The nation’s weather


Weather Underground Forecast for Wednesday, July 20, 2016

An area of low pressure will keep stormy weather in the forecast for the northern tier of the country on Wednesday, while monsoonal thunderstorms fire up across the Southwest.

A large ridge of high pressure will build over the southern Plains. This high pressure system will usher warm and moist air over the Plains and the Midwest. A wave of low pressure will transition slowly across the northern Plains. This system will collide with the aforementioned air mass, producing rain and thunderstorms in the northern Plains and the Midwest. Prolonged heavy rain will bring threats of flash flooding to southern Wisconsin, eastern Iowa, Illinois and northwest Indiana. Most of the central and southern Plains will experience hot and dry weather.

Meanwhile, the remnants of a frontal boundary will interact with moisture-rich air, keeping showers and thunderstorms in the forecast for Mid-Atlantic, the Southeast and the Deep South. High pressure will bring dry and pleasant to New England.

Out west, monsoonal moisture will surge across the Four Corners. Daytime heating will aid in producing showers and thunderstorms over the region.

Further to the west, a trough of low pressure will stall out along the coast of the Pacific Northwest. This system will usher cool air over the northwestern corner of the country, and will also trigger isolated showers and thunderstorms across Washington and the northern Rockies.

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Temperatures in the Lower 48 states Tuesday have ranged from a morning low of 35 degrees at Stanley, Idaho to a high of 122 degrees at Lakeland Region, Fla.