Storm Spotters Witness Monster Tornado in Iowa's Heartland

Aug. 12, 2009— -- Moments before a massive tornado would wreak havoc on their community, destroying hundreds of homes and killing nine residents, almost no one in the small town of Parkersburg, Iowa, had any idea what was about to hit them.

But with conditions that seemed just right for a tornado, storm-spotters like Ben McMillan were out surveying the Iowa countryside. During tornado season, storm spotters are often deployed to monitor bad weather as it rolls in.

McMillan is a member of Central Iowa Skywarn, a volunteer organization that partners with the National Weather Service (NWS) to track storm conditions and issue tornado warnings around the state.

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On the afternoon of May 25, 2008 -- the Sunday of Memorial Day weekend -- McMillan was on a storm-spotting mission near Parkersburg when a dangerous mix of meteorological forces began to coalesce just outside the town of 1,900 residents.

"[The National Weather Service] issued a tornado watch called a PDS tornado watch, or a 'particularly dangerous situation," McMillan said. "When you see the words PDS or hear the words 'particularly dangerous situation,' watch out, because that's something that's pretty rare."

Initially, the storm spotters honed in on area to the west of the town. "One of our initial targets was the city of Ackley, which is just to the west … and we had a large storm cloud go up right over the city of Ackley. And, at that point, we felt that that was going to be a potential candidate to become a very violent storm," he told ABC News' Sam Champion.

"I just seem to have a knack for being places when stuff happens," McMillan said. "I've seen a lot of major tornados over the past 10 years."

Suddenly, the forces of nature began to align and a dark, foreboding cloud-wall formed on the horizon less than ten miles outside of town. The storm came together at an alarmingly fast rate.

Click here to watch McMillan's video of the tornado brewing.

"The earth was releasing so much built-up pressure in this case, that it just -- formed more rapidly than a storm I'd ever seen before. Most tornadoes, it's a process -- this was on steroids. It was so violent, so quickly it went from nothing to the most violent tornado on earth. This was like an atom bomb going off," he said.