P34 The Madden-Julian Oscillation and extreme precipitation over the USA

Jones, Charles, and Leila M. Carvalho, University of California

The Madden–Julian Oscillation (MJO) has a significant role in weather and climate variability. The MJO significantly influences the occurrence of heavy precipitation around the globe. Since the MJO involves intense tropical convective heating anomalies, tropical–extratropical interactions are significant during its life cycle. Consequently, the MJO modulates the skill of weather forecasts in the medium and extended ranges especially the predictability of extreme precipitation.

This poster will discuss precipitation over the United States during November-March 2004-05, a season marked by extreme precipitation. The Weather Research and Forecasting (WRF) model is used to investigate the role of the MJO. Experiments use two domains with 150 km and 50 km horizontal grid spacing and 35 vertical levels. The first domain (0-360, 60S-60N) is used to capture tropical intraseasonal variability associated with the MJO and teleconnection patterns to the mid-latitudes of North America; the nested domain (50 km) covers the contiguous United States. The presentation will discuss how different characteristics of the MJO modulate extreme precipitation over the western United States.