The Impact of the Madden-Julian Oscillation on Extreme Winter Weather in the United States

Abstract

Winter weather has substantial impacts on human activity, but it is challenging to predict more than 7-10 days in advance. Subseasonal-to-seasonal (S2S) prediction is a rapidly developing field of meteorology that could be used to improve winter weather prediction at longer time scales. The Madden-Julian Oscillation (MJO) is a major driver of global S2S variability. This study seeks to examine how the MJO affects the frequency of winter weather over the contiguous United States, which will help further improve winter weather prediction in the future. This is done by comparing the frequency of winter weather reports and snow accumulation data at surface meteorological stations in a given phase of the MJO to its climatology. We find that the MJO has significant impacts on increasing the frequency of extreme winter weather in the Northeast when MJO convection is in the western Indian Ocean (phase 1), the Southern Great Plains when MJO convection is in the central Indian Ocean (phase 2), and the Northern Great Plains when MJO convection is over the Maritime Continent (phase 4). These results are primarily driven by the forcing of the MJO on the jet stream and its subsequent impacts on geopotential height, as well as temperature and wind in the lower atmosphere. MJO impacts on the frequency of extreme winter weather can be seen up to 15 days in advance, suggesting utility in S2S forecasting.