With a buried weak layer and a building surface slab,
Thursday will be a good time to take it easy.
Expect fresh windslab development with increasing winds and snowfall. These will initially come from the West and then switching to Northerly as a cooler airmass moves in from the North.
Up to 50cm of new snow this week is settling into a slab and sits on a persistent weak layer from January 7th. This weak layer has been found in profiles at Treeline and above, and is expected to become increasingly reactive as the slab continues to grow with the incoming snowfall and wind.
Skier triggered sz 3 in Lone Pine Monday, ran ~1000m and accumulated significant mass.
Several natural avalanches to sz 2.5 were observed Monday afternoon, triggered by solar input on S through W slopes.
There have been several reports of rider triggered avalanches up to size 1 in terrain adjacent to Glacier National Park.
A complex upper snowpack will be increasingly challenging to manage with incoming wind and snow.
New snow will cover facetted snow or pockets of windslab in exposed areas. 30-40cm down, there is a weak interface (Jan 7th layer) of surface hoar into the high alpine, and a thin crust on steep S aspects. As the surface stiffens into a slab, expect increasingly large avalanches on this Jan 7th layer.
Overall the mid and lower snowpack is strong and well settled.
A brief pulse of snow and strong wind Thursday, followed by plummeting temps.
Tonight Clear periods. Alpine low -6°C. Moderate SW ridgetop winds.
Thurs Flurries, up to 10cm. Alp high -6°C. Gusty strong-extreme West wind.
Fri Sun/cloud/isolated flurries. Alp low -16°C, high -11°C. Moderate gusty North wind.
Sat Mixed sun and cloud. Alp low -20°C, high -15°C. Light N wind.
