Forecast: Floods in Midwest, dry Calif.

While no major flooding is predicted this spring, federal forecasters said Thursday that minor to moderate floods are still possible, with the worst occurring primarily in the northern Plains and Great Lakes states.

Overall, rivers in half of the continental U.S. are at some risk of flooding.

“This year’s spring flood potential is widespread and includes rivers in highly populated areas, putting millions of Americans at risk,” said Louis Uccellini, director of the National Weather Service. “Although widespread major river flooding is not expected, an abrupt warming or heavy rainfall event could lead to isolated major flooding.”

In the northern Plains, the National Oceanic and Atmospheric Administration warned that there is a risk of moderate flooding along the Red River of the North between eastern North Dakota and northwest Minnesota, and along the Souris River below Minot, N.D. This is because of river ice, snowpack and significant frozen ground.

Around the Great Lakes, moderate flooding is possible in parts of southern Wisconsin, southern Michigan and portions of Illinois, Indiana and Iowa. This is because of the current snowpack, the deep layer of frozen ground and the expected warming temperatures and rainfall.

On the other end of the scale, drought is expected to continue and intensify in California, Nevada, most of interior Oregon and Utah, Arizona, NewMexico, southeast Colorado, western Oklahoma, and most of west Texas. This is because of belowaverage rain or snow this winter and the start of the typical dry season in April.

Drought in California now encompasses 99.8 percent of the state, according to this week’s U.S. Drought Monitor, a federal website that tracks drought.