Bollettino valanghe

Whitefish Range

Flathead Avalanche Center
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Pericolo valanghe

Sun
Alta quota
2 · Moderato
Limite del bosco
1 · Debole
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

Light snow and winds may form thin slabs reactive to your weight. As you gain elevation, these will increase in size and thickness and will be largest in areas favored by snowfall. Cracking beneath you or your machine indicates you have found an unstable slab. Terrain sheltered from the wind offers a safer alternative.

The northern Whitefish Range received more snow; the danger is higher there than in the southern Whitefish Range.

 

Problemi valanghivi

  • Wind Slabs

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

    Several inches of fresh snow and gusty winds may form small, thin slabs reactive to the weight of a rider or their machine. These features may be found just below the downwind side of a ridgeline or saddle and on the sidewalls of cross-loaded gullies. Their size and thickness will increase as you gain elevation. More precipitation was recorded in the northern Whitefish Range, where slabs will be larger than in areas further south around WMR. Active wind transport, dunes, a scalloped surface, and dense fresh snow indicate that wind has been or is at work. Cracking beneath your feet signifies you have found an unstable slab. Utilize terrain sheltered from the wind as your safer alternative.

    (12/19/2023)

    The windloading on the Swan Crest has been just enough the last few days to produce isolated windslabs.

    Photo: guy zoellner

Avalanche Discussion

A welcome cold front arrived late last night, dropping temperatures and depositing light snow. Overnight snow totals at ridgetop locations are modest, with 1-3 inches reported as of 0500 this morning. Stahl Peak in the northern Whitefish Range seems to be an outlier, with 0.7 inches of SWE recorded overnight. In many locations, snow fell on a slick surface crust, which may inhibit bonding. Wind speeds are strong enough for transport and variable from the SE-SW-NW. Above 6000 feet, small, thin slabs of wind-drifted snow may be encountered in areas favored by snowfall and wind. The size of today's slabs will probably be too small to bury you; however, even taking a ride in a small avalanche could have a nasty outcome due to all of the exposed surface obstacles.

Before the arrival of the cooler air, temperatures were downright balmy at all elevations for the workweek. The mid-elevation Noisy Basin SNOTEL (6040 feet) remained above freezing from early Monday morning until Friday evening, or 110 hours. Marias Pass (5230 feet) recorded 39 F or higher throughout the winter solstice or over 40 hours. These unusually warm temperatures melted our thin snowpack, especially at low and mid-elevations. In John F. Stevens Canyon, the valley floor Shed 4 station (4557 feet) is snow-free, and Marias Pass reports a mere 3 inches. In the Swan Range, a dedicated observer noted snow on the ground nearly disappeared below 5000 feet on northerly aspects and below 6000 feet on the west and southwest aspects.  

On Wednesday, warm air and rain initiated a small, wet loose avalanche cycle on all aspects at mid-elevations (Observation). The arrival of cooler air has likely left a crust this morning on mid and upper-elevation slopes that were previously wet and now have frozen rollerballs and debris.  

 

 

 

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