An "impactful" winter storm is set to arrive in the Chicago area this week, but how many inches of snow can you expect as the region braces for what could be the largest snow event of the winter season so far?

While the forecast continues to develop, some areas could see higher totals than others.

Still, nearly all of the Chicago area is under a winter storm watch beginning Wednesday.

Winter storm watch

Beginning Wednesday morning, the Chicago area will be under a winter storm watch, with heavy accumulating snow expected throughout the day.

Local

Another watch begins Wednesday afternoon in LaPorte County in Indiana. That watch continues through Thursday morning.

How many inches of snow?

The winter storm watch for much of the region warns of snow totals that could exceed 6 inches for parts of the area.

According to the NBC 5 Storm Team , totals are 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.

When it comes to 8 inches of snow or more, the probability appears to drop for many.

According to the NBC 5 Storm team, higher amounts remain 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.

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.

NBC 5 Storm Team Meteorologist Alicia Roman stressed that the watch could be upgraded to a warning ahead of the snow.

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

" 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.

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.

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.