We went to assist with the DOT shoot on Thane Road today, to see what the explosive rounds from their 105 mm howitzer would bring down. The first shot brought the biggest slide of the day, shown in the photo sequence below.

It was not a large slide, but it grew and ran long due to the low density snow on the lower slopes. Though our avalanches often run quite well across bare ground, they do go farther and faster when the friction is lowered by dry snow to sea level.

Additional rounds brought down smaller slides. It quickly became apparent that the starting zones had been eroded by wind down to the December 23 to 24 melt freeze crust in many places. Rounds landing on windblown bumps blew craters in the icy snow, those that landed in the windloaded pockets released slides.

These results are another indicator that high spatial variability is the norm now. Tests may produce no results but large slabs can still be released.

There has been a temperature inversion today as warm onshore airflow aloft has overridden the cooler air that has been here for the last week. While sea level temperatures stayed below freezing all day, the temperature at 700 m rose above freezing at 8 am and stayed there all day. There was little or no precipitation, but some cinnamon rolls were visible as testimony to wetting of the surface snow layers on the higher slopes.

We did the Juneau Rounds, our standard transect of the urban paths, yesterday and today and still found no natural releases. It appears that the higher starting zones have many areas where the snow is either blown away or reasonably well bonded to the underlying crust and windslab, awaiting a trigger or more load to release it. Backcountry travelers should still choose their terrain very cautiously and the large mainland paths are still triggerable.

Today's gentle warming and reprieve from new snow loading should help the snowpack adjust, but further new snow, windloading, or warming will take us back into a trend toward greater instability.