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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Non aggiornato — questo bollettino è scaduto 3 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

The avalanche danger may rise later today as snow and wind return to the Flathead. You could trigger an avalanche where the winds have formed drifts or stiffened the snow surface. Choose sheltered terrain to enjoy today's refresh safely.

Problemi valanghivi

  • Loose Dry

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    If today's snow arrives as forecast, natural and triggered sluffs may occur on steep slopes sheltered from the wind this afternoon. Today's snow will fall onto a crust on many slopes, which may limit bonding. Due to the underlying crust, sluffs may travel surprisingly far and fast. 

    We anticipate today's sluffs to be generally harmless unless you get knocked off your feet and pushed into a surface obstacle or a depression where the snow can pile up deep. Utilize sluff management and be aware of this problem while traveling in long-running gullies or above terrain traps.

     

     

    (1/13/2023)

    A thin, Dry Loose slide triggered by a skier in the top few inches of snow on an east aspect at 6400'.

    Photo: Mark Dundas

  • Wind Slabs

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

    Developing snowfall and moderate to strong southwesterly winds may form thin slabs of snow on leeward aspects. Slabs should thicken throughout the day and become more extensive in areas favored by today's snowfall. Look for them near ridgelines and mid-slope terrain features like ribs and gullies. 

    Slabs may form on weak faceted snow or crusts, inhibiting bonding and potentially propagating wider than expected. Blowing snow will indicate which slopes are most dangerous. You've likely found a wind slab if the soft, light snow you're moving through suddenly becomes heavy (dense) or you run up onto stiff snow that supports your weight. Cracks shooting out from your skis or sled indicate the slab's instability. Choose terrain sheltered from the winds for a safer, more enjoyable experience.

     

Avalanche Discussion

Snow returns to the Flathead Valley today with a Winter Weather Advisory from 6 AM this morning to 9 AM Sunday for the West Glacier Region. Unfortunately, moderate to strong winds at all elevations will accompany the new snow. There is a Wind Advisory from 9 AM this morning to 8 PM this evening for the Flathead Valley.

The Tunnel Ridge station (5895') picked up 3 inches of snow overnight, with 2 inches recorded at Shed 7 (6400') in John F. Stevens Canyon and an inch or so in central Glacier Park. Today's forecast favors the mountains along the Montana/Idaho border with a foot or more snow. As is the case this season, we will receive the leftover scraps. Regardless, today's refresh may deliver up to 6-8 inches in the Swan and Flathead Range. Winds overnight ramped up and have been sustained strong with gale force gusts at the Aeneas Ridge station (7186') since midnight. Wind speeds at all mid and upper-elevation stations will be strong enough to transport snow throughout the day.

After around 12 days of LOW danger, we are increasing the hazard to MODERATE due to the new snow and primarily the wind.  Conditions this morning begin with LOW danger but are expected to rise if forecasted snow totals develop.

There remains a slim chance that you could trigger a slide on a buried weak layer resulting in a large avalanche. Thin, wind-swept, or rocky areas are locations where the layer is closest to the surface and where your weight is most likely to affect this weak snow.

Rob visited the Sixmile area of the Swan Range yesterday, where he found a melt-freeze crust of varying thickness and supportability. This crust was most robust and skiable on steep and sparsely treed southerly slopes. Elsewhere it was less consistent and required defensive skiing. He found up to 6 inches of well-preserved dry powder on the north and northeast slopes. Wind transport was surprising, considering the limited recent snow. Isolated and thin pockets of soft slab were trending toward reactive on leeward terrain along upper elevation ridges.

FAC will issue daily forecasts through Easter Sunday, April 9. Following this, we will issue snowpack updates several times a week through April if conditions dictate. 

 

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