Thursday night snow showers left a dusting of snow across the region, with northern Carroll County receiving as much as 3 inches, according to the National Weather Service.
Hunt Valley and Glyndon in Northern Baltimore County received about an inch, while areas further south and east received less after a disturbance in the atmosphere overnight.
The weather service reported 0.1 inches at Baltimore-Washington International Thurgood Marshall Airport, the first measurable snow at Baltimore's point of record this winter.
A weekend storm will be larger and more intense across the Southeast, but meteorologists said it's difficult to predict if it will come far enough north to affect the Baltimore region. Heavy snow is expected in Southern Maryland and on the Lower Eastern Shore.
A dusting of snow, or no accumulation at all, is likely for most of the Baltimore region. But if snow stretches northward enough and starts falling before daybreak Saturday, there is the potential for as much as 3 inches along Interstate 95 and as much as 5 inches in Anne Arundel County, according to the weather service.
St. Mary's, Dorchester, Wicomico, Somerset and Worcester counties are under a winter storm starting at 1 a.m. Saturday. As much as 7 inches of snow are expected in those areas.
Queen Anne's, Talbot, and Caroline counties on the Eastern Shore are under a winter storm watch, with the potential for 5 inches of snow. Charles and Calvert counties in Southern Maryland are under a winter weather advisory, with 1 to 3 inches of snow possible.
But north of there, a narrow gradient is expected to divide areas that get accumulating snow, only flurries or no precipitation at all. That makes the forecast difficult to pin down for the Baltimore region, meteorologists said.
"Will need to monitor this system closely as a slower progression would result in potential snowfall impacts for the Mid-Atlantic region," they wrote.
Chances for snow Saturday are best in southern portions of the Baltimore region.
On Friday morning, the heaviest snow was in northern and western suburbs -- schools in the Hereford Zone of Baltimore County, as well as those schools in Allegany, Garrett, Frederick and Carroll counties announced they would open two hours late.
Dunbar High in Baltimore City is closed for mechanical issues, but all other schools in the city are open.
Find live school closings and delays at bsun.md/snowday.
“If this were a little deeper into winter or we had been in a very active pattern, this would be, ‘OK, on to the next one,’” said Dave Dombek, an AccuWeather.com senior meteorologist. “It really hasn’t done much of anything — so it’s significant in that people will see some snow in the air and on the ground.”
State Highway Administration crews pre-treated roadways with a salt brine solution, helping to prevent roadways from freezing once precipitation starts falling, officials said.
Nevertheless, SHA Administrator Gregory C. Johnson urged drivers to make “smart and informed travel choices Friday morning by delaying commuting to enable crews to effectively treat roads.”
Baltimore County schools officials canceled after-school activities Thursday, and in Carroll County, Manchester Valley High School officials notified parents that a ski club trip to Ski Liberty would be canceled because of the snow. The Maryland Zoo in Baltimore said it will open at 11 a.m. Friday.
Temperatures may not break out of the 20s until Monday, and aren't expected to rise above freezing until Tuesday, with lows in the teens.
Baltimore County officials said the county's freezing weather shelter at the North Point Government Center in Dundalk is open through Monday.
Traces of snow were reported at BWI on three occasions last month, the second consecutive year Baltimore saw no measurable snow during December.
Last year, a record-setting January storm bumped up the seasonal snow total to about 35 inches.
But the last time Baltimore saw no measurable snow in December, in winter 2011-2012, the region got only 1.8 inches of snow all season.