Bollettino valanghe

Whitefish Range

Flathead Avalanche Center
Vedi sulla mappa

Pericolo valanghe

Thu
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

Look for and steer around pockets of wind-drifted snow. Wind slabs will become larger in size the higher you climb. Seek out slopes sheltered from the wind for a safer and better experience. If you choose to ski and ride in avalanche-prone terrain, post your partner in a safe location where they can see you as you descend or ride. Once you descend, repeat the process for your partner.

Problemi valanghivi

  • Wind Slabs

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

    Roughly three to five inches of snow fell Sunday night while sustained winds blew out of the southwest. I suspect wind slabs are gaining strength; however, slabs of drifted snow now rest on weak faceted snow, crusts, or stiff wind board. I recommend objectives sheltered from the wind and giving freshly formed slabs time to adjust. Terrain sheltered from the wind will also be where the higher-quality riding is.

    (1/9/2023)

    Guy doing a hand hardness on the upper part of the snowpack. We found a thin slab (shown in the cut out block) and a layer of near surface facets above the Christmas crust. 

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely
    Dimensione
    2–3

    We are currently in a holding pattern since the last audible collapse on January 6th. This collapse appeared to be loud and significant enough to shift the snowpack. We remain wary of removing the problem due to the consequences at stake. Our primary advice for you all chasing steeper objectives is to select slopes with less consequential runouts to reduce the chances of trauma or deep burial.

    (1/7/2023)

    A very large avalanche which failed during the rain event sometime between December 26 to December 28. 

    Photo: Kevin Oberholser

Avalanche Discussion

A ridge of high pressure settles into the forecast region today. Winds shifted to the north yesterday (Monday) afternoon. This wind shift dropped wind speeds to single digits and brought cooler air. Temperatures will climb back up 30 degrees F at roughly 6000 feet today. Cloud cover appears to drift back and forth between clear and partly cloudy.

This weather pattern will do little to change the avalanche danger. The primary change we may see today is if the sun sticks its head out longer than expected. This may cause a few loose dry sluffs out of steep, rocky terrain in the new snow. If this happens, I suspect they will be primarily small and easy to manage. One "defensive riding strategy" for managing sluff is to cut across the top of the slope and allow your sluff to run before descending. One observation from yesterday noted southerly aspects getting cooked in the Flathead Range while the southern Whitefish Range remained in the clouds. There is a lower likelihood for this to happen in areas with a sun crust from yesterday.

Many of the recent observations note variable wind-drifting. Some recent drifts have altered riders' planned objectives and directed them to wind-sheltered slopes. I will take this and run with it today. First of all, there is less of a chance of triggering a slab avalanche that is potentially large enough to bury you in wind-protected terrain. Secondly, the riding quality is better where winds haven't drifted or scoured the snow surface.

We lack observations from the Swan Range, where more snow fell Sunday night. This snow has fallen onto various weak surfaces and may behave more like a persistent slab problem. If you observe signs of shooting cracks, recent avalanches or can remotely trigger avalanches, take a big step back and select slopes with low angles.

Regioni coperte