Blizzard forms in U.S. Midwest, Plains

CHICAGO (Reuters) - A blizzard is set to blanket the central United States on Wednesday, likely shutting roads, reducing visibility to near zero and causing power outages in its wake, forecasters said.

For many, it will also be a white Christmas on Friday as the system dumps more than a foot of snow in some areas.

Traders were concerned the wintry blast could slow livestock movement to market, and this was helping to support Chicago Mercantile Exchange cattle and hog futures.

And the corn harvest in the Midwest, already one of the slowest in decades, will be backed up even more although the bulk of the crop has been cut by farmers.

"This is a very large and powerful winter storm," Lynn Maximuk, National Weather Service central region director, said in a written release. "There will be numerous areas that will get more than a foot of snow by Christmas Day. People should not take chances with this storm."

A mixture of snow, ice and rain is expected in the U.S. Midwest. Strong winds could reach 20 to 30 miles per hour, with gusts near 40 mph. The western Midwest could see snow accumulation ranging between 8 and 15 inches, while the eastern portion is expected to be mostly rainy and windy.

Temperatures are expected to range in 20s to 30s degrees Fahrenheit (minus 6 to 4 Celsius) for the rest of the week.

"There is potential for a lot of problems, but at this point it is not clear what the magnitude of those problems will be or who is going to (get chit) the worst," said Harry Hillaker, state climatologist for the Iowa Department of Agriculture in Des Moines, Iowa.

The snowy and windy weather will stress cattle in the feedlots, and transportation is going to be shut down, Mike Palmerino of DTN Meteorlogix said. Areas of Iowa and Nebraska could see 6 to 15 inches of snow.

"The weather is a supportive factor short-term because this (storm) is going to be wide enough that it is going to disrupt some of the trucking out here. It is going to delay transportation of hogs," said Don Roose, president of U.S. Commodities Inc.

In the northern Plains, the Dakotas are expected to experience a major blizzard, with up to 20 inches of snow. The additional snowfall will cause producers to leave the remaining corn crop in the fields until the spring, Palmerino added

The U.S. Agriculture Department said on Tuesday North Dakota had only completed 68 percent of its corn harvest. Nationwide, 5 percent, or 4 million acres, of corn still remain in the fields.

In the northern plains, temperatures are expected to be in the teens and low 20s degrees Fahrenheit (minus 10 to minus 2 degree Celsius) for the next seven days, with lows ranging in the single digits above and below zero.

In Canada, the southern portion of Saskatchewan will be affected by the same snow system bringing a blizzard to the Dakotas. Environment Canada is calling for between 4 to 8 inches of snow in southern Saskatchewan on Wednesday, which will delay already slow grain deliveries by farmers.

(Additional reporting by Jerry Biezsk and Rod Nickel; Editing by John Picinich)