The atmospheric river is forecast to bring heavy rain, lightning and thunderstorms to parts of California, the National Weather Service said. In Northern California and the Central Valley — including Sacramento, Modesto, Merced and Fresno — rainfall is expected to begin Wednesday, Nov. 12.

As a storm moves through Northern California, the real work is just beginning for atmospheric river researchers.

A level three event on the atmospheric river scale is a long-duration, high-intensity storm that could produce flooding throughout San Diego County.

For an all-to-brief moment as the sun dipped toward the horizon Wednesday, a crack of sky appeared amid the ever-growing gray clouds and lit up the region with a bedazzling sunset. Yet, even as that was happening, the first handful of drops from an anticipated atmospheric river storm were beginning to come down.

A strong atmospheric river moving inland Wednesday night through Friday will bring widespread rain, mountain snow, and gusty winds across California.

The incoming storm is expected to make landfall in San Diego County late Thursday and clear out by midday Friday.

The storm could trigger dangerous flash floods and mudslides, but it may also extinguish California’s wildfire season.