Bollettino valanghe

Whitefish Range

Flathead Avalanche Center
Vedi sulla mappa

Pericolo valanghe

Mon
Alta quota
1 · Debole
Limite del bosco
1 · Debole
Sotto il limite
1 · Debole
Open full map
Non aggiornato — questo bollettino è scaduto 4 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Light snow and wind continue to form thin slabs of wind-drifted snow at upper elevations. Look and feel for denser snow that may be reactive to the weight of a rider. Triggering a wet avalanche remains possible in mushy surface snow below around 5000 feet.

Problemi valanghivi

  • Wind Slabs

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

    Slabs of wind-drifted snow will grow in size the higher you climb. Look closely for dune-shaped drifts and textured surfaces for places to steer around. Yesterday an observer got shooting cracks away from their skis in the Flathead Range, and on Wednesday, a rider remotely triggered a slab avalanche on a leeward-facing slope in the Swan Range. We suspect wind slabs will be smaller in size in the Whitefish Range due to less recent snowfall. Utilize small and inconsequential test slopes similar to the slopes you want to ride before committing to larger terrain.

    (1/15/2023)

    Cracking in freshly wind-drifted snow

    Photo: Kevin Oberholser

  • Loose Wet

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

    Temperatures at lower-elevation stations have been above freezing for the past 72 hours. The exception is in the eastern portion of our area, where temperatures dropped below freezing overnight. Expect a wet unsupportable snow surface this morning below around 5000 feet. The natural wet avalanche activity is over, but human-triggered avalanches remain possible. If you find yourself or a machine sinking into a mushy surface, limit your time spent above terrain traps where debris can pile up deep. Opt for lower-angle slopes to minimize the chance of triggering a slide and getting caught up in this moving quicksand.  You should be able to avoid this problem by recreating at mid and upper elevations.

    (1/14/2023) Term 1

Avalanche Discussion

The January thaw arrived just in time to put a damper on conditions for the MLK weekend. Temperatures rose well-above freezing at mid-elevation stations Thursday and remained there into Saturday. Even the upper-elevation Snowslip station in John F. Stevens Canyon climbed into the mid-30s for 18 hours. Before the warm-up, the snow surface comprised several inches of cool, dry snow resting on either a melt-freeze crust extending above 7000 feet formed last Saturday, wind-affected snow, or loose snow in sheltered upper-elevation locations. Extensive fields of rollerballs formed as the near-surface snow warmed. Observations are limited, with reports of Loose Wet slides below 6000 feet, which ranged from D1 to D2 in size.

Temperatures cooled overnight, dropping below freezing at mid-elevation stations and low-elevations in John F. Stevens Canyon. Observers yesterday noted wet concrete-like snow at low elevations but winter-like conditions above 6000 feet, where a couple of inches of new snow fell onto the recently formed crust. In the Middle Fork, cracking in new cornice growth was noted. 

This morning, expect to find a thin, newly developed melt-freeze crust at mid-elevation locations. This crust extends to at least 6700 feet or the limit of Friday's warming. It is currently unknown how thick or strong this crust is. Low-elevation stations have remained above freezing for nearly 72 hours, and we expect the snow surface to be wet. The exception may be in the eastern portion of the advisory area, where temperatures cooled below freezing in John F. Stevens Canyon. 

We have removed the Wet Loose problem from the middle elevations due to cooling temperatures. The crust at mid-elevations is starting to lock up the surface but has probably not fully developed into a supportable surface. There remains a chance that a rider or their snowmachine could punch through the crust into the wet snow beneath and trigger a wet slide. At low elevations, the surface remains wet, but avalanche terrain and the amount of snow available for entrainment are limited.

 

Education: Human-powered partner rescue class on Saturday, January 21, 2023. Find out more here. 

                         Motorized partner rescue on Saturday, January 28, 2023. Find out more here.

Regioni coperte