Bollettino valanghe

East Slopes Central

Northwest Avalanche Center
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Pericolo valanghe

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

Light new snow and increasing wind speeds will create a fresh batch of shallow wind-drifted slabs at upper elevations. Some of these slabs could fail easily if they form over weak snow surfaces sitting on a crust. Use visual clues like fresh drifts or blowing snow to help you identify where wind-drifted snow could be lurking. 

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    1-2 inches of new snow and moderate NW winds will create small, shallow wind slabs at upper elevations. These slabs could fail easily if they form on top of weak snow on the early February crust.

     The most likely places you'll encounter these wind drifted slabs will be on the leeward sides of ridges, below cornices, and forming under rock and cliff bands. As you travel, look for blowing snow and textured surfaces to help you identify problematic slopes. 

    These slabs won't be large but could knock you off guard in steeper terrain features like chutes or couloirs at upper elevations. The best strategy will be to steer around freshly wind-drifted terrain, especially if you notice shooting cracks of whumping collapses. 

    (1/7/2024)

    Look for blowing snow to help you identify where the wind has been at work. 

    Photo: Willie Webster

Avalanche Discussion

Unfortunately, we're not expecting much precipitation out of this system. However, you may encounter a couple of inches of new snow on the western edges of the zone in places like the Salmon La Sac, Stuart Range, or up near Trinity. The Wenatchee Mtns will be lucky if they get a skiff. 

Across much of the zone, you'll  find 3-5" of new snow over the recent crust at mid and upper elevations, with more the higher you go. Observers have been finding surface hoar over the early February crust, including forecasters on Tuesday at Blewett Pass. It was difficult to identify, but the feel of slipperyness over the crust beneath a few inches of new snow was a hint that it was there (see photo below). Any new wind slabs that do form could become reactive with potential for buried surface hoar or facets over the crust. Check out another observation from the Wenatchee Mountains where they found collapsing of the new snow on the crust. 

It's February, so if the sun is out, expect snow surfaces to warm during the daytime. Keep an eye out for snow becoming moist and sticky during the day. Rollerballs could lead to small wet loose slides on steep enough slopes. Slick crusts, avalanche debris, open creeks, and thin coverage could add challenges to your mountain travel. Make sure to bring appropriate equipment for these conditions.

An avalanche cycle from prolonged warm weather and rain or high elevation snow lasted from January 21st through February 1st. We are still observing debris from this event. On January 28-30th, many natural and skier-triggered, very large avalanches (D2.5-3) were reported throughout the zone and in neighboring zones. Slides on Big Chiwaukum Mtn and Tumwater Canyon ran to the ground (see photos below). Forecasters at the Holden Mine reported natural wet slab and wet loose avalanches to size D3 on the 27th and 28th. If you find evidence of a large or very large avalanche that we haven't logged in our avalanche observations, take a photo and let us know by submitting a public observation!

 

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