The National Weather Service in the Quad Cities conducted a storm damage survey near Prophetstown in Whiteside county based off an eyewitness report of an observed tornado moving through the area on Tuesday afternoon around 2:55pm. This report along with radar data has led to the confirmation of an EF0 tornado just 4 miles to the west northwest of Prophetstown Illinois.
The survey found no damage, however most of the surrounding area is made up of farm fields.
Here is a map using the coordinates from the National Weather Service report.
Here is the official NWS report.
NOUS43 KDVN 242048
PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
348 PM CDT Wed May 24 2017
...NWS DAMAGE SURVEY FOR 05/23/17 TORNADO EVENT
Funnel clouds were reported across northwestern Illinois on 5/23/17.
Eyewitness reports along with radar data confirmed one briefly
ESTIMATED PEAK WIND: Unknown
PATH LENGTH /STATUTE/: Unknown
PATH WIDTH /MAXIMUM/: Unknown
START DATE: 05/23/2017
START TIME: 255 PM CDT
START LOCATION: 4 Miles WNW Prophetstown, IL
START LAT/LON: 41.6885N/-90.003
END DATE: 05/23/2017
END TIME: 255 PM CDT
END LOCATION: 4 Miles WNW Prophetstown, IL
END LAT/LON: 41.6885N/-90.003
A tornado was observed by eyewitnesses along with radar debris
signature. Eyewitness said that they had to slow down and wait for the
tornado to pass in front of them on the road. The point above is the point
where this occurred. A survey found no damage, however most of the area
was farm fields. Radar suggests a path that is likely longer than the
was actually on the ground.
EF SCALE: THE ENHANCED FUJITA SCALE CLASSIFIES TORNADOES INTO THE
FOLLOWING CATEGORIES BASED ON THE DAMAGE THEY CAUSE.
EF0...WEAK......65 TO 85 MPH
EF1...WEAK......86 TO 110 MPH
EF2...STRONG....111 TO 135 MPH
EF3...STRONG....136 TO 165 MPH
EF4...VIOLENT...166 TO 200 MPH
THE INFORMATION IN THIS STATEMENT IS PRELIMINARY AND SUBJECT TO
CHANGE PENDING FINAL REVIEW OF THE EVENT AND PUBLICATION IN NWS