National Weather Service: Blizzard will be a prolonged winter weather event
10:14 a.m. Wednesday
SIOUX FALLS, S.D. - Holiday travel will be severely impacted by the life-threatening storm rapidly approaching the Midwest, warned the National Weather Service Wednesday.
The storm will be a prolonged winter weather event, with the storm leaving the Rockies in two or three systems.
Snowfall accumulations are expected to be major late this afternoon through Christmas Day. Developing strong winds Thursday through Christmas Day will make travel extremely difficult.
"Do not travel if you can avoid it," the National Weather Service stated.
Icy conditions from freezing drizzle and cold moist air will cost extra hazards today for those trying to get travel completed before the winter storm arrives. Those in urban areas or major highways where roads have been treated should be aware that they will run into very icy conditions. People on foot should be aware that they risk a dangerous fall if they step onto an icy driveway or sidewalk.
A winter weather advisory will remain in effect until 3 p.m. today, followed immediately by a winter storm warning to remain in effect from 3 p.m. today until 6 a.m. Saturday.
6:15 p.m. Tuesday
SIOUX FALLS, S.D. - The National Weather Service warned travelers to stay off the road except for emergencies Tuesday, issuing a winter storm warning for 3 p.m. Wednesday to 6 p.m. Friday for southwest Minnesota and northwest Iowa.
The storm is said to be a "once in a quarter century storm," and will move onto the plains Wednesday, intensifying into Thursday. Wind gusts of up to 30 to 40 miles per hour and 10 to 20 inches of snow are expected, along with freezing rain.
A large area of snow, sometimes heavy, will lift north into the tri-state area Wednesday afternoon into Wednesday evening. By Thursday morning the wind will become more northerly, with gusts of 30 to 40 miles per hour and a widespread 10 to 20 inches of snow. Significant blowing and drifting will occur on Thursday and Friday.
Parts of northwest Iowa, mainly south of an Elk Point to Spencer line, will see freezing rain develop during this time, then continue into Thursday morning. Around a third of an inch of ice will be possible during this time, which will create very slick conditions. The snow will become heavy Thursday afternoon and night with around a foot of snow possible on top of the ice.
"This is a life-threatening system," the National Weather Service warned, "and any travel from Wednesday night into Friday will be treacherous."
Snow will spread north across the area Wednesday, changing to or becoming mixed with freezing rain later Wednesday through Thursday south of Elk Point to Jackson. Snow should becoming widespread again Thursday night into early Friday.
Snowfall totals of 10 to 20 inches will be possible with this storm, with the heaviest amounts likely toward the South Dakota border. Ice accumulations may reach a quarter to a third of an inch for much of northwest Iowa, southeast of a line from Elk Point to Jackson Wednesday afternoon through Thursday.
Wind and Visibility
East winds of 10 to 20 miles per hour can be expected Wednesday, increasing gradually Wednesday night and Thursday. Winds will become north 25 to 35 miles per hour Thursday night and Friday. The winds combined with the snowfall may reduce visibility to near zero at times.
A winter storm warning for heavy snow means severe winter weather conditions are expected or occurring. Significant amounts of snow are forecast that make travel dangerous. Only travel in an emergency.
If you must travel, the National Weather Service said, keep an extra flashlight, food and water in the vehicle in case of an emergency.
Travel is predicted to be very hazardous or impossible.
12:35 p.m. Tuesday
SIOUX FALLS, S.D. - Holiday travel will be severely impacted by the potentially life-threatening winter storm rapidly approaching southwest Minnesota and northwest Iowa, the National Weather Service warned Tuesday.
A winter storm watch remains in effect from Wednesday afternoon to Friday afternoon for Lyon, Osceola, Dickinson and O'Brien counties in Iowa and Nobles, Jackson, Rock, Murray, Cottonwood and Pipestone counties in Minnesota.
Leading into the system today and tonight, areas of freezing drizzle are possible.
A winter storm watch means there is a potential for significant snow, sleet or ice accumulations that may impact travel. Anyone intending to travel should continue to monitor the latest forecasts.
Strong low pressure will develop across the southern plains Wednesday and intensify as it moves north into Iowa on Friday.
The first round of snowfall will begin Wednesday, building northward out of Nebraska and Iowa and becoming widespread in the afternoon and night. Warmer temperatures aloft will create potential for freezing rain and sleet through much of northwest Iowa.
The greatest threat for persistent snowfall appears to have shifted more to the northwest through the early parts of the storm, favoring heavier snowfall through northern portions of southwest Minnesota.
As the low pressure area strengthens Thursday, winds will increase, with widespread snow and blowing snow Thursday night into Friday. With gusty winds likely to reach 25 to 35 miles per hour later Thursday through Friday, areas of blizzard or near blizzard conditions appear probable.
Heavy snow in excess of 10 inches is likely with this storm, with some amounts in excess of 15 inches, especially through southeast South Dakota. Ice accumulations from a quarter to a third of an inch will be possible for areas roughly southeast of a Sioux City, Iowa, to Spencer, Iowa, line.
Snow will spread north across the area on Wednesday. The snow will change to or become mixed with sleet or freezing rain later Wednesday through Thursday. Snow should become widespread again Thursday night into early Friday.
Snowfall totals of 10 to 15 inches will be possible with this storm, with the heaviest accumulation toward the South Dakota border. Ice accumulation may reach a quarter to a third of an inch for much of northwest Iowa southeast of a line from Spencer to Sioux City Wednesday afternoon through Thursday.
Wind and Visibility
East winds of 10 to 20 miles per hour can be expected Wednesday, increasing gradually Wednesday night and Thursday. Winds will become north 25 to 35 miles per hour for Thursday night and Friday. The winds combined with the snowfall may reduce visibilities to near zero at times.