The vernal equinox, otherwise known as spring, arrives Monday and it could become one to remember.

Meteorologists are predicting flood threats for a large portion of the U.S. this spring.

About 44% of the U.S. is at risk for flooding, Ed Clark, director of National Oceanic and Atmospheric Administration's National Water Center, told reporters.

There is a risk of flooding in most of the eastern half of the U.S. including most of the Mississippi River Basin, NOAA said. Currently, nearly 1.5 million people on Mississippi River are under major flood threat this spring, John Gottschalck, chief of operational prediction branch at NOAA’s Climate Prediction Center, a division of National Weather Service, told ABC News.

In the West, the historic snowpack along the Sierra Nevada mountain range, combined with elevated soil moisture, is heightening the potential for spring floods across much of California's coast.

Two weather patterns came together to create such extreme winter precipitation over California, including the jet stream extending further south and an increase in available moisture in the Pacific due to a reoccurring phenomena known as Madden Julian Oscillation, an eastward moving disturbance of clouds, rainfall, winds and pressure, Gottschalck said.

Story Date: March 20, 2023