Natural avalanches will be possible this afternoon and tonight as new and wind-driven snow overload a weak snowpack. Travel carefully today, especially near any wind-loaded slopes above 8,500’. Triggering a large avalanche that can fail above, beside as well as below you will become likely in wind-loaded areas. Low elevation slopes have much less snow cover with lesser avalanche hazard.
New snow and strong winds will form slabs one foot or more thick in upper elevation areas, especially in the northern parts of both mountain ranges. This avalanche problem will develop later in the day as new snow accumulates. Look for signs of cracking in surface snow and realize that a triggered wind slab could step down into older weak snow and form a much larger avalanche.
Several weak layers formed during the periods of drought in November. These layers were beginning to adjust to the new snow load but will be reactivated again today. Expect avalanches to involve all of the snow down to the thick crust formed just before Thanksgiving. Avalanches will run faster and farther on this crust where it is continuous. The focus of the recent avalanche activity was on northeast aspects though avalanches still occurred on northwest through southeast aspects which were sheltered from strong sunshine and warm temperatures in November. Avalanches could be two to three feet thick today in high elevations if they receive the maximum forecasted snowfall amounts.
Skier triggered avalanches were observed 2 days ago, failing on weak snow near the ground. Expect more of the same today. While the likelihood has gone down, the consequences remain high due to early season conditions.
Photo: Joey Manship
Exact snowfall amounts will vary north to south but the potential range of 4-8” of new snow by nightfall combined with strong wind is enough to cause significant avalanche concerns. Additionally, warm temperatures will weaken pre-existing slabs and make for touchy, upside-down conditions. Weak layers deep in the snowpack were settling down over the past couple days are likely to resume their whoompfing and cracking.
