Tornado-days in the United States by phase of the Madden–Julian oscillation and global wind oscillation

Tornado activity in the United States varies over multiple time scales. The Madden–Julian oscillation (MJO) and global wind oscillation (GWO) are sources of climate variability at the seasonal and subseasonal scales. The univariate distributions of tornado-days across the phases of these oscillations have been documented, but the bivariate distribution of tornado-days across both oscillations has not been. Here, the bivariate distribution of tornado-days across the phases of the MJO and GWO is documented and analyzed. Results herein refine the previously reported univariate distributions and highlight variability across the phases of one of the oscillations while holding the phase of the other constant (e.g., tornado-days are more likely during phase 2 of the GWO, but the likelihood varies across the phase of MJO).