Areas of MODERATE avalanche danger are expected to form today both above and below treeline on NW-N-NE-E-SE aspects on slopes 32 degrees and steeper. For all other areas, avalanche danger is LOW. Expect wind slabs near and above treeline and potential pockets of storm slab below treeline. The areas of greatest avalanche danger will exist north of Hwy 50.
A new round of wind slab formation is expected to occur today as new snow and wind combine to build fresh slabs in wind loaded areas. The likelihood of human triggered avalanches will increase as the day progresses in near and above treeline terrain on NW-N-NE-E-SE aspects. The largest wind slabs are expected to form north of Hwy 50 along the Sierra Crest.
In wind protected open areas near and below treeline, the potential exists for areas of surface hoar to become a buried weak layer today. Shallow human triggered storm slab avalanches could occur in open wind protected areas where the upper end of forecast new snow amounts are reached. Surface hoar will need to have survived destruction by increasing SE to SW winds last night and this morning for this to become an avalanche problem.
Observations made yesterday in the Carson Pass area on both Red Lake Peak and near Frog Lake Cliffs revealed that difficult to trigger wind slabs remained present in the area. Evidence of instability was limited to snowpit tests on NW and NE aspects. Variable test results were noted on the widespread weak layer of lower density recent storm snow that exists at the base of the surface wind slab. Additional observations made yesterday in the Mount Rose area revealed small, isolated, and difficult to trigger wind slabs on NW-N-NE aspects. A public submitted observation indicated improving snowpack stability on the north side of Castle Peak (Donner Summit area). Sizeable areas of 1 to 10 mm surface hoar have been noted around the forecast area over the past two days. The potential exists for this surface hoar to become a buried weak layer today.
