A winter weather advisory in effect Tuesday morning predicts as much as 4 inches of snow falling north of the Long Island Expressway and up to half that much to the south, according to the National Weather Service.

The fast-moving system should bring snowfall beginning about 6 a.m., the weather service forecast. The winter weather advisory is in effect until 6 p.m.

advertisement | advertise on newsday

The system will move west to east and clear out of the area between 3 and 4 p.m., said Tim Morrin, weather service meteorologist in Upton.

There could be 2 to 4 inches of snow along the North Shore and 1 to 2 inches nearer to the South Shore, forecasters said Monday.

With snow expected to become occasionally "moderate to locally heavy" by midmorning, visibility could be reduced at times to half a mile or less, the advisory said.

Expect "slippery roadways and hazardous travel conditions, especially on untreated roadways," so caution was advised, the advisory said. Snow is forecast to turn to snow showers and taper off at the start of the afternoon commute, the weather service said.

advertisement | advertise on newsday

Snow totals from Saturday's storm ranged from 2 to 5 inches in Suffolk. In Nassau, there was less on the South Shore, but 4 to 6 inches fell on the North Shore, meteorologist Lauren Nash said. By late Saturday that snow began turning to rain.