Snowy conditions forced a South Carolina Waffle House to close Sunday.

The restaurant in Travelers Rest was locked with no indication of when it would reopen, WHNS reported.

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Upstate areas of South Carolina were expected to receive more than a foot of snow throughout the weekend, according to the National Weather Service.

With more than 1,500 restaurant locations across the Southeast that are typically open 24 hours every day of the year, a closure is a big deal, so much so that federal emergency management officials informally determine how bad a storm is based on what is referred to as the Waffle House Index.

"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. Because Waffle House is well-prepared for disasters … it's rare for the index to hit red," according to the Federal Emergency Management Agency.