Bollettino valanghe

East Slopes North

Northwest Avalanche Center
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Pericolo valanghe

Fri
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 7 months ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

This storm is only bringing us modest precipitation amounts. But it might be just enough drift snow into shallow slabs on slopes below ridgelines where you could trigger a small avalanche. Consider steering around steep slopes with shallow drifts, especially in terrain with cliffs, gullies, or rocks, where a small slide could have high consequences. 

Problemi valanghivi

  • Wind Slabs

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

    While there isn't much precipitation in the forecast, moderate winds could easily drift snow into shallow wind slabs. Actively blowing snow or a dappled texture to the snow surface are good ways to identify areas of wind drifting. Wind slabs may form over slick or weak surfaces, particularly at upper elevations. In most terrain, these avalanches wouldn't pose much of a hazard. But in very steep, confined, or cliffy terrain, a small avalanche could cause a dangerous fall. Use extra caution and consider steering around more aggressive terrain features. 

    (1/5/2023)

    An example of a shallow wind slab you could trigger in steep lee terrain below ridgelines at higher elevations.

    Photo: NWAC Public obs

Avalanche Discussion

Wednesday's snow totals weren't quite a total no-show, but it felt close. Some areas near and west of Washington Pass saw 1-2" of new snow, while farther east, snow totals were much lower. Thankfully, we'll see a bit more accumulation overnight and into Thursday, but it's still not a powerful storm by any standards, and warming temperatures won't help. Thankfully, the magic of the east north zone will once again keep temperatures colder than the bulk of the Cascades, but expect rain to climb into the lower-elevation band by Thursday afternoon. Since there won't be much fresh, dry snow to rain on, we expect that any wet loose activity will be limited to widespread rollerballs and snail armies. 

On Sunday, an NWAC Forecaster near Cutthroat Lake found widespread surface hoar below the inversion line, and shaded, northerly aspects had a breakable surface crust with faceted grains beneath. With incoming snow, this is a great time to track the bond with the old snow surfaces. There is a lot of uncertainty about how well the new snow will bond to these old surfaces. As you travel, track the bond at this new interface using quick hand pits to see how the new snow reacts. If the new snow slides easily as one cohesive block, avalanches may be more likely as we get additional snow. 

Travel conditions have been challenging to say the least. We hope this storm is enough to improve conditions, but you should still expect rough surfaces, breakable crusts, and old, frozen rain runnels. Rain and warm snow may soften surface crusts, but it is probably still wise to bring equipment to prevent long sliding falls. Better to have it and not use it than not have it when you need it most. 

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