Lawinenlagebericht

West Slopes Central

Northwest Avalanche Center
Auf der Karte ansehen

Lawinengefahr

Sun
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
3 · Erheblich
Open full map
Veraltet — dieser Lagebericht ist 4 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

On Saturday, the West Central will likely see an end to the atmospheric river that has pummeled the zone since Wednesday.  Rain, high-elevation snow, gusty winds, and generally stormy weather have resulted in dangerous avalanche conditions around the zone. A good bet will be to avoid slopes over 35 degrees until the snowpack has had time to heal.

Lawinenprobleme

  • Wet Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    2–2.5

    Even as the atmospheric river wraps up on Saturday, recent rain that has soaked our snowpack up to around 6500 feet will still need some time to drain. Wet avalanches are not well understood and difficult to forecast, but they can occur long after the rain has stopped. These unpredictable slides are difficult to manage, so your best tool will be to avoid slopes over 35 degrees on Saturday where an avalanche can start, run, or stop. This includes being aware of the terrain above you such as sagging cornices, blocks of snow on rock ledges, or larger avalanche paths. 

    Wet avalanches could come in a variety of forms on Saturday, including Wet Loose avalanches starting from a point and fanning out as they descend, pockets of Wet Slabs, or larger Glides and Cornices. They could even be intermingled with loose slides triggering slabs for example. Regardless of what avalanche problem you encounter, your management of them will generally be the same. Put these slides on your radar anywhere you encounter wet and soggy snow.

    This is an old photo of a very large natural wet snow avalanche that ran down a gulley to below treeline.  This was on the southeast aspect of Mt. Ross and ran several thousand feet and reached Highway 20 near Newhalem. Avalanches could be similar to this one on Friday. Photo: Andrew Kiefer

  • Storm Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    2–2.5

    Near the highest peaks, you could reach an elevation where the rain wasn’t able to extend. In these areas, drastically different conditions could await you, with potentially several feet of new snow. Multiple rounds of precipitation during the past few days likely created some interstorm layers that you will need to investigate before stepping into consequential terrain. Use small test slopes to see how the snow is reacting to your weight. You may want to spend some time digging in the snow with your shovel to see how much new snow there is above the Christmas Crust and where the potential layers of concern exist. When in doubt, you should avoid all slopes over 35 degrees.

    (2/17/2021)

    A large storm slab avalanche which is similar to one that might occur on Friday.  Photo: NWAC Observations

    Photo: NWAC Observation

Avalanche Discussion

Observations are extremely limited in the data-sparse West Central zone. Due to the ferocity of the current atmospheric river, we have even less data than we typically like heading into a holiday weekend. Prior to the storm, it was a busy week with natural and human-triggered Wind Slab avalanches reported from last weekend through Tuesday. As of Friday afternoon, NWAC’s weather station at Mt. Baker has recorded over 6 inches of precipitation since Wednesday evening, much of which is rain. At least the northern half of the West Central may have seen similar precipitation amounts as this storm track favored the area. We’re not done quite yet as another 0.5” of water is forecasted to fall in the Barlow Pass area Friday night into Saturday. We suspect that a natural wet avalanche cycle occurred in recent days and could linger into Saturday as precipitation continues.

As this event winds down, temperatures should slowly start to cool and winds should increase. This will help the snowpack to stabilize from the top down, eventually creating a new crust. When formed, this crust will be just one of the multiple surfaces you may encounter as you venture back into the mountains. Wet punchy snow, breakable crust, firm crust, swollen creeks, exposed natural hazards, and refrozen avalanche debris could all present different hazards as you travel. If you’re out there, please send us some pictures of what you’re seeing by submitting an observation.

Abgedeckte Regionen