An inch or two of snowfall is forecast across Maryland by Friday morning, possibly starting during the Thursday evening rush hour.
And then meteorologists said what looked like a chance for a significant snowfall over the weekend is instead likely to materialize as heavy rain — but could still include periods of snow or a wintry mix.
Early Thursday morning the National Weather Service issued a hazardous weather outlook for central and western Maryland with the exception of Garrett County. Light snow is expected to affect the evening commute, especially north and west of Interstate 95.
The weekend forecast was proving difficult to pin down, with a narrow line expected to form between those areas that could get heavy snow and those that could see more of a mix of precipitation types.
First, a low-pressure system is forecast to move in from the west and pass quickly through Maryland from late Thursday into Friday. Meteorologists said snow could start falling Thursday afternoon, potentially slickening roads just as many commuters are heading home.
Forecasters had previously predicted a glaze of ice could cover the region by Friday morning, but the latest weather models suggested air would remain cold enough for light snow to continue falling through the overnight hours. Precipitation is expected to taper off by daybreak Friday.
After that, forecasters are still watching a more potent storm system likely to move across the eastern United States this weekend. It is expected to pull in abundant cold air from Arctic high pressure moving down from the north, and a flow of Gulf of Mexico moisture from the south, potentially producing as much as 2 feet of snow across Ohio, Pennsylvania, upstate New York and into New England.
In Maryland, precipitation could start as snow or a wintry mix during the day Saturday, especially north and west of Baltimore. Areas farther south and east are more likely to see mostly rain, or a brief wintry mix turning into rain.
But meteorologists said forecasts of precipitation types and any snow accumulations could change in the coming days. Strong high pressure is forecast to be north of Maryland over the weekend, acting to lock in cold air potentially increasing chances for snow.
AccuWeather.com forecasters predicted Central Maryland will be on the edge of any accumulating snow, with an inch or two possible north and west of Baltimore. But they noted that a northward or southward shift in the storm’s expected track, by as little as 50 miles, could “have a profound impact on temperatures and snowfall accumulation.”
On the northwest side of the storm, temperatures are expected to remain below freezing; on the warmer southwest side, temperatures could rise into the 50s. That contrast helps explain why the storm is expected to be so potent, fueled by the clash between those two air masses.
As the storm departs, bitterly cold air is forecast to move into Maryland and across the eastern U.S. That could produce some snow showers on the tail end of the storm, Sunday afternoon or evening.
Weather service forecasters said temperatures could drop into the single digits, with wind chills below zero, by early Monday morning. Forecasters warned of rapid freezing overnight that could produce widespread black ice.
Monday is expected to be bitterly cold, with highs only in the mid-20s and 15-20 mph winds making it feel like the single digits. But winds are expected to diminish in the evening with Tuesday expected to be slightly warmer.