The Valdez, Alaska area Central Chugach got a HUGE refresh after a three week dry spell.

By the afternoon of Friday, March 17 there was 18”+ new snow at ~500’ elevation in the transition zone from maritime to intermountain snow climates. More snow fell through March 18.

The snowpack needs time to adjust to this significant load.

While the few to several feet of accumulation at mid to upper elevations may not impact older buried weak layers, as the snowpack became very strong and was cemented from high winds and melt-freeze during the three week dry spell, there will be significant danger for natural and human triggered avalanches in the coming days at the new-old snow interface 18”+ deep.

The old snow surface is a weak interface on most aspects at most elevations: a hard, low friction, “boilerplate” bed surface. In many areas this weak interface is exacerbated by a thin layer of facets on top of the hard, relatively slick, wind-packed snow.

On Friday many red flags were present, and the mountains were screaming “danger”: active wind loading, collapsing (“whumphing”), recent natural avalanches, and remote human triggered avalanches. Basically, all slopes steep enough to slide would with the slightest human disturbance. This photo shows a remote triggered ~18” soft slab in forested terrain at ~700’ elevation N aspect.

Danger remained high Saturday with more snow and wind loading. Danger remained elevated Sunday with collapsing (“whumphing”) and spring sunshine initiating a natural avalanche cycle on steep, rocky, solar aspects as the new snow was exposed to sun for the first time.

Video and photos below from Sunday, March 19 when skies cleared.

On Monday, March 20 high grade powder was observed from the coast to the interior nearly everywhere above rain line (which reached up to 1400′ on the coast) except for the most sun-exposed terrain which was crusted.

A snowpit at ~4300′ N aspect in the transition zone between intermountain and continental snow climates only yielded a series of ECTNs with no persistent weak layers evident in the upper 4′ of the snowpack. However, only a couple hundred feet higher in a thinner area of the snowpack advanced facets and facet chains were found only ~8″ deep below a few inch P+ wind-packed layer (as seen in this photo).

CMI professional snowpack interpretation is that the storm snow is generally bonding readily to the old snow surface after 36+ hours but there are definitely thinner, weaker areas of the snowpack that could be problematic (especially further interior) for human triggered hard slab avalanches.