This personal blog contains snow, avalanche and weather data along with weekly commentary that may be useful in planning your Hakuba backcountry outings.

More important than anything else

1. Hakuba Avalanche Bulletin by the Japan Avalanche Network.
2. Understand the Avalanche Danger Scale.
3. Know what the avalanche problem is and how to avoid it.
4. Carry beacon, shovel and probe in the backcountry. Know how to use them.

Other useful info

+ Unofficial Avalanche Terrain Exposure Scale (ATES) for Hakuba
+ Backcountry conditions from Japan Avalanche Network members.
+ Hakuba MountainLife Magazine. Especially the centerfold.
+ Hakuba MountainLife Facebook page

Recent weather data recorded at 6am each day for the preceding 24 hours. Altitude 800m.

Date Cloud Cover Precip type and rate Rain Altitude 6am temp Max temp Min temp 24hr New Snow 24hr New Water Equiv 24hr New Density Storm Total Snow Depth Baro Pressure
20150129 Clear Nil ~ -14C -3C -14C 0cm ~ ~ 0cm 221cm 928mbar
20150128 Overcast S < 1cm/hr ~ -6C 3C -6C 6cm 5mm 85kg/m3 6cm 225cm 918mbar
20150127 Broken Nil 1500 0C 4C 0C 0cm ~ ~ 0cm 227cm 918mbar
20150126 Broken Nil ~ -4C 3C -4C 0cm ~ ~ 0cm 237cm 927mbar

2015.01.29 Hakuba Backcountry Conditions Weekly Report

Besides summarising, I won't repeat anything that is already available in the above sources of info. Please read them, especially the JAN avalanche bulletin. Seriously, if you are not reading the avalanche bulletin, then don't bother reading this either.

The last week:
A week ago last Thursday it was raining to 1300m, but that delivered a trivial impact, and by Friday and Saturday powder was back, with some very nice lower altitude tree skiing as the weather cleared. Higher and more open terrain such as the Happo back bowls was also popular, which makes sense. But many big start zones were getting center punched hard on Sunday as though confidence was high, which was odd considering few people had been it that terrain after a couple of days of bad weather. Confidence is a rare commodity in avalanche terrain, and it takes time to accumulate. Yet people seem to turn it on like a light switch with blue skies in these parts. They go home thinking their day was a decision making success, rather than an episode of luck due to a forgiving snowpack. One visiting professional guide commented that "the snowpack saves a lot of lives here". As opposed to good terrain use. Natural windlsab avalanches were observed over the weekend along ridges. The distribution of touchy windslab was isolated, with some some E and N terrain at 2000m offering soft skiing whilst 5km away similar terrain was slabby and easy to trigger to Size 1.5. Monday had broken skies and some slabby snow around thanks to more overnight wind, though skiing was generally ok in the alpine above Tsugaike. Monday night and Tuesday it rained to 1500m thanks to yet another passing low pressure system, delivering 20-25cm of new snow at treeline and into the alpine, and new windslab. This low altitude rain destroyed a healthy but patchy surface hoar layer at 1400m which was about 15cm deep at the time. Wednesday we woke to drier snow as the low passed by and the usual Siberian northerly flow was sucked down behind it. However this event produced less "lake effect" snow than usual, perhaps only 15cm at treeline with wind, and Size 1.5 and Size 2 skier triggered avalanches on terrain that regularly produces avalanches. Somewhere in that flow a dose of brown dust from the Gobi Desert was delivered. Then today, Thursday, was clear creating a sun crust on steep lower terrain, winds were almost calm, but temperatures still cold. Skiers were triggering windslab avalanches from size 1 - 2 on the Happo ridge.

Now:
Today is Thursday the 29th. Besides wind slab, we have a well settled deep snowpack. However the rain crust that is present below 1500m is only shallow. This crust will be worth tracking carefully as a new storm approaches. So far this season we have been dealing with relatively easy to identify and avoid avalanche problems such as Storm Slabs and Wind Slabs. From now, popular steep lower altitude terrain, which includes a lot of the Goryu and Happo ridges, may be more of a gamble with that rain crust in the upper snowpack. It may not be buried deeply in a hurry, and the bond with the crust may weaken with time even if it starts out stronger. A potentially bad combination would be for the crust and underlying moist snow to remain warm (near zero degrees C), be buried under only perhaps 50cm of cold powder, and for air temperatures to remain well below freezing at say 1300m for a week or so. This may produce faceting at the crust due to a steep temperature gradient between the warm crust and cold air. Or it could turn out just fine like it often does. Either way, the crust is only below 1500m, and thicker from 1300m down, which is only a small percentage of the terrain.

The next few days:
Friday 30th will be warmer with possible drizzle at valley bottom and snow to Tokyo (another low pressure cell!). That may be good for crust bonding. Then the next Siberian storm will arrive over the weekend. This may deliver between 30 and 70cm at treeline. It is hard for me to say. Freezing level will remain well below valley bottom, and treeline temps may stay at -10C until next Wednesday, with broken clouds and on-going small amounts of daily snowfall. So we have the chance of seeing a warm crust under possibly cold thin snow, itself under persistently cold air for 5 days straight. For now, do not put too much confidence in that crust on steep terrain below 1500m.

Remember:
Stress v.s Strength. Confidence v.s Uncertainty. Emotional Decisions v.s Systematic Rational Decisions. Wouldn't backcountry skiing be great if it were not for avalanches. It gets much worse than we usually see here in Hakuba, but nonetheless, if it all seems too hard then stick to obviously safe terrain. For example the low angle south facing conifer forest along the western end of the Hiyodori ridge which is easily accessed via a summer road skin track from 1650m, just above the Tsugaike gondola station. You can pump out 6-8 x 150m laps in those trees in a day, and if it isn't too deep, it can be very fast fluid fun tree skiing for little effort or commitment to terrain. With gradual daily top-ups of snow, cold air, and cloudy skies, that simple zone could be good day after day once Saturday's storm subsides. It is an easy no-brainer area that most people walk past, but seldom ski. Always tell someone where you are going, and never ski into terrain that you have not carefully planned and visualized first using maps and photographs. The south facing east end of the Hiyodori ridge has a sparse gladed hardwood forest and is steeper, the far eastern end near the trailhead is steeper still and closed to backcountry skiers as it includes a well known avalanche path which unfortunately claimed a life just last season. Stay out of that area.

-damian

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