There are a lot of ways the Federal Emergency Management Agency (FEMA) assesses and addresses the severity of a natural disaster. Meteorology can predict movement patterns, wind gusts, and precipitation. Resources are dispatched to areas hit hardest by torrential weather.

But when the agency needs an accurate, ground-level gauge for how a community is coping during a crisis, they turn to Waffle House.

Since 2004, FEMA has utilized what former administrator Craig Fugate called the “Waffle House Index.” Because the casual dining chain is open 24 hours a day, seven days a week, tracking to see if a location is closed or working with limited supplies can help inform the agency as to whether affected areas are ailing or taking steps toward normalcy.

“If a Waffle House is closed because there's a disaster, it's bad,” Fugate told NPR in 2011. “We call it red. If they're open but have a limited menu, that's yellow ... If they're green, we're good, keep going. You haven't found the bad stuff yet.”

For FEMA, the ability to order a plate of smothered and covered hash browns is an important analytic. If a Waffle House is having trouble getting stock, then transportation has been interrupted. If the menu is limited, then it’s possible they have some utilities but not others. If its locations have locked their doors, inclement weather has taken over. The chain’s locations would normally stay open even in severe conditions to help first responders.

The company has opened a Waffle House Storm Center to gather data in anticipation of Hurricane Florence, a Category 2 storm expected to touch down in the Carolinas this week. But not all locations are taking a wait-and-see approach. One Waffle House in Myrtle Beach, South Carolina has already closed due to the looming threat, making it the first red dot on the Index.

[h/t CNN]