The Baltimore region is under a winter storm warning from late Monday night through Tuesday night, and as much as 9 inches of snow could accumulate.
Precipitation is forecast to arrive by late Monday afternoon or early evening, starting as a mix of rain and snow and then turning to all snow, according to the National Weather Service. The winter storm running begins at 10 p.m. and is set to last through 6 a.m. Wednesday.
Periods of heavy snow are expected overnight and through the day Tuesday.
About 4-8 inches of snow is forecast across the region, with the heaviest totals likely along the Mason-Dixon Line in northern Carroll, Baltimore and Harford counties, according to the weather service. Anne Arundel County could see lesser totals, about 1-3 inches.
If the precipitation is delayed in changing from rain to snow, totals would be diminished, a possibility meteorologists acknowledged.
Temperatures are forecast to reach the lower to mid-40s Monday afternoon and then drop down to freezing by around midnight. While snow could fall even if the air temperature close to the ground is above freezing, accumulation could be hampered. Highs Tuesday are forecast in the mid-30s.
In a worst-case scenario, the storm is capable of producing 5-7 inches across Anne Arundel County and 10 inches to a foot around Baltimore and to the north.
The State Highway Administration began pre-treating highways and other main arteries on Sunday, spraying down a brine solution that can delay snow accumulation on the pavement. State highway officials and the Maryland Emergency Management Agency urged residents to avoid driving in the snow, if possible, to keep roads clear for plows and emergency vehicles.
"With another storm expected to begin during or just after the evening commute, we implore motorists to be part of the solution, not part of the problem," SHA Administrator Gregory C. Johnson said in a statement.
The snow is forecast to come from a low-pressure system that is expected to form over the mid-Atlantic by Monday night, after a complex system over the Great Lakes transfers its energy to the southeast.
A separate snowy system was bringing blizzard conditions and as much as 18 inches of snow to southeastern Massachusetts and as much as 10 inches of snow to the rest of Massachusetts, Rhode Island and most of Connecticut. It is the second winter storm in four days to hit the Northeast.
After the snow passes by the Baltimore area by Wednesday morning, temperatures are forecast to plummet. Temperatures are forecast to stay below freezing from Thursday through the weekend, at least, with highs in the 20s and lows in the teens and even single digits.