A heatwave is approaching California this week, threatening to rapidly melt a record snowpack and cause flooding risks in the state’s Central Valley.

The Sierra Nevada’s snowpack is some of the “state’s deepest snowpack ever recorded,” The Los Angeles Times reported. As it melts, the runoff is expected to hit the San Joaquin Valley, which is already flooding.

“This upcoming week is looking prime for accelerating snowmelt Sierra Nevada-wide with continued warming — especially warm, above freezing nights — and plenty of sunshine,” Benjamin Hatchett, a professor at the Desert Research Institute, told The Washington Post. “This will elevate stream flows on both sides of the Sierra Nevada with flooding likely.”

Gov. Gavin Newsom visits Tulare Basin

The Tulare Lake Basin has also brought flooding to the region, and faces even more flooding from the snowmelt.

In response to the threat of long-term flooding, California Gov. Gavin Newsom visited the Tulare Basin on Tuesday to see the impacts of flooding and to outline the state’s emergency response.

“California is here for the Tulare Basin, the Central Valley and all parts of our state still dealing with the impacts of the historic deluge of atmospheric rivers we experienced and preparing for future flooding due to snowmelt,” Newsom stated, according to a press release.

“Our focus is keeping these communities safe, and we’re working with our federal and local counterparts to provide on-the-ground assistance and the support locals need. This weather whiplash is what the climate crisis looks like — and that’s why California is investing billions of dollars to protect our communities from weather extremes like flooding, drought and extreme heat.”

Yosemite National Park closes due to flood risks

On Tuesday, the National Park Service announced that most of the Yosemite Valley will close starting Friday due to the expected flooding.

The eastern section of Yosemite Valley will be closed until at least Wednesday, May 3.

“Additional flooding and closures may occur later in May or June,” a tweet from the Yosemite National Park twitter account reads.