Weather across America

(NATIONAL) A Slight Risk of excessive rainfall over parts of the Central Plains and Middle Mississippi Valley, a Slight Risk of severe thunderstorms over parts of the Upper Great Lakes to the Central High Plains, and a front extending from the Upper Mississippi Valley moving eastward to the Lower Great Lakes and Southern Plains.

Showers and severe thunderstorms will develop along and ahead of the boundary over parts of the Upper Great Lakes and Upper/Middle Mississippi Valley and Central Plains/Central High Plains. Therefore, the SPC has issued a Slight Risk (level 2/5) of severe over parts of the Upper Great Lakes and Upper/Middle Mississippi Valley and Central Plains/Central High Plains through Monday morning. The hazards associated with these thunderstorms are frequent lightning, severe thunderstorm wind gusts, hail, and a minimal threat of tornadoes.

In addition, showers and thunderstorms with heavy rain will develop over parts of the Central Plains/Middle Mississippi Valley. Therefore, the WPC has issued a Slight Risk (level 2/4) of excessive rainfall over parts of the Central Plains/Middle Mississippi Valley through Monday morning. The associated heavy rain will create mainly localized areas of flash flooding, with urban areas, roads, small streams, and low-lying areas the most vulnerable. 

A quasi-stationary front over the Mid-Atlantic will aid in producing showers and strong to severe thunderstorms on Sunday. Therefore, the SPC has issued a Marginal Risk (level 1/5) of severe thunderstorms over parts of the Mid-Atlantic through Monday morning. The hazards associated with these thunderstorms are frequent lightning, severe thunderstorm wind gusts, and a minimal threat of tornadoes and hail. 

South of the front, upper-level impulses, daytime heating, and moisture will create showers and thunderstorms on Sunday over the Ohio/Tennessee Valleys, Southern Plains, Lower Mississippi Valley, and the Southeast. Similarly, upper-level impulses, daytime heating, and moisture will create showers and thunderstorms over parts of the Southern High Plains. Also, on Sunday, scattered rain showers will develop over parts of Northern New England as low pressure moves eastward into Southeastern Canada.  

On Monday, as the front moves into the Great Lakes and Ohio Valley, showers and strong to severe thunderstorms will develop over parts of the Upper Great Lakes/Upper Mississippi Valley into the Ohio Valley and parts of the Mid-Atlantic.  

Moreover, upper-level impulses, daytime heating, and moisture will produce showers and thunderstorms over parts of the southern Mid-Atlantic/Southeast, the Gulf Coast States into the Middle/Lower Mississippi Valley and the Central/Southern Plains. Upper-level ridging will build into parts of the Pacific Northwest, prompting Heat Advisories over parts of Washington State, Oregon, and Idaho from Monday morning into Tuesday.