Bollettino valanghe

Seeley Lake

West Central Montana Avalanche Center
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Pericolo valanghe

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

In sintesi

The snowpack in the Seeley Lake zone is generally stable. However, there may be small isolated pockets of reactive wind slab on steep, upper elevation, east aspects. Carefully evaluate the snowpack for signs of instability, such as shooting cracks, before committing to slopes over 35º. 

Problemi valanghivi

  • Wind Slabs

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

    The Seeley Lake zone received 1 to 2 inches of new snow and strong west winds yesterday. An additional 1 to 2 inches of snow is expected today. This is less new snow than in other zones, and consequently, any fresh wind slabs will be very small and isolated. However, there may also be lingering pockets of older wind slabs that are still reactive. The rider triggered wind slab last Friday that caught two people highlights this possibility. Snowmobilers may be more likely to find the trigger point because they can affect the snowpack deeper than a skier. The mountains are never without some risk of avalanches, and continual diligence is required. 

    Wind slabs appear smooth and rounded and are often found just below ridges and in cross-loaded gullies. Cornices, wind lips, and drifts all indicate wind direction and loading. Signs of instability like shooting cracks warn you to stay off steep slopes. Carefully evaluate the snowpack before committing to wind loaded terrain over 35º. 

Avalanche Discussion

After a beautiful sunny weekend, a cold front moved through yesterday, bringing strong west winds and light snowfall to the region. The Central Bitterroot received the most snow yesterday, and there were reactive fresh wind slabs growing at upper elevations. In the Rattlesnake and East Lolo area, there was less fresh snow, and wind slab development was limited. 

Showery snowfall continued overnight, but the wind died down to light to moderate. Snow totals thus far are variable due to the showery nature of the snowfall. The Central Bitterroot has been the winner with 8 inches of new snow at the Twin Lakes SNOTEL. In the Central Bitterroot, triggering a wind slab is likely, and the hazard may be Considerable at upper elevations. Other areas in the region have only received 1-3 inches. Today, we can expect light to moderate northwest winds and continued light snow showers accumulating 1 to 5 inches. The Rattlesnake and Central Bitterroot are favored for the highest snow totals. In areas that receive the most snow, wind slabs will grow along upper elevation ridgelines and cross loaded gullies. Wind slabs yesterday were found low on slopes due to the very strong winds. With lighter winds today, they will grow near ridge tops. 

A crust facet combo buried 1-2 ft deep has been found in isolated locations in the Bitterroot. Yesterday it was found on a middle elevation east aspect in the East Lolo area. Over the weekend, it was found on an upper-elevation north-northeast aspect in the Southern Bitterroot. Last week, observers found it on upper elevation south aspects. There is uncertainty regarding the sensitivity and spatial variability of this layer. It has produced propagating snowpit test results, but signs of instability have been limited. It appears to be most sensitive in shallower areas at middle and upper elevations, like around wind-swept ridges. It is worth investigating the snowpack by digging a snowpit before you commit to steep terrain. Be prepared to change objectives if you find unexpected unstable results or signs of instability like whumpfing or cracking. 

Today’s fresh wind slabs are a hiccup in a general trend of improving stability. Skiers and riders have been stepping out into bigger terrain. However, in the last week, there have been several unintentionally triggered avalanches. Thankfully, everyone involved has avoided injury or burial. We still have a dry mid-winter snowpack with isolated weak layers. Remember that even a small avalanche can have serious consequences in unforgiving terrain. Do your homework before committing to steeper slopes, and use safe travel practices, such as riding one at a time. 

Please let us know what you find out there by submitting an observation.

Ski and ride safe. 

Regioni coperte