The North Atlantic Oscillation: Impact on Snowfall Conditions in the Northeastern United States

摘要

This study examines the relationship between theNAO and winter (November – March) snowfall totalsin northeastern U.S. between 1961 and 2010. Theanalysis revealed an inverse relationship betweenNAO phase and seasonal snowfall, with positive(negative) NAO index years associated with lower(higher) average snowfall and snowfall days.Significantly greater snowfall during the NAOnegative phase was mainly located along the EastCoast as well as the interior southern half of the studyregion. A composite analysis of various troposphericvariables (e.g., 500-hPa heights) showed NAOnegative years produced greater snowfall due to moreextreme weather conditions affecting the Northeast,such as below normal sea level pressure, a deepenedmid-tropospheric trough and weaker upper-levelwesterlies that permitted more frequent polaroutbreaks. Stations indicating no relationship betweenNAO and snowfall were mainly located in western andcentral New York, northern Vermont, and Maine.These regions of the Northeast correspond to those thatreceive snowfall in either NAO phase, as exhibited inthe case studies, due to the effects of nearby lakes andhigher terrain related to the storm tracks through theseareas.