Derecho May Hit Illinois As Storms Create Tornado Potential

ILLINOIS — As the Chicago area braces for dangerous heat and humidity — with Tuesday and Wednesday expected to be the hottest days this week — severe storms are also possible Monday, and a derecho may even move into the area.

"Chicago, Detroit, and Pittsburgh will be among the locations potentially impacted by intense, fast moving storms this afternoon through the late night hours," AccuWeather said. "While not a certainty, a derecho may form as storms develop, bringing a wide swath of destructive winds as storms race across the Midwest. Alternatively, even if a derecho doesn't form, a large swath of wind damage can occur as a storm complex moves eastward."

"Derecho" refers to widespread, long-lasting, destructive straight-line winds. The term for the fast-moving winds was coined in 1888 to differentiate the weather pattern from that of tornadoes.

The National Weather Service said two rounds of storms are expected Monday, with the first round developing in late morning/early afternoon, followed by a late afternoon/early evening threat.

The highest threat of storms will be from noon to 3 p.m. and 5 to 8 p.m. Monday, with the second round possibly hitting northeast Illinois and northwest Indiana.

AccuWeather describes the afternoon thunderstorm threat as severe, while Monday night could bring "gusty" thunderstorms.

The storms could bring destructive winds of more than 75 mph, damaging hail capable of denting cars and siding, and a "brief tornado" threat with both rounds of storms.

Dangerous heat

Meanwhile, a heat advisory will take effect for the entire Chicago area from noon Tuesday to 8 p.m. Wednesday.

Peak afternoon heat indexes of 105 to 109 are possible Tuesday and Wednesday.

Tuesday will be humid and breezy, according to AccuWeather.

Temperatures could near 100 degrees on Tuesday, with a high of 98 degrees. Tuesday night is expected to be "abnormally warm with little opportunity for relief," according to the National Weather Service.

More storms could hit Wednesday as well, according to the National Weather Service, before temperatures drop into the upper 80s on Thursday.

The humidity is expected to be lower on Wednesday, with high temperatures in the mid- to upper 90s, before a cold front brings some relief from extreme heat Thursday through the weekend.

Tips for staying safe

As extreme heat hits the Chicago area, the National Weather Service offers advice for staying safe:

Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. Young children and pets should never be left unattended in vehicles under any circumstances.

Take extra precautions if you work or spend time outside. When possible, reschedule strenuous activities to early morning or evening. Know the signs and symptoms of heat exhaustion and heat stroke. Wear lightweight and loose fitting clothing when possible.

To reduce risk during outdoor work, the Occupational Safety and Health Administration recommends scheduling frequent rest breaks in shaded or air-conditioned environments. Anyone overcome by heat should be moved to a cool and shaded location. Heat stroke is an emergency. Call 911.