A fluctuation in the jet stream unusual for mid-winter has created a wild range of weather.
Tornado watches have been issued for parts of Oklahoma, Texas, Kansas, Missouri and Arkansas, and April-like thunderstorms are expected in Chicago.
Other states from Texas to Florida, Kansas and parts of the Midwest and Northeast are experiencing record heat. Record warmth is expected today ahead of the storms, with record highs possible in Chicago, St. Louis and Tampa that could reach 60 degrees or more, 73 degrees and 83 degrees, respectively.
Additionally, a powerful cold front will slam into the mid-Mississippi Valley today, producing tornadoes and gusty winds near 80 mph. The biggest chance for tornadoes is from Little Rock, Ark., to Memphis, Tenn., but the entire area from Dallas to Houston, New Orleans, Chicago, Indianapolis and St. Louis could see tornadoes and damaging winds.
The storms will also create flooding from the Midwest to the Northeast, with some areas getting as much as three inches of rain.
The unusual weather will linger through this evening. Areas most at risk for tornadoes include southern Illinois, southwest Indiana, western Kentucky, northern Louisiana, Mississippi, southeast Oklahoma, western Tennessee and northeast Texas, according to NOAA's Storm Prediction Center.
Behind the flooding rain and record warmth, cold air is expected to move in this week.
Already in the West, 18 states from Michigan to New Mexico and up to Washington have winter weather warnings and advisories. Blizzard-like conditions might develop on Thursday for places including Des Moines, Iowa; Rochester, Minn.; Eau Clair, Wis., and Green Bay, Wis. These areas will see as much as eight inches of snow, with gusty winds near 35 to 45 mph. The combination could create white-out conditions.
The weather will shift dramatically in Chicago by Thursday, dropping from the record high of more than 60 degrees today to 17. Sub-zero wind chill temperatures are likely for most of the Midwest.
Along the East Coast, warm air is moving in. Highs will approach 50 degrees today in New York City, with a high of 60 possible Wednesday. Washington, D.C., will approach the mid- to upper-60s Wednesday.
The cold air will finally arrive in the Northeast and the East Coast by Friday, blasting the areas with frigid temperatures for the weekend, sweeping in from D.C. to Boston.