The storm that produced the EF4 tornado that leveled unincorporated Fairdale in DeKalb County headed straight for Marengo on the evening of April 9, 2015.

Trained spotters saw a large, wedge-shaped tornado heading northeast. McHenry County municipalities blew their outdoor warning sirens. The National Weather Service told Marengo residents in a blunt warning that, "You are in a life-threatening situation."

And then, yet again, luck or otherwise – the tornado dissipated and spared the county. The powerful storm system that killed two and injured seven in Fairdale – and packed winds of between 166 and 200 mph – ran out of energy and petered out.

The sole casualty discovered in McHenry County in the wake of the first EF4 or stronger tornado in the Chicago area since the 1990 Plainfield tornado was a dead chicken.

A small tornado that barely rated as such touched down for about a minute southeast of Harvard, but only snapped or uprooted a few trees.

It's been half a century since someone in McHenry County died in a tornado – when the Palm Sunday tornado leveled Crystal Lake and tore a path of destruction to Island Lake, killing six and injuring almost 100.

The storm that barely affected Harvard happened two days before the 50th anniversary of the Palm Sunday tornado, but luck sooner or later runs out.

Rick Slusin, a 40-year storm spotter who watched the Fairdale tornado fizzle out at the county border, said people in McHenry County might be lulled into a false sense of security, which will make things much worse when the area finally does get a large tornado.

“It’s the old, ‘It’s not gonna happen here,’ and when it does, they’re not prepared,” said Slusin, a retired Crystal Lake fire chief.

With severe weather season again almost upon us, Slusin and McHenry County Emergency Management Agency Director David Christensen said that simple and common-sense measures will protect lives when the day comes.

An important thing that people overlook is the simple act of taking the time at the start of the day to check the forecast, Christensen said. He recommended the daily and regularly updated hazardous weather outlook put out by the weather service’s Chicago office.

Weather service forecasters had been advising people five days before the Fairdale tornado that an unusual bout of early April severe weather was a possibility.

“Know that something is coming,” Christensen said. “All of our weather hazards are predictable. We’re not dealing with earthquakes, like out on the West Coast … where it comes without warning. All of ours are predictable. The information is there as to whether it’s going to be a bad day or a good day.”

Christensen and Slusin urge that every home have a NOAA all-hazards radio that sounds alarms when it receives watches, warnings or government emergency broadcasts. These radios, which are cheap and have a battery backup, can be programmed to sound warnings only for your particular county.

And in an age when everyone has a smartphone with GPS, people can carry their weather alerts with them, Slusin said. Besides the built-in emergency alert feature that sounds warnings, people can sign up for text alerts – the Northwest Herald sends out severe weather alerts through such a feature – and download weather warning apps.

“If there’s something going on within range of the cell tower, and the weather service pushes something out, it’s going to your cellphone,” Christensen said.

Christensen and other experts for years have warned people that relying on getting adequate warning from outdoor sirens is a dangerous myth. They are not meant to be heard indoors, but rather to warn people outside to seek shelter, hence the name. Also, they have a range of only about half a mile in optimal conditions, they cannot be heard through modern construction, and McHenry County does not have a cohesive grid of sirens that provides 100 percent coverage.

People also should prepare for what to do after a tornado hits. Besides having a "ready bag" with three days of supplies for everyone in the family, people should have their emergency numbers written down.

“Have a plan,” Slusin said.

On the Web

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