Bollettino valanghe

East Slopes Central

Northwest Avalanche Center
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Pericolo valanghe

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

In sintesi

Strong and gusty wind raked the zone during this recent storm and formed fresh slabs in some very strange places. You could encounter wind drifts well below ridgeline and along the sides of gullies. Don’t trust any steep wind-loaded slope.

Problemi valanghivi

  • Wind Slabs

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

    Gusty winds typified this storm. That often results in more erratic loading patterns. Normal wind features like cornices, drifts, and scouring can help demonstrate local winds. However, you’ll likely need to key into subtle surface textures that indicate wind-loaded snow and feel for those firmer pillows as you travel.

    The new snow fell on a variety of old surfaces. This will make predicting how any one slope will react nearly impossible. As these wind slabs become harder to trigger, it might take finding that one place where it overlies a slick crust or weak old snow that let's you trigger the slide. 

    Unless you’re certain the wind-loaded pocket will be very small and inconsequential, consider giving those steep slopes a wide berth. Firm wind slabs can break much further back and even above you. The biggest and most dangerous slabs will likely be higher in the terrain and in areas of the zone that received more snow like the Teanaway and Wenatchee mountains.

    (12/14/2024) slab debris slid about 4' on steep slope (40degrees est) Photo: Mike Rolfs

Avalanche Discussion

Sure the storm is ending and the skies are clearing, but the wind has already done its damage. We're just exiting the storm and trying to figure out how exactly this snowpack changed. The few observations on Saturday indicated plenty of scoured slopes and loaded areas. This storm favored certain parts of the East Central zone. Places like Mission Ridge, the Enchantments, and Tumwater likely received more snow than areas closer to the crest. Storm totals for the zone range from 6 to 10 inches. 

As the sun comes out, you could see snow shed from rocks and trees. While this might result in piles of rollerballs, it should stop short of being a significant problem. Wind hammered snow surfaces, cold air temperatures, a low December sun, and increasing high clouds should all work in your favor. 

This recent snow fell on a variety of old surfaces and it still remains to be seen if any of the weak snow noted prior to the storm survived. Underneath the fresh snow, you could find smooth crusts, firm old wind slabs, settled powder, or weak facets/surface hoar. The latter would be most likely in wind-sheltered terrain. 

Saturday’s stormy weather limited observations around the zone. Even still information came in from near Mission Ridge. A backcountry traveler was surprised when he triggered a small avalanche that broke further back than expected. At the ski area, ski patrol reported wind slabs 6-30 inches deep during mitigation work, and one natural cornice triggered slide. All of these observations highlight the variable nature of fresh wind slabs. 

Lower elevations are still thin and tough to navigate. While this limits the avalanche danger it presents its own set of hazards.

Regioni coperte