Extreme heat and the risk of severe thunderstorms threaten several areas of the country

The National Weather Service (NWS), through the Weather Prediction Center, warned that dangerous heat will continue to affect large areas of the central and southern parts of the country over the next few days, while several regions will face a high risk of severe storms and flash flooding.

According to the short-range forecast issued this Sunday, a persistent high-pressure system in the upper atmosphere will keep high temperatures between 90 and 100 F across much of the central and southern parts of the country. In isolated areas of the southwestern desert, temperatures could reach between 115 and 120 F.

The agency noted that the combination of high temperatures and high humidity will result in heat indices exceeding 105–115 F, creating an increased heat risk across the Great Plains, the Mississippi Valley, the Midwest, parts of the Rocky Mountains and the southern United States through Monday. In addition, it warned that several consecutive days of intense heat, combined with nights of high temperatures, could cause health problems for those who are not sufficiently hydrated or do not have access to cooling systems.

Meanwhile, a low-pressure system will move from southern Canada toward the Great Lakes region and the northeastern United States, interacting with atmospheric fronts that will favor the development of organized thunderstorms.

The nearly stationary front, which extends from the Northern Plains to the Upper Midwest, will move slowly toward the middle Mississippi Valley, the Ohio Valley and the Northeast on Sunday. According to the NWS, the combination of strong mid-level winds, atmospheric instability and abundant moisture will favor severe thunderstorms and heavy rain with a risk of flash flooding in parts of the Upper Midwest, the Great Lakes region and the Ohio Valley.

These storms could also produce large hail and destructive winds from the middle Missouri River Valley to the Upper Mississippi Valley and the Great Lakes. By Monday, the strengthening of a low-pressure system and the eastward movement of the front will intensify the threat of severe storms and flash flooding over the Great Lakes, the Ohio Valley and parts of the Northeast.

In the southwestern part of the country, monsoon-related moisture will continue to create unstable conditions. Daytime warming, instability and abundant moisture will favor isolated and scattered thunderstorms through Monday.