We went up Mt Troy today to see how the new storm snow was bonding to the underlying layers, and how it was reacting to load. At the time of our observations, there was only some 10 cm of new snow, but as we finished the rate of snowfall increased to over 2 cm/hr and the SE winds began to increase.

During the day, we only found sensitive windslabs (#2 on the slab test, ripping out most of the undermined area cleanly and energetically) in localized areas on the upper slopes of the mountain, but tonight they are becoming widespread as the snowfall rate and winds increase.

The new snow was being blown into drifts today in some areas, and scoured right down to the December 23 to 24th melt freeze crust in others. Spatial variability will be the norm, with new snow poorly bonded to melt freeze crusts in the more windswept areas, and even more poorly bonded to facets and surface hoar in the more sheltered areas.

The new snow sluffed easily on slopes over 35° today, not yet wind affected or thick enough to produce slabs but obviously very poorly bonded. In both the Rutschblock and AK Block tests, the surface layer and the snow from several days ago both released upon stepping onto the block (#2) or upon an ankle flex (#3) on a 48° test slope in the lee of a row of trees at 660 m on the lower slopes of Mt Troy.

No deeper weak layers released in our tests, but the thick windslab may have made the snowpack less reactive to skier triggering at this site. Deep weak layers are generally harder to trigger, though the consequences of triggering them are worse. These thick dense windslabs were much less faceted than the corresponding layers in the other less windloaded sites we have tested in the last week.

An avalanche cycle is beginning tonight from the new and windloaded snow tonight on a very weak snowpack, with slides heard already on Mt Juneau. Smaller slides are likely overnight, areas that do not release early will produce larger slides if heavy snowfall and wind continue. Warming temperatures will also trigger larger slides when and if they arrive.

The combination of low friction bed surfaces and light snow all the way to sea level increase the likelihood of fast-moving slides reaching low elevations, though starting zone volumes are still low. By tomorrow, if the heavy snowfall continues, starting zone volumes are likely to be large enough to bring larger debris piles to lower elevations.

Tomorrow should be an epic powder day at Eaglecrest, and a good day to stay inbounds. Backcountry conditions will be very tempting to powder-starved riders, but the avalanche conditions there are likely to be treacherous.