Bollettino valanghe

West Slopes Central

Northwest Avalanche Center
Vedi sulla mappa

Pericolo valanghe

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

In sintesi

We'll get over a foot of snow at upper elevations Monday night, likely accompanied by a natural avalanche cycle. Large human-triggered dry snow avalanches are likely at upper elevations, and at lower elevations wet snow avalanches are likely as well. Avoid all steep slopes on Tuesday, and consider avoiding lower angle terrain beneath steep slopes if you see new natural avalanche activity.

Problemi valanghivi

  • Storm Slabs

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

    Most of the snow will arrive overnight. Forecasts are calling for over an inch of water, possibly equating to over a foot of snow at upper elevations. We expect a natural avalanche cycle to accompany the higher precipitation amounts during the overnight time period. Avalanche danger will be highest in the morning, and will slowly taper throughout the day. 

    Temperature fluctuations and variations in the storm snow mean that any slope, even non wind-loaded ones, could avalanche with a human trigger. Some slabs may be moist and heavy. A large portion of avalanche activity will likely happen on wind loaded slopes. In these areas, avalanches will be more reactive, and larger. You can expect that most dry snow avalanches will fail as slabs, which could surprise you spanning far, and deeper than you suspect. Danger will likely be higher with increasing elevation. 

    Considering the new snowfall amounts, avoid all slopes greater than 30°. This isn't the time to try and outsmart the avalanche problem- enough snow has fallen that it's a good day to just avoid steep terrain altogether. If you notice any natural avalanches, avoid lower angle terrain and gullies beneath steep slopes as well. 

    Example photo: Avalanches could break in the new snow layer, around a foot down like in this photo. They may occur in wind loaded or non wind-loaded areas.  Photo: Irene Henninger

  • Loose Wet

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

    Wet loose avalanches have been happening for days now. These ones will be a little different, as we've got more inputs with more low-elevation rain and mid-elevation heavy wet snow to add to the mix. We expect most avalanches to be limited to snow above the Early April Crust. Down lower this may be less than 6 inches, but at mid elevations it could be closer to a foot in depth. At lower elevations the crust may have broken down and avalanches could gouge into any deeper snow that exists. 

    Wet heavy snow may slide naturally, but there is a greater likelihood that a human trigger on a steep slope will result in a wet snow avalanche. Avoid traveling on slopes greater than 30°, the same as our dry snow recommendation. Possibly even moreso at these lower elevations, beware of natural avalanches running from above. This isn't the right time to be traveling through gullies at lower elevations, where in some areas there may not be much snow for an avalanche starting at this elevation, yet overhead start zones may send large amounts of snow down onto you. 

    Example photo: Wet loose avalanches could behave in many ways on Tuesday- and possibly like this one. They will probably run in the top 6" to foot of snow, but possibly deeper. Even though this one was very shallow, it still sure packed a punch. 

    Photo: Matt Primomo

Avalanche Discussion

Spring unsettled weather means there are a lot of uncertainties with how this storm will pan out. Somewhere in the mid-elevation band, there will be a transition from wet to moist to dry snow, and it may be tricky to read what kind of avalanche you'll come across. Maybe you'll have a loose avalanche run beneath you. A slab could surprise you by propagating far, or even breaking above you if you decide to venture onto a steep slope midway down.  Avalanches could be an unusual mix of not quite loose and not quite slab. 

Large new amounts of moisture and weight, especially with warmer temperatures, means it's a good time to avoid being beneath cornices or glide cracks. Other springtime hazards such as hidden creek holes and other inconspicuous holes in the snow are additional springtime hazards to remain alert for if you get out on Tuesday. 

Your avalanche, snowpack, or weather observations are extremely valuable to the avalanche community. Help create a more accurate forecast by submitting your observations HERE. 

Regioni coperte