@article{a62b6dd4f9954ea0aa32a8462aa3f894,
title = "Elevated potential instability in the comma head: Distribution and development",
abstract = "The development of elevated potential instability within the comma head of a continental winter cyclone over the north-central United States is examined using a 63-h Weather Research and Forecasting (WRF) Model simulation. The simulation is first compared to the observed cyclone. The distribution of most unstable convective available potential energy (MUCAPE) within the comma head is then analyzed. The region with positive MUCAPE was based from 2- to 4-km altitude with MUCAPE values up to 93 J kg-1. Backward trajectories from five sublayers within the region of elevated convection in the comma head were calculated to investigate how elevated potential instability developed. Air in the lowest sublayer, the source air for convective cells, originated 63 h earlier near Baja California at elevations between 2.25- and 2.75-km altitude. Air atop the layer where convection occurred originated at altitudes between 9.25 and 9.75 km in the Arctic, 5000 km away from the origin of air in the lowest sublayer. All air in the layer in which convection occurred originated over the Pacific coast of Mexico, the Pacific Ocean, or arctic regions of Canada. Diabatic processes strongly influenced air properties during transit to the comma head. Air underwent radiative cooling, was affected by mixing during passage over mountains, and underwent interactions with clouds and precipitation. Notably, no trajectory followed an isentropic surface during the transit. The changes in thermodynamic properties along the trajectories led to an arrangement of air masses in the comma head that promoted the development of potential instability and elevated convection.",
keywords = "Atmosphere, Extratropical cyclones, Instability, Snowfall, Trajectories, Winter/cool season",
author = "Rosenow, {Andrew A.} and Rauber, {Robert M.} and Jewett, {Brian F.} and Mcfarquhar, {Greg M.} and Keeler, {Jason M.}",
note = "Funding Information: Acknowledgments. This work was funded under National Science Foundation Grants ATM-0833828 and AGS-1247404. Additional funding was provided by NOAA/Office of Oceanic and Atmospheric Research under NOAA–University of Oklahoma Cooperative Agreement NA11OAR4320072, U.S. Department of Commerce. The authors acknowledge the Texas Advanced Computing Center (TACC) at The University of Texas at Austin for providing HPC resources that have contributed to the research results reported within this paper. These computing resources were provided under XSEDE Award TG-ATM050014N. The composite radar analysis appearing in Figs. 3a and 6a was provided by the Iowa Environmental Mesonet, maintained by the Iowa State University Department of Agronomy. RUC data were provided by the National Climatic Data Center. The authors thank the three anonymous reviewers, whose suggestions improved this manuscript. Funding Information: This work was funded under National Science Foundation Grants ATM-0833828 and AGS-1247404. Additional funding was provided by NOAA/Office of Oceanic and Atmospheric Research under NOAA-University of Oklahoma Cooperative Agreement NA11OAR4320072, U.S. Department of Commerce. The authors acknowledge the Texas Advanced Computing Center (TACC) at The University of Texas at Austin for providing HPC resources that have contributed to the research results reported within this paper. These computing resources were provided under XSEDE Award TG-ATM050014N. The composite radar analysis appearing in Figs. 3a and 6a was provided by the Iowa Environmental Mesonet, maintained by the Iowa State University Department of Agronomy. RUC data were provided by the National Climatic Data Center. The authors thank the three anonymous reviewers, whose suggestions improved this manuscript Publisher Copyright: {\textcopyright} 2018 American Meteorological Society.",
year = "2018",
month = apr,
day = "1",
doi = "10.1175/MWR-D-17-0283.1",
language = "English (US)",
volume = "146",
pages = "1259--1278",
journal = "Monthly Weather Review",
issn = "0027-0644",
publisher = "American Meteorological Society",
number = "4",
}