The Madden-Julian Oscillation and Predictability of Extreme Precipitation in the United States

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AbstractResearch under this grant examines changes in the predictability of extreme precipitation events (i.e. rainfall or snowfall exceeding the 90th percentile of the climatological distribution) associated with different phases of the Madden-Julian Oscillation (MJO). The MJO is a large-scale precipitation and circulation anomaly which forms over the Indian Ocean and propagates slowly eastward to the central equatorial Pacific. Preliminary work by the PIs under their previous NSF grant shows that the skill of extreme precipitation forecasts over the continental US (CONUS) for week one and week two of the forecast varies over the course of the MJO lifecycle, the portion of CONUS land area in which significant skill exists being largest in phases 1, 2, 7, and 8 of the MJO. Work under this grant explores the skill differences using hindcast integrations of the Weather Research and Forecasting (WRF) model on a global domain. The work examines the skill of forecasts and also seeks to understand the dynamical mechanisms through which the phase and amplitude of the MJO affect the skill of extreme precipitation forecasts.The research has broader impacts through the economic and social value of better long-range weather forecasts associated with MJO behavior. Preliminary work estimates the economic value of improvements in the skill of extreme precipitation forecasts in the above MJO phases, which is largest along the eastern seabord and in the midwest. In addition, the project supports a graduate student and postdoctoral researcher, thereby contributing to the development of the workforce in atmospheric science. The Principal Investigators for this award are also engaged in a number of outreach activities, including a six-week summer research program for high school students, and seminars conducted during National Geographic's Geography Awareness Week.