Developing Low Pressure System Will Usher In Fall-Like Temperatures

Around this time of year, the majority of us begin to wonder when we’re about to get a little cooler weather. Sometimes, parts of the United States manage to get a few days of fall-like temperatures in later August, and luckily, a feature currently moving across the Central Plains is going to make that happen.

A potent shortwave has begun to swing southeastward into the Central Plains, which has made conditions favorable for the development of a surface low pressure system across eastern Kansas. This low has certainly tapped into Gulf of Mexico moisture, and given favorable dynamics, a shield of rain and thunderstorms currently aligns from Arkansas up through the Central Plains. Persistent cloudiness managed to keep most of those areas under stable conditions today, but enhanced low-level shear and better instability has allowed some storms to become briefly tornadic across southern Missouri and northwestern Arkansas.

The surface low will continue advancing northeastward overnight tonight and tomorrow. There will be a chance for severe thunderstorms across the middle Mississippi Valley, western Tennessee Valley, and as far northward as eastern Iowa, southern Illinois, and southwestern Indiana tomorrow. Once the severe weather threat passes for that region, the current airmass will be replaced with less humid and slightly cooler air by Tuesday morning. The passage of the cold front will continue to advance less humid and cooler air all the way to the East Coast and Gulf coast by Wednesday and Wednesday evening. Eastern Ohio, western Pennsylvania, and regions just south of there may have to be monitored for severe weather chances on Tuesday, given that dynamics will become more conductive and diurnal heating could increase instability.

Surface map for Thursday morning

With the eastward advancement of the Central Plains shortwave combined with another shortwave digging southeastward from Canada, this will result in a longwave trough temporarily becoming established across the eastern United States mid-to-late this week. Thanks to this pattern, a cooler airmass will be further reinforced across the region, and temperatures will get all the way down into the 50s Wednesday and Thursday nights as far south as the northern Gulf coast states and along and just southeast of the Appalachian mountains. Lows in the 50s don’t seem all that impressive in the fall, but during the summer, it’s not too shabby!

Low temperatures Thursday morning

Low temperature anomalies Thursday morning

Make sure you enjoy the cooler weather while it lasts, because a warming trend is expected after this brief taste of fall!