The last 4 days have featured heat and humidity that have baked the central Midwest. Actual highs have been running about 10 degrees above normal in the low 90s. However, with dew points in the low to mid 70s, heat index values have climbed into the range of 100-105 degrees.
The core of the heat has been centered around an upper level high over the Ohio Valley. Under the high the air is compressed and that sinking motion allows it to heat up. The warmth extends into the highest levels of the atmosphere creating a cap that prohibits thunderstorms.
On the periphery of the heat dome where cooler air exists, an area known as the ring of fire is established. Here, where the heat and humidity clash the environment is ripe for thunderstorms. You can clearly see its existence in Monday's late afternoon satellite image.
So far the ring of fire zone has remained north of my area but now is in the process of shifting southeast as the high pressure aloft weakens. The result will be much cooler temperatures the next 7 days. You can see that trend reflected in the day 2-7 temperature departures-(June 20-25th).
The trade off for enjoying cooler temperatures will be the closer proximity of the ring of fire. An unsettled wet pattern looks to lock in place the rest of this week that should bring multiple rounds of showers and thunderstorms. With PWAT's (precipitable water vapor) running in the 1.5 to 2" range the potential is high for a broad area of significant rains over the central Midwest. Here's the PWAT's Monday night.
Compare that to Thursday night. If anything the deep moisture has expanded through the lower Mississippi Valley.
All the major models are indicating the potential of widespread heavy rains. The question is just how heavy and where? The EURO shows this as of Monday evening. It's very robust and if it comes close to verifying flash flooding as well as river flooding would most certainly occur in some part of the region. This would be a high impact scenario and needs to be watched closely in coming days.
The GFS is not as extreme but certainly quite wet showing 16 day rainfall totals that look like this.
The Weather Prediction Center is also projecting big rain totals the next 7 days.
It's certainly a forecast that needs monitoring the next 72 hours. As the saying goes, if it ain't one thing it's another as we transition from heat to wet conditions the next few days. Roll weather...TS