Scattered storms were expected across parts of eastern Nebraska and southwest Iowa on Friday, with the storms becoming stronger and more widespread by afternoon, forecasters said.
The strongest storms may produce locally damaging winds and 1-inch hail, the National Weather Service office in Valley said. Heavy rainfall will be possible through the night, with flash flooding also possible in some locations.
Some storms will be isolated and could produce a few brief downpours Friday, including in the Omaha area.
The weather service said there is a marginal to slight risk for severe weather Friday through Saturday morning in the region, including in the Omaha area.
The main threats from any severe weather will be lightning and areas of heavy rain, forecasters said, with strong wind gusts and small hail also possible.
The weather service issued a flash-flood watch for Friday night into Saturday morning for parts of eastern and southeast Nebraska, including Omaha and Lincoln, and for parts of west-central and southwest Iowa, including Council Bluffs.
Slow-moving thunderstorms could lead to heavy rainfall across the region. Average rainfall amounts will likely be 1 or 2 inches, forecasters said, but pockets of heavier rainfall totaling 3 or more inches could occur, producing some flash flooding.
In the Omaha area Friday, there is a good chance of showers and thunderstorms, mainly after noon. Showers could pop up at any time during the day, forecasters said. Expect a high temperature in the mid- to upper 80s.
Friday night, showers and thunderstorms and a low around 70 are likely, the weather service said. The Omaha area could receive 1 to 2 inches of rainfall Friday night, forecasters said.
Showers and thunderstorms again are likely Saturday, mainly before 2 p.m., in the Omaha area. The high should reach the mid-80s.
Saturday night's forecast calls for a 40 percent chance of showers and thunderstorms and a low around 70, forecasters said.
Sunday in the Omaha area will bring a slight chance of showers and thunderstorms and a high in the upper 80s, the weather service said.