Eastside Region

Avalanche problems

• 

  Loose Wet

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Unlikely

  Size

  1–2

  Temperatures will be significantly warmer today with relatively light winds out of the north. Surface moistening and an increased risk of rockfall should be expected on solar aspects today, particularly if winds are less intense than forecasted.  Expect more easterly terrain to warm first followed by due south aspects and finally westerly aspects as the sun moves through the sky. Partly cloudy skies and warm overnight temperatures last night led to a greenhouse effect and surface temperatures in the Mammoth area suggest a superficial refreeze. It will be important to keep an eye out for signs of excessive warming on more shaded northerly terrain as well, particularly at lower elevations. Be particularly cautious in areas where the snow is still in a state of transition such as higher elevations and aspects with indirect sun.  Keep an eye out for early warning signs such as sticky and moist surface snow, rollerballs & pinwheels, and increasing boot penetration. These are clues that may foreshadow larger point-release avalanches. Consequential areas of unstable snow are more likely in areas with higher snow accumulations from our recent storm near cliff bands & rock outcroppings, and in confined southerly facing terrain features. Couloirs like the Pinner on Mt laurel and the SE couloir on Mt Baldwin come to mind as areas where even a relatively small avalanche could have very high consequences.  Be wary of your exposure to terrain hazards and be prepared to retreat to more shaded aspects if you notice that surface warming is reaching concerning levels.

• 

  Wind Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Possible

  Size

  1–1.5

  Continued slab development is not likely today; however, it remains possible to find reactive winds slabs sensitive to human triggers in isolated areas near and above treeline.  Leeward terrain features and catchment zones on southerly aspects will be areas of primary concern however, reactive wind slabs can be found on more northerly terrain features as well. The distribution on northerly and easterly aspects may be particularly tricky to read. Damaging north winds following our storm largely stripped high elevation starting zones back to old snow surfaces. As a result panels of wind slab are more likely to be found in mid-slope catchment zones such as near cliff bands, in cross-loaded gully features, and further down slopes than you may typically expect to find them.  Be particularly cautious in extreme & complex terrain where even a small avalanche could cause a bad fall. Large drifts, recent cornice growth, stiff hollow feeling snow, and uneven snow surfaces are all clues that indicate nearby wind deposits. Do your own localized assessments and be suspect of terrain features that encourage drifting such as the leeward sides of ridgelines, alpine couloirs, gully features, and cross-loaded depressions.