On the internet, it's wise to take everything you read with a healthy dose of skepticism. There are plenty of half-truths and outright lies online, so when you hear something outlandish, there's a good chance it's a falsehood spread through social media posts and unscrupulous blogs. However, there are a handful of cases where these outlandish claims are legitimate — the Waffle House Index is one such example.

Waffle restaurants as a disaster measurement tool? Sounds crazy, but it actually works.

It may be hard to believe, but the Waffle House Index is a real metric used by the Federal Emergency Management Agency (FEMA) to measure the scale and severity of a storm. It's based on the casual restaurant chain with more than 2,000 locations throughout the southern United States. Every Waffle House location is open 24 hours a day, 365 days a year, and the chain has become famous for staying open during severe weather.

Photo: Flickr / Steve Snodgrass

It's not unheard of for a restaurant to stay open rain or shine, but you may be thinking that a city-wide power outage would surely cause Waffle House to close its doors. Not so — the company actually has an impressive disaster response plan in place. Popular Science reports, “Waffle House is a leader in disaster preparedness. It maintains its own fleet of portable generators, operates a mobile command center to assist in disaster recovery, and trains employees in crisis management to ensure that it can resume operations as quickly as possible—often within hours. And since 2012, it reports all this information directly to FEMA via email.”

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There's a special limited menu for when generators are in use or food supplies are running low, but Waffle House won't close unless it's absolutely necessary. Locations in Joplin, Missouri stayed open even as a multiple-vortex EF5 tornado struck the city.

This Waffle House on the Biloxi, Mississippi coast was torn to shreds by Hurricane Katrina. Photo: Carol M. Highsmith...

When Waffle House closes due to a storm, there's serious cause for concern. FEMA Administrator Craig Fugate coined the term, and told the Wall Street Journal, “If you get there and the Waffle House is closed? That's really bad. That's when you go to work.” This led to the development of the Waffle House Index as an informal metric for measuring the effects of storms, hurricanes, and even tornadoes. The index has three levels:

• Green – The situation is relatively normal, and the restaurant is still serving its full menu. Power outages and structural damage are unlikely.
• Yellow – The restaurant is serving a limited menu, and may be operating with a generator and/or limited food reserves.
• Red – The restaurant is closed. This typically happens only if structural damage is severe or food reserves have run out.

While the Waffle House Index isn't a formal measurement of disasters, it's still a real metric tracked by FEMA — believe it or not. So, if you're ever in a Waffle House and employees start closing up shop during a storm, you'd better get out of Dodge ASAP.

Written by Patrick McCarthy