7/18 - 10:40pm - Storm Spotting in Your Own Front Yard
Most storms that erupted today across Kentuckiana and West Tennessee were pretty typical. For the most part they were disorganized and each individual storm didn't last very long but a few did get strong enough for some severe thunderstorm warnings. Unfortunately these storms did pack some nasty cloud-to-ground lightning in the city of Louisville and that sparked some structure fires. Later in the day around 7:30pm just after most storms had exited the city there was a spectacular collision of two outflow boundaries near the I-64/I-264 interchange in St. Matthews. These outflow boundaries, one from Clark County, IN and the other from Shelby County, KY in this case, are just rushes of cold air that come out of other storms and create something akin to a miniature cold front. When these two boundaries collided they created an incredible amount of convergence which birthed a complex of storms right over the city. We're talking about the radar being clear at 7:30pm and there being storms on radar in East Louisville at 7:36pm. This collision also created some weak rotation briefly and dropped quite a base cloud as the complex moved south. The cloud created quite a show in my front yard and I was quite surprised to see such a well-defined (and briefly rotating!) updraft base as I was driving down my driveway this afternoon!
Now that all that excitement is over, we're going to be in for more storms tomorrow and Friday. A cold front will be approaching Kentucky and Tennessee from the Upper Midwest that should create a focus for storm development or at least create storms that will send outflow boundaries toward the south to create more storms. These will largely be powered by the heat and humidity that we'll be seeing over the next couple of days but with the front coming into play there's a possibility that storms may form earlier in the day or even possibly in the morning tomorrow and Friday.
Strong winds will be possible with any storm that forms along with more of the same lightning that we've seen around the region today. Storms could reach severe limits thanks to all the moisture in the environment and the front moving closer so the Storm Prediction Center has issued a Slight Risk for severe weather tomorrow for all of Kentucky and some of Northwest Tennessee. Storms will again be possible on Friday as the front moves through, but we'll dry out behind the front for the weekend.