Tenki and Yuki Diary 22 Feb 08

Know the weather = know the snow pack = know the stability.  For previous weather and snow reports use the Diary link at the top of the page.

Steep Deep Japan Hakuba  weather data for the 24 hours to 7am for 860m asl Max temp +6C, min temp -7C and  -3C at 7am. 0cm of new snow in the last 24 hours.  Barometer is steady at 916mbar and the skies are mostly clear, with 25% cloud cover.  Wind aloft is moderate to strong in gusts from the SW through NW.  The clear night had produced 1mm surface hoar at 860m asl.

Field observations:  Yesterday we travelled to 2000m in the backcountry on south, east and north aspects.  All solar aspects where being hit very hard by the sun on the previous new snow.  South aspects are terrible and will thick crusts each morning and be very sun-soft by midday.  The forecast storm will not likely bond well on south aspects.  North aspects remained cold and sheltered, thus preserving patches of surface hoar created on the 18th and 19th.  The strong wind (that came with 20cm new snow) would have destroyed some hoar, however in protected and loading slopes it was buried by snow fall and drifted snow.  This wind slab varies in thickness and harness depending on aspect and altitude, however recent wind direction is of limited use in determining loaded terrain due to wind variability at the micro level between peaks.  We found significant north aspect cross loading and pen hardness windslab above 1600m asl, along with a size 2 skier triggered hard slab avalanche.  I was the skier (snowboarder) in the slide, it took me 300m down hill through trees and had me buried most of the time, leaving me on the surface at the end.  This incident came after we significantly scaled back our plans for the day based on new snow and strong wind.  We were heading up above Tsugaike but turned away leaving it to other parties and found something hopefully more protected. It happened on a take-it-easy day.  Scaling back your risk acceptance from a high level still leaves you in the normal and perfectly dangerous risk zone of everyday backcountry travel, something that is too easily forgotten at potentially great consequences.

A number of other natural releases of size 2.5 were visible in the alpine around 2500-2800m asl on south aspects.

Please refer to the Hakuba backcountry travel advisory from the guides at Evergreen Outdoors. (Frequency of update is unreliable)