind during the next big warm-up.
