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ニセコなだれ情報 第112号 Niseko Avalanche Info No.112

山麓6時-1度降雪わずか、モイワ800m-4度北北西8.74m/s雪庇ふきだまり発達、アンヌプリ1100m-8.3度西北西8.10m/s積雪深250cm、ヒラフ山頂-7度西寄りの強風で浅いふきだまりが発達、ヒラフ1000m-8.3度西6.0m/s、アメダス倶知安0.3度西北西7.1m/s積雪深86cm、海上弁慶岬北北西17m/s、神威岬北西11m/s気圧1006hPa波高2.5m、

 

気圧の傾き強く標高800m以上は西寄りの風雪で雪庇ふきだまりが発達、量は少ないが崩れやすく割れやすい。昼前後に風は弱まるが朝のうち風下側ノール、ふきだまり斜面の雪崩リスクは高い。標高1000m付近、谷の側壁や雪庇斜面では硬いふきだまり(クラスト)が滑走刺激で割れて広い範囲に雪崩を起こしやすい。厚さは10cm程度だが速度が速く逃げられないので危険。風が弱まるまでこれらの斜面の滑走は控えたほうが良い。

下部は融雪が進む。スノーブリッジの崩壊に注意。森の中には10cmの新雪が入っているが底あたりする。ゲートの開閉は未定。パトロールの指示に従うこと。

 

名古屋大学と防災科研の人工雪崩実験は無事終了した。モイワ6番ゲートは閉じられているが見返りボウルではデブリと雪庇面の亀裂に注意。協力してくれたモイワスキー場と圧雪車オペレーターに感謝する。

 

Mountain base 6am: -1, slight snowfall. Moiwa800m: -4, NNW8.74m/s, cornice and snowdrifts developments. Annupuri1100m: -8.3, WNW8.1m/s, 250cm snow depth. Hirafu peak: -7, strong westerly wind developing snowdrifts. Hirafu1000m: -8.3, W6m/s, Kutchan weather station: 0.3, WNW7.1m/s, 86cm snow depth. Benkei cape: NNW17m/s, Kamui cape: NW11m/s, 1006hPa, 2.5m waves.

 

The atmospheric pressure gradient is steep and a strong westerly wind is blowing above 800m elevation, making snowdrifts and cornices develop quickly. Although not thick, those snowdrifts are very unstable and the avalanche risk will remain high in leeward steep slopes and knoll terrain during the morning, even after the wind calms down. Wide avalanches triggered by riding stimulation of crusty snowdrifts are also to be expected in 1000m valley sidewalls and cornice slopes. 10cm thick slides can run very fast and cannot be overrun. It is strongly recommended to avoid those kind of slopes until the wind calms down.

 

Thaw will progress in lower elevation, beware of falling snow-bridges. 10cm of fresh snow has blanketed the tree-runs. Gates opening is undetermined, please respect the ski patrol’s instructions. The artificial avalanche experimentation operated by Nagoya University and NIED has finished successfully. Debris and cracks are present in Mikaeri bowl, although the Moiwa gate 6 is closed, please use caution when touring in this area. We would like to thank the cooperation of Moiwa resort and their cat operators.

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