Severe Thunderstorms Roll Through Chicago Area, Pitchfork Briefly Evacuated

(CBS) -- A line of severe thunderstorms moved through the Chicago area and prompted a brief evacuation of the Pitchfork Music Festival on a hot and humid Saturday afternoon.

The storms prompted the evacuation of the music festival, held in Union Park on the Near West Side. The festival reopened at 4:20 p.m. after being closed for about a half hour.

The Chicago area was under a Tornado Watch late Saturday evening.

The watch area includes Cook, DuPage, Grundy, Kane, Kankakee, Kendall, Lake (Ill.), McHenry and Will counties in Illinois and Benton, Jasper, Lake (Ind.), Newton, Porter counties in Northwest Indiana.

A Tornado Warning was in effect for parts of McHenry County, which expired just before 3 p.m. There were reports of heavy rain and hail and funnel clouds in the area, including a possible touch down near Harvard, Ill.

the Chicago area was also under a heat advisory, with high temperatures and humidity.

For information on cooling centers in Chicago, click here. For cooling centers in Illinois, click here.

The National Weather Service says the combination of excessive heat and humidity will create oppressive conditions and prolonged exposure could lead to the development of heat-related illness.

Mayor Emanuel is asking Chicagoans to check on neighbors, especially the elderly.

"This is the first time this summer the truth is that Chicago has experienced some real warmth in the weather so we have extended the hours at three of our cooling centers to make sure that those who are vulnerable in the sense they don't have air conditioning, they are on in there years, that they have a place to go where they can actually be comfortable," Emanuel said.

The Chicago Fire Department is also concerned.

"We do worry about open hydrants," said fire spokesman Larry Langford. "When it gets hot, it seems to be some kind of tradition to open a hydrant up and it is a dangerous tradition. We don't like it."

Open hydrants can cause a drop in pressure and Langoford says it also dangerous because the spray can hide kids and several years a go a child playing in the spray from a hydrant and was hit by a car and killed.

Attendees at the 5th Annual Taste of WVON were doing their best to stay hydrated

"We still came out even though they said it was going to be extremely hot," said Jasmine Parker. "We came with a lot of water."

"For safety purposes, we want the kids to stay hydrated, including myself," said Clayton Roberts.

Registered nurse and taste goer Vanessa Grandberry came prepared with the essentials for a hot day.

"I definitely recommend a hat," she said. "I saw some people walking around with umbrellas. That's good too."

As the temperature and humidity soar, Dr. Tony Kremer says we can't forget about pets and heat stroke.

"The pet becomes wobbly, dizzy, they're going to pant, they may look incoherent," said Dr. Kremer. "It becomes critical very fast."