The Avalanche Warning has been downgraded to a Special Avalanche Bulletin. The storm that was to bring significant snowfall overnight and throughout the day has moved south of the area. However the chance for natural avalanche activity continues, and riders and skiers could easily trigger newly formed wind slabs at the high elevations as well as slabs that lie upon older weak layers at all elevations. These older weaknesses will be most sensitive at the low elevations where faceted snow is prevalent and where warming and some rain has weakened the snowpack.
The possibility exists to trigger newly formed wind slabs at the high elevations. Strong southwest to west winds have formed dense slabs on leeward slopes near peaks and along ridge crests. Slab depths to eighteen inches could be easily triggered and once triggered could step down to deeper weaknesses in the snowpack.
Buried layers of weak snow persist at all elevations. Slabs that lie upon these weaknesses could be triggered by backcountry riders and skiers today. These slabs could be hard or soft, and could have depths to four feet. These slabs will be most sensitive at low elevations where heavy snow and rain have weakened a snowpack underlain by faceted snow. Steep slopes, road cuts and roof slides could release naturally today.
Periods of snow showers are possible overnight and through the morning before another strong system impacts the area Friday afternoon. Temperatures are to be even warmer tomorrow with mountain temps in the upper twenties during the afternoon and above freezing temperatures at lower elevations when the storm arrives. This is likely to result in rain in the valleys as well as low elevation terrain and snow at higher elevations.The general avalanche hazard could be Considerable or High tomorrow. Factors such as overnight temperatures and rain and snow amounts as well as the timing of the next system will affect this outcome. At the least, backcountry travelers could easily trigger slides at all elevations and natural activity will be possible. Slides could involve recently formed slabs in steep terrain above 8000 feet or at all elevations it could involve deeper weak layers in the snowpack resulting in full depth avalanches to the ground. These full depth avalanches will be most likely in areas where the snowpack is somewhat shallow and underlain by faceted snow. Remember that rain quickly weakens any snowpack and in areas where significant rain falls, natural activity will be likely.
