It seems hard to believe, but the deadliest tornado to ever hit the Tristate was 10 years ago this month.

Flash back to April 9, 1999. The twister struck in the early morning hours, wasting parts of Blue Ash and Montgomery. It was part of an outbreak that had begun the day previous in Nebraska, spawning 54 tornados across the Midwest.

The F-4 storm killed four Cincinnatians, leveled homes across the northern suburbs, and resulted in an estimated $82 million in damage. (An F-4 is the second most severe on the Fujita Scale, the equivalent of the Richter Scale for earthquakes.)

Formed by what television weathercaster Steve Horstmeyer, formerly of Channel 12, recalled as a supercell, “this supercell thunderstorm was west of Louisville and rapidly intensified as it moved into a tongue of warm moist air from the Gulf of Mexico.

“The thunderstorm rotation was supported by an ideal wind environment as it crossed Hamilton County,” he adds of the tragic quirk of fate and conditions spawning the storm. “In the space of 15 minutes, it was transformed from a chaotic-looking complex of thunderstorms and heavy showers into an F-4 killer.”

The twister had first touched down in Rexville, Ind., around 4:15 a.m. By 4:54 a.m., it reached Addyston. And at 5:10 a.m., the rotating mass pitched up to speeds of 207 miles per hour as it crossed Interstate 71. In the next five minutes, four people would die (two in their homes, two in vehicles).

It was one of those moments where you remember exactly where you were standing when you heard the news. I was getting ready for the first session of the early morning at the annual Society of Professional Journalists regional conference, held that year at the Clarion Hotel Riverview in Covington. Suffice to say, the conference room cleared out, as reporters and photographers from across five states — who had gathered to learn, ironically, how to cover a crisis — instead found themselves in the middle of the breaking story. Later, reporters in newsrooms from Ann Arbor to Nashville would say the convention admission was the single best $49 they ever invested, for the chance to be on top of the news for their hometown papers. (Newshounds are never a very sentimental bunch; bad news always sells circulation, not to mention winning journalism prizes.)

The impact of the storm stayed with the Tristate for years. In Hamilton County alone, 91 homes and apartments and 37 businesses were totally destroyed, while more than 700 other structures were damaged.

“We lost the garage and the whole roof,” Blue Ash homeowner Kent Meiser told theLos Angeles Times. “They’re probably going to have to raze it and start over.” Down the street from Meiser, Suzanne Smith told of hearing the freakish wind howl. “I opened the front door and looked over there (at Meiser’s home) and I couldn’t believe it.”

As then Vice President Al Gore toured the devastated Cincy suburbs along with FEMA officials, he told Montgomery resident Laurie Arshonsky, whose house was leveled, that “I’m sorry for what you all have been through. You people have really suffered through a lot.”

The storm did mark a positive first for the Tristate. Meteorologist Pete Delkus got the chance to rev up Channel 9’s new “street mapping” capability. Using Doppler radar and an intensive computer program, Delkus could click on the center of the storm (indicated by a red blotch) and read street names in the twister’s path. “If these streets sound familiar to you at all,” he told viewers, “get in your basement now.”

Yet another first: Geo-physicist Bob Vincent — researching a paper for the Bulletin of the Seismological Society of America — discovered that a University of Cincinnati seismograph, normally associated with tracking earthquakes, had accidentally recorded the thud (like a bowling ball hitting the ground) of the touchdown. The revelation opened a whole new line of thought: “Right now, warning is particularly difficult,” Vincent observed. “We’re still depending on people seeing funnel clouds. It’s very difficult at night.”

Vincent postulated the quirk of fate at UC could open an entirely new window for weather scientists and stormchasers: Following a twister via a series of devices intended to track earthquakes.

For those who lived in the Tristate on that fateful day a decade ago, such a seismic early-warning system could come none too soon.