Bollettino valanghe

Stevens Pass

Northwest Avalanche Center
Vedi sulla mappa

Pericolo valanghe

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

In sintesi

A powerful storm with warming temperatures is expected to create very dangerous avalanche conditions Sunday night through Monday. Avalanches could run full path to valley bottoms, with wet and destructive debris. Stay out of avalanche terrain, and well out from underneath steep slopes at all elevations while this natural cycle runs its course.

Problemi valanghivi

  • Storm Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Very Likely
    Dimensione
    2–3.5

    Heavy snow/rain, rising temperatures, and strong wind are a perfect recipe for slab avalanches. Our current layered snowpack is fairly weak, and riddled with buried layers of surface hoar, facets, and poorly bonded suncrusts. Beneath all of this is a stout crust from Valentines day. Storm slabs were touchy on Sunday, and we expect these may begin to step down to the deeper Valentines Crust as the storm takes aim at the zone on Monday. More snow will accumulate at higher elevations, and combined with intense wind transport these slabs could become over well over 4ft deep and encompass entire start zones. 

    Monday is not a day to mess around in or underneath any steep slope, better to let this natural cycle run its course.

    Example very large natural avalanche from earlier in the season

     

  • Loose Wet

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

    Rain on snow will create wet avalanches as temperatures rise. These will probably gouge down to older crust layers, entraining heavy, wet snow and become destructive on large slopes. Rollerballs and other, recent wet slides are great evidence that these can continue. Stay out from underneath steep slopes while heavy precipitation creates very dangerous conditions. 

    Example loose wet slides in the Highway Chutes across from Highway 2 on the west side of Stevens Pass. This was from January 14th, with much less snow in the paths. Avalanches this time around could be much larger in the same avalanche paths. 

    Photo: Matt Primomo

Avalanche Discussion

Observers noted very reactive conditions on Sunday, with storm slabs breaking about a foot deep, on the old snow interface. Many riders triggered slab avalanches that were in the small to large range (D1-2), and there was a close call with a rider buried to their neck on a NW aspect near Skyline. Some avalanches on south-facing slopes even triggered other pockets nearby (sympathetic). Stevens Pass Mountain Resort snow safety reported one slide that stepped down to a deeper crust layer. These are all bullseye information that tell us its dangerous. With a powerful storm of the atmospheric river variety making landfall, avalanches are a pretty sure bet over the next 24 hours. Slides may become destructive in nature with wet snow debris. It'll be a drastic change for our cold and weak snowpack, and add much-needed snow to the highest elevations of the Cascades. 

On Saturday, surface facets stayed intact, even on direct south-facing aspects. Beneath the surface, there are a number of crusts and potential weaker layers in the upper 3ft of the snowpack. The Valentines Crust serves as a prominent marker, as it's fairly thick in most places. On northerly aspects, it may be crumbly and mixed with facets, on southerly aspects its a stronger melt-freeze crust. At the time of this writing, there is about 2.5-3.5ft of recent snow over it near the crest, and about 1-3ft over it further east in the zone. 

Regioni coperte