After a pre-dawn round of showers and thunderstorms with some fog this morning, we're clearing out. The satellite view to the right shows the clearing skies and that will help us build instability this afternoon for additional storm development. Outflow boundaries, or surges of cool air that come out of thunderstorms, from this morning's activity are present mainly just south of Louisville at the moment. There may, in fact, be a convergence of these outflow boundaries just north of the Western Kentucky and Blue Grass Parkways based on how the morning's storms set up on radar a few hours ago. This convergence would be the sweet spot for storm formation this afternoon.
The HRRR model picks up on the potential for maximum storm formation just south of Louisville well. Even the RPM model has it. The agreement here for where the storms will be this afternoon looks fairly solid, and the outflow boundaries plus this morning's clearing on satellite seem to back that up. These storms would begin to "pop" on radar after 2pm and most of this would fade away around sunset. The low pressure and cold front behind these storms will move through around midnight, shutting down any lingering storm activity.
Even though the sun is coming out we'll have to see exactly how much instability we are able to build in for storm development. The HRRR model has us near 1000 J/kg by 6pm (see right), which would be pretty decent if that's realized. Notice how the max instability is in Kentucky, another check mark supporting the theory that most of today's storms will happen along/south of I-64. Wind shear will be more speed-based than directional today, which would mean more of a clustered/multicell thunderstorm setup like the one you see on the HRRR loop above. These storm cells will likely interact with each other though and interact with the aforementioned outflow boundaries. This can generate more supercell-like structures as those interactions increase low-level directional shear. We'll watch for that... it's the reason why we can't take out the tornado chance completely today. Wind and hail will be the main threats though.
The SPC maintains only a Marginal Risk of severe weather today in most of our counties, excluding Southern Kentucky where lingering clouds, later exit of morning rain activity, and lack of a trigger will keep storm potential down in that region. The Marginal Risk includes a 2% tornado risk and 5% wind and hail risks. The discussion states that they may upgrade parts of the area to a Slight Risk if the instability truly builds in today like the HRRR model output above. We'll have to monitor this threat hour-by-hour today, so be sure to stay close to social media and the WAVE 3 News Weather App.
Check out the video below for a more detailed discussion of today's severe weather potential and an update on the Derby week forecast!