Tenki and Yuki Diary 14 Feb 08

Know the weather = know the snow pack = know the stability.

This storm is forecast to continue, or overlap with a two more storms.  Today is a break-day before the next onset of snow.  Hakuba receives an average of 11m cumulative snowfall per season (I am not sure what altitude that is measured at).  Per my own weather station data, we are due to get another 4m of snow to hit average. 

Steep Deep Japan Hakuba  weather data for the 24 hours to 7am for 860m asl Max temp -5C, min temp -10C and  -5C at 7am. 10cm of new snow in the last 24 hours, quite heavy 83kg/m³, equivalent to 9.7% water.  The new snowfall has been influenced by gusty strong winds and is of variable thickness depending on wind exposure.   The barometer has fallen back to 907mbar after rising during yesterday. Wind is moderate from the west with strong gusts and snow continues to fall about 1cm per hour.

Field observations:  Yesterday winds aloft were strong enough to close many resort lifts.  I did not travel in the backcountry due to the conditions.

This new snow has arrived with winds well over 30kph in the peaks, which is high enough to produce moderate to intense snow transport and the creation of windslab much thicker than the depth of new snowfall.  Conditions are primed for avalanches today, particularly above tree line and into the Alpine.  The last time we had a similar weather combination, this avalanche happened (its worth checking that photo combo)

Please also refer to the Hakuba backcountry travel advisory from the guides at Evergreen Outdoors.