As Hurricane Florence heads towards the East Coast of the United States the Waffle House Storm Centre has been activated, and the Federal Emergency Management Agency is keeping a close eye on it.

Known for staying open no matter the circumstances, the popular chain plays an important role in FEMA’s hurricane forecasting – if Waffle House decides to close, or even offer a limited menu, that means that the situation is rapidly deteriorating. FEMA monitors Waffle House locations, in what is very seriously called the Waffle House Index.

Waffle House is an important indicator on how a community is coping during a disaster.

“The Waffle House test doesn’t just tell us how quickly a business might rebound — it also tells us how the larger community is faring,” Dan Stoneking wrote for FEMA in 2011. “The sooner restaurants, grocery and corner stores, or banks can reopen, the sooner local economies will start generating revenue again — signalling a stronger recovery for that community.”

The system is colour-coded, with green signalling that a Waffle House is open and offering a full menu, yellow meaning a limited menu, and red meaning closed. So far in the face of Hurricane Florence, only one location has closed – Myrtle Beach in Florida – and some residents are choosing whether or not to evacuate based on the status of their local Waffle House.

During Hurricane Matthew in 2016, one Waffle House stayed open right up until the building began to fall apart.