Central Cascades

Avalanche problems

• 

  Wind Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Possible

  Size

  1–2

  There were multiple reports of wind slabs triggered on north and east facing slopes near treeline on Wednesday. With minimal amounts of blowing snow on Wednesday, and another day for wind slabs to settle, they may not be easily triggered on Thursday, but it is still possible. Possible means it can happen. Careful evaluation of wind loaded slopes is essential before dropping into avalanche terrain, especially on steep and committing slopes. 

  Use small test slopes or low angle terrain to evaluate wind slabs before committing to steep slopes. Monitor the depth of wind slabs. Deeper wind slabs can result in larger avalanches. Look for a wavy surface texture or pillowy drifts to help identify where wind slabs have formed. Wind slabs will not be everywhere, so use a careful eye to identify wind loaded slopes. The usual suspect terrain includes below ridge tops, peaks, and around features that catch blowing snow from cross slope winds.

  Watch for signs of wind deposited snow in clearings and areas with sparse trees even below what you typically thing of as 'treeline'. Burned areas and slopes with dead trees can experience a big wind affect and get a lot of wind drifted snow. 

  

• 

  Cornices

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Possible

  Size

  1–2

  Cornices have been observed along ridgetops throughout the terrain. Over the last few days, cornices have been fragile and have been observed to break easily. Cornices can be sneaky and are not evident when approaching ridges. Be cautious in places where you do not have a good vantage to see if cornices are present. They can break easily if you step out onto them and can result in you going for an unintended air drop. Falling cornice debris can also trigger avalanches on the slope below. Cornices in the direct sun along with warming can weaken and break naturally. 

  

• 

  Loose Wet

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Possible

  Size

  1

  Wet loose avalanches will be possible on Thursday as temperatures are expected to rise into the upper 30's F at lower elevations. This problem will be more prevalent at lower elevations where warming combined with direct sun will cause surface snow to become wet, heavy, slushy, and loose cohesion. Steep mid elevation slopes in the direct sun may warm up enough to bring on wet loose avalanches. Watch for signs such as roller balls, pinwheels, and the surface snow becoming wet/slushy as indicators of this problem. Small wet loose avalanches can have consequences on steep slopes and above terrain traps. Use visual clues on the snow surface and timing to avoid this problem. Slopes in the direct sun will be more likely to experience wet loose avalanches.