That big boom you heard around lunchtime Tuesday in Davis and Weber counties? It was a planned detonation at the Utah Test and Training Range.

The Air Force blew up a motor from a Trident I ballistic missile at 12:28 p.m., a Hill Air Force Base news release said.

The detonation was part of an ongoing effort to eliminate old rocket propellant and destroy motors, as directed under the START treaty with Russia to reduce the number of ballistic missiles.

Officials said the detonations occur two or three times a week between May and October. But while more than 300 motors have been destroyed since 2012 at the range, most aren’t noticed by nearby Utahns. 

The Air Force said it takes atmospheric readings to check wind speed, direction and other factors to see if the explosion will be too loud for communities along the Wasatch Front. And Tuesday’s detonation was within the “allowable permit range,” the news release said. 

Yet it turned out Tuesday’s weather wasn’t as ideal as initially thought.

“With the variability of upper atmospheric weather conditions this time of year, the model does not always accurately predict sound levels along the Wasatch Front,” Michelle Cottle, chief of the 75th Civil Engineer Group’s Environmental Branch, said in the release. “We had something similar happen in 2014.”