A day of snowfall may slow the flocks of post-holiday shoppers seeking to return those not-quite-right gifts — and delight those who had dreamed of a white Christmas.

At 6:33 this morning, a winter weather advisory was issued for the Twin Cities, as well as for central and southern Minnesota and western Wisconsin. The advisory means that periods of snow, sleet or freezing rain will cause travel difficulties, according to the National Oceanic and Atmospheric Administration. The advisory remains in effect until 6 p.m.

At 9:30 a.m., the National Weather Service said to expect two-tenths to 1.5 inches more of snow in the Twin Cities by noon, for a total of 3 to 5 inches by the end of today. Heavier amounts — 6 to 8 inches — were expected west of the Twin Cities.

The bulk will have fallen by 6 p.m. Saturday, said National Weather Service meteorologist Tony Zaleski.

While the wintry weather may make travel difficult, it’s sure to please those who have been pining for it. Minnesotans hoping to ski, skate and play in the snow will soon have their chance.

And the flakes will stick around. Colder air from Canada will spread over the Upper Midwest today and last at least until New Year’s Day, Zaleski said.

Snow coated the Government Center Plaza and the quiet surrounding streets Saturday morning in downtown Minneapolis.

“We’re not going to be seeing any 40-degree temperatures for a while,” he said.

Temperatures are expected to fall Sunday and most of next week to highs in the 20s and lows in the teens.

“Should be a white New Year’s, unless something drastic happens,” Zaleski said.

January, too, is likely to be much colder than the winter weather we’ve seen so far, due to “pent-up Arctic air,” Zaleski said.

Another system might bring more snow into the area late Monday night into Tuesday, said Weather Service meteorologist Andy Lahr, but he said it’s too early to predict how much might fall.

Brown Christmases are not all that unusual in the Twin Cities. According to the state Department of Natural Resources, a white Christmas happens in the Twin Cities only about 72 percent of the time.

The Christmas-weekend snowstorm is coming after a Christmas that broke records for warmth in parts of the United States, including New York City, where it was 66 degrees Friday afternoon.

Tampa, Fla., saw a high of 86, among the nation’s warmest.

Saturday is expected to be a busy day of commerce at area malls and shopping centers. Minnesota road crews are primed for snowfall and roads will be continuously plowed, state Department of Transportation spokesman Kevin Gutknecht said Friday.

The snow is falling at an opportune time, considering Sunday is a major travel day of Christmas weekend, he said.

“We should be able to get it pretty well cleaned up by Sunday, so travel should be OK,” he said.