A winter storm is intensifying across central and northern Illinois.

The heaviest snowfall is affecting an area from Galesburg in the west and arching up to Chicago. That snow is accumulating at more than an inch per hour in places.

The National Weather Service expects 4-8 inches to fall in that area by the end of Saturday afternoon, making travel conditions dangerous.

Smaller amounts of between 3-6 inches are expected to the north and south of that zone.

South of a line from Pontiac to Kankakee the storm is bringing a quarter inch of freezing rain mixed with snow.

In a sign of just how tough this winter has been, weather service data show that the month of January in the Chicago area was the third snowiest since 1884.