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| Juneau Area Avalanche Advisory | ||||||||||||||
| 2006-01-10 | ||||||||||||||
| Mt. Stewart | ||||||||||||||
| by Bill Glude, SAAC Observer | ||||||||||||||
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| After returning from a long weekend of teaching in Petersburg, we returned to Mt. Stewart today to see how the new snow was doing. We found thick fog, so did not venture above Bunny Tow Pass.
There is new snow, though it is dense, slow, and underlain by a breakable rime crust from the weekend. The good news is that it is making excellent base material and continuing to accumulate slowly but steadily, and the snow level is below the Eaglecrest base elevation so the lower portion of the ski area is getting snow. We found some shooting cracks in drifted areas but they were small and localized. Other signs of instability were minor or absent. Most areas scored a moderate energy #3 on the Slab Test, fracturing irregularly over more than half the undermined area. Our block tests on a 44° slope yielded a fairly weak #4 (first gentle jump) on the Rutschblock and AK Block at average shear quality (RB4Q2, AK4Q2) and a weak #2 (just stepping onto the block) at average shear quality on the Cutback AK Block, (CAK2Q2), all on the 129cm rime crust and hardness change. The Cutback AK Block also fractured on multiple hard jumps at average shear quality on the 83cm faceted melt freeze crust (CAK6Q2). Though this lower layer did not show great weakness in our tests it bears watching because it is a faceted melt-freeze layer, known to be unpredictably weak and variable, and is overlain by persistently weak and sugary faceted grains. We rated the strength as -, the stress as ~, the energy as +, and the structure as +, where + indicates a stronger snowpack, - weaker, and ~ neutral. These layers are not particularly sensitive today but there is weakness in the snowpack and stability could change if there is loading by new snow or wind. |
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| Field Notes | ||||||||||||||
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| Photos | ||||||||||||||
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| The 159cm rime crust from last weekend was prominently displayed on the trees at mid elevations. In the snowpack, it was under about 10cm of heavy 190 Kg/m3 density moist rimed and fragmented new snow and early rounds, but could still be felt collapsing under skis. | ||||||||||||||
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| Drifts were quite sensitive but the cracking was localized to small areas. | ||||||||||||||
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| Slab Test results were a consistent amd moderate-energy #3, with more than half the undermined area fracturing, but with an irregular character. | ||||||||||||||
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| Bill Glude is pitched off balance as the Cutback AK Block shears at average quality on the 129cm rime crust and hardness change when as he begins to step onto it (CAK2Q2) on a 44° slope. This was the weakest test result in our three-block set today. The Rutschblock and AK Block had identical results while this small and cutback block sheared more easily, suggesting that the lack of cutback in the AK Block is balanced by the smaller block size. Mike Janes photo. | ||||||||||||||
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| Bill Glude shears the AK Block on a first gentle jump on the same 129cm rime crust and hardness change at average shear quality (AK4Q2) on a 44° slope. This result was more typical of what we found today. Mike Janes photo. | ||||||||||||||
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