Avalanche forecast

Flathead Range & Glacier NP

Flathead Avalanche Center
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Avalanche danger

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

Congratulations, you're starting the New Year off on the right foot by reading this forecast! This week's shifting winds have left old and new slabs on multiple aspects at and above the treeline. Look for signs of slabs such as cracking or stiff, dense snow before committing to steep slopes. Today's cold weather requires a short and straightforward plan to ensure a safe return.

Avalanche problems

  • Wind Slabs

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

    The past several days have seen shifting winds as Arctic air from the northeast battles our typical westerly flow resulting in several generations of slabs around the compass, primarily above the treeline. Expect to find stiff slabs that are not allowing your skis or machine to sink much below the surface. You may notice a hollow sound where dense snow rests on top of soft snow. Fresh slabs may present themselves with more obvious signs such as cracking. Utilize hand pits and test slopes to determine how well the surface slab bonds to the underlying layer. Why ride the wind-packed snow when there is still great soft snow to be enjoyed in sheltered terrain.

    (12/31/2021)

    We found 6-8 inch surface slabs in hand pits, and ski pole tests revealed stiff snow over softer snow. 

    Photo: Dundas

Avalanche Discussion

We can expect one more day of Arctic temperatures before slightly warmer air moves into our area tomorrow. Since Christmas Day, we have experienced unseasonably cold temperatures as an air mass moved east over the Divide and took up residence. During this time, winds have shifted numerous times from easterly to westerly and back again, resulting in wind slabs on all aspects above the treeline. Reports of instability and avalanche activity tapered off as the week went on due to a lack of new snow available for transport. 

Jenny and I went to the Apgar Range Friday, where we found slabs at mid-elevations that were starting to resemble hard slabs. They rested on softer snow underneath and noted a hollow-like sound as we traveled on them. Turning our ski poles upside down and inserting them into the surface clued us into the near-surface snow structure. Hand pits revealed 6 - 8 inch slabs that popped out with moderate force. We could not get any shooting cracks or failures on small test slopes despite these concerning observations. Regardless, we recognized the potential hazard and steered away from the pillowy-looking features on our descent.

Blase was also in the Apgars Friday and noted thick drifts and pillows on the northern sides of ridges that were not reactive to stomping. He and his partner found weak snow on southerly, mid-elevation slopes scoured by the past month's winds. The snowpack on these slopes was shallow (<30-40 cm) and consisted of a dense slab of drifted snow over a well-developed depth hoar. They avoided this terrain on their descent.

Moisture and warmer temperatures are on the horizon as a storm is forecast to impact our area Monday night into Tuesday. In anticipation of the return of fresh snow, we are looking at the snow surface to determine what the snow will fall on. Due to the recent cold temperatures, observations have been limited but show little surface hoar evidence. If you get out this weekend and send us some beneficial information, let us know whether or not you find surface hoar in your travels.

Check out the weekly summary under the Conditions Blog tab. Clancy wrote a summary and produced a video summarizing the past week's weather, snowpack, and avalanche conditions.

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