A winter weather advisory is in effect until 7 p.m. for much of the Baltimore area as a wintry mix of snow and sleet with pockets of freezing rain moves in from the south, the National Weather Service reported.
Forecasters said the mix of precipitation will continue through the evening, dropping about an inch of snow and sleet with winds from the northeast between 15 and 25 mph and gusts of 35 mph. Drivers should be prepared for slippery roads, the Weather Service warned. Forecasters canceled the winter weather advisory for Anne Arundel and Prince George's counties about 3 p.m. and in Howard and southern Baltimore counties about 4:30 p.m., with temperatures above freezing.
It was the second snowy event to take the region by surprise in three days, after a wet snow blanketed much of the region Christmas Eve before melting away on Christmas Day. Meanwhile, forecasters are eyeing another possible bout of wintry precipitation over the weekend.
The accumulating snow was hard to predict in both Monday's and Wednesday's storms because the line between wintry precipitation and rain is falling about over the Baltimore area, said Bryan Jackson, a meteorologist with the weather service's Baltimore/Washington forecast office in Sterling, Va.
"There's a finer line than what we can put into the forecast a day in advance," Jackson said. "The message we've been saying is snow and sleet, changing into rain. In both cases, the snow did accumulate across the Baltimore area before changing into rain."
Jackson said at about 1 p.m. forecasters do not expect much more snow in the region, with a 60 mph wind blowing in warm air about 2,000 feet above the ground. That causes precipitation to melt into rain before turning to freezing rain or sleet as it moves through colder air closer to the ground.
Still, the precipitation was causing travel headaches and other concerns. The Weather Service said the weight of snow and ice could knock down tree limbs and power lines. The Baltimore County Bureau of Highways, Snowfighters, reported that its highway crews are plowing and salting.
Roadways across the state were snow-covered or wet and slushy, according to the State Highway Administration. Snow covered roadways in the Hereford and Westminster areas, with isolated spots of snow coverage on roads in Howard County and parts of Baltimore and Anne Arundel counties. Roadways were wet around Baltimore City and around both Baltimore harbor tunnels.
State highway officials encouraged motorists to drive carefully, particularly after temperatures drop in the evening.
"People who are out tonight need to be really careful because whatever is on the ground is going to freeze," said state highway spokeswoman Sandra Dobson.
At Baltimore-Washington International Thurgood Marshall Airport, the weather was causing some departure delays, according to the airport's Twitter page. The airport's website showed several delays for both arriving and departing flights.
In Western Maryland, heavier snow prompted closures. Both District and Circuit courts in Garrett County are scheduled to close at noon Wednesday, according to the state judiciary. The Washington County Circuit Court will close at 1 p.m.
In Southern Maryland and the lower Chesapeake Bay region, isolated thunderstorms with strong gusty winds are possible in the afternoon. A small craft advisory is in effect for the tidal Potomac River and Maryland portions of the Chesapeake until Wednesday evening. Minor tidal flooding may be possible during high tide late in the afternoon and in the evening for locations on the western shore of the Chesapeake and tidal Potomac River.
Thursday’s forecast calls for high winds and a chance of showers before 9 a.m. The day will be cloudy, then gradually sunny, with a high near 41 degrees and a low of about 29 degrees Thursday night. A wind advisory is in effect from 9 a.m. to 6 p.m., with northwest winds 20-25 mph gusting to 50 mph.
Meteorologists are forecasting another low pressure system to move from the Gulf Coast to the mid-Atlantic on Saturday and Sunday, though they are still uncertain of its timing and strength. Snow accumulation is possible across the Northeast and northern mid-Atlantic states, according to the Hydrometeorological Prediction Center.
An earlier version of this post misstated the forecast snow totals for the Baltimore area on Wednesday. The Sun regrets the error.