Parts of the US are facing a “significant Arctic outbreak” over the Thanksgiving holiday, which includes some of the country’s busiest travel days of the year.

The National Weather Service (NWS) expects “dangerously cold wind chills” across the northern Plains on Thursday.

Meanwhile, parts of the Northeast, including New England, could see heavy snow, and the East Coast is expected to be hit by thunderstorms.

The severe conditions come in a week that is expected to set records for Thanksgiving travel. Thousands of flights were delayed and dozens were canceled on Wednesday, according to tracking website FlightAware.

Snow expected on Thursday could fall in Maine, New York state and the northern Appalachians, BBC weather forecaster Elizabeth Rizzini said.

The thunderstorms could affect Georgia as well as North and South Carolina, she added.

Stormy conditions are then expected to reach the Midwest on Friday, bringing snow-like snow and severe thunderstorms.

Lake effect snow occurs when cold air flows over unfrozen and relatively warm water – in this case in the Great Lakes – causing the air to rise and form clouds that produce snow. According to the NWS, up to 20 cm could fall in some places.

Flight disruptions have been reported as holidaymakers try to make seasonal trips. More than 4,500 delays within, to or from the US were logged by FlightAware on Wednesday. There were 61 cancellations.

According to the US Transportation Security Administration (TSA), passenger traffic during this year’s Thanksgiving holiday has already reached record highs.

The busiest days are expected to be the Tuesday and Wednesday before Thanksgiving and the Sunday after the holiday. The TSA estimates that nearly nine million people will be screened at airports in these three days alone.

And a record number of nearly 80 million Americans were expected to travel at least 50 miles (80 km) by car during the week. Insurance company AAA said the expected increase was because gasoline prices were lower than this time last year.

On the other side of the country, there are thick fog warnings for the Pacific Northwest and California and freezing fog warnings for Oregon and parts of Washington state on Thursday, BBC forecaster Elizabeth Rizzini said.

Earlier this week, a winter storm brought heavy snow and strong winds to higher elevations to the west. Central California was also hit by another “atmospheric river” event on Tuesday, following a similar phenomenon last week. The weather event occurs when water evaporates into the air and is carried away by the wind.

And communities across the Pacific Northwest continue to recover from last week’s bomb cyclone, a violent weather event that occurs when air pressure drops rapidly off the coast. The storm caused mass flooding and power outages.