A series of storms are forecast to pound much of the United States this week, delivering an extended bout of rain, ice and snow just as millions of drivers are expected to hit the roads for Thanksgiving.

The winter weather had already begun Sunday in the North and the Northeast, with heavy snow and slick conditions reported from Ohio and Pennsylvania to Massachusetts and Vermont.

In Columbus, Ohio, a single-car crash accident turned into a multiple vehicle wreck after a car slid across an icy interstate bridge and crashed into a responding police cruiser, NBC affiliate WCMH reported.

The cruiser then crashed into a medic, according to the station. No one was injured in the incident.

In Pennsylvania, the National Weather Service issued a severe weather alert for the Philadelphia region as a quick-moving storm unloaded a burst of heavy snow, NBC Philadelphia reported.

The agency pleaded with drivers on the New Jersey Turnpike and surrounding interstates to slow down, according to the station.

The American Automobile Association expected the country’s highways to remain clogged throughout the week: more than 49 million people plan on driving to their holiday destination, the association said — the most since 2005 and a nearly 3 percent increase over last year.

The worst gridlock is anticipated Wednesday in large metropolitan regions such as Atlanta, Los Angeles, New York and Houston, the association said.

The traffic slowdowns will come as another band of storms blanket a broad swath of the country, the weather service said.

Thanksgiving holiday travel weather: part II. Wed/Thu: heavy mountain snow and lower elev rains - West U.S., windy w/ snow north and rain east on Wed -East U.S. Fri/Sat: snow, and potential for blowing snow - Upper Midwest/Grt Lakes, rain - S/Cntrl Plains to Northeast U.S. pic.twitter.com/BvvpgcuASE — National Weather Service (@NWS) November 24, 2019

Snow and sleet were forecast from the southwest to the Great Lakes beginning Monday, while showers are expected to drench the country’s middle section, the agency said.

The wet, cold weather will persist through the end of the week, the agency said, with rain and snow forecast from California and Oregon to the Upper Midwest and the East Coast.