A thunderstorm doesn’t have to be severe to be dangerous. Even the most mundane of storms can generate lightning, which kills dozens of people in the United States annually. As of late August this year, according to the National Weather Service, 22 people had died in 13 states from lightning strikes.

Given the risk, and the number of severe thunderstorms in the Washington region, a weather app that offers lightning detection sounds appealing. So when Germantown, Md.-based Earth Networks added a “personal lightning detector” to its WeatherBug app, curious Washington Post editors asked me, a meteorologist, to take a look.

The lightning detector, called Spark, is just one small feature of the WeatherBug app (free for iOS and Android), which also provides current weather conditions, an hourly and 10-day forecast, and severe weather warnings. It’s powered by WeatherBug’s own 1,000-sensor lightning-detection network, rather than relying on the two well-known lightning networks that many weather services use: Vaisala and WSI, a sister company of the Weather Channel.

Opening Spark will show you how far you are from the nearest lightning strike, which is useful because you don’t necessarily have to be directly under a thunderstorm to be at risk. “Bolts from the blue” have been documented up to 25 miles from their parent storms.

But while being able to see where lightning has been detected is valuable, ideally you wouldn’t have to be aware of impending thunderstorms and continually checking your phone for lightning strikes. Instead, you’d get an alert when lightning was detected within a certain distance of your location. To that end, WeatherBug employs an algorithm that detects not just the bolts that hit the ground, but also the flashes within the cloud. Using this data, the app will send a push notification to your device if you’re in the path of a “dangerous thunderstorm” that might not have yet prompted a severe thunderstorm warning.

Spark is WeatherBug's lightning detector.

A couple of drawbacks: WeatherBug does not offer an option to get basic lightning alerts; you have to trust the app’s algorithm to push you those Dangerous Thunderstorm Alerts. And despite the app’s claim that Spark will “follow” you, it does so only when the app is open. It will not geolocate you when the app is closed; instead, it uses a fixed location of your choosing.

And though the app provides useful data and information, its interface and graphics are poor. Users have to weed through a lot of screens and options to find what they’re looking for. Spark itself is buried in the sidebar menu with no mention on the home screen; once you get there the map is clunky, with just a few zoom levels to choose from.

Bottom line: Spark is interesting and potentially useful if you’re already paying attention to the weather. But the lack of geolocated push alerts is a deal breaker.

Capital Weather Gang member Angela Fritz is The Post’s deputy weather editor.

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