A winter storm watch issued for the Chicago area ahead of an upcoming snow system has now been upgraded to a winter weather advisory.

The alert from the National Weather Service, which takes effect Wednesday morning, warns of the potential for anywhere from 3 to 6 inches of snow across the region.

The advisory is set to begin at 9 a.m. CT Wednesday and continue through 3 a.m. Thursday.

A winter storm warning was also issued for Kenosha County in Wisconsin.

Local

The warning is in effect from noon Wednesday to 3 a.m. Thursday and warns of snow accumulations between 6 and 9 inches.

A winter storm watch also remains in effect for LaPorte County in Indiana.

How much snow?

According to the NBC 5 Storm Team , snow totals in the Chicago area were largely expected to range between 4 and 7 inches, as of projections Tuesday morning.

The National Weather Service noted the "highest snow totals are likely north of a Pontiac, IL to Valparaiso, IN line."

While much of the Chicago area was under a "high probability" of 4 or more inches of snow, only some locations were under a high probability of 6 or more inches, the NWS reported. Areas like Elgin, Waukegan, northern parts of Chicago could see some of the higher amounts.

According to the NBC 5 Storm team, higher totals are possible along Lake Michigan. There's also a possibility that a rain-snow line could set up for some southern suburbs. If that happens, that could lead to lower snow totals in those locations.

"A mix of sleet and freezing rain may reduce snowfall farther south," the NWS also reported.

In Newton and Jasper counties, the winter weather advisory warns of 2 to 4 inches of snow, along with the potential for some freezing rain, which could lead to ice accumulations of up to a tenth of an inch.

Timing

Snow will begin to move in around 6 a.m. or 7 a.m. Wednesday, Roman said, hitting Chicago's western counties first. The snow will continue to push eastward, with a winter storm watch taking effect for all of Northeastern Illinois at 9 a.m.

Heavy, widespread snow was expected to continue throughout the day Wednesday, with the highest totals expected during the afternoon and evening.

Snow was expected to continue falling across the area though late Wednesday night, Roman said.

Wednesday's system is the first of two rounds of snow expected this week, Roman said.

While a break in the snow was expected for most of the day Thursday, more winter weather developing Friday night could dump several more inches of snow across the area, leading to higher accumulations overall.

"Another winter storm possible late Friday," the NWS said.

Watch vs. Advisory

According to the NWS , a winter weather advisory means a hazardous weather event is "occurring, imminent or likely."

The alert means there's more certainty surrounding a forecast compared to a winter storm watch, but it indicates "less serious conditions" compared to a warning.

Hazardous travel possible

" Prepare for hazardous travel conditions , especially during the afternoon and evening commute when we expect the highest snowfall rates (potentially exceeding 1 inch per hour at times)," the NWS said.

Sharply reduced visibility, snow-covered roads and treacherous travel were all possible, the NWS warned.

Live updates and radar

The NBC 5 Storm Team will continue to update this as the forecast develops. Sign up for push alerts in the NBC Chicago app to be notified as weather alerts are issued in your area.

NOTE: Special weather coverage of the winter storm begins at 4 a.m. Wednesday on NBC 5, the NBC 5 Chicago News Streaming channel and right here on NBCChicago.com and the NBC Chicago app.