Brief sunny breaks can rapidly increase danger levels on southerly aspects. The mid-February sun has some punch to it.
Weather Forecast
Mainly cloudy today with isolated flurries, light to moderate SW winds, and alpine highs of -5*C. The sun may pop out for brief periods so expect warmth with its appearance. Freezing levels rising to 1500m by the afternoon. Flurries tonight bringing up to 5cm of snow, then a slightly cooler Monday with isolated flurries.
Snowpack Summary
20-40 cm of storm snow sits on top of a strong temperature or sun crust. At higher elevations where sheltered from sun and wind, the storm snow buried surface hoar. Mod to strong south winds have formed windslabs at ridgetop. At lower elevations, the rain-soaked upper snowpack has frozen into a crust on the surface.
Avalanche Summary
No new avalanches observed yesterday. Whumphing and cracking was observed in the alpine along shallow, faceted S/SW aspects at ridge-top. The cooler temp's have ended the natural avalanche cycle from several days ago, where avalanches were generally in the size 2-2.5 range, with lots of activity at lower elevations.
Confidence
Timing or intensity of solar radiation is uncertain
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
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.