I like to describe Monday evening's Midtown storm this way: An ordinary summer thunderstorm gone bad! Because that's what it was - just an isolated pop-up that grew to great heights in the atmosphere and had enough energy at its mature stage to produce a strong downdraft that surged outward after hitting the ground.
The downburst wind happened on a small enough scale - just a few miles - to qualify as a microburst*, knocking trees down and causing minor structural damage. NWS meteorologists in Peachtree City, from photos alone, speculated that winds could have reached 75 miles per hour. From the damage I saw, I might go a little higher than that, possibly over 80. When that wind continues for a minute or two and not just in a brief gust, it creates damage.
Storms like this are not that unusual here during the summer. A notably similar one happened July 24, 2004 on a Saturday evening in almost the same area, actually just a bit north closer to Hilton Avenue and the Columbus Country Club. Similar damage occurred but on an even smaller scale.
So what makes a storm like this different from the other 99.9% of summer storms we get? Extra energy is the usual culprit, and a lot of that extra "kick" comes from the heat of the day. Temperatures peaked at 97º late afternoon, and intense heating near the ground like that increases the air column's instability to a high level. Other factors aloft combine with the low-level instability to lead to a very high CAPE environment (CAPE is a derived quantity of available energy), which leads to the stronger than normal downdrafts. In fact, on the really hot summer days, those close to 100ºF, you can bet that almost any thunderstorm that pops up is going to have some high winds with it - they just don't usually hit 80 MPH.
And how localized was this? Where I live in north Columbus, it didn't rain a drop, the sun was shining the whole time, and there was no wind! Storms like this are impossible to forecast with any pinpoint accuracy; although Doppler radar can detect the winds, by that time the storm would likely have collapsed and the downburst ended.
Next few days, with even more heat and humidity present we're likely to be in a more stable environment, but if we do manage to pop a few storms on a particularly hot day, be sure to watch from the safety of your home (or anywhere indoors)! Although these are totally different animals from tornadoes, you see the damage a microburst can do.
Kurt Schmitz, Senior Meteorologist
*Specifically, this qualified as a wet microburst. In the more arid West, they are often dry microbursts with little or no rain.