Lawinenlagebericht

West Slopes Central

Northwest Avalanche Center
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Lawinengefahr

Tue
Hochgebirge
4 · Gross
Waldgrenze
4 · Gross
Unterhalb
3 · Erheblich
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Kernpunkte

Expect very dangerous avalanche conditions and challenging travel due to heavy snow and strong winds.  Avoid being on or under steep slopes near and above treeline. Natural avalanches from higher terrain can still pose a threat even if you are traveling on lower angle slopes below. 

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Very Likely
    Größe
    1.5–3

    The storm that began Sunday will intensify overnight with 2’ of new snow and sustained winds of 30-40mph. New wind slabs will build in both the typical locations near ridgeline but also at lower elevations where you may not normally see wind transported snow. In addition to human triggered avalanches, rapid loading will likely initiate a natural avalanche cycle. Snowfall intensity will diminish through the day but strong winds - and therefore wind loading - should continue. It just won't be the day to venture anyplace beyond the simplest terrain. A storm-induced route-finding mistake such as wandering into an area with big terrain overhead or getting too close to a sensitive new cornice could have a bad outcome.

    While wind loaded areas are easily identifiable, all steep slopes are considered suspect during periods of intense snowfall, sun breaks, or other weather factors that cause conditions to rapidly change. Between avalanche danger and stormy conditions, it will be a good day to simply avoid exposure to avalanche terrain. Stick with lower angle slopes with no overhead hazard.

    Natural avalanches like this are expected on Monday.

    Photo: Adam Ü 

Avalanche Discussion

Another avalanche problem to consider is deep slabs releasing in a layer of facets that could “wake-up” with the coming storm. Very large avalanches of this character were reported from the 16th through 27th of March in conjunction with various storms and then warming. All occurred in upper elevation, northerly terrain, and all but one were naturally triggered. It’s quite unlikely a single person could trigger an avalanche such as this - but there is a chance one could be provoked by a load of new or wind drifted snow, cornice fall, or another avalanche from above. It’s really just another reason to stay out from under all avalanche terrain tomorrow including paths that start at much higher elevations.

West Central is on track to meet forecasted precipitation Sunday with 0.2-0.4” recorded at lower elevations, especially in the northern portion of the zone. Weather stations at Stevens Passe recorded 0.1” or less while Snoqualmie Pass did not receive measurable precipitation. Weather station data (Snotel)  from other areas of West Central in not currently available

The beginning of April brought some respite from the rain and warm temperatures that plagued the Cascades late last month. Weak storms and lower snow levels added a few inches of snow across the zone. The dry snow formed sensitive but generally small slabs during periods of stronger wind. Wet avalanche activity was also noted with sun breaks. This is a reminder that sun breaks and other warming this time of year can rapidly transform the snow surface and initiate avalanche activity. Also, note that a rapid rise in freezing levels Wednesday and Thursday will create another spike in natural avalanche activity as cold new snow becomes unstable with warming.

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