Bollettino valanghe

West Slopes North

Northwest Avalanche Center
Vedi sulla mappa

Pericolo valanghe

Sat
Alta quota
2 · Moderato
Limite del bosco
1 · Debole
Sotto il limite
1 · Debole
Open full map
Non aggiornato — questo bollettino è scaduto 3 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Wet snow is the predominant snow surface at all elevations up to near the top of our upper elevation band. There's a chance you could trigger a shallow wet snow avalanche in the moist new snow layer at mid and upper elevations. The snow may start firmer, but if you're sinking into wet, gloppy snow past your ankles or see rollerballs running down a steep slope, wet avalanches might result. 

Problemi valanghivi

  • Loose Wet

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

    Wet snow may freeze up a little overnight, but it will probably soften on Friday. Freezing levels are forecasted to rise to 6500 feet, and snow will become increasingly wet. There's uncertainty whether this warming will result in any wet loose avalanche activity. The snow may just stubbornly stick to slopes, even steep ones. 

    Evaluate conditions as you travel. Observe how far your feet are sinking into wet snow. If you're sinking into snow past your ankles, consider avoiding steep slopes. If you do start seeing any rollerballs or small slides starting to come down, steer around steep slopes as well. 

    (12/28/2023)

    Chunky rollerballs and thinly covered rock slab in Upper Bagley on Thursday. A few small wet loose avalanches were visible on Table Mountain.

    Photo: Lee Lazzarra

  • Wind Slabs

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

    If you make it above about 6500 feet, you might find dry snow. Strong, gusty winds likely redistributed any soft snow into heavier wind slabs.  There's still a small chance you could trigger a wind slab avalanche in a newly drifted deposit, although warm temperatures are expected to quickly improve the stability. Strong southerly winds may have redistributed snow into unusual locations, or further downslope than you're used to. 

    If you do make it to upper elevations, be prepared to evaluate conditions for yourself. Search for hollow-feeling snow or wind drifts around features, in gullies, or along ridgelines.  Dig down beneath the new snow layer and assess the bond with underlying layers. Avoid steep slopes if you identify any weaknesses or have any uncertainties.  

    Exmple Photo: A human triggered wind slab avalanche on a steep roll, similar to something that you have a very small possibility of triggering on Friday.  Photo: Pete Durr, USFS Backcountry Ranger

Avalanche Discussion

Observers traveled to 5000ft in the Baker backcountry on Thursday. They were hoping to wait until the precipitation intensity died down midday, but it didn't slow much. They still got really wet, even reporting sideways rain. Three inches of dry snow had fallen overnight at 5000 feet but was subsequently wetted. The observers saw very small dribbles of wet avalanche activity. They tried triggering wet loose avalanches, but the snow was just really sticky, and pushing snow downhill mainly resulted in stubborn rollerballs. 

This southerly system overproduced in the West North zone, with about 2 inches of water reported in 24 hours and ending Thursday afternoon. As has been the case lately, the precipitation was rain at lower elevations and a mix of snow that shifted to rain at mid elevations.

Most of the snow we've received in the last week at mid elevations is now wet. A crust exists below the newer moist snow layers. This crust caps a combination of moist grains and crusts down to the ground. Total snow depths are around 3 feet. Upper elevations have more snow above the crust, possibly 2 feet or more. All of this is likely very wind-affected. At lower elevations, snow loss is continuing. Patchy snow cover and  exposed obstacles are present at lower and mid elevations. 

Regioni coperte