Strong storms break excessive heat across the heartland this week

By Jared Shelton News-Press NOW meteorologist

From searing heat and humidity to damaging thunderstorms, this week has offered a sampling of summer’s dark side across the Midwest.

Monday was marked by extreme heat indices across the mid-Missouri River Valley, which ran well into the triple digits for over ten consecutive hours. Despite a high temperature of 97 degrees here in St. Joseph, excessive humidity resulted in a peak heat index of 119 degrees. Moisture content was so high on Monday afternoon, water vapor left a thin haze across the landscape, despite blue skies and blazing sunshine

While we were baking in stifling heat, states to our north and east were being pummeled by high intensity storms Monday afternoon and evening. A cluster of severe thunderstorms produced widespread wind damage across parts of Iowa, and continued eastward along the periphery of the sizzling air mass to the south. In a pattern coined “The Ring Of Fire”, these storms sustained themselves on extreme instability provided by the oppressive air mass, growing into a destructive squall line that produced 70 to 90 mph wind gusts, and even a handful of tornadoes across large swaths of Illinois and Indiana.

Monday evening’s storms were classified by the Storm Prediction Center as a derecho, with a swath of damaging winds stretching well over 240 miles.

The same front which triggered the destructive storms along the I-80 corridor Monday, sank south to the I-70 corridor early Tuesday. St. Joseph was spared, but parts of Northeast Kansas including Lawrence, Valley Falls and Topeka sustained straight-line wind damage. Wind gusts of 70 to 75 mph were reported on several occasions in western parts of the Kansas City metro as well.

Tuesday morning’s storms were ultimately a necessary evil, as the front which delivered them also served to break the excessive heat and humidity, ushering in a cooler and drier Canadian air mass. During the cold season, Canadian air is known to be forebodingly frigid, but in mid-July it can be a godsent across America’s heartland.

While overnight low temperatures struggled to fall below 80 degrees early this week, Thursday and Friday morning were crisp and even a bit cool as temperatures dipped into the upper 50s and low 60s. To top it all off, afternoon highs have also been below average since Thursday, even with lots of sunshine. Thanks Canada!