Though Illinois residents had a brief reprieve, the heat is back in full swing this week.
The National Weather Service has issued heat advisories throughout much of the state Tuesday through Thursday and predicts heat indexes surpassing 100 degrees.
Some weather experts are referring to the warming trend as a “heat dome,” explaining that the phenomenon is more common than we may think.
Here’s what that means and when we can expect relief.
What is a heat dome?
Heat domes, also known as death ridges, are basically expansive bulges of warm air that can stretch for 1,000 miles, according to the Weather Channel. This sinking air compresses and warms as it nears the surface, causing temperatures to skyrocket in days-long heat waves.
The phenomenon dries out the ground and air above it, suppressing the formation of thunderstorms and potentially halting winds. These domes can strengthen and expand during vicious cycles of warming and drying until something pushes them elsewhere.
Fortunately, these domes can also deflect tropical storms away from the U.S.
Where is heat dome?
The heat dome appears to be sitting over the middle of the U.S., with states in the southeast experiencing the most extreme temperatures, according to data published by the National Weather Service.
The NWS classified the majority of Illinois in either Category 1 or 2 heat risk today, with parts of the southernmost tip of the state classified as Category 3.
Most of the state will be classified as Category 3 heat risk on Wednesday and Thursday as the heat dome migrates east.
How hot will Illinois get this week?
On Tuesday, the heat indexes in Peoria and Springfield are expected to peak at 100 degrees around 3 p.m., according to the National Weather Service.
The heat indexes will then peak near 110 degrees in the afternoon on Wednesday and Thursday throughout Illinois. Temperatures will lower a bit by Friday with increased cloud coverage and a chance of rain, bringing the heat index down below 100, but hot weather may continue for several more days.
A Heat Advisory is in effect for Tuesday, July 22, west of I-55, and an Excessive Heat Watch is in effect for Wednesday and Thursday for all of central and southeast Illinois.
The NWS recommends drinking plenty of fluids, staying in an air-conditioned room, staying out of the sun and checking up on relatives and neighbors. Do not leave young children and pets in unattended vehicles, as car interiors will reach lethal temperatures in a matter of minutes.
Heat safety tips
During extreme heat, it’s important to drink plenty of fluids, stay in an air-conditioned room whenever possible, stay out of the sun and check on relatives and neighbors, according to the NWS.
Take extra precautions when outside, such as wearing lightweight, loose-fitting clothing, trying to limit strenuous activities to early morning or evening and taking action when you see symptoms of heat exhaustion and heat stroke. Take frequent rest breaks in shaded or air-conditioned environments.
Chicago residents can call 3-1-1 to request well-being checks for elderly friends or family members or for information on finding the nearest cooling center. Otherwise, you can call 9-1-1 if you or someone else is experiencing heat stroke or another emergency.
This article originally appeared on Journal Star: What is a heat dome? NWS issues heat advisories throughout Illinois this week
Reporting by Hannah Hudnall, USA TODAY NETWORK / Journal Star
USA TODAY Network via Reuters Connect
