Folks need to know what type of emergency they’re preparing for

I’m in the Dallas area. People here think they’re tornado sirens, but they’re really outdoor warning sirens. They sound for a tornado warning, winds in excess of 70 mph, hail greater than 1.5", or anything else that creates an outdoor risk. They mean “go indoors and check local news.”

we have ones that warn of lightening in parks.

In my state, they (along with the Emergency Broadcast System) were part of the civil defense network created during the Cold War. They were initially intended for war, imminent threat of war, or other national crises. Their brief was later expanded to be used for state and local emergencies. Exactly what they’re used for (tornadoes, tsunamis, flood warning, etc) and under what conditions they can be used, depends on your state and local officials.

I’d also add that the government has tried to be rather restrictive about what conditions it could be used under. They want the siren use to be unusual enough that people respond to it as it there’s an actual emergency. Unlike, for example, the fire drills you’d have in school or work, where people would debate whether to bother leaving their desks, head back to the office to get their things, etc.

It’s hard enough to get people to respect the sirens when they’re for tornados. Use them for other shit and people will straight up ignore them.

Other kinds of severe weather are predictable, whereas there’s a big difference between “this pattern could develop into a tornado over the next half hour, batten down the hatches” and “A TORNADO HAS TOUCHED DOWN NEAR YOU, GET TO A SHELTER WITHIN THE NEXT MINUTE OR YOU’LL DIE!”