Arts and Sciences
Elevated mixed layers (EML) are a thermodynamic profile most commonly observed in the Midwest that have been associated with high-impact weather such as hail, tornadoes, and elevated surface temperatures and dew points. An EML forms when a surface-based mixed layer at high terrain is advected over moist air at lower elevation. No comprehensive study of EMLs and their associated high-impact weather has been done across the United States, except for a few regional case studies. Thus, this presentation examines a thirty year (1991-2020) climatology of EMLs at one station in each of nine climate regions across the CONUS in order to determine the best layer to look at to find EMLs.
The monthly distribution of EMLs were found to be different at each station, but generally peaked in the spring and were at a minimum in the late summer. The greatest frequency of EMLs were found east of the Rocky Mountains. However, the vertical distribution of where the EMLs lie in the atmosphere was not always within the typically considered 700-500mb layer. Thus, EMLs were examined in five different 200-mb deep layers (900-700mb, 850-650mb, 800-600mb, 750-550mb, 700-500mb). It was found that the number of 700-500mb EMLs were consistently the most frequent. However, there were a substantial number of EMLs in other layers that would not have been captured by just looking between 700 and 500 mb.
Camden, Peyton, "Climatology and Vertical Distribution of Elevated Mixed Layers in the United States" (2022). Symposium on Undergraduate Research and Creative Expression (SOURCE). 1073.