We found the windslabs that are now about six days old are much stronger and less sensitive than when they were fresh, but still potentially triggerable. We did not find fresh windslabs of any size, but lee slopes in the windier spots are likely to have very tender windslabs.

The surface layers of the snowpack are a setup for major avalanche cycles when and if we get the next big storms. Neither the facets nor the ice will bond well to new snow, and the faceting process has greatly weakened the lower layers as well so they may become involved once a slide is in motion.

This is likely to be our last post for several weeks. These postings are an all volunteer effort and we must travel for the jobs that pay the bills. So we won't be here to offer advice, but beware if we get big windloading, or wet snow, or 30 cm or more of dry snow, or snow with wind, or snow and wind followed by rain to higher elevations. Any of these will probably trigger an avalanche cycle.

We are less likely to have a cycle if it warms gently and slowly, without much snow or rain, or if we only get small amounts of snow without wind, or if it just stays cold and dry until spring.

Take care out there. We will post as we are able to, but will not be back on a regular basis until March 23.

The slab has had time to "relax" and bond to the underlying snow, and the grains in it have become quite faceted, making them weaker and less strongly bonded within the slab. Fresh windslabs or thicker, more extensive old windslabs will still be sensitive.

There is always depth hoar here in all the thin snow spots near the rocks and ridges on the Icefield and on the higher peaks and it is not unusual on Douglas Island either, but it is unusually well-developed this year. The reason is that the thin snowpack and cold weather have made a strong temperature gradient (difference in temperature per unit distance) between the warm ground and the cold air. That temperature gradient drives water vapor from warm to cold through the snowpack, and as the water molecules migrate they keep changing from vapor to solid and back, creating new crystals.

The growing crystals have six-sided symmetry and crisp edges, like snowflakes, and those sharp angled edges are the facets that give them their name. They are the easily visible shapes like little hex or machine nuts on the edges of the grains in these photos taken with our super macro lens.

The grains grow larger in this process and the bonds between them weaken. This causes their sugary texture. Juneau residents, check the snow in your yard right now, where it has not been packed. You'll find coarse sugary grains. Look at them under magnification and they will resemble smaller versions of what is in these photos.

When faceted grains grow really big, they develop hollow forms and are called depth hoar. These grains of hoarfrost form at the base of the snowpack, at depth, hence the name. The wind kept blowing the largest grains off our crystal card today before we could photograph them but even the ones that were left show hollow forms beginning to develop.

You can also see striations, lines of crystal growth or steps that run parallel to the crystal faces. These are another sign that the process is at intermediate to advanced stages.

These grains are growing in an unusual situation for depth hoar because they began their life on the ground as moist snow drifting in between large globular growths and feathers of rime, made up of depopsits of ice from supercooled (below freezing but not frozen because it has nothing to crystallize onto) water droplets in the atmosphere.

Rime grows abundantly when oceanic airmasses meet coastal mountain ranges. Moisture-rich clouds without dust or other impurities to seed crystal growth have many supercooled droplets that freeze onto the windward sides of our ridges.

The rime here grew in our warm storms earlier in the season. Then the cold weather we have had recently turned all the grains where there was enough porosity for vapor flow and grain growth into depth hoar. So here we have a classically moist coastal snow form intermingled with a classically interior climate cold dry snow form. See why we say that we see more varied snow forms here than just about anywhere?