Swan Drive

We have seen few observations from the Swan Range lately, but wind chills today were dangerously cold. So, I took a drive along the Swan's western slope to look for recent avalanche activity, wind affect, and the snow surface on slopes accessible from the road. I stopped under the western side of the Apgar Range and found similar conditions there as well.

• Flat light and clouds socking in the crest made for poor visibility. However, a period of sun mid-day allowed me to spot a small natural wind slab avalanche that likely failed last night when the winds were sweeping over and across the Swan from the east. See avalanche tab for more details.
• Snow, or lack thereof, in the trees and obviously drifted snow visible through my binoculars told the complex story of shifting winds in the Swan over the past 2 days.
  • At middle elevations, especially further south, many slopes typically scoured by westerly winds still had snow in the trees (on northwest, west, and southwest aspects).
  • Snow was absent from trees on most lower-elevation slopes. I expect that this is because of the winds hitting from multiple directions over the course of 2 days.
  • From what I could see of upper elevations, cornices on typically leeward (northerly) slopes were still cantilevered over their usual slopes. But, some northerly slopes were scoured near rollovers and ridgelines, and some small cornices have developed over west- and southwest-facing slopes.
• I stopped to check on several wind-affected road cuts at lower elevations.
  • Wind-affected snow was widespread at lower elevations. Ripples, scalloped texture, and small wind lips pointed to recent winds rushing down the Swan front, and funneling through east-west canyons towards the Flathead Valley.
  • The drifts I found were mostly soft (F+), almost too soft to hold in my hand. Those that were stiffer (1F) were only firm for the first few feet down-wind of rollovers and trees.
  • Slabs did crack around my boots, but nothing slid downslope.
  • The thickest slabs I found were 6-12 inches just below mini ridgelines. These tappered to just a few inches 5-10 feet down slope.
  • Thin, soft wind slab and wind skins sat atop 3-5 inches of very low-density storm snow. Under that, a decomposing crust and large sugary facets.