The nation’s weather


Weather Underground Forecast for Tuesday, July 19, 2016

A frontal system will drift across the East Coast on Tuesday, while a low pressure area makes its way over the northern Plains.

A cold frontal boundary will stretch southwestward from the coast of New England to the middle Mississippi Valley. This frontal system will transition eastward, generating showers and thunderstorms across the Mid-Atlantic, the Tennessee Valley and the middle Mississippi Valley. Moisture rich air and daytime heating will keep showers and thunderstorms in the picture for much of the Southeast and the Deep South. High pressure should keep the majority of New England clear of wet weather.

Meanwhile, a wave of low pressure will shift eastward across the upper Intermountain West and the northern Plains. This system will collide with warm and humid air, which will generate several clusters of showers and thunderstorms. These storms will form over the northern Plains and parts of the Midwest.

A large ridge of high pressure will build over the southern and central Plains. A warm air mass will linger over the region, as well as the Southwest. The same system will usher monsoonal moisture over the Four Corners. Daytime heating will trigger isolated showers and thunderstorms across parts of the Desert Southwest, the southern Rockies and the eastern Great Basin.

Out west, an area of low pressure will linger over the coast of the Pacific Northwest. This system will keep cool air in place over western Washington, western Oregon and northwest California. Scattered showers and stray thunderstorms will also be possible in the Northwest on Tuesday.

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Temperatures in the Lower 48 states Monday have ranged from a morning low of 37 degrees at Afton Municipal Airport, Wyo. to a high of 102 degrees at Needles, Calif.