Regions
Northwest Inland.
Confidence
Fair - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
A Pacific frontal system will arrive on the North Coast Tuesday morning. While the coast can expect substantial precipitation for Tuesday and Wednesday, it does not look like much will push into the inland region. Thursday is expected to be dry.Tuesday: Snow or rain 2-4mm, freezing level 300-600m overnight, 1400m afternoon, ridgetop winds 50-70 km/h SWTues. Night/Wednesday: Snow or rain 3-6mm, freezing level 1400m overnight, 1200m in the afternoon, ridgetop winds 50-70 km/h SW, easing in the afternoonThursday: A mix of sun and cloud, dry conditions, freezing level 400m overnight, 1000m afternoon, ridgetop winds light SW-W
Avalanche Summary
Numerous natural (to size 2.5) and skier controlled avalanches (to size 2) were reported on Saturday. Most of these released on the recently buried snow surface, but some may have stepped down to the mid February layer. There was also a report of several remotely triggered avalanches. No new avalanches were reported on Sunday but widespread whumpfing was reported suggesting that prime conditions for triggering avalanches still exists. Snowpack test results are also showing the potential for human-triggered avalanches which have the potential for good propagation.
Snowpack Summary
Around 20-50 cm of dense storm snow now sits on a layer of surface hoar and/or a thick layer of facetted snow on shady slopes at all elevations, a sun crust on steep solar aspects, and various wind affected surfaces in exposed terrain. Strong southwest winds have created dense wind slabs on exposed lee slopes and in cross-loaded features. The early February weak layer of facets, crusts, and surface hoar is buried down about 70-120 cm. There is no new info on this weak layer, but I suspect it remains active in many areas. Basal facets and depth hoar remain a concern in areas with thin or variable snow cover.
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.