Peoria, Ill. (WMBD) — One day after a strong cold front brought heavy rain and thunderstorms to Central Illinois strong winds brought power outages and localized reports of tree and power line damage to the area. Here’s a list of the strongest wind reports from across the region.

Peoria (PIA) – 55 MPH
Bloomington (CIRA) – 53 MPH
Towanda – 53 MPH
La Salle/Peru – 53 MPH
Pontiac – 53 MPH
Galesburg – 49 MPH
Macomb – 47 MPH
Eureka – 39 MPH
Arrowsmith – 38 MPH
Germantown Hills – 38 MPH
Pekin – 34 MPH
South Pekin – 34 MPH

The strong winds lead to occasional power outages across Central Illinois throughout the afternoon. You can see the coverage of those outages below.

Why was it so windy?

The winds were the result of the Midwest sitting between a 991 millibar (mb) low pressure system to the north and a 1022 millibar (mb) high pressure system to the south. This created a large change in air pressure over a relatively short distance, what we call a tight pressure gradient, across the state of Illinois. You can see this by how close the isobars (lines of equal pressure) are across the state in the second explainer graphic below. The tighter the pressure gradient the faster the wind will blow as it moves away from the high pressure and towards the area of low pressure.

The tight pressure gradient wasn’t the only culprit to bring strong winds to the area. The temperature & wind profile of the atmosphere above the ground was ideal to allow stronger winds aloft to mix down to the surface. For strong winds to reach the surface you typically need two things:

  • Strong winds above the surface
  • A way to bring these winds down to the surface, in this case a well mixed boundary layer (lowest layer of the atmosphere)

The best way to explain this is to look at this model forecast sounding from Thursday afternoon over Peoria. Here you can see the temperature profile (red line) cooling rapidly with height and stronger wind speeds over 55 knots (63 mph) aloft. With temperatures cooling with height, this means that pockets of rising and sinking air will develop near the surface causing a well mixed and drier boundary layer. This creates ideal conditions for the stronger winds aloft to be mixed down to the surface creating the strong gusts we experienced today. As the surface temperatures cool around sun set, a temperature inversion just above the surface will prevent those stronger winds from reaching the surface causing the gusty winds to subside.