How AccuWeather Detects Lightning Strikes

AccuWeather.com was one of the earliest companies to put lightning data onto the internet and television. Lightning data began being transmitted from Vaisala Inc. to AccuWeather.com in 1989. This is when AccuWeather.com introduced UltraGraphix, ultra-high spatial and color resolution graphics that were ready-for-air television, according to AccuWeather.com Meteorologist and Social Media Coordinator, Jesse Ferrell.

Throughout the years, AccuWeather.com has made improvements and updates to their lightning maps, such as reducing delayed time between lightning strikes.

AccuWeather Social Media Coordinator and Meteorologist Jesse Ferrell captured this lightning photo on June 12, 2011 at Duck, N.C.

In 2008, AccuWeather released MapSpace™ which provided Premium and Professional customers with state-level 12-minute-delayed lightning maps and 30-minute delays for AccuWeather.com. This decreased the delay time from 20 minutes to 12 minutes for Premium and Professional customers.

Vaisala uses National Lightning Detection Network to gather their lightning strike data, which is then transmitted to AccuWeather.com. There are 114 ground-based sensors that Vaisala uses to collect lightning data, according to Vaisala's Marketing Manager, Melanie Scott. The National Lightning Detection Network collects lightning data from cloud-to-ground and cloud-to-cloud lightning, according to vaisala.com.

"The technology used depends on the type of lightning being detected (cloud-to-ground vs. cloud lightning), but essentially Vaisala uses both magnetic direction and time of arrival in order to properly detect, classify and provide the final customer information," Scott said.

Vaisala has sensors placed throughout the United States that collect and transmit data to the companies main control center located in Tucson, Ariz. The data is then dispersed to companies that use Vaisala's data, such as AccuWeather.com.

Sensors that are used to detect thunderstorms and lightning detection both have above a 95 percent accuracy rate, according to Scott. Vaisala can pinpoint a cloud-to-ground lightning strike's location within 250-500 meters, something Ferrell has personally verified.

AccuWeather.com makes Vaisala lightning strike maps available for free on AccuWeather.com and AccuWeather.com MapSpace. AccuWeather also gives access (via subscription services) to real-time street-level lightning strikes from the U.S. Precision Lightning Network (a competing national lightning detection array).

An AccuWeather.com Lightning Plus customer can see lightning maps that portray lightning strikes at a street level in real-time and take advantage of a 30-minute lightning forecast system, including email alerts according to Ferrell.

An example of a Lightning Plus map from AccuWeather shows a street level map with lightning strikes plotted on it.

Ferrell said that as long as you have a forecast and are monitoring the weather conditions outside, you usually can anticipate when lightning is possible.

Although lightning strikes may be somewhat predictable, the type of lightning that a storm brings may be harder to predict.

AccuWeather.com Senior Meteorologist Dan Pydynowski said it is hard to determine what kind of lightning will strike, either cloud-to-ground or cloud-to-cloud.

"Once a storm forms, or line of thunderstorms form, and it has a history of producing lightning, it will probably continue, but it is hard to say in advance of the formation what kind of lightning the storm will produce," Pydynowski said.

The time between seeing lightning and hearing the thunder after suggests how far away the storm is, Pydynowski said, since light travels faster than sound. If you hear thunder, lightning can be expected.

"Thunder is a by-product of the lightning; thunder is a sonic boom from the lightning. If you see lightning and hear thunder directly after, that means the storm is close," he said.

In order to avoid being struck by lightning, keep a watchful eye on the sky.

"To reduce the likelihood of being struck by lightning you should observe the darkening sky. Every time you hear thunder, lightning can be expected. It certainly doesn't have to be raining for someone to be struck by lightning," Ferrell said.

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