Weekly Summary
January 16th-22nd
It was the best of times, it was the worst of times. The avalanche danger this week started at considerable and trended down to low. Normally moderate and low conditions after a big storm are a backcountry enthusiast's dream. While everyone is dreaming of powder, the reality is the rain crust from 1/13 has made much of the riding unappealing.
This week we continued to get reports about the avalanche cycle from the storm on 1/13 and the distribution of the crust. Hundreds of D1 to D3.5 avalanches ran. In the Whitefish Range, the crust disappears between 6300’ and 7000'. In the Flathead Range and Glacier National Park the crust reaches up to at least 7000’ and in the Swan, the crust goes above 7000’. Higher than the 1/13 crust, persistent slabs continued to be a concern. There are surface hoar and facet crust combos buried 1’-4’ down in the snowpack creating the structure for a persistent slab. However, these problems have been slowly healing and it has been over a week since there has been a reported slide that failed on these layers.
On Sunday the 17th the region picked up a couple of inches of fresh snow but still kept us thinking, “Please, sir, I want some more”. The Swan range picked up the most and the avalanche danger in that range bumped up to considerable at upper elevations from storm slab concerns. Small natural avalanches were reported in the Swan from this storm slab sliding on the slick 1/13 crust. The winds picked up on Tuesday the 19th pushing around the snow from Sunday creating wind slabs at upper elevations. These new wind slabs kept the avalanche danger at moderate across the forecast region. Mild temperatures, no new snow, and now stubborn wind slabs, wrapped up the week’s forecast at low.
Next week does not look a lot different from the past two days. The lack of upcoming precipitation, a light breeze, and cold clear nights will create ideal conditions for surface hoar growth and near surface faceting. Reports across the region have already noted facets above and below the 1/13 crust. Change begets change. Nothing propagates so fast. The next storm that comes this way will most likely fall on well developed facets, which sounds like a recipe for disaster.
