Hatcher Pass

Lawinenprobleme

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  Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Hochgebirge
  • Waldgrenze
  • Unterhalb der Waldgrenze

  Wahrscheinlichkeit

  Very Likely

  Größe

  1–2.5

  The good news? Our snowpack is about to double in size. The bad? This storm is falling on an awful snowpack, transformed by the weeks of drought we experienced in December. 

  With a significant load over our current snowpack structure today, natural avalanche activity is very likely. Expect hazardous avalanche conditions that are extremely sensitive to human triggers as this storm event unfolds. Persistent slab avalanches could be large--up to 2-4' deep--and will run more widely across pathways than last week's avalanches. You are most likely to find deeper, more consequential persistent slabs on specific leeward aspects (SW-NE, Clockwise) where extreme winds built larger hard slabs during wind events earlier in January. Traveling in avalanche terrain is not recommended today. 

  This last week, we have already seen how our widespread and weak "upside down" structure has contributed to instability. With even a small increase in load during trickling snow events, we experienced an uptick in reactivity. Specifically, we saw several large remote-triggered avalanches and one catch and carry on multiple aspects and elevations (see recent avalanches below). There are two persistent weak layers of concern: 1.  Midpack facets and crusts below hard, buried slabs 2. Weak, large basal facets/depth hoar at the bottom of the snowpack. While these larger, problematic snow grains at the bottom are in a variety of sizes and states of transition, expect them to be increasingly activated by this storm. 

  

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  Storm Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Hochgebirge
  • Waldgrenze
  • Unterhalb der Waldgrenze

  Wahrscheinlichkeit

  Likely

  Größe

  1–2

  This storm has kicked off with 8" of snow at mid-upper elevations and 3" at low elevations as of this morning. Look for signs of cohesive slabs forming as storm snow builds throughout the day and expect this hazard to increase with accumulation. 

  There is some uncertainty at what altitude the rain/snow line will be today. Regardless, we can expect a generally upside down, warm storm event to be overloading a weak snowpack at all elevations. At low elevations where we have not seen as stiff slabs in the snowpack, this large amount of storm snow will fall on weak, sugary snow.  

  Pay close attention to slope angle and slope size as you travel. The widespread nature of this problem means that it will be easy to find and easy to trigger with natural avalanches possible. Be cautious traveling in gully/drainage features, even at low elevations. It is a good reminder that there is terrain capable of burying and killing someone with this problem, even in low-angle terrain (the "Road Run" and "the Glades"). 

  Pole tests, hand shears and test slopes are great tools for this problem. Whumphing and shooting cracks are signs of cohesive slabs and instability. If you travel today, spot your partners and travel one at a time through suspect slopes, even if terrain features seem small in size and consequence.  

  WIND SLAB:

  Winds have been gusting moderate out of the south and are expected to gust 24-34mph during the storm. There is plenty of new snow available for transport. Be observant if wind speeds increase or shift during the day and you are out traveling. Lookout for signs of active wind loading (drifting, blowing snow) and stiffer slabs forming.