CHARLOTTE, N.C. -- Thousands of travelers are expected to be on the roads or in the air Sunday as they return home from their holiday trips.

The North Carolina Highway Patrol said troopers will be out in full force.

Drivers had to deal with fog on both Saturday and Sunday.

Troopers urged drivers to take their time when roads are slick, even if it will add extra time to their trips.

Fliers were crowded in Charlotte Douglas International Airport also Sunday morning.

So far, the Federal Aviation Administration’s Web site did not post any significant delays at any major airport. However, winter weather across the nation forced several flights to be canceled or delayed, especially across the Midwest.

Rain and rapidly rising temperatures accompanied by thick fog threatened to cause flooding in the Midwest after days of Arctic cold, heavy snow and ice.

The National Weather Service posted flood watches and warnings Saturday for parts of Illinois, Iowa, Wisconsin, Indiana, Michigan and Missouri. As much as 2 inches of rain fell in two hours during the night in west-central Illinois, the weather service reported Saturday.

And as warm air collided with cold, the weather service posted tornado watches for parts of Texas, Oklahoma, Arkansas, Missouri, Illinois and Kansas.

After subzero temperatures in places earlier in the week, Saturday morning readings were in the 40s as far north as Cheboygan, Mich., at the top of the state's Lower Peninsula, the weather service said. However, up to 7 inches of snow is possible in the state Sunday, the agency said.

In eastern Washington, 4 to 7 inches of new snow fell overnight in the Spokane area, where it began snowing a week before Christmas.

Slippery roads and cold have been blamed for at least 44 deaths this week: 11 in Indiana; eight in Wisconsin; five each in Ohio and Michigan; four each in Kentucky and Missouri; two in Kansas; and one apiece in Illinois, Oklahoma, Iowa, Massachusetts and West Virginia.