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Confidence
Fair - Due to the number of field observations
Weather Forecast
The current ridge of high pressure will persist through Wednesday bringing a mix of sun and cloud. On Thursday and Friday, however, a weak disturbance will track across the region, although only light amounts of snow and overcast skies are expected. Freezing levels should hover around valley bottom for the period with ridge top winds remaining generally light from the northwest.
Avalanche Summary
On Monday, several loose wet avalanches to size 2 occurred on sun-exposed slopes. We also received a report of a size 2.5 deep persistent avalanche which was triggered by a cornice fall. With a general cooling pattern forecast for the next few days, I would expect avalanche activity of this nature to taper-off.
Snowpack Summary
Light amounts of loose dry snow (5-20 cm) cover 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. Wind slabs may still be reactive in high elevation lee terrain from recent northwest 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
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.