VHF total lightning mapping is defined as the detection of both cloud and cloud-to-ground (CG) lightning flashes, including the detection and mapping of the horizontal extent of cloud lightning flashes. Data from regional VHF total lightning networks, with detection efficiencies over 90%, can provide a substantial improvement over networks that detect only CG lightning for certain meteorological and safety nowcasting applications. This paper will summarize survey results obtained from forecasters at several different forecast offices aimed at identifying the value of VHF total lightning mapping data for improved weather nowcasts.

Over the past several years, forecasters at the National Weather Service (NWS) Dallas-Fort Worth, Huntsville, Birmingham and Nashville Forecast Offices and the Finnish Meteorological Institute (FMI) have been evaluating the use of VHF total lightning mapping data for thunderstorm nowcasting. The program involving the Dallas-Forth Worth and FMI forecast offices has been directed by Vaisala. The program involving the Huntsville, Birmingham and Nashville forecast offices has been directed by the National Aeronautics and Space Administration (NASA) Marshall Space Flight Center (MSFC) as part of the Short-term Prediction Research and Transition Center (SPoRT) program. Whenever possible, forecasters filled out surveys created by Vaisala and NASA MSFC after severe thunderstorm events or other thunderstorm events that were of interest to the forecasters. The surveys asked forecasters to rank the relative importance of several data types, including radar reflectivity, VHF total lightning mapping data, and NLDN CG data during the period indicated on the survey.

The combined results of all forecaster surveys indicated that VHF total lightning mapping data ranked first for all non-severe thunderstorm cases. These cases typically involved modifying aviation products or communicating CG lightning risk to the general public. For severe thunderstorm cases, the combined results of all forecaster surveys indicated that VHF total lightning mapping data ranked second, behind radar reflectivity. These cases typically involved hail, straight-line winds and tornadoes.