Minnesota braced for a massive winter storm that threatened to shut down interstates, ground flights and bury much of the state in more than a foot of snow.
MPR meteorologist Paul Huttner said the storm arriving Friday evening could be the largest since the famous "Halloween Mega Storm" of 1991, when more than 28 inches of snow fell in the Twin Cities and nearly 37 fell in Duluth.
"I have not seen a set of maps like this in some years," Huttner said.
By late Saturday, snow accumulations could approach 10 to 20 inches for much of east-central Minnesota -- including the Twin Cities -- and western Wisconsin, Huttner said.
MPR meteorologist Craig Edwards said "very dangerous if not impossible traffic conditions" are expected Saturday.
"Winds gusting to over 40 mph will create near blizzard conditions on Saturday along with dangerously cold wind chill readings," Edwards said.
Plows may not be able to keep up, which could lead the Minnesota Department of Transportation to close down interstates.
By midnight on Saturday morning, reports of southwest Minnesota was seeing reports of freezing rain with ice accumulation.
The National Weather Service says a blizzard warning will remain in effect until 9 p.m. Saturday.
Huttner made this forecast Friday:
- The snow will spread into southwestern Minnesota Friday afternoon, and should begin in the Twin Cities area sometime between 9 p.m. and midnight.
- The snow will pick up in intensity after midnight, and snowfall rates could exceed 1 inch per hour from midnight through about 9 or 10 a.m. Saturday.
- Snow will continue through much of Saturday afternoon before winding down late.
- Strong winds between 25 and 40 mph will kick up Saturday into Saturday night, causing severe blowing and drifting of relatively dry powdery snowfall. Blizzard or near blizzard conditions are expected Saturday and Saturday night.
- The storm will likely mix with freezing rain along the Interstate 90 corridor and sleet in south-central Minnesota.
The Minnesota Department of Transportation was getting its plows ready to help keep the roads clear and assist counties.
Department of Public Safety spokesman Doug Neville said counties can request Gov. Tim Pawlenty to deploy the National Guard if things get really bad.
The Minnesota State Patrol planned to have more troopers working on Saturday.
"We're obviously preparing for a very busy night and busy day tomorrow," said State Patrol Lt. Eric Roeske.
Roeske said authorities are asking people to avoid unnecessary travel once the storm starts -- not only will the roads be dangerous, but the snow could make it difficult for emergency vehicles to respond to accidents.
Flying in or out of the Twin Cities airport might also be a challenge.
"This storm looks like it's going to be a probable single-runway operation," said Steve Wareham, director of operations at Minneapolis-St. Paul International Airport. "The amount of flights coming in and out of here will have to be thinned down."
Wareham said snow removal crews are prepared to stay overnight in bunks at the airport, and will work long hours to keep things moving as much as possible.
But he said there will likely be flight cancellations, and that passengers should check with their airline before heading to the airport.
The storm will likely prompt snow emergencies in the metro area, so residents should be prepared for parking restrictions. St. Paul officials anticipate declaring a snow emergency on Saturday night.
Arctic low temperatures will follow the snowstorm. Temperatures will drop into the single digits on Saturday night, and well into the double digits below zero on Sunday night across much of the state. Lows could approach 20 below zero in western Minnesota from the Canadian border to Willmar.
(MPR reporters Tim Nelson and Rupa Shenoy contributed to this report.)