Steep Deep Japan

Yesterday in Hakuba's backcountry: after this storm the snow pack has settled at an amazingly fast pace with huge quantities of powder being transformed into quite dense snow in the space of an afternoon the previous day. Warm temperatures ad strong humid winds were to blame. Ski quality was still ok and stability had improved a lot.

This past storm produced a very widespread avalanche cycle with many size 2's on the NE chutes behind Happo. Gara Gara had a size 2.5, possible 3. The Tsugaike area had multiple size 2's on the north side of Hiyodori. On the south side of Hiyodori the well known slide path had run almost full length, reaching the bottom cat track. This took out a mature hardwood in the lower third of the path.

It was a very active cycle with steep obvious paths all running and much less frequent paths putting on a show as well.

Now rain has arrived in the valley with an uncertain ran/snow line. We will report more on this tomorrow.

I fell behind a day so just a quick data update for now this post.

Extreme winds from the NW yesterday (120kph at 2000m and 60kph gusts at valley bottom). Also heavy snowfall - see data below. High avalanche danger in steep backcountry right now as it has been for a few days running. We are staying on lower angle unthreatening terrain in areas of less storm snow.

Please note that this is not an official avalanche bulletin. It isn't even an amateur one. I am only providing some info that we see in the mountains along with my personal and informal opinion. Often the data is incomplete and my opinion wrong. You should only use it as a small input to your own decision making.

A large (size 2.5) avalanche triggered by a snowboarder was reported for 1800m in Oshidashi on the north side of Happo. The crown wall was 80-150cm deep and the sliding surface was the Jan 28 melt freeze crust. This comes after continued snowfall, but relatively light winds on Happo.

Snow stability at the moment is poor and with additional load from this storm it will trend towards very poor. We had 48cm of snow overnight and it is a raging storm this morning. Staying out of the backcountry.