Lawinenlagebericht

Lawinenlagebericht

Payette Avalanche Center
Auf der Karte ansehen

Lawinengefahr

Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
Veraltet — dieser Lagebericht ist 2 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

You could find wind slabs 6-12" thick on east-facing terrain above 7500'. Pay attention to the changes in the new snow as you gain elevation and enter wind-affected terrain. Triggering a 3' deep persistent slab avalanche is becoming unlikely.

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–1.5

    6-10" of new snow along with S/SW winds have built fresh wind slabs above 7000'. Yesterday, we observed a noticeable change in the very soft surface snow to more of a stiff, slabby feel at around 7500'. This elevation may be different depending on terrain features. Yesterday, S/SW winds were blowing and drifting snow onto north through east aspect. Overnight, the winds shifted out of the NW. Shifting wind directions can cross load certain terrain features. Pay attention to clues like drifts, pillows, or dunes that indicate the wind has been at work. 

    Additional Discussion: In areas that haven't been affected by the wind, there is 10-12" of light snow at the surface. Be aware of small dry loose avalanches (sluff) in wind-sheltered terrain steeper than 35 degrees. 

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Unlikely
    Größe
    1.5–2.5

    A slab 3-4 feet thick formed during a multi-day storm cycle in early February. This slab buried weak snow (facets, surface hoar, and crusts) that formed during our January dry spell. This persistent slab problem was most active on slopes that face W-E on the north side of the compass. Instability peaked over 10 days ago (sometime around the 3rd-4th). Although we have not observed much avalanche activity in recent days, the photo to the right indicates areas where you could still trigger a persistent slab (steep, rocky terrain where the slab is thin). Be most suspect of steep, rocky slopes that face the polar side of the compass, especially areas that did not avalanche during last week's cycle. The weight of a snowmachine will be more likely to trigger a persistent slab than the weight of a person.

    (2/12/2025)

    Snowmobile-triggered avalanche north of Pearl Lake. Looks to be from the last 3-5 days. Steep, rocky areas like this are places where you could still get into trouble. SS-AM-R1-D1.5

    Photo: Kevin Studley

Avalanche Discussion

A small storm system brought 6-10" to the West Central mountains Thursday through Friday. Most of the new snow was light and fell on very light snow sitting on the surface since last week. Yesterday, we observed a soft, unconsolidated upper snowpack, lacking any slab below 7500'. As you climb higher in elevation, you may notice a difference from soft to slabby. Pay attention to subtle clues of wind slabs if you are entering upper elevation terrain that has been impacted by the wind. 

For nearly three straight weeks in January, high pressure persisted across the region. During this time, weak snow (facets and surface hoar) and crusts formed at or near the snow surface. These layers were buried on January 31st as a mulit-day atmospheric river brought 4-5 feet of snow (7-8"SWE) from January 31st-February 5th. Some light snow showers continued from February 7-9, bringing some low-density snow atop the recent storm snow. Instability peak sometime Sunday-Tuesday (2nd-4th), with widespread natural and human-triggered avalanche activity. Many observers reported remote triggering across the forecast zone. Since the peak, avalanche activity and obvious signs of instability have decreased substantially. A very dense slab 3-4 feet thick is overlying the weak snow that formed during the January drought. The good and bad news is how deep these persistent weak layers are buried. Good, because it's becoming difficult to trigger and these weak layers are beginning to strengthen. Bad, because if you trigger a persistent slab, it's likely to be 3' deep and you may not see any obvious signs of instability. It's relatively easy to stay out of harm's way when the snowpack is screaming at you (peak instability). It's much more difficult to be patient after the storm passes and the in-your-face signs are absent. I am most suspect of steep, rocky terrain that did not already avalanche. 

Thanks to all those folks who submitted observations during last week's cycle. We received some great information over the past 10 days. Submitting observations helps improve our avalanche forecasts.