National Weather Service officials said the freezing drizzle and icy conditions in the Chicago area are expected to end as temperatures rise to the low 40s Thursday. Patchy fog was in portions of Chicago and the surrounding areas but also was expected to end before 9 a.

The National Weather Service recorded about an inch of snow at its Seattle office from the overnight precipitation, with another chance for showers before 10 a.m.

Cold air and icy conditions lingered early Thursday in the Greater Pittsburgh area, triggering meteorologists to extend a winter weather advisory three additional hours — through 10 a.m. Temperatures could reach the upper 40s Thursday but hovered early in the morning around freezing through much of the region.