Strong storms moved through the area, leaving down trees, power lines, and flooding in Bartlett (SOURCE: CBS Chicago). YouTube Tips ⓘ
Outdoor Warning Sirens were activated in Arlington Heights by Northwest Central Dispatch System (NWCDS) Wednesday night outside of the National Weather Service tornado-warned area (a polygon), which included Streamwood, West Dundee and Carpentersville — not Arlington Heights. Although, the Tornado Warning system is much improved, Wednesday night highlights the difficulty and shortcomings of the system established to warn citizens about tornadoes. Imagine activating the appropriate geo-located sirens in your community to match with a polygon overlayed on a map provided by the National Weather Service.
The closest storm damage to Arlington Heights on Wednesday night was in Streamwood and Bartlett. Streamwood is about 10 miles southwest of Arlington Heights. There were trees uprooted in Streamwood and Bartlett, and some trees fell on homes and vehicles. Initially, there is no confirmation that there was a tornado Wednesday, June 24, 2026 in Streamwood or Bartlett. The only Tornado Damage Reports from the official report list from the National Weather Service Storm Prediction Center were in Huntley in McHenry County, Illinois. McHenry County EMA reported roof damage to a barn along Harmony Road near Brier Hill Road.
Video shared to social media showed a likely tornado with lofted debris in the vicinity of Huntley …
There were no Tornado Warning posts for a Huntley tornado posted on official NWS X accounts Wednesday evening …
X.com/nwschicago, or
“Tornado Sirens” or the new official name of “Outdoor Warning Sirens” were activated in Arlington Heights at 6:13 p.m. Wednesday, June 24, 2026 and sounded until 6:16 p.m. (exactly three minutes). There were no recycled alerts in Arlington Heights, although the NWS Tornado Warning for a radar indicated tornado was active until 6:45 p.m.
There were outdoor warning sirens that were activated again southwest of Arlington Heights from an unknown area as late as 6:25 p.m. and 6:29 p.m.
The nearby NWS Tornado Warning polygon that was activated at 6:09 p.m. Wednesday was active concurrently when the Arlington Heights outdoor sirens activated at 6:13 p.m., but the NWS Tornado Warning polygon did not include Arlington Heights. The polygon was active for an area that included Carpentersville, West Dundee, and the north side of Streamwood. The east border of the NWS Tornado Warning polygon was west of Inverness and west of South Barrington, and did not include Arlington Heights.
An additional NWS Tornado Warning polygon was activated at 6:31 p.m. that did not include Carpentersville and did not include West Dundee, but did include East Dundee. Again, this second polygon was west of Inverness and west of South Barrington, and did not include Arlington Heights.
Outdoor Warning Sirens typically are activated by local authorities for three to five minutes for an area that is included in a National Weather Service Tornado Warning polygon. Siren activation may be recycled in time intervals. The Outdoor Warning sirens in Arlington Heights and surrounding suburbs, including Streamwood, are activated by Northwest Central Dispatch System 9-1-1 center (NWCDS). Typically, the sirens can be activated in Streamwood without activation in Arlington Heights. The decision and control of siren activation is managed by the NWCDS 9-1-1 center and not the National Weather Service. NWCDS Executive Director John Ferraro is the highest authority responsible for the administration of proper activation of Outdoor Warning Sirens at NWCDS.
NWCDS has been planning to use a system that would automatically activate the appropriate sirens that are located in a National Weather Service Tornado Warning polygon, instead of a system that requires human decisions with manual activation in the area. Currently it is unknown if the automated system has been implemented at NWCDS.
On Wednesday night, there was no validating notification regarding Outdoor Warning Siren activation from the official NWCDS Facebook page. Additionally, there was no validating official notification regarding Outdoor Warning Siren activation from the official Village of Arlington Heights Facebook page or the Arlington Heights Police Department Facebook page. The Arlington Heights Fire Department doesn’t have a Facebook page.
Outdoor Warning Sirens can also be activated for Severe Thunderstorm Warnings with predicted sustained winds of 70 MPH or greater and/or hail larger than 1.25 inches in diameter.
There was a Severe Thunderstorm Warning with predicted winds up to 70 MPH that was activated at 6:26 p.m., but the north border of the polygon was south of Arlington Heights with the northern border of the polygon around I-90.
There was also a Severe Thunderstorm Warning with predicted winds up to 70 MPH that was activated at 6:44 p.m. that included Elk Grove Village, but not Arlington Heights.
Activation of an Outdoor Warning Siren outside a National Weather Service Tornado Warning polygon is a concern. Additionally, a time gap of four minutes from Tornado Warning polygon activation to Outdoor Warning Sign activation is a concern.
The typical forward ground speed of a tornado is 10 to 20 MPH, but ranges from stationary to 60 MPH, according to NOAA National Severe Storms Laboratory.
A tornado moving at 60 MPH will travel four miles in four minutes.
A tornado moving at 30 MPH will travel two miles in four minutes.
A tornado moving at 20 MPH will travel 1.3 miles in four minutes.
The Village of Arlington Heights is about 4 miles wide, east to west.
The Village of Arlington Heights is about 8 miles long, south to north.
Note of Interest: There are two official X accounts from the National Weather Service that apply to Chicagoland when Tornado Warnings are activated or issued.
x.com/nwstornado
Posted the first Tornado Warning at 6:15 p.m.
Posted the second Tornado Warning at 6:24 p.m.
x.com/nwschicago
Posted the first Tornado Warning at 6:09 p.m.
Did not post a second Tornado Warning that would have coincided with the second Tornado Warning provided by x.com/nwstornado
Strong storms knock down trees, power lines in Algonquin, Bartlett, East Dundee, and Streamwood (John Garcia/ABC 7 Chicago). YouTube Tips ⓘ
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