Heat dome causes radio interference, triggering false alarms and signal disruptions in US Midwest

A heat dome in the US Midwest has led to tropospheric ducting, causing radio signals to travel hundreds of miles and accidentally activate emergency sirens.

• On 1 July, an emergency siren in Huntington County, Indiana activated accidentally after receiving radio signals from Iowa, 300 miles away, during the heat dome.
• In Ohio, drivers experienced radio stations from hundreds of miles away or blank coverage due to the same atmospheric phenomenon.
• Kyle Spillane, a member of the Mid-MO Amateur Radio Club, said tropospheric ducting creates "little tunnels in the sky" that can carry radio waves over long distances, affecting TV and cellphone signals.
• A US Forest Service spokesperson said firefighters experience little to no impact on radio systems due to heat.