Keep an eye on the temperatures on Monday. Solar radiation and rising freezing levels can weaken the snowpack and make destructive avalanches more likely.
Confidence
Fair - Timing or intensity of solar radiation is uncertain on Monday
Weather Forecast
The dry ridge will persist throughout the forecast period bringing a mix of sun and cloud until Wednesday. Winds will generally remain light from the northwest, although strong gusts are likely on Tuesday. On Monday we can expect an inversion with above-freezing alpine temperatures. Freezing levels will hover around 1500m on Tuesday, and then drop to about 800m on Wednesday.
Avalanche Summary
Avalanche activity has gradually tapered off throughout the past week, although there has been some wind slab activity to size 1.5 at higher elevations over the weekend in response to northwest to northeast winds redistributing recent snow accumulations. Looking forward, wind slabs may remain sensitive to human triggering, while loose wet avalanches may fail under sunny skies and rising freezing levels on Monday.
Snowpack Summary
Up to 10 cm of recent snow covers the previous variable snow surface of surface hoar, crusts, dry facetted snow, or wind affected snow depending on aspect and elevation. The "Valentine's Day" crust is just below the surface and is now strong and thick in most places. New wind slabs may have formed in lee terrain from recent W-NW winds, and cornices remain large and weak. The late-Jan crust/surface hoar layer (up to 100 cm deep) and the mid-January surface hoar (80-120 cm deep) are generally dormant, and chances of triggering these weaknesses have decreased. However, triggering may be possible with a large input such as cornice fall, or an avalanche stepping down, especially on sun drenched slopes.
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.