The Severe Thunderstorm Electrification and Precipitation Study

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During May–July 2000, the Severe Thunderstorm Electrification and Precipitation Study (STEPS) occurred in the High Plains, near the Colorado–Kansas border. STEPS aimed to achieve a better understanding of the interactions between kinematics, precipitation, and electrification in severe thunderstorms. Specific scientific objectives included 1) understanding the apparent major differences in precipitation output from supercells that have led to them being classified as low precipitation (LP), classic or medium precipitation, and high precipitation; 2) understanding lightning formation and behavior in storms, and how lightning differs among storm types, particularly to better understand the mechanisms by which storms produce predominantly positive cloud-to-ground (CG) lightning; and 3) verifying and improving microphysical interpretations from polarimetric radar. The project involved the use of a multiple-Doppler polarimetric radar network, as well as a time-of-arrival very high frequency (VHF) lightning mapping system, an armored research aircraft, electric field meters carried on balloons, mobile mesonet vehicles, instruments to detect and classify transient luminous events (TLEs; e.g., sprites and blue jets) over thunderstorms, and mobile atmospheric sounding equipment. The project featured significant collaboration with the local National Weather Service office in Goodland, Kansas, as well as outreach to the general public. The project gathered data on a number of different cases, including LP storms, supercells, and mesoscale convective systems, among others. Many of the storms produced mostly positive CG lightning during significant portions of their lifetimes and also exhibited unusual electrical structures with opposite polarity to ordinary thunderstorms. The field data from STEPS is expected to bring new advances to understanding of supercells, positive CG lightning, TLEs, and precipitation formation in convective storms.

Colorado State University, Fort Collins, Colorado

National Center for Atmospheric Research, Boulder, Colorado

National Weather Service, Lincoln, Illinois

South Dakota School of Mines and Technology, Rapid City, South Dakota

Colorado Climate Center, Fort Collins, Colorado

New Mexico Institute of Mining and Technology, Socorro, New Mexico

FMA Research, Inc., Fort Collins, Colorado

National Severe Storms Laboratory, Norman, Oklahoma

CORRESPONDING AUTHOR: Timothy J. Lang, Department of Atmospheric Science, Colorado State University, Fort Collins, CO 80523, E-mail: tlang@atmos.colostate.edu

During May–July 2000, the Severe Thunderstorm Electrification and Precipitation Study (STEPS) occurred in the High Plains, near the Colorado–Kansas border. STEPS aimed to achieve a better understanding of the interactions between kinematics, precipitation, and electrification in severe thunderstorms. Specific scientific objectives included 1) understanding the apparent major differences in precipitation output from supercells that have led to them being classified as low precipitation (LP), classic or medium precipitation, and high precipitation; 2) understanding lightning formation and behavior in storms, and how lightning differs among storm types, particularly to better understand the mechanisms by which storms produce predominantly positive cloud-to-ground (CG) lightning; and 3) verifying and improving microphysical interpretations from polarimetric radar. The project involved the use of a multiple-Doppler polarimetric radar network, as well as a time-of-arrival very high frequency (VHF) lightning mapping system, an armored research aircraft, electric field meters carried on balloons, mobile mesonet vehicles, instruments to detect and classify transient luminous events (TLEs; e.g., sprites and blue jets) over thunderstorms, and mobile atmospheric sounding equipment. The project featured significant collaboration with the local National Weather Service office in Goodland, Kansas, as well as outreach to the general public. The project gathered data on a number of different cases, including LP storms, supercells, and mesoscale convective systems, among others. Many of the storms produced mostly positive CG lightning during significant portions of their lifetimes and also exhibited unusual electrical structures with opposite polarity to ordinary thunderstorms. The field data from STEPS is expected to bring new advances to understanding of supercells, positive CG lightning, TLEs, and precipitation formation in convective storms.

Colorado State University, Fort Collins, Colorado

National Center for Atmospheric Research, Boulder, Colorado

National Weather Service, Lincoln, Illinois

South Dakota School of Mines and Technology, Rapid City, South Dakota

Colorado Climate Center, Fort Collins, Colorado

New Mexico Institute of Mining and Technology, Socorro, New Mexico

FMA Research, Inc., Fort Collins, Colorado

National Severe Storms Laboratory, Norman, Oklahoma

CORRESPONDING AUTHOR: Timothy J. Lang, Department of Atmospheric Science, Colorado State University, Fort Collins, CO 80523, E-mail: tlang@atmos.colostate.edu
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