The nation’s weather

Weather Underground Forecast for Saturday, July 23, 2016

Extreme weather will impact the Plains and the Midwest on Saturday, while above normal temperatures persist from the southern Plains to the Southwest.

A wave of low pressure will move eastward across south central Canada. A cold frontal boundary associated with this system will extend southwestward. As this frontal boundary collides with anomalously hot air, it will generate strong to severe thunderstorms from the northern Plains to the upper Midwest. Severe thunderstorms will be possible in eastern North Dakota, eastern South Dakota, northeast Nebraska, northern Iowa, Minnesota and western Wisconsin. These thunderstorms will be capable of producing large hail, dangerous straight line winds and isolated tornadoes. In addition, heavy rain will bring threats of flash flooding to eastern North Dakota, northeast South Dakota, Minnesota, eastern Iowa, Wisconsin, Illinois and western Indiana.

Meanwhile, moisture-rich air and daytime heating will initiate showers and thunderstorms across the Deep South and the Southeast. A slow moving frontal boundary will also generate storms across the northern Mid-Atlantic and New England. Afternoon temperatures will rise into the mid 90s over the Mid-Atlantic on Saturday.

Out west, a dominant high pressure system will keep scorching temperatures in the forecast for the southern Plains and the Southwest. Excessive heat warnings and heat advisories are in effect for parts of southern California and Arizona. Additionally, monsoonal thunderstorms will fire up across the Four Corners and the central high Plains.

Temperatures in the Lower 48 states Friday have ranged from a morning low of 32 degrees at Truckee-Tahoe, Calif. to a high of 111 degrees at Needles, Calif.