Madden-Julian Oscillation Relationships with Cool Season Cyclogenesis, Daily Precipitation, and Cool Season Severe Weather Frequencies in the Gulf of Mexico Region

Tropical cyclone variability in the Gulf of Mexico (GoM) has been the focus of a considerable amount of research. Variability on both interannual scales, related to the El Niño-Southern Oscillation (ENSO), and on subseasonal scales, related to the Madden-Julian Oscillation (MJO), is well documented. By contrast, very little research exists on the relationships between the MJO and cool season, non-tropical cyclones in the GoM. The MJO influence on cool season (October-March) cyclogenesis in the GoM variability is explored here. Additionally, daily precipitation variability and cool season severe weather variability is examined for areas near and just inland of the GoM. Monte Carlo simulations are used to identify statistically significant relationships between specific phases of the MJO and cyclogenesis, precipitation, and severe weather variability around the GoM region. The Monte Carlo simulation results indicate a preference for increased storminess in the GoM region during MJO Phases 7, 8, and 1, with a preference for a more tranquil pattern during Phases 4, 5, and 6. The significant associations found here between the MJO and cyclogenesis, daily precipitation, and daily severe weather frequencies are likely linked to modification of the synoptic scale Rossby wave train by the convective clusters associated with the MJO. In particular, anomaly plots of NCEP/NCAR Reanalysis data show that measures of atmospheric pressure, moisture, and instability favor (oppose) the development of convection in the GoM region during Phases 7, 8, and 1 (4, 5, and 6).