Weather across America 7/20/25

(NATIONAL) Widespread thunderstorms across the Northern Plains, Midwest, Ohio Valley, and Southeast, severe storms likely across the Northeast, scattered thunderstorms in the Southwest with the potential for flash flooding, and dangerously hot conditions in the Central Plains, Lower and Middle Mississippi Valley, and Southeast.

The weather pattern across the Continental U.S. is driven by a ridge of high pressure over the Southeast and an active jet stream across the northern U.S. The position of high pressure over the Gulf of Mexico and a longwave trough over the western U.S. will sustain a steadfast low-level jet over the Southern Plains that directs copious amounts of moisture northward into the Northern Plains, Midwest, and Ohio Valley. This moisture will intersect a frontal boundary over the Midwest and Ohio Valley that allows for widespread thunderstorms Sunday.

The Weather Prediction Center (WPC) has issued a Moderate Risk (threat level 3/4) for portions of northeast Missouri and central Illinois where there is a greater opportunity for locally significant flash flooding Sunday. Meanwhile, WPC has an expansive Slight Risk area (threat level 2/4) that stretches from northern Missouri and eastern Iowa to as far east as the central and southern Appalachians, as well as another Slight Risk in the eastern Dakotas. As a cold front pushes southward through the Mid-Atlantic on Monday, the focus for Excessive Rainfall will become more pronounced over the Ohio and Tennessee Valleys where a Slight Risk has been issued.

The aforementioned cold front will also direct the plume of anomalous moisture as far east as the Southeast on Monday where widespread showers and storms pose a Marginal Risk (threat level 1/4) for flash flooding. Lastly, as an upper-level trough over the Pacific Northwest approaches, storms will pose a flash flood risk in the Northern Plains on Monday, followed by the Upper Midwest on Tuesday where there is a Slight Risk for flash flooding in northern Minnesota, northern Wisconsin, and the western-most communities of the Michigan Upper Peninsula.

This stormy pattern also contains several areas for organized severe weather Sunday. The Storm Prediction Center (SPC) has Slight Risks (threat level 2/5) in place for portions of the Dakotas, the Ohio Valley, and the Northeast. The Northeast Slight Risk area contains urbanized metro areas such as NYC, Hartford, Providence, and Boston. The severe storms could also lead to localized areas of flash flooding in the urbanized Northeast corridor as well.

Severe storms Sunday will be capable of producing damaging winds, large hail, and tornadoes. SPC has a pair of Marginal Risks (threat level 1/5) in the Northern Plains and the Southeast for isolated instances of severe storms on Monday. Elsewhere, the Southwest will contend with daily rounds of thunderstorms containing torrential downpours. Localized flash flooding is possible in parts of Arizona, New Mexico, West Texas, and Colorado each afternoon and evening, especially along rugged terrain and burn scars.

The aforementioned ridge of high pressure over the Southeast will anchor in place the kind of searing heat and oppressive humidity that occurs during the "Dog Days of Summer" from the Southern Plains and Lower-to-Middle Mississippi Valley to the Southeast. HeatRisk shows a large footprint of Major Impacts (level of heat that affects anyone without adequate cooling and/or hydration) in many of these regions through Monday. Heat indices throughout the southeastern U.S. will range between 105-110F with some instances where heat indices hover around 115F.

Extreme Heat Warnings and Watches are in place for parts of the Central Plains and Middle Mississippi Valley that linger into the first half of the work-week. There are also Heat Advisories for portions of the Southern Plains, Lower Mississippi Valley, and along the Southeast coast. The Southeast U.S. ridge will expand father north into the Mississippi Valley by Tuesday, causing sizzling temperatures to become stretch farther north into the Midwest by mid-week.