Flathead Range & Glacier NP

With the weather forecast for today, avalanche conditions remain complex and very dangerous. Large to very large natural avalanches are likely at upper elevations; the debris from these slides could entrain wet snow and run into mid- and low elevation terrain. Wet snow avalanches are likely at mid-elevations. The best and safest travel today is somewhere else.

The limited observations from Monday (all from the Flathead Range) indicate the region saw a widespread cycle of large and very large natural avalanches. Most involved wet surface snow failing on steep slopes, triggered by rain showers, direct sun, and rising temperatures. This before and after image is a good example. Large dry slab avalanches ran on many leeward, upper-elevation slopes. And some very large natural avalanches released on weak layers buried mid-pack, or near the ground. Using the trees in this image, it appears some crowns were over six feet deep. To be clear, those reports are all from the Flathead zone; we have no reports from the other zones. The pattern I see is wet snow avalanches below the rain/ snow line and dry snow avalanches at upper elevations - roughly above 6800 feet.

With temperatures remaining above freezing overnight yet forecast to rise into the 40s even at upper elevations, what can we expect today? To be frank, I'm not sure. This is a new pattern for me, even with 30+ years in the business. My biggest uncertainty - and concern - is conditions at upper elevations. We've seen 2 to 4 feet of new snow above 6500 feet in the past week, often accompanied by powerful winds that drifted it into thicker slabs. Avalanche activity diminishes with an end to precip and diminishing winds - that's basic, right? But we've got rain showers, late-winter sun, and freezing levels rising above the summits of the highest peaks in Glacier NP today. Monday afternoon, brief sunny periods were enough to trigger large natural avalanches in the Skyland area. Check out Lydia's video in the media section to see it happen. 

Here's my best guess: we'll see more natural avalanche activity today at upper elevations. Less than Monday. However, some slides may run from start zones well above 7000 feet, where slabs of new and drifted snow are even thicker and larger than most of what we've seen as of today. So I expect fewer but bigger slides. And the instability could jump rapidly, with a rain showers or a few minutes of direct sun. Westerly slopes may be the most likely to join the party, because late in the day, temperatures will be warmer and direct sun stronger.

In the Swan and Whitefish Ranges, freezing levels have already climbed above all but the highest summits. Wet snow avalanches will be the most widespread hazard; Considerable danger. Keep in mind that the uncertainty is highest in those zones because of the lack of obs.

In the Flthead Range and Glacier National Park, there's still plenty of real estate above freezing levels this morning. Plenty of leeward start zones and upper elevation terrain with dry snow. Given the complexity and the potential for destructive avalanches that run to low elevations, I'll keep the danger at upper elevations at High/ L4 for the Flathead Range. As Mike noted in our discussion this morning, "The safest riding today will be on slopes that slid to the ground with no hangfire." The best riding might be on a bike, even if it's raining. 

All the warming, rain, and meltwater are increasing the likelihood that open glide cracks will fail. Many of these are camoflaged by recent snow. Be alert for rumpled snow surfaces on steep, southerly slopes, particularly in the Swan Range.