Hakuba Snow Report March 17th

The birds that have been chirping around got a bit of a shock to wake up to white trees with some fresh wet snow accumulated in the valley. Thunder & lightning was our alarm clock this morning which held up lift operations early but things are moving now. Light snow is still falling at 800m and there would have been some decent snowfall at altitude.

The forecast is for clearing today and blue skies tomorrow with temperatures warming to a possible high of 20 on Thursday.

SNOW STABILITY INFORMATION (as at Monday 16th):

Yesterday’s rain left lower elevations with another melt freeze crust that was later covered with 10 ~ 20 cm of new snow. The rain crust was not found above 1800 m in the Tsugaike area and areas of wind deposited snow measured 30 cm in some lee and cross loaded areas. Bonding to the melt freeze crust and to the non rain affected past storm snow of March 11th was observed to be good with weak temperature gradients on south and north aspects. There is however still some instability in the new snow especially on steep solar radiated slopes. Staying to supported terrain is still good sense.

Past melt freeze crusts may also become reactive with the weight of the new snow and rain. The addition of wind loaded snow will increase the chance that slabs down to past melt freeze crusts and may propagate from shallow points near ridges and around rocks and trees on solar aspects. Be aware of what is going on down deep in the snow pack.

Snowpack Tests:

March 15th
Compression tests on Northerly aspect of Nishi Hiodori @ 1850 metres a.s.l. found Moderate and Hard results.
CTM/H (19‚22) RP down 45 cm on grauple layer at March 11th interface.
RB5 SP down 43 cm on same grauple layer.
March 10th
Compression tests on a Northerly aspect of Nishi Hiodori @ 1900 metres a.s.l. found Hard results.
CTH(27‚23)B down 33cm
March 9th
Compression tests on a Southerly aspect of Happo One @ 2200 metres a.s.l. found easy results around a buried sun crust down 10 cm.
CTE/M(7‚11)SC down 10cm below sun crust.
Compression tests on a northerly aspect of Happo One @ 2200 metres a.s.l. found Easy to hard results that also had Sudden Collapse fracture characteristics.
CTE(1‚2)PC down 2cm; CTM/H(17‚21)RP down 38cm; CTH(24)SC down 47cm (all Crust and facet related)
March 8th
Compression tests on an Easterly aspect in the Tsugaike Seicho valley at 1800 metres a.s.l found very easy results just below the recent breakable rain crust at 11 cm.
CTE(1‚2)SC down 11cm on decomposing crystals size 2.
There were also Moderate compression‚ Sudden Planner results at the past storm snow / February 26th rain crust interface.
CTM(15)SP down 59cm on decomposing crystals size 1~2.
The layer to keep an eye on was much lower at 133 cms from the surface at the interface above the even older rain layer that is still retaining heat and a lot of moisture and has mixed forms of facets and decomposing snow right above it. There were varying results on this layer from easy shovel shear tests to moderate and hard sudden planner results from compression tests. This is definitely a layer to keep an eye on as if it goes on this one‚ expect a very large and destructive slide.
CTM/H(20‚23)SP down 133cm on mixed forms and facets over a thick rain layer

Travel Advisory:

Avoid steep gullies‚ bowls and wind loaded lee slopes. Possibility of triggering avalanches in in the past storm snow in certain terrain such as‚ steep lee slopes or cross loaded gullies from rocks and cliff bands. Keep travel to supported slopes and be careful of run outs from above. Use proper spacing in more complex terrain and solar radiated slopes.

Avalanche Hazard Rating:

Below Tree Line: Moderate
Tree Line: Considerable trending to High with more snow‚ rain or intense mid-day time warming and solar radiation.
Alpine: High risk of slides info we have continued wind paturm

Heavy snowfall
Rapid increase of weight on snow pack
Grauple layer under new snow
High density new snow over lower density snow layer
Steadily increasing air temperature
Cornice fall
rapid settlement of surface snow causing load on buried weak layers
Warming of surface snow causing instability in surface and near surface layers
Use caution if crossing solar radiated slopes.
Increased caution advised around rocky outcroppings‚ cliffs and well spaced trees in start zones.
Windward scouring of ridges and rock out-crops creating uneven loading of slopes
Due caution on cross loaded slopes
Facet layer around buried crust
Due caution in steep and convex terrain

Danger level 4 : High

Natural and human triggered avalanches likely.

Danger level ratings are set for conditions at tree line
and may vary from below tree line and High Alpine areas.
Use this information as a guideline only.