Title: Physical Constraints and Future Projections of Midlatitude Moist Heat Extremes
Abstract:
Extreme near-surface moist heat and severe convective storms are among the leading causes of weather-related damages worldwide. Episodes of extreme moist heat and severe convection frequently co-occur across midlatitude land regions, yet the processes that constrain their maximum intensities remain poorly understood. Here, a theoretical framework is developed that links their maximum intensities to preexisting low-level energy inversions in the atmosphere. By accounting for the stored-energy nature of midlatitude severe convection, in which near-surface moist heat and atmospheric instability accumulate before convection initiates, this framework identifies low-level inversions as a critical factor shaping compound extreme heat and convective weather risks. Under climate change, these moist weather extremes are projected to intensify substantially in the midlatitudes, particularly downstream of major highland terrains. This intensification is tightly constrained by changes in low-level atmospheric inversions: amplified warming over western highlands is transported downstream by prevailing westerlies, strengthening inversions and raising the attainable maxima of moist heat and convection. These results highlight low-level inversions as a key regulator of midlatitude moist weather extremes and their response to climate change.
