Bollettino valanghe

Flathead Range & Glacier NP

Flathead Avalanche Center
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Pericolo valanghe

Sun
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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In sintesi

Today's avalanche danger may rise if the sun makes a sustained appearance. An extended period of sunshine could initiate wet loose slides in the surface snow.  Rollerballs and snow falling from trees is a precursor to these slides.  Steer around thin, fresh slabs of wind drifted snow at upper elevations. 

Problemi valanghivi

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    Up to a foot of cold, dry snow is resting on a crust in many locations. High pressure is building over the Flathead Valley today with the potential for sunshine and warm temperatures. That is if a deck of stratus clouds does not develop. This problem may or may not form depending on today's weather conditions. Dry, cold snow warming for the first time may initiate a wet loose avalanche cycle on sunny slopes. Slides have the potential to entrain surface snow and travel long distances on the crust. If you notice snow falling from tree branches or small rollerballs or pinwheels moving downhill, it is time to move to a shaded aspect. Stay ahead of the sun during your travels and limit your time spent above terrain traps.

    (2/13/2022)

    Wet loose avalanches on solar aspects from February 12th. 

    Photo: Mark Ambre

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely
    Dimensione
    1–2

    Winds returned to a westerly flow Wednesday afternoon and slowly increased in speed. Thin, small slabs are likely developing in the usual locations - below ridgelines and saddles and on cross-loaded features. In areas scoured by easterly winds earlier in the week, slabs may form on a crust that could inhibit bonding. These fresh wind features should be small and relatively harmless unless they knock you off your feet or machine and push you into surface obstacles like trees or exposed rocks. Pillow-shaped features and etched surface snow are a clue of their existence. All observations from this past week note the great snow quality in sheltered terrain. Why would you go anywhere else?

    (2/25/2022) null Photo: Mark Dundas

Avalanche Discussion

The past week's weather was unique and deserves a quick recap. A moisture-laden storm dropped a foot of snow and up to an inch of water in both valley and mountain locations Sunday. During the storm, winds shifted to the east and remained sustained into Wednesday. Well below-average temperatures lasted from Sunday through the workweek. Winds shifted to a westerly flow Wednesday afternoon and have slowly increased.

High pressure builds over the Flathead today with warming temperatures and possibly extended periods of sun. If a layer of stratus clouds does not block the sun, we may develop a wet loose avalanche problem. Currently, the surface snow is COLD and dry. Friday, I found up to 12 inches of surface snow in the Flathead Range, which sluffed on steep slopes. An observer in southern Glacier Park found similar amounts in wind-sheltered areas. Blase was outside WMR and reported 5 inches of low-density snow that fell throughout the day. The late February sun is relatively high in the sky, and sustained solar input can moisten and weaken the surface snow. The snow which fell Sunday is resting on a crust in many locations, which will aid in the development of the wet loose activity.

We dropped the avalanche danger to LOW Friday with observations showing slabs that formed from north and east winds to be unreactive. Winds shifted back to a more typical westerly flow Wednesday afternoon, developing slabs on the eastern side of the compass. We have removed slabs formed from atypical winds earlier in the week from today's wind slab rose.

 

 

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