If you’re from Boston or enjoy checking in on the city during its coldest time of year, chances are you’ve heard of the French Toast Alert System.

Or, now you’re scratching your head wondering what that could possibly be.

“French toast storms have been a sort of joke around here for a long time,” said Universal Hub founder Adam Gaffin. “Because when a storm's coming, people rush to the store to get bread, milk and eggs — the key ingredients for French toast.”

The French Toast Alert System ranks the severity of storms from a scale of one slice (lowest risk) to five slices (severe risk). It uses data from local weather emergency officials who track storms to let people know when they need to rush to the shelves for those essential ingredients.

The ranking began around 2007. Gaffin said he joked with people about the alert system on a forum he used to run.

“I mean, what else are you going to do when snowmageddon approaches?” said Gaffin. “I decided to try to quantify how much people should panic before a storm. This was during the days of Homeland Security and its color-coded terror ranking, so I adapted that for local use.”

Since then, Gaffin said the system has gained a lot of local attention, and when a storm is coming, people in Boston — or what he calls “the Greater French Toast Area” — look to his website for its ranking.

“Before storms now, people send me pictures of empty supermarket shelves. Then, during and after [a storm], they send me photos of their French toast,” Gaffin said.

Gaffin said one local enthusiast created Facebook and Twitter accounts for the alert system's rankings to be posted easily. Whenever weather predictions become severe, such as this weekend's storm, Gaffin said he always sees a burst of interest on social media.

“My favorite tweet from yesterday, though, was: ‘I just moved here and I can’t tell how much of this is supposed to be a joke, but I went out to get French toast stuff just in case,’” Gaffin said.

The approaching blizzard has created even more buzz about the French Toast Alert System. The forecast for Boston, which is expected to get up to 2 feet of snow, caused the system to upgrade the storm to its most severe tier: a five-slice storm. The last five-slice ranking was on March 1, 2018.

“Yesterday [Jan. 27], when the alert was still at four slices, Harvey Leonard posted his first 2-feet-plus map, and pretty much immediately people started asking me when I was going to five,” Gaffin said.

Harvey Leonard is a meteorologist for WCVB-TV. Gaffin referred to him as "the dean of local weather people."

“He's famous for basically starting his career by correctly calling the blizzard of 1978, so it seemed to make sense to get him incorporated somehow,” he said.

As Boston prepares for its first major storm of the year, Gaffin has some words of wisdom.

“Even if a forecast turns out to be a bust — and the forecasts for this storm were, well, all over the map until yesterday — don't worry: French toast is good all the time,” said Gaffin. “Also, clear your vent before you start your dryer and your tailpipe before you start up your car.”