Flathead Range & Glacier NP

Slabs of drifted snow again pose the primary avalanche hazard. These will be larger, more dangerous, and more common as you climb higher.  Sticking to slopes sheltered from the wind that are less than 35 degrees is the most straightforward and reliable way of approaching this hazard.

The weather pattern that's dominated the region's weather for the past 10 days continues, so avalanche conditions remain relatively similar from day to day. Monday saw 1 to 5 inches of new snow, less than forecast. The snowfall favored the Flathead Range. Mild temperatures made for a pleasant change from the cold that's dominated the past week. Winds were southwesterly with moderate gusts - enough to move snow - before veering northerly overnight and decreasing. 

The winds were strong enough to move snow at mid and upper elevations, layering another generation of wind slabs onto a stack of existing slabs. Mark found that Monday's winds drifted snow into fresh slabs in the Lake McDonald area. These were 3 to 6 inches thick and notably softer and more reactive than older slabs below them. He was on a typically windward or crossloaded aspect. A rider near Stryker Peak also reported blustery winds and swirling snow on windward aspects, with winds feeling less strong higher and on the leeward side. The weekend's observations included numerous reports of drifted snow, cracking in wind-affected snow, and several triggered and natural avalanches involving wind-blown snow. The largest of these occurred at upper elevations on the lee (easterly) side of the Flathead Range. 

So similar conditions and travel advice to many recent days: reactive soft slabs large enough to bury or injure you on isolated slopes at upper elevations. Stubborn older slabs masked by a few inches of low-density snow, or softer slabs. Smaller slabs at mid-elevations and cross-loaded onto usually windward aspects by northerly and easterly winds. Pay close attention to the feel and texture of surface snow. Due your due diligence before committing to terrain steeper than 35 degrees. Variable snow depths on windward slopes make for more potential trigger points.

Multiple observations over the past week have highlighted layers of soft, weak snow 10 to 18 inches below the snow surface. These sometimes propagate in snowpack tests. No one has yet reported triggering a slide on these layers. It's worth checking for these potential failure planes using hand pits, test slopes, and column tests before launching onto steep slopes.