Weathermen took to the airwaves Thursday declaring Hurricane Matthew historic, a storm like no other central Florida had seen, one that would rage and ravage. Millions along the East Coast were instructed to evacuate. Grocery store shelves emptied. Gasoline ran out. The Sunshine State’s governor said “this storm will kill you.”

To all tuning in, it was clear this storm was dangerous.

But some Floridians refused to accept the true gravity of Hurricane Matthew’s destructive spin until the South’s most reliable, authoritative voice spoke out.

“All Waffle House restaurants on 1-95 between Titusville, Fla. and Fort Pierce, Fla. are closed,” the restaurant tweeted Thursday afternoon. “Stay safe Waffle Nation!”

Then it sank in.

One tweet summarized the reaction like this:

News: “Evacuate Florida”

Floridians: “Nah”

News: “Waffle House closed”

Floridians: “IT’S THE END OF DAYS!! F—— SAVE US BABY JESUS!!”

It’s rare for the 24/7 truck stop diner, known for its cheap, albeit greasy food, to ever cease service — even in the middle of a natural disaster. The chain’s more than 1,500 restaurants speckling the South make them particularly vulnerable to hurricanes. But Waffle House’s emergency management plans are so thorough and well-regarded that even the federal government unofficially uses the chain’s status to gauge the seriousness of a storm.

They call it the Waffle House Index.

Magazine EHS Today explained it like this:

“ . . . if a Waffle House store is open and offering a full menu, the index is green. If it is open but serving from a limited menu, it’s yellow. When the location has been forced to close, the index is red.”

FEMA director Craig Fugate first used the Waffle House Index when he served as head of Florida’s emergency management department during an active 2004 hurricane season. If the Waffle House restaurants in a particular area were closed, reported EHS Today, he knew the situation was dire.

Their status in the aftermath predicted how quickly a community would rebound.

“If you get there and the Waffle House is closed?” Fugate has said, reported The Wall Street Journal. “That’s really bad. That’s where you go to work.”

But even if certain locations close because of a natural disaster, Waffle House works diligently to reopen as quickly as possible, often making it the first meal the displaced consume in the midst of a tragedy.

“I hadn’t had a hot meal in two days, and I knew they’d be open,” Nicole Gainey, a secretary for a truck-repair company, told the WSJ in 2011 after Hurricane Irene knocked out power across North Carolina.

In total, 22 Waffle House restaurants lost power across North Carolina, Virginia, Maryland and Delaware during Hurricane Irene, the WSJ reported. Within days, all but one in coastal Virginia, where the storm hit particularly hard, were back in business. Waffles Houses in Joplin, Mo., stayed open after a historically deadly tornado tore through the city the same year Irene hit, and when a spate of tornadoes wreaked havoc across Alabama and Georgia, 20 restaurants that had lost power were open within three days.

“They know immediately which stores are going to be affected and they call their employees to know who can show up and who cannot,” Panos Kouvelis, a Washington University business professor, told EHS Today, in reference to Waffle House. “They have temporary warehouses where they can store food and most importantly, they know they can operate without a full menu. This is a great example of a company that has learned from the past and developed an excellent emergency plan.”

The plan, reported Fox News, was assembled after the 2005 wreckage of Hurricane Katrina destroyed seven Waffle House restaurants and closed 100 more. Senior executives developed a manual with post-disaster instructions, acquired portable generators, gave employees key fobs with emergency contact information and bought a mobile command center, according to a WSJ profile of the company.

The manual tells employees what food to prepare based on the available resources, and how and when to limit the menu.

Walt Ehmer, former chief operating officer and current chief executive of Waffle House, told Fox News in 2012 that he is thankful his company can play such a vital role aiding FEMA in the midst of a natural disaster, but that he is more proud of the way the restaurants help communities.

“It’s the one thing we know we can do,” Ehmer said. “We can be there and serve food for people and, after many of the storms … it’s very often that we’ll hear from folks, ‘This is the first hot meal I’ve had in a week.’”