Jeff Cowall, an amateur radio operator and severe weather spotter, drives down Dexter-Townhall Road using his HAM radio just as he did on March 15, the day an EF-3 tornado hit Dexter.

Courtney Sacco I AnnArvor.com

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Jeff Cowall had waited for this moment for 24 years.

He was speeding through the Dexter countryside in the early evening of March 15, cresting a hill on Dexter-Townhall Road when he saw a "majestic, tall, huge, dark, body of cloud."

He pulled his truck over. The otherwise fluffy mass of precipitation was flat at the bottom— an unmistakable sign that a tornado could be forming.

In the minutes that flowed a dark cyclone dropped from the ominous cloud. The display quickly transformed into a natural disaster: an EF-3 strength twister that would travel 7.2 miles and rip through hundreds of homes before finally dissipating.

Cowall and his son Michael Kundak-Cowall, both amateur skywarn weather spotters trained to use emergency HAM radio systems, watched as two football fields away the powerful swirling vortex touched ground water, lifting and manipulating the liquid so it looked like a thin, wildly twisting rope.

"We’re on the radio calling this in and they’re saying get out of there," recalled Jeff Cowall, a University of Michigan data architect who first began weather spotting in 1988. Despite having spotted for decades, never before had he seen a tornado up close. "So when we're not on air we’re screaming like little babies at each other."

A reader-submitted photo of the March 15 funnel cloud that swept through Dexter.

Nicole De'Sales Myint

Cowall says the tornado moved across the ground slowly, but its funnel twisted quickly and its girth seemed brutal. "It was like this big spinning eraser grinding things up from the ground," he recalled.

The two were the first to report the tornado and, potentially, the only people who watched it form. They radioed it in at 5:26 p.m. and seconds later 39 sirens throughout Washtenaw County began sounding, alerting the public of an official county-wide tornado warning.

Twenty-one minutes earlier, the National Weather Service had issued the first tornado warning for the northern part of the county. Radar technology suggested that a hook of precipitation was forming near Dexter, indicating the possibility of funneling wind.

The path of the March 15 twister that swept through Dexter.

National Weather Service map

Although not common, tornado watches and warnings occur nearly every year in Washtenaw County. Between 35 and 40 percent precede legitimate tornado-like activity, said Washtenaw County emergency manager Marc Breckenridge.

In 2011, Washtenaw County issued four tornado watches and warnings but no actual tornadoes touched down. Between 1992 and 2011, the county averaged nearly four watches and warnings a year. During that 19-year period, six tornados touched down, but all were low-strength twisters in rural areas where the effect on people was minimal.

After Cowall's first sighting, he didn't leave and go home. Instead, he and his son chased the tornado as it neared Dexter-Pinckney Road.

"The adrenaline was up, the commitment was there," Cowall explained. "I was a part of it, at this point you’re not a civilian aymore, you’ve trained for this."

Radar image of the March tornado forming.

They drove through a thundering hailstorm and saw flashes of multicolor light above Dexter as the winds toppled power lines, blowing up transformers.

When they reached Busch's Fresh Food Market on Dexter Ann Arbor Road, the father-son team once again came face-to-face with the tornado. They watched it rip into a condominium complex, and fragments of pink insulation hit their truck. Instead of looking empty like before, the funnel cloud seemed huge because it was filled with debris from destroyed houses.

"It hit us emotionally at that point. We were watching lives. We were watching the destruction of a big part of Dexter. It was right there in front of us," Cowall said.

"It had been a phenomena of nature up until that point. It was all science," he continued. "But when things that were obviously part of somebody's house, not just leaves and trees but siding and toys and insulation and shingles are flying through the air sideways,... that's when it hit me.

"It was like watching a slow-motion bomb."

Cowall and his son are two of 650 registered Skywarn spotters in Washtenaw County. About 15 percent of those spotters are licensed to use the HAM radio system. During the tornado, 24 spotters were using the radio as they looked for the funnel cloud and tried to assess damage.

The spotters, Breckenridge said, meant the difference between life and death for some victims.

"Our amateur radio operators did help to save lives by confirming the existence of a tornado and its location, which reinforces the gravity and importance of the warning in the eyes of the public because it's not just a warning, it's actually happening," he said. "They were instrumental in triggering our notifications to all of the public agencies and the media that a tornado was on the ground."

Without spotters, it's likely that government officials wouldn't have known about the touchdown until the first 911 call, and by then some of the safety measures taken —including the second emergency warning— might have been too late.

The tornado damaged 380 homes —either obliterating or seriously damaging 36 houses— uprooted hundreds of trees and caused more than $9.1 million in damage, but miraculously nobody was harmed. When Cowall reflects on the lack of mortal damage, he can't help but breathe of sigh of relief and think he and his fellow HAM operators might have contributed.

"I was absolutely amazed," he said. "I'm very proud of my community."

Today, when Cowall drives through the stretch of Dexter-Pinckney Road where the tornado was the most damaging, the memories of the cyclone ripping though homes and uprooting massive trees remain fresh.

"I get a chill every time," he says. "I remember the trees, I remember what was there and it was just massive."

The location where Cowall first saw the tornado has been corrected. Kellie Woodhouse covers higher education for AnnArbor.com. Reach her at kelliewoodhouse@annarbor.com or 734-623-4602 and follow her on twitter.