Another chinook! Winds are increasing as well as temps! Watch for fresh storm and windslabs in open wind affected terrain. Also, there may be some decreases in stability on steep solar aspects as temperatures warm up so use caution.
Weather Forecast
A chinook is rolling through the region once again. No new snow is expected and winds are forecast to be strong out of the SW at upper elevations. Skies are expected to be clear so watch for decreases in stability on solar aspects related to the daytime warming.
Avalanche Summary
Only one small sz 1 slab avalanche was observed on Mt Fister (N or Mt Nestor). on a steep E aspect alpine feature. The slide was 20m wide and ran 100m.
Snowpack Summary
A few new cm of snow at higher elevations. Close to 30-35cm of new snow is now overlying the 0123 windslabs/storm snow interface. Mid day on friday the chinook started rolling in, winds increased and storm slabs begin to further develop in Alpine areas sure to the strong SW flow. The snowpack is weak and facetted in lower elevations but above 2000m the midpack gains strength and improves. 140cm on average at TL.
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.