Good morning Sports Fans, and a happy morning it is indeedy-do!
At the 0700 hr. reading time our tireless snow-elf had the pleasant duty of clearing 6 cm of fluffy snow from the daily Height of New Snow in 24 Hours (HN24) snow board*. The forecast is for a break in the precipitation early today. But for a resumption later in the day that may indeed continue well into the week. It may be a good time to call in as "too well to work" on Monday. The clouds are down to below the 1,290 m a.s.l. summit of Iwa Take. You cannot see the ridge crest across the valley.
The driving conditions in the valley are less than ideal. With a low temperature of -7C overnight before the snow began to fall the daily melt water has turned to ice and is lurking below the new snow. Also this new snow at the present -1C temperature is quite slippery when packed. Pay special attention at road intersections: more ice forms there and someone may just go sliding, out of control, across the intersection.
* 1981, V.G. Schleiss, P. Schaerer
Once you get to the slopes bear in mind that this is mostly just "fluff on crust" and the rocks and other assorted obstacles and what-not are just barely covered. As a reminder I will reiterate yesterday's comment: "our on-slope team of observers report lots of rocks and other obstacles (mysterious holes, drainage ditches, odd bits brick-a-brack) on the lift accessible, groomed terrain. This is especially true at the lower elevations."
The crust this morning at 830 m a.s.l. was extremely weak.
The Hira Kawa Snow Study Plot (830m) the 0700 hr. reading is:
Temperature: Present: -1.2C
Maximum: 8C (-3C was observed at 1300 hrs. at 2,230m a.s.l., above the Happo One Lift Company
Precipitation: snowing such as to accumulate less than 1 cm per hour (S -1)
Barometer and trend: 918 hPa and falling rapidly
Height of new snow in 24 hours (HN24): 6 cm
Total depth of snowpack (HS): 26 cm
Crust: 1 cm and weak
We had one backcountry team out yesterday. They travelled up the ridge above the Happo One Lift Company terrrain to 2,230 m a.s.l. Very good visibility gave a clear view of Mt. Fuji. No new avalanches were observed but there were many fracture lines in skiable and unskiable (for normal individuals) terrain from the last cycle (about 2006-12-30). Ski penetration was up to 10 cm on the northerly aspect of the ridge crest area and up to 20 in lee features further down. Of special note was the surface hoar up to size 5 mm. This was first observed above 1,400 m a.s.l. and continued to be observed all the way to 2,230 m a.s.l. This is probably covered and preserved with this new snow. We will refer to it as the "January 6th layer" from now on as that is the date of its burial. Likewise the December 13th layer of buried surface hoar.
A "test" snow profile was done at 2,230 m a.s.l. on a North-east exposure down to a depth of 165 cm. The HS was 260 cm. The pit site was about 10 metres vertically below the ridge crest (i.e. the start zone for the avalanche path). The most interesting feature of the profile is probably the very strong temperature gradient in the upper snowpack. The temperature of the air (Ta) was -3.0C, the temperature of the snow surface (Ts) was -13.5C, and the temperature of the snow down 10 cm was -15.0C. At 50 cm below the surface the temperature was -7.0C. Compression tests results: down 5 cm, "Easy" at 5 taps on decomposed and faceting crystals of size 1.5 mm. There was no rounding of the snow crystals observed until the layer down 65 cm to 156 cm down. Just below that, at the interface with the melt-freeze layer, was a thin layer of faceted crystals, size 1.0 mm. No shear was observed on this layer. Remember that as always this is just one little hole in a vast area and that the "spatial variation" in the snowpack can and will be tremendous.
Of note we observed that the fracture lines from the 2006-12-30 avalanche cycle at 2,200 m a.s.l. on the south-east exposure of the Happo One were filling in with wind transported snow.
The team descended to the Kara Matsu Sawa by traversing to the "Garagara Sawa" at above 1,800 m a.s.l. This was generally followed to the Kara Matsu Sawa with no real difficulties and only minor discomforts. The river crossing to the road out was easily affected in rubber soled boots while the plastic soled boot wearers suffered slippage and soakers. There was barely adequate coverage on the road to the bridge and paved, plowed and ungated road at 825 m a.s.l. The skiing quality varied from good (for good skiers) to poor (lots of old tracks, refrozen avalanche debris, melt-freeze ice, water-ice). The descent time was 2 1/2 hours for this strong, self-rescue capable team. Emphasis on "self-rescue capable".