Lawinenlagebericht

Lawinenlagebericht

Payette Avalanche Center
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Lawinengefahr

Mon
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
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Kernpunkte

The avalanche hazard will be increasing today. This morning, you may encounter shallow wind slabs in middle and upper elevation terrain on leeward slopes. Strong southwest winds have been moving the small amounts of surface snow available for transport onto north and east-facing terrain. A winter storm is impacting our advisory area today through tonight. 4-8 inches of new snow accompanied by strong southwest winds will increase the hazard of wind slab avalanches near ridgetops today, as well as the potential for dry loose avalanches on steeper slopes.

Pay attention to clues that indicate wind slab development (drifted snow, scoured or etched snow surface, hollow or slabby feeling). If you are finding these clues, find a safe travel route away from consequences such as terrain traps.  Use caution and best travel practices in steep terrain, near ridge tops, in natural catchments(like gullies or other confined terrain).

Lawinenprobleme

  • Wind Slabs

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

    This morning, wind slabs will likely be shallow and small. Heavy snow and strong winds can build wind slabs rapidly. Pay attention to wind slab development on ridgetops and leeward terrain features. Later in the day, wind slab hazard will increase in likelihood and destructive size. As the storm progresses, you may be able to trigger wind slabs in areas near ridgetops, in natural depressions, or gullies. Tune into the snow as you travel into upper elevation terrain and dial back terrain selection if you encounter evidence of wind slab. 

  • Loose Dry

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

     The new storm snow may have difficulty bonding to the previous interface. Yesterday, we experienced a significant warming event that moistened the snow surface on solar aspects. Temperatures dropped ahead of the storm this morning and there may be a crust on the new/old interface. On other parts of the compass, the previous snow surface was firm from wind-affected snow. New snow will not bond well to wind-scoured surfaces. On steeper terrain, new snow could have the potential to run as loose snow avalanches or sluffs. Watch for surface snow moving with you if you travel on steeper slopes.

Avalanche Discussion

Today's advisory is sponsored by Mile High Powersports just South of McCall on highway 55, Thanks for supporting the PAC and the Friends!

Yesterday, we saw a spring-like warmup across the advisory area with temperatures climbing around 45 F above 6500 ft. The sun and warm temperatures were accompanied by strong southwest winds. Winds were easily moving snow and impacting the snow surfaces. There was not much snow available for transport so wind slab development was minimal yesterday. A winter storm will be impacting our region this morning into the evening. 4-8 inches of snow is expected at upper elevations along with strong southwest winds. This morning, winds were gusting into the 30 M.P.H range on Granite mountain (link here) and into the 50's on West mountain. Snowfall is heavy in the southern portion of our zone near West mountain where current snowfall rates are 1-2 inches an hour.

Expect the avalanche hazard to increase throughout the day. New snow and strong winds will add stress to the existing snowpack in a short amount of time and we could begin to see human-triggered avalanches today.  A significant weather pattern shift is in store this week. Although yesterday may have felt like spring, winter will be bearing down on us this week. Our snowpack has developed some buried weak layers over the past several weeks. A rain crust is close to the surface on elevations below 7800' and a weak layer with facets is buried about 2-3 feet down. These layers will be tested as more weight is added. Keep these concerns in mind as you travel in the mountains for the next several days. Expect the avalanche hazard to increase and adjust your terrain selection to be more conservative in and around avalanche terrain.