Monitor for snow that feels dense or "slabby" from exposure to wind. Seek out sheltered areas where powder prevails!
Strong southwest winds during the recent storm drifted the new snow into dense slabs on leeward terrain features. These wind slabs may remain possible to human trigger, particularly near ridge-crests and roll-overs.
Sunday night: Decreasing cloudiness, no new snow expected, light northerly winds, low treeline temperatures near -6 C, freezing level around 300 m.
Monday: Sunny, no new snow expected, light northerly winds, high treeline temperatures near -2 C, freezing level around 400 m.
Tuesday: Increasing cloudiness, isolated afternoon flurries with trace accumulations, winds becoming southwest and increasing to strong, high treeline temperatures near 0 C with an above freezing layer between 1000-1500 m.
Wednesday: Mostly cloudy, 10-20 mm of precipitation, falling as snow above 1400 m, strong southwest winds, treeline temperatures cooling from 0 C to -2 C, freezing level dropping from 1500 to 700 m.
On Saturday, operators reported several small (size 1-1.5) human and explosive-trigged avalanches on north and west aspects at treeline elevations that released in wind-drifted areas.
It remains possible to trigger wind slabs on lee terrain features, such as down-wind of ridges and roll-overs. See this MIN report from the Mt. Washington area for a helpful illustration of this problem in local terrain.
Premium snow quality continues with cold, clear weather in the aftermath of the storm. The mountains picked up 20-50 cm of snow over the weekend, with higher totals accumulating in the southwest of the region. A gradual temperature rise may have formed a crust layer within the storm snow in areas below 1000 m in the northern half of the region and closer to 1200 m in the southern half.
Strong southwest winds during the storm had an ample supply of snow to drift into reactive slabs. Winds have since shifted to the north and decreased to very light, but these wind slabs may remain possible to human trigger, particularly near ridge-crests and roll-overs. If you are increasing your exposure to avalanche terrain, do it gradually as you gather information. Monitor for changing slab conditions as you move into wind-exposed terrain and pay attention to cracking or hollow sounds. Seek out softer conditions in wind-sheltered terrain.
Below a meter of snow from mid-December storms, two crust layers can be found that formed in early December. Small facets (sugary snow) had been reported near these crusts that are likely trending unreactive. Below these crust layers, the snowpack is generally well-settled. Early season hazards such as rocks, stumps, and open creeks remain at lower elevations.
