The Influence of Regional Storm Tracking and Teleconnections on Winter Precipitation in the Northeastern United States
Secular changes in regional storm tracking are examined as physical mechanisms for observed teleconnections between the New England hydroclimate and four predictor variables: the Southern Oscillation Index, the North Atlantic Oscillation, the Pacific Decadal Oscillation, and regional sea-surface temperatures. The main modes of New England winter precipitation, snowfall, and cyclone variability are resolved using varimax rotated principal component analysis. The first rotated principal component of regional cyclone variability defines an out-of-phase relationship between marine versus continental cyclone activity and is statistically linked with the Southern Oscillation, the Pacific Decadal Oscillation, and precipitation in northern New England. Also, El Niño winters generally accompany a slight increase in southern New England precipitation. The second cyclone rotated principal component, defining an inverse relationship between cyclone occurrences along the East Coast and cyclone occurrences along the northern boundary of the Gulf Stream, is well correlated with regional precipitation and snowfall, demonstrating the significance of marine storm tracking as a control on New England winter hydro-climatic variability.
Extreme North Atlantic Oscillation conditions are linked with distinct regional storm tracking patterns such that northwestern New England experiences fewer cyclones during negative North Atlantic Oscillation winter months. Statistical relationships between sea-surface temperatures and principal modes of regional cyclone occurrences are also noteworthy; however, more work is needed to assess the utility of sea-surface temperatures in the development of future seasonal forecasts. Also, confirming earlier findings, cool sea-surface temperature conditions are shown to accompany both drier conditions inland and greater winter snowfall totals in southern coastal regions.
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