Item: The extraordinary 2017-2018 winter season in Aosta Valley
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Title: The extraordinary 2017-2018 winter season in Aosta Valley
Proceedings: International Snow Science Workshop Proceedings 2018, Innsbruck, Austria
Authors:
- A. Debernardi [ Fondazione Montagna sicura, Villa Cameron, Località Villard de la Palud 1, 11013 Courmayeur (AO), Italy ]
- G. Burelli [ Fondazione Montagna sicura, Villa Cameron, Località Villard de la Palud 1, 11013 Courmayeur (AO), Italy; ]
- N. Durand [ Fondazione Montagna sicura, Villa Cameron, Località Villard de la Palud 1, 11013 Courmayeur (AO), Italy; ]
- V.Segor [ Ufficio neve e valanghe, Assetto idrogeologico dei bacini montani, Regione Autonoma Valle d’Aosta, Loc. Amérique 33, 11020 Quart (AO), Italy ]
Date: 2018-10-07
Abstract: In this work we will focus in particular on the exceptional avalanche events that occurred in January. The start of the winter season was not promising, still no snow in November. Finally a strong storm brought one meter of fresh snow on the whole Region on the 10th of December. The rising spontaneous avalanche activity forced the local avalanche commissions to take the first preventive closure measures for the valley's road systems. But it's in January that winter got exceptional for snowfalls and avalanches events. A series of storms brought much snow in the first part of the month. Then other two meters of fresh snow fell from 7th th to 9th of January with strong SE winds, mild temperatures and groupel snow for storm effects in some valleys. The avalanche danger degree rose to 5-very high in the Gran Paradiso valleys, Lys valley, Ayas and the upper Valtournenche. The valleys most affected by the strong avalanche activity after the great snowfalls were the Gran Paradiso valleys, in particular the valley of Cogne and Valsavarenche that were closed for several days. The avalanches reached exceptional sizes much larger than the historical limits, never seen by old people. In Cogne valley many avalanches reached the valley floor and the main road, the same happened in Valsavarenche where the events damaged the high voltage cables, brought boulders of hundreds of cubic meters on the regional road and damaged some infrastructures. The upper part of Valsavarenche was affected by a large avalanche that covered the regional road for several hundred meters with a 8 meters thick deposit leaving the last part of the road closed for about twenty days. In other valleys, avalanches also affected the road network and some had to be closed to traffic for several days. Other snowfalls affected the Region from the 17th of January after a short clear period characterized by a lot of surface hoar which caused many avalanches, either spontaneous or triggered. New heavy snowfalls occurred in the north part of the Region, in Valpelline, from the 21st to 23rd of January. Again many large avalanches reached the valley floor and the road network, closed in advance. Some events exceeded the known historical limits, some were not known at all and destroyed the electricity and telephone lines, one chalet and lapped some house.
Object ID: ISSW2018_P06.13.pdf
Language of Article: English
Presenter(s):
Keywords: danger avalanches, avalanches bulletin, surface hoar, spontaneous and triggered avalanche, avalanche cadastre
Page Number(s): 577-581
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