Bollettino valanghe

East Slopes South

Northwest Avalanche Center
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Pericolo valanghe

Sat
Alta quota
1 · Debole
Limite del bosco
1 · Debole
Sotto il limite
1 · Debole
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In sintesi

Older and more recent slab may still be reactive in extreme terrain at upper elevations. Steer around areas of active drifting and re-evaluate if you encounter a shooting crack. Early season hazards are still abundant and can easily exacerbate the consequence of being caught in an avalanche. 

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    3-day-old wind slabs may have enough longevity to take you for a ride in extreme, upper-elevation terrain. Rocks and other early season hazards would make any ride painful. Take note of the shallow slabs and interfaces within the snowpack as you ascend in the terrain as these could serve to prolong wind slab reactivity.  An observation from 11/27 highlights some soft layering and interfaces within the shallow snowpack around Cleman Mountain. It also highlights the SE winds during the last storm.  Active snow transport from an increased westerly wind may also occur at upper elevations on Friday. Areas of deposition will help you identify any freshly forming shallow slabs. 

    Remember, if there's enough snow to ride, there's enough snow to slide. Look for sastrugi on the windward side of ridgelines and anticipate slabs on the leeward side. Other notably suspect locations include below cornices or adjacent to rock and cliff bands in exposed terrain. Visual clues such as ripples or textured surfaces help you identify where the wind has been at work.  Red flags that should prompt re-evaluation include shooting cracks or whumphs as you move through the terrain. If you plan to travel on wind-loaded upper-elevation slopes, use test slopes or hand pits to evaluate the potential for slabs. 

    (11/27/2024)

    Shooting cracks are clear signs of instability that you should not ignore. 

    Photo: Payton Schiff

Avalanche Discussion

Temperatures rose into the mid to upper 30s at middle and upper elevation stations in the East South zone on Thanksgiving Day.  Sunshine likely accelerated the wind slab healing process on sun-exposed aspects, but expect a breakable crust to have formed on these same aspects by Friday morning. These crusts may or may not soften in some areas as cooler temperatures arrive with some wind on Friday. In sheltered areas, expect snow to soften with direct sunshine and possibly shed off rocks.

We have a healthy snowpack across the East South for late November, especially around Bumping Lake and SR 410 which received over 14 inches of new snow during the last system that wrapped up on Monday.  On Wednesday the DOT reported that two large natural avalanches occurred in this area on SE aspects at 6000 ft,  just east of Chinook Pass. These slabs likely released at the tail end of the last storm cycle. 

Lower (and in some cases middle) elevations are still quite shallow and access is challenging in many areas. The Cleman Mountain observation highlights the shallow snowpack. However, as you climb above 5000 ft you’ll find depths of 3-4 ft on average. Recent observations in the East Central near Mission Ridge and Blewett Pass have reported a strong lower and mid snowpack, while the upper 'pack consists of new snow over a crust that formed late last week. NWAC forecasters found small wind slabs failing on this crust earlier this week in the Mission Ridge area that are gradually gaining strength. We suspect similar conditions in the East South. 

 

 

If you get out, let us know what you see by submitting a public observation!

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