Figure 1: Example image of GR2 Analyst software depicting radar reflectivity, the Lightning Stoplight Tool, and convective warning polygons for an ongoing severe weather outbreak on April 27th, 2026.
The newest version of the Lightning Stoplight Tool incorporating both space- and ground-based lightning observations is now available to view in the commonly used radar software GR2 Analyst. This visual guide to the spatial coverage and recency of lightning strikes is created using flashes observed by the Geostationary Lightning Mapper (GLM) instruments and the Earth Networks Total Lightning Network (ENTLN) antennae, and publicly-accessible placefiles show the lightning strikes observed between these two detection systems over the previous 30 minutes. The red, yellow, and green shadings represent the amount of time since lightning flashes were observed over that area, representing lightning strikes within the last 10, 20, and 30 minutes, respectively. Radar reflectivity from the KLSX radar near Saint Louis, MO is overlaid on top of these shaded areas in Figure 1 above. This Stoplight product highlights how much broader of an area is impacted by increasing lightning threats from convective storms than just what is covered by radar returns or even convective warning polygons, especially in areas trailing or perpendicular to the direction of the predominant storm motion (towards the northeast).
Figure 2: Side-by-side comparison of the Lightning Stoplight Tool in GR2 Analyst with the same data sets at the same time, with the Lightning Stoplight Tool overlaid on top of radar reflectivity on the left and vice versa on the right. The inset in the top-center (white box) represents the mouse-over text showing how long ago individual lightning flashes were observed.
Placefiles which can be easily ingested by the GR2 Analyst software are especially useful for NWS forecasters because many Weather Forecast Offices prominently display radar data using this software during operations. While the entire polygons created within the placefiles cannot produce mouse-over text over the entire area of the polygon, it can be formatted to include this information when the mouse cursor is positioned over the edges or boundaries of the individual polygons representing either individual flashes or the time since any flash was observed over a certain area within a certain period of time. On the left side of Figure 2 above, the red, yellow, and green polygons produced as part of the Lightning Stoplight placefiles are overlaid on top of the radar reflectivity data, whereas the radar reflectivity data is overlaid on top of the Lightning Stoplight polygons in the right side. This contrast shows how a large area of risk for nearby lightning strikes exists beyond just the stronger, more convective storms towards the south. The broader, larger red polygons showing lightning observed within the last 10 minutes branch far north of the main line of convective thunderstorms into the large stratiform region covering much of east-central Indiana and western Ohio.
In a DSS environment as an operational forecaster, this Lightning Stoplight Tool highlights these often overlooked areas where a distinct lightning safety threat persists despite no longer being affected by more traditional types of severe weather, like tornadoes or large hailstones. Additionally, having access to this Lightning Stoplight Tool within GR2 Analyst allows forecasters who may be dispatched onsite to provide timely weather information showcasing the spatial coverage and close proximity of lightning strikes even though they may be far from their typical AWIPS workstations. Progress is being made to get this stoplight imagery into AWIPS as well, with similar imagery as with GR2 Analyst expected to be created later this week.
-Dusty
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