Geostationary Lightning Mapper Utility for IDSS

The Geostationary Lightning Mapper (GLM) is currently one of the best tools to use for lightning detection and short-term lightning forecasting. Currently, National Weather Service (NWS) forecasters have three primary products: Flash Extent Density (FED), Average Flash Area (AFA), and Total Optical Energy (TOE). Due to parallax with geostationary satellite products, these products are best used in concert with traditional ground-based lightning detection networks. The integration of GLM with ground-based lightning networks provide forecasters the ability to forecast cloud-to-ground (CG) lightning up to 5-10 minutes in advance since intracloud (IC) lightning often precedes CG lightning. However, each product is better suited for certain situations. For example, the AFA product has potential for utility in Impact-Based Decision Support Services (IDSS) when used with an optimized color curve. This product looks at the horizontal/areal extent of lighting at 2 km. Having an optimized color curve that more accurately represents each end of the spectrum can help forecasters with partner decision support. By analyzing the AFA product, forecasters can message the threat of lightning during convective events to emergency managers or law enforcement on whether lightning threats are increasing or decreasing. With the AFA product, knowing whether the flashes are small can help identify new and intensifying convection and when they are large it can help determine if stratiform/anvil regions and/or decaying storms pose a threat of lightning. When long stratiform lightning occurs, the associated lightning channels often connect to remnants of earlier convection. For these reasons, this makes the AFA GLM product especially useful when providing IDSS for large outdoor events.