URBANA — The National Weather Service confirmed the event that swept across Champaign County late Tuesday morning was a “gustnado.”

“They classify it as a small whirlwind that forms as an eddy in the leading edge of a thunderstorm. They do not connect with cloud-based rotation and are not tornadoes,” said John Dwyer, director of the Champaign County Emergency Management Agency.

UPDATED: Officials explain why sirens sounded in Champaign Police wanted to be quick to send out an Illini Alert since thousands of students are moving into dorms today.

About 11 a.m., a Champaign police officer saw low-hanging clouds and whatever was moving close to the ground kicking up debris in west Champaign as it moved into the area from the west to the east. That officer urged Dwyer to sound the tornado sirens.

“We had other reports of rotation of clouds both inside and outside the county,” Dwyer said. That prompted him to err on the side of caution.

“Four minutes later, the weather service said it’s likely a gustnado,” he said. “It’s so unpredictable. You do what you can. Do I wait four minutes to say, ‘This is really what it is?’ We see stuff on the ground that (the NWS) may not see on radar. It’s a cooperative effort.”

In that four-minute interim, schools and other governmental agencies had taken steps to keep their charges safe.

At the University of Illinois, where students were moving into residence halls and apartments Tuesday, officials sent out an “Illini Alert” once the sirens sounded, referencing a “tornado warning.”

Police officials later acknowledged the alert could have been worded better, but said it was a “no-brainer” to send it out once the sirens sounded, which is the protocol.

“We determined it was a real emergency,” said UI Police Lt. Todd Short, who leads campus emergency preparedness efforts. “I know there was some consternation about the definition of a warning. Regardless of whether that occurs or not, when the emergency management agency director presses the button to activate tornado sirens, that tells us this is a warning.”

The Illini Alert system has multiple levels of redundancy, so the police chief, deputy chief and any lieutenant or sergeant have authority to send one out if there’s an immediate threat to life and safety, he said.

“I’d much rather send out an Illini Alert to tens of thousands of people and have nobody hurt than not send it out with the hair on the back of my neck standing up” and regret it later, Short said.

Taking cover at Central

While elementary students in the Gibson City Melvin-Sibley school district adapted to an unplanned indoor recess due to heavy rains, students at Champaign Central High took shelter as sirens rang about 11 a.m.

“On day one, that is not ideal,” GCMS Superintendent Jeremy Darnell said.

Central Principal Joe Williams commended his staff for moving quickly once the sirens sounded.

“For a take-shelter weather event to take place on the third full day of school and have it go so well — major kudos to the staff in our schools,” Williams said.

For “15-20” minutes, Williams said students took shelter in predetermined areas of the school.

“The experts have said taking shelter in the basement, first and second floor is safe as long as we are away from large expanses of windows, such as in the stairwells,” he said, adding that the Central community is “fortunate to have a storm shelter being built as part of the (Unit 4 referendum construction project) as well.”

Monticello’s current building renovation project is also being designed for severe weather. Its next gym will come with reinforced office walls that double as a storm shelter, with capacity for 650 people, said Superintendent Vic Zimmerman.

Before sirens ever ring or students are told to take cover, though, superintendents and principals said Tuesday that they constantly check the weather radar, news coverage and alerts to determine the safest course of action to take.

On Tuesday, “we were monitoring the storm, and we were working with our school resource officer, Bill Ward, who was in contact with local authorities,” said Mahomet-Seymour High School Principal Chad Benedict. “I felt like we had a good handle on things.”

Shelter at courthouse

In downtown Urbana, the county courthouse had several busy courtrooms.

Sheriff’s Sgt. Michelle Mennenga, who supervises courthouse security, had been watching the weather and was in touch with Dwyer and Dana Brenner, facilities director for the county.

Coincidentally, Sheriff Dustin Heuerman, whose office is just across the street and would normally be monitoring the severe weather and giving direction to employees, was in emergency management training at the Fire Service Institute in south Champaign.

Mennenga said she had made the rounds of the first-floor offices reminding employees where to shelter, and was on her way to the second and third floors when someone radioed her that the weather sirens were sounding.

“As I got closer to the windows, I could hear the sirens myself and gave the notification to start moving to shelters,” she said.

All those in third-floor courtrooms were sent to the second floor to stay inside courtrooms that are in the middle of the building. Employees in courthouse offices such as the state’s attorney, probation, public defender, circuit clerk and the judges and their support staff, have designated areas to wait out storms.

“We want them to be where there are no windows, make sure we keep everybody out of the hallways,” she said of anyone in the building.

About 11:20 a.m., Sheriff’s Capt. Shane Cook, who was in the office across the street, sounded the return to normal quarters.

'Everybody inside!'

University Housing staff members were already outside investigating a gas leak near a cluster of UI residence halls at Fourth Street and Peabody Drive when the first weather alert came in just after 11 a.m.

As they were discussing with Ameren workers and UI police how to redirect move-in traffic if the intersection had to be shut down, a police officer reported that a suspected tornado had been spotted at Kirby Avenue and Staley Road. Then the tornado sirens sounded.

“We were like, ‘Everybody inside!’” said Housing Director Alma Sealine.

About 50 cars were lined up in the pouring rain along Euclid Avenue and in nearby parking lots, waiting to unload, so staff members ran alongside, urging students and parents to get out and run into a nearby residence hall.

“We were able to get everyone out,” said Sealine, who joined about 15 other people in the basement of Taft Van Doren Hall to wait out the storm.

The same scene played out at other residence halls across campus, where hundreds of students assigned to “Living and Learning Communities” were moving into residence halls early for an orientation program. More than 2,600 students had moved in as of Tuesday afternoon.

“No one was hurt, but it was the first time for a move-in that I sheltered in place in the basement of a residence hall,” Sealine said. “It’s been quite a day.”

Luckily, she said, the gas leak was plugged, and the street didn’t have to be closed.

And parents and students were good-natured about the disruption, though “many of them were wetter than they wanted to be,” she said.

“We’ll not forget this move-in day,” she said, “and neither will the students or their families.”

Uni evacuates to UI

Employees across campus headed to building interiors or basements when the sirens sounded, though judging by comments on Twitter some weren’t sure at first if it was the real thing. Some employees couldn’t remember the last time a suspected tornado swept through during a work day.

Every UI building has an emergency plan, updated annually, covering different hazards, including severe weather, Short said. Floor coordinators are assigned to specific areas of the building, charged with making sure people in that area follow the plan, he said.

Students from University High School joined UI employees taking shelter at the Digital Computer Lab across Mathews Avenue, as Uni doesn’t have a basement. It’s standard operating procedure when there’s time to get the 325 students across the street, said Uni communications coordinator Carol Lombardi.

If not, students and staff stay in the school on the first floor, lined up against the lockers with their backs to the hallway, she said.

Parkland on alert

The sirens didn’t faze shoppers at Champaign’s mall.

Market Place Shopping Center has a “take cover” announcement in case there’s a tornado watch or warning, General Manager Dennis Robertson said. But that’s only used in the event of “an immediate threat,” he said, “and that was not the case in this situation.”

There was no damage reported at Parkland College, where classes had just started a day earlier. Like at the UI, a Parkland alert was sent to the campus community when the sirens sounded, with floor coordinators helping guide people to their designated shelter spot.

“We had no damage that I’m aware of,” said campus spokeswoman Stephanie Stuart. But “it kept this morning interesting.”

Lyndsay Jones, Tim Ditman, Ben Zigterman and Steve Hoffman contributed to this report.