A cool-off for the Heartland; more rain from the southern Plains to the Midwest Corn Belt

An early-season heat wave will gradually end across the southern and eastern U.S., although Eastern heat will linger through the weekend.  Meanwhile, markedly cooler air will overspread much of the country, including the northern and central Plains and the Midwest. 

Weekend frost and freezes could affect the northwestern half of the Plains, extending as far south as eastern Colorado and northwestern Kansas.  Frost may also extend into parts of the upper Midwest. 

Prior to the arrival of the cool, dry air, widespread showers and thunderstorms will span the northern U.S. 

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