National Weather Service Contributions to the CSTAR High Shear/Low CAPE Severe Convective Storms Project

Severe convection occurring in environments characterized by low values of Convective Available Potential Energy (CAPE < 500 J kg-1) and high values of wind shear (> 35 kt in the 0-6 km layer) are one of the primary problems facing operational forecasters in the Eastern United States. Radar signatures associated with these phenomena are often non-classical, short-lived, and/or not observed due to radar sampling limitations. From a warning services perspective, this often results in low probability of detection of severe weather, particularly with regard to tornadoes. In order to improve operational forecasting and warnings of high shear/low CAPE (HSLC) severe weather, an investigation funded through the Collaborative Science Training and Research (CSTAR) program is underway as a partnership between researchers at North Carolina State University (NCSU) and several National Weather Service (NWS) Weather Forecast Offices (WFOs) in the Southeast and mid-Atlantic. Previous experience in the CSTAR project has shown that effective infusion of research results into forecast operations is most likely when NWS personnel are directly involved in the investigation. Therefore, at least one representative from ten WFOs in the Southeast and mid-Atlantic has volunteered to participate in the HSLC project. The primary role of NWS personnel has been to identify the cases to be used by the principal investigators (PIs) at NCSU for development of a parameter-based and radar signature-based climatology, and to compile a database of null cases in which HSLC environments were identified, but severe convection did not occur. In order to identify potential commonalities in environmental characteristics and radar signatures among HSLC events, NWS investigators will provide several comprehensive case studies to compliment the climatological analyses. This paper will describe the methodology used to identify HSLC cases and null cases. The methodology that NWS investigators are following for case study development will also be presented, along with an abbreviated version of a “template” HSLC case study. Finally, preliminary plans for infusing the results of the research into NWS operations will be discussed.