Environmental Factors Contributing to the Development of Above-Anvil Cirrus Plumes

The formation of above-anvil cirrus plumes atop deep convection is an important contributor to water vapor transfer from the troposphere to the lower stratosphere. It has been observed that these plume features have been associated with severe weather activity. However, the factors contributing to the development of these cirrus plumes are unknown. Here we show that the main ingredients required for this process are directional wind shear between cell motion and upper level detrainment and penetration of the tropopause using a combination of geostationary satellite imagery, high-resolution three-dimensional radar observations, and radiosonde observations. Temperature and vertical wind speed shear do not show consistent characteristics for environments conducive to the development of above-anvil cirrus. Some plume cases show fluctuations in cloud top heat signatures when analyzed with infrared satellite imagery, indicating mixing of the plume into the lower stratosphere. Our results demonstrate how environmental and physical characteristics affect plume formation and support assertions in previous studies on the relevance of above-anvil cirrus plumes for increases in stratospheric water vapor content, which is relevant to predictions of future climate. We also present a relationship between hail occurrence and overshooting top depth that may result in an increase in lead time for warnings of severe storms.