Indexed on: 25 Jan '17Published on: 24 Jan '17Published in: International Journal of Climatology
The relationships between the synoptic climatology, large-scale teleconnections and the regional avalanche activity index (RAAI) inferred from tree-rings were evaluated for the Presidential Range in the White Mountains (New Hampshire, USA). During the period 1936–2012, 18 years of regional avalanche activity were compared with the winter-scale prevailing joint temperature/climatic modes (cold/wet (CW), cold/dry (CD), warm/wet (WW) and warm/dry (WW)), the North Atlantic Oscillation (NAO), the El Niño-Southern Oscillation (ENSO), the 500-mbar composite anomaly maps and the ratio of snow from different storm tracks. The total winter snowfall and the NAO negatively correlate with the RAAI. There is also a significant difference in avalanche activity between winters with a NAO under or above −3. Winters of regional avalanche activity were present in the four climatic modes, albeit the ratio of avalanche/non-avalanche years is superior for CW winters compared to the three other modes, as well as for wet winters compared to dry winters. CW, CD and WW winters exhibit a negative NAO anomaly, which is eastbound for the wet years. Cold winters (CW, CD) receive more snow from the Great Lakes, whereas coastal depressions are more important during wet winters (CW, WW). The NAO is an adequate predictor of snowfall, but does not provide information about the storm tracks. On the contrary, the ENSO is poorly correlated with snowfall, but its relationship is significant with the ratio of snow produced by coastal depressions (positive relationship) and Great Lakes storms (negative relationship). These are the first results quantifying the atmospheric circulation – synoptic meteorology – snow avalanche relationships in Northeastern North America.