The summer has been an active one when it comes to severe weather, especially over the central United States. AccuWeather meteorologists continue to warn of an ongoing severe thunderstorm threat for the region this week and say that complexes of thunderstorms are likely along with the risk of high winds and flooding rainfall from portions of the central Plains to the Mississippi Valley.
Over the past 10 years, there have been an average of 19,700 incidents of severe weather per year across the U.S., according to the National Oceanic and Atmospheric Administration (NOAA). But over a recent stretch from June 1 through July 4, there have been more than 6,600 incidents of severe weather ranging from tornadoes to high winds and hail. That’s about 34% of the annual average in 34 days. The majority of these incidents have occurred west of the Appalachians and east of the Rockies.
The driving force behind the severe weather in recent weeks has been a dome of high pressure over Texas and an active jet stream pattern across the northern half of the nation, AccuWeather Meteorologist Alex DaSilva said.
“Even though the high pressure area and associated heat dome will tend to migrate farther west this week, the jet stream will remain very active across the north,” said DaSilva. Thunderstorms spawned by ripples in the jet stream will be given a boost by the heat to the south and southwest.
Thunderstorms will tend to erupt on the rim of the heat from the Rockies to the Appalachians. However, on one or more occasions, thunderstorms will group into complexes that can travel for dozens of miles.
When a thunderstorm complex produces consistent wind damage along a swath at least 400 miles long and 60 miles wide, it is called a derecho, according to NOAA.
The setup is not quite as favorable for a derecho this week as opposed to prior weeks this summer. Regardless, there will be a moderate risk of severe weather on multiple occasions this week.
Severe weather will likely develop across two areas of the middle of the country into Monday night. One zone will include the High Plains from Nebraska to the Texas Panhandle. Within this part of the U.S., AccuWeather meteorologists have outlined an area where a moderate risk exists. These storms will be capable of producing the full spectrum of severe weather which ranges from isolated tornadoes and high wind gusts to large hail and flash flooding.
There also is a moderate risk of severe weather from central and northern Wisconsin to southeastern Minnesota, northwestern Iowa and southeastern South Dakota. Storms in this area will erupt along a ripple in the jet stream and a cool front.
On Tuesday, AccuWeather meteorologists will be monitoring the potential for a complex of severe thunderstorms to evolve in parts of central and eastern Nebraska. The risk of severe weather will extend outward as well from much of South Dakota and southern Minnesota to northeastern Kansas and northern Missouri into Tuesday night. Surrounding this area will be pockets of severe weather.
All modes of severe weather will be possible once again on Tuesday. However, wind gusts ranging from 60-80 mph are likely, and some of the strongest storms could bring an AccuWeather Local StormMax™ gust of 90 mph. Winds of this force can cause significant damage to trees and power lines as well as to property.
Should the thunderstorm complex develop, it may continue to travel toward the east and southeast Tuesday night and may then turn southward on Wednesday over portions of Missouri and western Illinois.
There is a chance that a second complex could form in this area on Wednesday and move toward the south and southeast, potentially reaching eastern Arkansas, western Tennessee and northern Mississippi.
There is not only a moderate risk of thunderstorms with damaging wind gusts from the central Plains to the middle part of the Mississippi Valley but also the likelihood of heavy rainfall that could lead to flash flooding.
There is the potential for several inches to half a foot of rain to fall in the region. Some locations could receive a couple of inches of rain over the course of an hour.
St. Louis is one of the major metro areas that may be in the path of dangerous and disruptive storms on Wednesday.
It was about a year ago, on July 26, 2022, when St. Louis was hit by repeating thunderstorms that dumped 8-12 inches of rain in eight hours and triggered severe flooding around the city and surrounding areas.
At the very least, travelers should expect significant delays and possible road closures, while people spending time outdoors may need to seek shelter as storms approach the St. Louis area and other locations.
Even though Chicago and Indianapolis may dodge the worst of the severe weather, there is still the likelihood of locally drenching showers and perhaps a gusty thunderstorm on Wednesday. Severe storms could take a turn toward Kansas City, Missouri, or Memphis, Tennessee, at midweek.
Little may change in the overall severe weather potential for the latter part of the week and the weekend in the Central states. However, as drier air presses farther to the south, the zone of severe thunderstorms and the potential for a derecho may shift farther south as well. Areas from the Plains to the lower Mississippi Valley may end up with multiple rounds of severe weather.
Locally severe thunderstorms will affect parts of the Southeast into Monday night.
After a brief break from severe weather and flooding rain on Tuesday and Wednesday in the Northeast, rounds of thunderstorms are likely to return later this week and continue into this weekend, AccuWeather Long-Range Meteorologist Brandon Buckingham said.
“Severe thunderstorms are possible in the pattern for the Northeast from Thursday to Sunday as ripples in the jet stream encounter warm and humid air,” Buckingham said. “In addition to the threat of severe weather, more locally heavy rain is possible as well.”
Produced in association with AccuWeather
Edited by Alberto Arellano and Kyana Jeanin Rubinfeld
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