Lawinenlagebericht

West Slopes South

Northwest Avalanche Center
Auf der Karte ansehen

Lawinengefahr

Thu
Hochgebirge
3 · Erheblich
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
Open full map
Veraltet — dieser Lagebericht ist 5 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

A storm starting Tuesday night will begin to build new avalanche problems that increase the danger throughout the day. As the snow begins to pile up and blow around, the wind may form new slabs along ridgelines and other exposed slopes. Look for blowing snow and textured surfaces to help you locate wind-loaded areas you may want to avoid.

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    1–2

    For most locations in the West South zone, the modest new snow totals and general cooling trend won’t be enough to create much of a hazard. However, in places where the wind can drift the snow into slightly firmer and deeper slabs, you could trigger an avalanche. Look for blowing snow on ridgelines and exposed features to help see which slopes you may want to avoid. Small drifts and textured snow surfaces can also help point out where these potential winds slabs may be forming. While steep slopes along ridges are the obvious place you may see this problem, you could also run into it along the sides of mid-slope gullies, the tops of chutes, or near the base of cliffs. If you suspect a slope holds wind deposited snow, steer around and seek out less wind affect areas.

    (12/21/2021)

    Wind drifts in the Tamanos area of Mt Rainier National Park. These features help show where wind loading likely occurred. 

    Photo: Andy Harrington

Avalanche Discussion

These avalanches problems will essentially be starting from scratch. So, it may take a bit for enough snow to fall and blow around before you see the hazard begin to rise. This will happen first at upper elevations where colder temperatures, stronger winds, and soft surface snow allow slabs to form quickly. Locations near the volcanoes like Mt Rainier and Mt St Helens could also see the hazard rise more rapidly. In these locations, lots of uncertainty exist about the weather forecast. If more snow falls than expected or if you begin to experience periods of heavy snow, dangerous avalanche conditions could develop on all open steep slopes. For other locations like Crystal and White Pass, if less snow accumulates than we anticipate, you may not find that the avalanche danger reaches Considerable before the end of the day.  Below the rain-snow line, you could see a chance for small loose wet avalanches to continue.

On Tuesday many areas around the West South zone experienced temperature inversions with warmer air at mid and upper elevations. In some locations, this resulted in lots of rollerballs, several natural small loose wet avalanches, and a warm snow surface. This should help the new snow bond well to the old interface. As this warm snow layer cools, it could form a new crust and snowpack marker to track over the next few days.  One large natural storm slab avalanche was observed in the White Pass backcountry Tuesday. This slide likely failed at the base of the recent snow late Monday afternoon or evening (12/20). While you can still see several storm layers in the upper snowpack (including the 12/20), numerous professionals observed generally strong snow without significant weak layers.  As a result, we expect any avalanche activity to remain in the new snow Wednesday.

Abgedeckte Regionen