We're likely to begin February with the biggest snowfall in Chicago's recorded history:
A Blizzard Watch is in effect Tuesday afternoon through Wednesday as a strengthening low pressure system moves up the Ohio Valley. Late Tuesday afternoon steady snow and stronger winds will push into the region, starting south of I-80 and spreading north during the evening.
Snowfall rates Tuesday night could approach 50 to 80 mm per hour and when combined with sustained winds at 50-60 km/h, visibilities are will drop significantly with near whiteout conditions possible.
Snow totals of 30 to 50 cm are possible between Monday night and Wednesday afternoon with locally higher amounts. Drifting and blowing snow will make travel dangerous and possibly life threatening Tuesday night.
Lakeshore flooding is also a possibility. Waves of 3 to 5 m will crash along the Illinois side of the Lake Michigan shoreline.