These appear to bursts of electromagnetic interferences (EMI). The rays are all centered on the location of the weather radars. As the weather radars rotate and receive interference they interpret it as a weather return in the direction they are pointing in at the time the interference signal is received. As these radars have no additional means of determining the direction of arrival of the signals we see these "spokes." The sources of this interference, which is EM radiation at the same wavelength of the radar, is typically from spillover from telecommunication equipment or other radars using in similar wavelengths.
Similar patterns can be seen is this image:
This figure is from Survey on Electromagnetic Interference in Weather Radars in Northwestern Italy,a paper studying the impact of interference on weather radar.