US weather forecast: Powerful storms to bring heavy snow and high winds, causing Thanksgiving travel chaos

Millions of Americans are bracing for two "powerful" storms expected to dump heavy blankets of snow and force road closures and flight delays as families prepare for a busy week of travel during the Thanksgiving holiday.

A snowy weather system could linger through the rest of the week and into the weekend as it moves east, potentially bringing snow to New England and delivering a wintry coast-to-coast blow to the holiday weekend.

The storm brewing in the central US will bring heavy snow from the Rocky Mountains to the upper Midwest, and its southern edge could deliver strong to "potentially damaging" winds from Texas to the Great Lakes, according to the National Weather Service.

Winter storm and wind warnings are in effect across nearly half the US.

The Denver International Airport had already reported seven inches of snow on Tuesday morning, with more snow expected throughout the day. The airport also was forced to cancel more than 460 flights, nearly a third of its daily flight schedule, though crews were working to clear runways to get some flights back on track.

Several highways in the region were also closed due to blizzard warnings.

AAA expects more than 55 million Americans to travel at least 50 miles to celebrate Thanksgiving this year, what the organisation says will be the second-highest travel volume since it began tracking in 2000, trailing just behind a record set in 2005.

Moderate to heavy snow is predicted from Colorado and Wyoming to Minnesota, Wisconsin and Michigan, and high wind warnings are expected from eastern New Mexico to southern Kansas, which could experience winds up to 55 mph.

High wind watches also are in effect for portions of the Midwest and Ohio Valley as the region braces for a forecasted impact on Wednesday.

Snow and high winds could potentially stall the nationally broadcast Macy's Thanksgiving Day Parade in New York.

Parade organisers in New York City are anticipating having to "ground" the parade's massive, iconic balloon floats if the storm does bring its forecasted wind gusts of up to 50 mph.

It would mark the first time that the parade has grounded its balloons due to high winds since 1971. The parade is prohibited from raising its balloons if sustained wind speeds exceed 23 mph and if wind gusts hit 34 mph.

Rules were put in place in 1998 after a Cat in the Hat balloon was caught in a gust of high winds and crashed into a crowd, injuring four people.

A much stronger storm developing in the Pacific Ocean on Tuesday afternoon could deliver hurricane-force winds, dangerous seas and heavy mountain snow to the West Coast.

Mountain regions in northern California and Oregon are likely to face blizzard conditions with one to three feet of snowfall expected for most of California's mountain ranges. Winter storm watches are in effect as far east as northern Arizona.