Internet connections and high-speed cellular services have improved people’s access to real-time weather information in the decade since the April 27, 2011 storms that wreaked havoc across Cullman County and much of Alabama.

But for many, the first sign that it’s time to take shelter is still the familiar blare of a local siren. In Cullman County, there are 42 tornado alert sirens covering both rural areas and municipalities. And unless the weather’s severe, they’re tested weekly every Wednesday morning, giving residents a momentary earful of their air-piercing power — a sure sign that they’re operating as intended.

For all the testing and the county-wide coverage, though, tornado alert sirens do have a weakness — and it’s one that became alarmingly apparent as that historically stormy day unfolded 10 years ago. The sirens run on rechargeable batteries, a necessary measure to ensure power outages won’t hamper their operation. But batteries, of course, can run out of power. And on April 27, 2011, every single one of them eventually did.

“They all ran out,” recalls Cullman Emergency Management Agency director Phyllis Little. “With the exception of one that’s been installed in the past five years or so, all of our sirens are battery-operated. Even the newer one is a solar unit that still uses batteries, though it runs on a solar panel instead of a trickle charger to keep the batteries fresh. But on a stormy day, there’s no sun to feed the solar panel — so even that has its limits.

“On April 27, our tornado sirens were activated so often during that 24-hour period that the batteries in all of them died. It takes 24 hours for the batteries to recharge to their maximum power, and Cullman County ended up without power for anywhere from three to seven days, depending on where you were. So sirens can be a lifesaving source of information about an approaching tornado, but they’re only one piece of a larger communication system that’s meant to have overlapping sources of weather information for residents. And because of their design, there’s really nothing we can do about their limitations.”

Over the past two months, a pair of tornado-spawning storms has caused significant property damage (but no injuries or fatalities) in two areas of eastern Cullman County. In both cases, tornado warnings weren’t in effect when the actual twisters descended from the skies, so the local sirens never sounded an alarm.

There’s an important lesson in that, said Little: Even when they’re working, tornado sirens aren’t always a failsafe way to know there’s danger on the immediate horizon. That’s why it’s crucial to make sure you always have more than one way to receive up-to-the-moment weather information — even if the weather service hasn’t issued a warning.

“It’s very important to realize that a tornado can drop out of a thunderstorm, even a seemingly innocuous thunderstorm, whether there’s an active weather alert or not,” she said. “The National Weather Service can be monitoring a storm system, but that system is changing by the second, faster than weather radar can show. In the brief moment that a tornado forms, it won’t necessarily show up on the weather radar right at that time.

“We constantly stress to people that they need to have multiple ways to stay informed about severe weather,” she added. “Having a weather radio, a weather app on your smart phone, and access to real-time information from emergency response agencies and media all are important pieces in an overall response plan to severe weather. Even common-sense observation of immediate conditions is important: If there have been waves of storms throughout the day or night, observe the conditions around you before deciding that it’s all clear.

“Sirens are useful, and if you hear a siren during severe weather, you should never ignore it. But they’re only one part of a larger information system. And that system only works when you’re vigilant about using all of its features to stay weather aware — and that includes using your own eyes and ears.”