WEATHER ALERT: Tornado watch issued for metro Atlanta until 2 a.m.

“Remember, don’t drive across water-covered roads,” Nitz warned. “You don’t know how deep it is and the road could be washed out.”

Floyd County Schools and the Polk School District have announced that classes are canceled Friday due to flooding, closed roads and power outages.

“We have many families with damage to their homes and widespread power outages,” the Polk School District said in a Facebook post. “In addition, several roads are blocked with fallen trees, and schools are now without power.”

— Please return to AJC.com for updates.

[5:50 p.m.]: The tornado warning in Bartow County has expired. Bartow was the final county in northwest Georgia that remained under a tornado warning.

[5:30 p.m.]: The Polk County school system has canceled classes for Friday due to damage from Thursday’s storms. Polk law enforcement officials are reporting multiple trees down in roads throughout the area.

[5:15 p.m.]: A tornado warning has been issued for Bartow County until 5:45 p.m. The warning has been lifted for Polk County and Floyd County.

[UPDATE: 4:19 p.m.]: Part of North Georgia is under a tornado warning until 5:15 p.m. Thursday, officials said.

The National Weather Service issued the warning after confirming that a tornado from Alabama crossed over into western Floyd and northern Polk counties. The tornado is moving northeast at 45 mph and is bringing quarter-size hail along with it, the NWS said.

The tornado is bringing quarter-size hail along with it, the NWS said, with heavy rain expected to follow later tonight.

The warning urged anyone in the area to stay inside, as “flying debris will be dangerous to those caught without shelter.”

“Please move to a safe place NOW!” the NWS said in a tweet. “Indoors. Lowest floor w/no windows. This tornado has a long history of producing significant damage.”

People in Rome, Cedartown, Rockmart, Aragon, Cave Spring, Shannon, Seney, Etna, Lindale, Coosa and Fish Creek should find a place to take shelter as quickly as possible, Channel 2 Action News meteorologists said.

“You need to be away from windows and doors,” Channel 2 meteorologist Glenn Burns said.

Power outages and fallen trees have already been reported in the area, officials said. The Polk sheriff’s office told Channel 2 that deputies had spotted a “rotation in the clouds.”

[ORIGINAL STORY]: Thunderstorms are creeping into metro Atlanta from the northwest earlier than expected Thursday, according to Channel 2 Action News.

Lightning, quarter-size hail, downed trees, gusty wind and heavy rain have been reported in parts of Polk, Paulding, Cherokee and Cobb counties at midday. Those are evidence of a “supercell thunderstorm,” Channel 2 meteorologist Brian Monahan said.

“No tornado warnings now, although we are keeping a close eye on that storm in Cherokee County and Cobb County,” he said just before 1:30 p.m.

Multiple severe thunderstorm warnings have been issued by the National Weather Service as storms move across the Northside.

“We are going to see that tornado risk going up over the next several hours, especially into northwest Georgia, where it is no longer a Level 3 severe weather risk, it is a Level 4,” Monahan said.

A tornado watch has been issued for several counties in northwest Georgia until 9 p.m. The strongest storms are expected to tee up in the northwest and swing into metro Atlanta after sunset, according to Channel 2.

The forecast may sound similar to that of last week, when severe storms that ravaged Mississippi and Alabama did not make it across the Georgia state line. But there is nothing to stop the storms this time, Monahan said.

The main difference is the temperature. Metro Atlanta is in the mid-70s as the storms are beginning to develop, which Monahan said is a 25- to 30-degree jump in temperature from last week. The projected high Thursday is 80 degrees.

“These will have some punch,” he said of the storms.

The Weather Service has categorized parts of west Georgia and the northwest Atlanta suburbs as a Level 3 threat, and the threat diminishes for those to the east.

“More or less to the east of I-85, a much lesser risk of strong to severe storms with a Level 1 threat,” chief meteorologist Glenn Burns said. “Any of these are capable of producing strong to severe winds across northern Georgia, large hail, and at any time, as you can see with the atmosphere that we have right now, a brief spinup tornado.”

» For a detailed forecast, visit The Atlanta Journal-Constitution weather page.

» For updated traffic information, listen to News 95.5 and AM 750 WSB and follow @ajcwsbtraffic on Twitter.

» Download The Atlanta Journal-Constitution app for weather alerts on-the-go.