Weather forecasters expect the area to receive between 10 and 18 inches of snow, along with sleet and rain, today through early Thursday.
National Weather Service meteorologist Kevin Lipton said between 10 and 14 inches are expected in lower regions of Fulton, Montgomery and southern Hamilton counties, while higher elevations could see between 14 and 18 inches.
The storm is expected to last until daybreak Thursday, but low temperatures will remain throughout the day.
"Really, for the bulk of the day [today], it is going to be snow," Lipton said this morning from Albany.
Sleet is expected in some sections of the Mohawk Valley, he said.
Lipton said temperatures will be in the low to mid-30s today before dropping into the 20s this afternoon and the single digits Thursday morning.
Gloversville Department of Public Works Director Kevin Jones said his crews are prepared to plow tonight during the on-street parking ban.
Many local school districts closed early today because of the storm.
The weather service warned a blizzard with winds up to 50 mph could paralyze the area from western New York to the Adirondacks.
Outside the region, forecasters warned the storm would drop heavy, wet snow in the Chicago area and northern Indiana, along the Great Lakes in Ohio and Pennsylvania.
The Associated Press contributed to this report.
Before dawn today, the forecast was coming true in Chicago, where early commuters carefully made their way to work.
"The roads were just horrible, it was pretty hazardous conditions out there," said Stephen Rodriguez, National Weather Service meteorologist in Romeoville, Ill. He said an initial forecast for 8 inches of snow in the city was perhaps overblown but that Chicagoans should prepare for up to 6 inches.
"The impact for the morning commute will probably be pretty significant in some places," Rodriguez said.
The agency said 5.2 inches of snow was reported near Midway Airport in the southwest of the city.
Forecasters warn that as much as 9 inches of snow could fall in parts of southeastern Michigan, with 4 to 8 inches in Detroit. Before the sun rose Wednesday, snow and sleet were making roads slippery across a large southern swath of the state. Hundreds of schools closed their doors for the day.
Chicago has already been buried by 75.5 inches of snow this winter - fourth most on record dating back to 1884-1885, according to the weather service. The snowfall expected into Wednesday could push the seasonal total into third place, ahead of the 77.0 inch total from 1969-1970. Southeastern Michigan could come close to breaking a 133-year-old snowfall record. The storm will likely move the Detroit area close to the seasonal snow total of 93.6 inches set in 1880-1881, according to the weather service.
Rainy Indianapolis experienced a swift temperature drop of about 30 degrees, from 68 late Tuesday afternoon to 37 early today. In Missouri, temperatures that peaked in the high 70s and in St. Louis as high as 83 degrees on Tuesday were replaced with high winds and temperatures in the low 30s this morning.