Lawinenlagebericht

Flathead Range & Glacier NP

Flathead Avalanche Center
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Lawinengefahr

Mon
Hochgebirge
2 · Mässig
Waldgrenze
1 · Gering
Unterhalb
1 · Gering
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Veraltet — dieser Lagebericht ist 5 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Today's warmer temperatures are a welcome relief, but the increasing winds are not. Slabs of freshly drifted snow remain our primary hazard and will be thickest and most troublesome above roughly 6500 feet. Look for blowing snow as you gain elevation. Areas sheltered from recent winds will offer the best riding.

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2

    Winds have shifted back to the southwest and will ramp up through the day. After several dry days, snow available for transport is diminishing. Still, today's gusty conditions and warmer temperatures may form new slabs in the usual spots - downwind of saddles, below ridges, and sidewalls of cross-loaded gullies. This problem is primarily found at the upper elevations, but I wouldn't be surprised if fresh slabs form below that in areas favored by southwest winds. Hand pits and small test slopes are a great way to get a handle on this surface problem. Sheltered terrain is not the blower powder it was a few days ago, but it still beats riding wind-affected snow. 

    (1/1/2022)

    Clancy and his partner found reactive wind slabs on the the leeward side of ridges. 

    Photo: Jess May

Avalanche Discussion

Balmy! Today will feel pleasant following a week of unseasonably cold temperatures, providing you are out of the wind. Temperatures this morning are 10 - 20 F warmer than yesterday. Check out our weather station table here. Unfortunately, wind speeds have also increased, with Mount Aeneas clocking in with sustained speeds of 30 mph and gusts to 45 mph, with a forecast to rise through the day. Winds have returned to a southwesterly flow through Monday.

Following a few dry days, several riders yesterday noted that surface conditions had deteriorated in quality from earlier in the week. They found scoured, stiff, and slabby conditions in areas open to the wind and a compacted surface from tree bombs and wind-affected snow in sheltered locations. Meanwhile, an observer northeast of WMR noted a minimal cohesive slab (8-12 inches thick) just off of ridges but not in sheltered areas. Clancy noted fresh wind transport and wind slab development on Saturday in the Flathead Range despite the lack of recent snow. He intentionally triggered two small wind slab avalanches on typical leeward slopes. Another rider in the Lake McDonald area also found active wind loading. This week's bitterly cold temperatures have led to the faceting of the surface snow and layers deeper in the pack.

Older slabs formed by north and east winds earlier in the week are harder and more difficult to trigger. Riders are unlikely to trigger these, and we have removed them from today's problem.

Check out the weekly update text and video that Clancy made summarizing the snowpack, weather, and avalanche conditions for the week ending December 31. This update can be found above in the Conditions Blog tab. 

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