The MJO-Lightning Connection: Understanding Intraseasonal Variations in Cloud-to-Ground Lightning Strikes over the Continental US

Cloud-to-ground (CG) lightning has been recognized as a chief ignition mechanism for wildfire across sections of the United States, especially in the western US. Regional wildfire outbreaks require increased resources that mandate advanced lead-times longer than those of deterministic weather forecasts. The Madden Julian Oscillation (MJO), the dominant mode of intraseasonal (20-90 days) variability in the tropics, represents an important, yet relatively unexploited source of predictability that straddles the weather-climate continuum. Although the eastward propagating convective signal is confined to the tropics, the upper-tropospheric response to the MJO produces an effective Rossby wave source capable of influencing weather regimes and extreme events over the US. To assess the feasibility of predicting weather-driven regional wildfire outbreaks, this study provides a unique perspective on the intraseasonal predictability of lightning strikes by examining the connection between the MJO and CG lightning frequency. Enhanced intraseasonal predictability of weather conditions conducive to the ignition and spread of fires, including not only lightning strikes, but also additional fire-danger weather (e.g., heat waves, enhanced surface winds, low relative humidities), may provide additional lead-time for improved use in fire management decision making applications.