Major winter storm threatens blizzard conditions in US Midwest
* Possible tornado blamed for damage in Mobile, Alabama
* Blizzard warnings for US Midwest and central Plains
* Dangerous travel conditions but some drought relief
CHICAGO, Dec 20 (Reuters) - The first major winter storm of the year took aim at the U.S. Midwest on Thursday, triggering high wind and blizzard warnings across a widespread area, and a threat of tornadoes in Gulf Coast states to the south.
"There are blizzard warnings in effect from southeastern Nebraska through much of Iowa into Wisconsin," said Bruce Terry, a senior National Weather Service forecaster at the HydroMeteorological Prediction Center in College Park, Maryland.
"It's going to be very windy with considerable blowing and drifting of snow," he said, calling the pre-Christmas cyclone "a major winter snow storm event for the Midwest and western Great Lakes."
Accumulations of up to a foot (30 cm) of snow were expected in some areas, Terry said, adding there was a potential for severe weather on the so-called "warm side" of the storm in the U.S. southeast.
One suspected twister damaged buildings, snapped trees, downed power lines and flipped vehicles near downtown Mobile, Alabama, early on Thursday, but there were no reports of injuries, authorities said.
"The potential is there certainly for some isolated tornadoes," Terry said, referring to a broad swath of Gulf of Mexico coast and inland territory stretching from southeast Louisiana through the western Florida Panhandle.
While the heavy snow in the Upper Midwest will create potentially dangerous travel conditions, meteorologist Jeff Masters said it was poised to put an end to this year's "record-length snowless streaks in a number of U.S. cities."
Writing on his website weatherunderground.com, Masters said the storm would also provide "welcome moisture for drought-parched areas of the Midwest."
The winter storm, named Draco, began Tuesday in the Rocky Mountains, marking a dramatic change from the mild December so far in most of the nation.
In western Nebraska, the storm prompted the closure of a 146-mile stretch of Interstate 80 late Wednesday as blowing snow reduced visibility and caused treacherous driving conditions.
In Colorado, Interstate 70 was also closed east of Denver to the Kansas state line late Wednesday due to high winds, wind-driven snow and reduced visibility, authorities said.