In the West, snow showers linger across the central Rockies. Elsewhere, mostly dry weather favors fieldwork, including rice planting in California and spring wheat planting in the Northwest.

On the Plains, a chilly rain is falling from eastern Colorado into South Dakota. Cool, dry weather prevails elsewhere, except for some thunderstorms near the Rio Grande. Harvest of the southern Plains’ drought-harmed winter wheat crop is underway.

In the Corn Belt
, very cool weather prevails in Minnesota, Nebraska, and the Dakotas. Warmth lingers from the Mississippi Valley eastward, although rain showers are beginning to close a window of opportunity for fieldwork in the central and eastern Corn Belt.

In the South, scattered showers are developing in the lower Mississippi Valley. The Mississippi River flood crest is passing Helena, Arkansas, where the river stands at its third-highest level on record, behind the February 1937 and April 1927 high-water marks. Warm, dry weather is promoting fieldwork and crop development in the Southeast.

Outlook: A storm system centered over Nebraska will drift eastward, reaching the Mid-Atlantic region duringthe weekend. Widespread showers associated with the storm will affect the eastern half of the U.S., with 1- to 3-inch rainfall totals expected in most areas. Very cool weather in the storm’s wake will eventually cover most areas from the Plains to the East Coast. Meanwhile, a slow-moving storm will arrive in the Northwest, resulting in locally heavy precipitation and sharply cooler conditions. In contrast, mostly dry weather will prevail from southern California to the southern High Plains. The NWS 6- to 10-day outlook for May 17-21 calls for below-normal temperatures nationwide, except for warmer-than-normal weather in the south-central U.S. and the far upper Midwest. Meanwhile, near- to above-normal precipitation across the majority of the U.S. will contrast with drier-than-normal conditions in the Great Lakes region, the central Gulf Coast region, and from southern California into the Rio Grande Valley.