Dramatic temperature plunge, snow clamp an icy grip on northern US

Temperatures crashed by dozens of degrees in portions of the northern and central Plains as snow and wind whipped across the region at midweek — and forecasters say that dangerous conditions could develop as temperatures take a free fall across the Midwest into Friday night.Marginally cold conditions have swooped in following storms in the Midwest so far this winter, but the current temperature plunge sweeping across the region has really sunk its teeth in.Actual temperatures took a free fall to as low as 30 to 10 degrees below zero Fahrenheit in the Dakotas, northwestern Iowa, much of Minnesota and northwestern Wisconsin on Thursday morning. Actual temperatures centered on the midwestern United States at 9 a.m. CST Thursday, Feb. 13, 2020. (AccuWeather) AccuWeather RealFeel® Temperatures plunged to 40 to 30 degrees below zero across Iowa and Minnesota Thursday morning.By Thursday morning, temperatures in Minneapolis dropped 42 degrees, falling to minus 10 degrees. The AccuWeather RealFeel® Temperature was even more bitter, going from 18 F to minus 36 F in a 24-hour span.At Des Moines, Iowa, actual temperatures plummeted from 35 above zero at 3 p.m. CST Wednesday to 10 below zero at 8 a.m. Thursday. The AccuWeather RealFeel® Temperature at 8 a.m. Thursday was 40 below zero.Many schools across Iowa, including Des Moines Public Schools, and Minnesota had two-hour delays due to frigid conditions on Thursday, and some even closed, such as Cedar Rapids Schools. The severe cold also prompted businesses and organizations to close on Thursday in portions of Nebraska and Iowa, according to the Associated Press.Minneapolis and St. Paul public schools did not delay Thursday due to their threshold for delaying schools being 35 below zero F, which was not met.In Chicago, the morning rush hour began with temperatures near 32 F, but temperatures had plummeted into the mid-teens by the end of the morning rush Thursday.CLICK HERE FOR THE FREE ACCUWEATHER APPThe combination of the storm over the Midwest and Arctic air lunging southeastward helped to produce blizzard conditions over the northern Plains on Wednesday, closing portions of highways, including Interstate 29, across the region."Do not travel" advisories were issued by the North Dakota Department of Transportation (NDDOT) across eastern portions of the state as the Grand Forks National Weather Service (NWS) office said that travel conditions were "near impossible" for a time.Places in North Dakota also experienced some of the most extreme temperature swings on Wednesday. In Grand Forks, AccuWeather RealFeel® Temperatures dropped 81 degrees Fahrenheit within eight hours, going from 20 F at midnight to minus 61 F by 8 a.m. Wednesday.The frigid cold didn't move for a while either. The AccuWeather RealFeel® Temperature in Grand Forks stayed below minus 60 F for over six hours on Wednesday.Some unique weather phenomena occurred amid the brutal cold, one of which is known as a sun halo. Residents in Grand Forks captured this rare occurrence on Thursday morning. The halos are created through the reflection and dispersion of light from ice particles found in cirrus or cirrostratus clouds cause by freezing weather. Sea smoke, another spectacle triggered by the painful cold, created an eerie start to the coldest morning of the season in Minnesota.Although blizzard conditions and the most extreme cold are not anticipated for much of the Midwest, the Arctic blast advancing over the region is expected to produce the lowest temperatures of the season so far for many locations. As snow plowed eastward, 2-6 inches accumulated from Chicago to Indianapolis and Columbus, Ohio. Snowy conditions and plunging temperatures have prompted 300 cancellations and nearly 1,000 delays of arriving and departing flights at Chicago's O'Hare International Airport as of early afternoon on Thursday, according to FlightAware.As the leading edge of Arctic air advances across the lower Great Lakes region and part of the Ohio Valley, temperatures will fall several degrees and even plummet 20 degrees or more during the day Thursday.> So far only a little bit of snow, but as the temperature continues to fall ?????? anything that is wet on the roads and sidewalks will freeze. So be careful as you are out and about through out the weekend. pic.twitter.com/kAXqqSCcT9> > — MSP Metro Detroit (@mspmetrodet) February 13, 2020By Friday morning, temperatures are forecast to range from 20 below zero in northern Michigan to near zero in central Missouri and the lower teens in southern Ohio.Temperatures during much of the snow hovered within a few degrees of the freezing mark (32 degrees Fahrenheit). At this temperature, some of the snow was naturally melting and turning to slush on roads, while in other cases, chemicals being used helped to expedite the melting."Road crews and property owners are encouraged to quickly remove snow and slush as temperatures plunging a couple dozen degrees in a few hours will cause wet and slushy areas to rapidly freeze solid," AccuWeather Senior Storm Warning Meteorologist Brian Wimer stated. This can be a real problem, including around the major cities of Chicago, Milwaukee, St. Louis, Detroit, Indianapolis and Cleveland, as well as hundreds of other communities where snow recently fell or will continue to fall into Thursday night.Similar rapid freeze-up conditions can be expected from the eastern Great Lakes and part of the Allegheny Plateau region to northern New England."Complicating matters will be a few bands of heavy lake-effect snow that linger in the wake of the recent snowstorm from Thursday night to Friday morning," Wimer said. "So, some motorists immediately southeast of the Great Lakes may not only have to deal with icy road conditions, but also rapid changes in visibility with local whiteouts from lake effect."Failure to promptly remove the slush may result in ice ruts to be "glued down" until temperatures rebound later Saturday and Sunday.Even in portions of Kentucky, Tennessee and West Virginia, the combination of sub-freezing temperatures and the amount of water lingering around from recent torrential rain can lead to an icy mess for a time into this weekend.Keep checking back on AccuWeather.com and stay tuned to the AccuWeather Network on DirecTV, Frontier and Verizon Fios.