Forecaster Observation - Wahoo Creek, Flathead Range

We traveled in the drainage of Wahoo Creek, located in the Flathead Range of the Middle Fork corridor.  Objectives for this tour were to note snow pack coverage, recent wind loading/distribution, evidence of recent storm slab avalanches and weak snow distribution. 

• As expected, coverage at low elevations was thin with numerous downed trees and brush obstructing our ascent and descent. We were surprised to find that the coverage was not much better as we gained elevation. Elevations up to 5700' harbored plenty of vegetative obstacles. We attributed this to both the majority of the snow that we have received this season as being low density and that we have not yet had a major avalanche cycle. Therefore, there is not enough weight in the overlying snowpack to "lay down" the infamous brush fields of the Middle Fork.
• Recent winds had affected the snow at all elevations. This was also a surprise to us because this drainage is fairly sheltered and heavily treed. Thin wind slabs were found at all elevations in any terrain that had openings. These slabs were often found overlying weak snow and would easily break beneath our skis on both our ascent and descent. These slabs did not have the energy to propagate in locations that we traveled. However we did not test large leeward slopes which would have retained this energy more than our relatively sheltered locations.
• Numerous storm slab avalanches that occurred Thursday night/Friday day were observed at low and mid elevations. These were thin (4-6") and did not propagate wide (10-30' on average). The sheer number of them was impressive. This avalanche cycle was the result of warmer denser snow (e.g. Big Mountain cream) falling on top of a layer of low density snow (e.g. cold smoke).
• At low elevations the snowpack consists almost entirely of relatively weak low density snow.  In many of these locations the basal layer consists of depth hoar and the pack is generally unsupportable and punchy.  Mid and upper elevation locations not affected by wind revealed thick layers of weak snow. In wind affected locations, numerous generations of wind slabs, along with occasional layers of weak snow, make up the upper pack. In some of these locations the basal layer consists of depth hoar.