Weekly Recap
Friday 1/17/20 - Thursday 1/23/20
This week on As the World Terns: By FAC Intern Rob Millspaugh. Video by Clancy Nelson Here
Winds gusting near 40 mph last Friday drifted the abundant loose snow into windlslabs. Throughout the day observers reporting roughly two dozen intentionally and unintentionally triggered D1 slides. Windslab remained a concern through the weekend until the arrival of a high pressure ridge brought rising temperatures and calming winds. We set a season-best record for days without a new crust. That streak lasted until Martin Luther King Day, when observers reported a rain crust of variable thickness at most elevations and aspects. In places this crust was topped with surface hoar and/or facets. Also concerning was how weakly the crust adhered to the loose snow below it. This structure could be troublesome where it is not destroyed by warming temperatures or rain. Speaking of warming temperatures: Loose Wet returned to our list of avalanche problems from 1/20 - 1/21 as temperatures climbed above freezing. However, valley inversions and cloud cover resulted in less activity than anticipated. Good visibility yielded more reports of large persistent slab avalanches in the Flathead Range which likely ran during the 1/12-1/13 cycle. The weak layers responsible for these slide fared better during this week’s thaw. Precipitation in the last week has been incremental with the exception of 1.1 inches of SWE at Stahl Peak on 1/22. Winds picked up again midweek bringing a new crop of windslabs and the threat of rain on snow caused Loose Wet to remain a concern.
