Elevated freezing levels, rapid snow settlement and touchy storm slab formation are leading to increased human triggered and natural avalanche hazard.
Weather Forecast
A band of warm moist air will bring elevated freezing levels (1900m+) and precipitation in the form of both snow and rain to the forecast area today with forecast amounts in the 10cm range. Cooling temps, and upwards of 30cm of snowfall are expected tonight through Wednesday accompanied by moderate SW winds. Look for an increasing avalanche danger.
Snowpack Summary
80cm+/- of new snow since Saturday. Warming temperatures have made for moist surface snow up to 2100m.This will be making for rapid settlement and storm slab formation through all elevation bands. Moderate S'ly winds have formed windslab on alpine lee slopes On solar aspects the late Feb crusts are down 70-120cm in the snowpack.
Avalanche Summary
Numerous natural avalanches occurred in the highway corridor in the last 48hrs. These slides were size 2-3 with several running full path. Avalanche control on Sunday gave numerous large avalanches running to full path. Expect that a widespread natural avalanche cycle has occurred in the back country as well. Freezing levels remain high
Confidence
Timing, track, or intensity of incoming weather system is uncertain
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.