Avalanche forecast

Flathead Range & Glacier NP

Flathead Avalanche Center
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Avalanche danger

Sun
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

Winter-like conditions make a return appearance to the Flathead. The avalanche danger will rise as today's storm develops. You may find slabs of wind drifted snow reactive to the weight of a rider or snowmachine by this afternoon. In sheltered locations, loose snow slides may occur on a slippery crust.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    Southwesterly winds increased overnight and are strong enough to transport today's forecasted low-density snow. Expect to find thin slabs of wind drifted snow forming on the downwind side of ridgelines and saddles and the sidewalls of cross-loaded gullies. Slabs will thicken as the storm develops and may not bond well to the underlying crust. Cracking and a denser feel to the snow are clues directing you to seek out terrain sheltered from the wind. 

  • Loose Dry

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    A loose dry problem may develop this afternoon on steep slopes sheltered from the wind as snowfall accumulates. New snow may fall onto a crust, inhibiting bonding and allowing slides to travel further than anticipated. These sluffs should be generally harmless except in long-running gullies or on areas above terrain traps. If today's snowfall exceeds forecasted totals, expect this problem to become more widespread. If you plan on stepping out into more aggressive terrain, be ready to manage your sluff. 

Avalanche Discussion

Winter-like conditions return for the closing weekend of WMR. Friday's unseasonably warm temperatures reached the 50s at mid-elevations and 40s at upper elevations. Fortunately, temperatures dipped below freezing around 10:00 p.m. with this morning's low reading of 19F at the WMR summit. Winds increased overnight, which helped cool the snow surface on slopes exposed to the wind. A developing storm will enter our area today into Sunday, with freezing levels dropping toward the valley floor. Snowfall favors the Swan Range and the Flathead Range with gusty west to southwest winds.

We have removed the wet avalanche hazards from today's problems in favor of new snow hazards. Friday morning in the Apgars, I found a supportable surface at low elevations due to an overnight temperature inversion. Unfortunately, this crust thinned, softened, and eventually disappeared around 5000 feet. Several inches of wet, mushy snow comprised the surface except in wind-loaded locations where up to 18" rested on a 12 - 14 inch crust from the late-March heatwave. In places where only a thin crust formed overnight, you could still trigger a loose wet avalanche in the damp snow beneath the crust.

The avalanche danger will rise through the day as snowfall accumulates. The danger is at LOW this morning but should reach MODERATE by nightfall. In locations favored with snowfall overnight, the Swan and the Flathead, the danger may rise to CONSIDERABLE by tomorrow morning. Continued stormy weather may keep the avalanche danger elevated into the middle of the workweek. 

Sunday, April 10, marks the last daily avalanche forecast for the season. This date may change depending on how this week's stormy pattern develops. Otherwise, we'll continue to issue conditions updates as needed into early May. Expect these at least twice a week, though we'll publish more frequently if conditions warrant. We'll post these in the afternoons.

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