Blue skies and warm temperatures today…definitely a Spring morning. 2 degrees at the top of Goryu and runs near the bottom of the mountains and getting steadily more desecrated. A high of 18 degrees predicted for this afternoon…t-shirt weather basically in effect, don’t forget the sun-screen. Tomorrow looks to be more of the same…
SNOW STABILITY INFORMATION:
Monday’s rain left lower elevations with another melt freeze crust and a rapidly disappearing snow pack in the valley. The freezing level was 1000 metres and the snow quality was progressively better with elevation. The new snow fell on wind altered snow on the Northern aspects‚ sun crust on the Southern aspects and on rain crust below 1800 metres. The new storm snow of March 15/16 started falling at relatively warm temperatures and progressively cooled through the night‚ hopefully‚ assisting the Crust / New Snow interface to bond. During the storm on Happo North faces surface instabilities were observed as multiple size 1 loose snow avalanches were triggered in 30 degree plus terrain. This new snow may be starting to bond to the past surface layers but there will definitely still be instability at the crust/ past snow surface and the new storm snow or possibly with in the new snow layer itself. Staying to supported terrain is good sense.
Past melt freeze crusts may also become reactive with the weight of the new snow‚ rain and intense solar radiation. 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. These type of slab avalanches could be observed Monday morning on Happo One and other east aspect alpine areas. Be aware of what is going on down deep in the snow pack as progressed faceting at those persistent weak layers around past crust could be weakening the bonds below and above the crusts.
Compression tests on Northerly aspect of Happo @ 1900 metres a.s.l. found Easy‚ Moderate and Hard results in the recent snow storms.
CTE(1‚2)SC down 10cm just under old rain crust that was once again exposed by wind. New snow on this layer could cause the layer to sheer below the crust and propagate out wide.
CTM(17‚19)SC down 55cm at past laminated rain crust that is seemingly breaking down as it is turning to facets.
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.
Compression tests on a Northerly aspect of Nishi Hiodori @ 1900 metres a.s.l. found Hard results.
CTH(27‚23)B down 33cm
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)
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
Avoid steep gullies‚ bowls and wind loaded lee slopes. Possibility of triggering avalanches in the past and recent storm snow in certain terrain such as‚ steep lee slopes or cross loaded gullies from rocks and cliff bands‚ convex and unsupported slopes‚ from trees and solar radiated slopes and cornices. 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 on solar aspects with intense mid-day time warming and solar radiation.
Alpine: High all aspects
Grauple layer under new snow
High density new snow over lower density snow layer
Rapid air temperature increase
rapid settlement of surface snow causing load on buried weak layers
Increase in loose snow avalanches and suffs
Extreme radiation and warming of southern exposures
Warming of surface snow causing instability in surface and near surface layers
Solar radiated cornices becoming weak with direct solar radiation.
Use caution if crossing solar radiated slopes.
Increased caution advised around rocky outcroppings‚ cliffs and well spaced trees in start zones.
Due caution on cross loaded slopes
Poor bonding at or around buried crust
Facet layer around buried crust
Stay away from steep and convex terrain
Danger Level Updated at 2009 03/18 (wed) 07:30
Danger level 4 : High
Natural and human triggered avalanches likely.
Danger level ratings are set for conditions at tree line
and may varry from below tree line and High Alpine areas.
Use this ingormation as a guideline only.