A winter storm making its way to western Pennsylvania is supposed to hit the region with the first significant snowfall of the season on Tuesday. 

National Weather Service Pittsburgh says a winter weather advisory currently stretches from Arkansas to New York, including the office's entire coverage area. While totals aren't expected to be unusually high, the heaviest snow is expected during the morning commute, making the timing tricky for drivers.  

How much snow will western Pennsylvania get? 

Nearly everyone in the Pittsburgh area is expected to see at least 2 inches of snow. The current estimates forecast 2 to 4 inches for most, including Allegheny, Washington, Westmoreland, Beaver and Butler counties. 

The highest totals are expected between Interstate 70 and Interstate 80, where some spots could even hit 5 inches. Northern counties, as well as parts of Somerset and Cambria, could get 3 to 5 inches. 

Greene and Fayette counties, meanwhile, could see 2 inches or less of snow.  

When will it start snowing? 

The timing raises the stakes because snow rates are expected to peak at around an inch an hour as the Tuesday morning commute gets underway. 

NWS Pittsburgh says snow will arrive after midnight, and the heaviest snow is expected between 4-8 a.m. Widespread snow will end in the morning, with showers tapering off through the afternoon.

Road crews said they're getting ready for the snow. They're asking drivers to leave themselves extra time for their morning commute, slow down and give plows and other vehicles space. 

Pittsburgh-area schools issue delays

Several school districts, including Seneca Valley, Albert Gallatin, Butler Area and Penn Hills, have issued two-hour delays to give crews time to clear the roads before buses head out. A few have also scheduled remote instruction.