In the West, cool air is expanding eastward, although warmth lingers across the central and southern Rockies. Across the northern half of the region, scattered showers are boosting topsoil moisture but causing minor fieldwork delays.

On the Plains, a cold front crossing Montana marks the leading edge of cooler air. Isolated showers precede and accompany the cooler conditions. In contrast, hot, mostly dry weather prevails on the central and southern High Plains, maintaining stress on rangeland, pastures, and winter wheat. Today’s high temperatures will exceed 100°F across parts of the southern High Plains.

In the Corn Belt, thundershowers are halting fieldwork in the upper Midwest. However, much of the remainder of the Corn Belt continues to experience a window of opportunity for corn and early-season soybean planting. Through May 12, U.S. corn planting—28% complete—was proceeding at the slowest pace since 1993.

In the South, showers and thunderstorms are slowing or halting fieldwork in the northern Mississippi Delta and the Tennessee Valley. Elsewhere, warm, dry weather favors winter wheat maturation and summer crop planting, emergence, and development.

Outlook: A pair of storms—one crossing the Southeast and the other developing over the Northwest—will maintain unsettled conditions for much of the U.S. The Southeastern storm will reach the southern Mid-Atlantic Coast during the weekend, resulting in 1- to 3-inch rainfall totals along its path. The Northwestern system will drift into the upper Midwest by early next week, producing as much as 2 to 4 inches of rain in the north-central U.S. In contrast, no rain will fall from California to the southern High Plains. Hot weather currently affecting the High Plains will arrive in the Midwest during the weekend and the Northeast by early next week. Meanwhile, cooler air will spread as far east as the Plains and upper Midwest. The NWS 6- to 10-day outlook for May 22-26 calls for near- to above-normal temperatures nationwide, except for cooler-than-normal conditions in northern California, the Northwest, and the Gulf Coast region. Meanwhile, above-normal precipitation in the East and Pacific Northwest will contrast with drier-than-normal weather in central and southern portions of the Rockies and Plains