Americans in at least 30 states are on high alert for snow, ice, flooding and tornadoes as storms sweep across the eastern half of the country.
They could bring damaging winds across the Deep South Thursday into Friday.
Excessive rain could lead to flooding across the Ohio Valley and the interior Northeast and ice jams are possible in the eastern Great Lakes.
Winter weather is expected from Wichita to Detroit. Half a foot of snow and icy conditions are expected through late Thursday.
A tornado watch is in place for Arkansas, Louisiana, Tennessee and Mississippi through 6 p.m. Central Time.
A few tornadoes are likely in addition to wind gusts up to 75 mph.
Very heavy rain and flood threats extend into Kentucky, Illinois, Indiana and Ohio.
Heavy snow is falling Thursday afternoon from Wichita to Chicago, with over 9 inches of snow already reported in the Kansas City area.
Storms will continue across Tennessee and Mississippi Thursday evening and severe weather will stretch from Louisville to Nashville to Birmingham.
Heavy rain and flood threats will move east across the Ohio Valley and into the interior Northeast, from Cincinnati to Buffalo.
Chicago could potentially see between 1 to 4 inches of snow and 4 to 8 inches of snow in Detroit by Thursday night.
A storm moves into the Northeast late Thursday night through early Friday morning, with rain likely.
Heavy downpours are expected overnight, with possible thunder as the storm moves through the I-95 corridor in the early morning.
High wind warnings are in place along the coast from Long Island to Cape Cod, where gusts could exceed 60 miles per hour. The winds could cause damage and power outages by Friday morning.
Parts of the Denver metro area got more than a half a foot of snow overnight Wednesday into Thursday, causing slick roads and closing parts of I-70.