29 Dec - Inversion

I saw this cool raicho today (ptarmigan in English). They hang out under the snow quite well hidden, then suddenly burst out of seemingly gentle powder and give you a hell of a fright. Anyway, the striking inversion, see picture below, across what appeared to be all of Nagano probably kept temperatures at valley bottom much lower than was forecast . I was measuring +4C at 1700m, +1.5 at 2400m, yet the high at 800m was only +2.5. My highest point was 2400m, winds were light to moderate, sun was strong, snow quality was ok. Solar aspects have been baked and were setting up a nice new breakable surface crust by afternoon.

With clear skies there was a lot of radiation cooling taking place with the snow surface remaining a lot cooler than the air temperatures on shaded slopes in the alpine.

I saw one Size 2 natural slab avalanche that started about mid-slope on a steep convex bowl at 2400m. Plus I was able to very easily trigger Size 1.5 loose snow avalanches on steep sunny terrain in the early afternoon. Had the slope been bigger, the resulting avalanche would have been equally bigger.

Did anyone see any avalanche activity at lower altitudes today? Edit: plenty reported from Happo. One detail below.


Apparently there was a decent sized slab avalanche today triggered below 1700m on the north side of the Happo ridge in the terrain that skis directly from the resort boundary. Sounds like it was a bit bigger than a Size 2, so not quite big enough to bury a car, but obviously more than enough to bury a person.

Lovely pictures Damian. I am a sucker for wildlife pics. My (small) undertanding for Raichos is that the black mark around the eye means it is a male. During the winter males stay up in the alpine and usually hang out in groups of 2 or 3 while the females head lower down in altitude. The place where you saw it is probably one the best places to spot them (after Tateyama). Not sure if I can see a red spot above the eye on your picture which I think has something to do with it being a juvenile or not. Anyway, great pics and info, thanks.

Hi Arnaud, that raicho was above Tsugaike, and I saw two in a small area. So perhaps they were buddies like you suggested. In Tateyama they can be so prolific that they lurk outside your tent during storms making their weird raicho noise.