6:15 p.m. Tuesday
SIOUX FALLS, S.D. - The National Weather Service Tuesday warned travelers to stay off the road except for emergencies in the coming storm, 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.