Hatcher Pass

Problemi valanghivi

• 

  Wind Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alta quota
  • Limite del bosco
  • Sotto il limite del bosco

  Probabilità

  Very Likely

  Dimensione

  1–2

  This storm was absurd. For review, we seek guidance from Webster: Absurd. /əbˈsərd/ adjective 1: ridiculously unreasonable, unsound, or incongruous"an absurd argument." Some years, Hatcher Pass gets 10" of SWE...for the whole season. We just got that in a long weekend. Ridiculously unreasonable! #absurd. 

  With tapering snow totals and strong gusting extreme winds, our new storm snow avalanche problem has transitioned from storm slabs to wind slabs. Yesterday, southeast winds blew steady at 25-35mph for more than 24 hours with gusts up to 60mph at upper elevations. Due to denser snow in this storm event, these likely did not build as large of slabs as possible, but with so much new storm snow and a rightside up finish, they will be out there today and they will be reactive to touchy at mid and upper elevations. 

  You are very likely to be able to trigger wind slab avalanches in specific leeward terrain (SW-NE, clockwise). These will vary in depth due to our terrain now being more connected thanks to deeper snow totals. On the shallower end, wind slabs could be 6". On the higher end, it will be possible for a human triggered avalanche to "step down" into our persistent slab problems, more than 5' deep (see below). This could be catastrophic and unsurvivable in steep terrain and terrain traps.

  STORM SLAB AND DRY LOOSE

  With the colder temperatures, you are less likely to encounter storm slab avalanches as new snow is likely settling gradually and loosening. You may find lingering storm slabs at the lower-mid elevation where the snow was denser. Expect new snow to create dry loose instabilities at mid and upper elevations with the potential to interact with deeper weak layers in old snow in steep and extreme terrain. 

  Remember, you are most likely to trigger avalanches 24-48 hours after a significant storm or wind event. 

  

• 

  Deep Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alta quota
  • Limite del bosco
  • Sotto il limite del bosco

  Probabilità

  Likely

  Dimensione

  2–3

  The weak structure throughout our snowpack experienced trial by fire during this storm event. Large to very large avalanches failed on basal facets and ran on the ground in many locations (see avalanches below) and covered parts of the Archangel Nordic ski trail and Hatcher Pass Road above mile marker 14. 

  At this time it is hard to determine the reactivity of persistent weak layers buried deep within the snowpack. Due to the egregious weather, we (and you) have not been able to observe the snowpack at mid and upper elevations. We do know that due to the weight, quantity, and quality of new snow coupled with the depth of these old persistent weak layers, there is a lower likelihood of large natural avalanches. That being said, you could still trigger or remote trigger an avalanche should you venture into terrain 30 degrees and steeper. 

  Triggering this type of avalanche will be large and extremely consequential, certainly able to bury, injure, or kill a person and destroy a car or small. Expect deep persistent slabs to be upwards of 2 to 5' deep at this point with the potential to go to valley bottoms. 

  Freezing levels bounced between 1,600 and 2,000'+ yesterday during heavy precipitation. While there is not much snowpack left (and the snow that remains is saturated and isothermic, for now), you could still trigger a persistent slab at lower elevations and shallower persistent slab avalanches below 2,500 are still possible. 

  A rapid cooling trend and dropping wind speeds will help moisture depart and loosen the upper snowpack but expect to be working with this problem for the time being.