Tenki Diary 13 Jan 08

Weather for the 24 hours to 7am 13 Jan: after 6 consecutive days 0f +6C in the valley, winter has arrived. Minimum temp –7C, max –2C at 860m asl. Strong gusty winds blowing a lot of snow, even in the valley. About 15cm new snow fell yesterday. At higher altitudes this new snow is being blown by the wind, ground up and deposited as denser slab on top of the 11 Dec rain surface. I regard this as a recipe for avalanches in the alpine.

Yesterday we spent time in the backcountry up to 1800m and found that the 11 Jan rain had even fallen there, with only 15cm new snow atop a sodden and quickly freezing snowpack as temperatures plunged from above freezing at 6am to –6C by midday. I am eager to go higher and inspect the distribution of rain from the 11th.

Temperatures are forecast to remain cold for the week, which will make the rate of snow pack stabilisation slower than normal in temperate Hakuba.

The good thing about the rain was that is probably destroyed the extensive dense windslab we found below 1800m on NE-NW aspects on the 10th. This of course has been replaced with new windslab on crust.

Planning a rewarding and safe day in the backcountry is quite challenging right now.