A winter storm warning was set to take effect at 8 p.m. Wednesday with 7 inches to a foot of snow across the region, according to the National Weather Service.
Snow is forecast to start around 9 p.m. and fall heavily, at rates of an inch or two per hour overnight, according to National Weather Service forecasters. About 3-6 inches could accumulate by daybreak Thursday. Sleet and rain are forecast to mix in with the snow during the day Thursday, with gusty winds of 20-35 mph.
Forecasters have since late Tuesday maintained calls for 6-8 inches across Baltimore and southern Baltimore and Harford counties, with 8-10 inches in areas at higher elevations on the Piedmont, including northern Baltimore, Howard and Harford counties. Carroll County could see as much as a foot of snow.
The snowstorm is predicted to be the largest for this winter season, and Gov. Martin O'Malley called for a state of emergency in advance. Trees, already weakened from last week's ice storm, could buckle and residents were told to prepare for possible power outages.
“It’s been a long winter for many Maryland families," O'Malley said in a statement.
Residents were advised to avoid driving and to carry a disaster supply kit if they do drive.
Temperatures Thursday are forecast between the mid-20s and mid-30s, with a north wind making it feel like the teens.
Snow is expected to resume by nightfall, and possibly until about 9 p.m.
Friday, temperatures could reach about 40 degrees before another cold weekend with highs in the mid-30s and lows in the teens.
Officials at Baltimore Washington International Thurgood Marshall Airport said some flights to and from southern cities were already being affected by the storm Wednesday morning. Some airlines have also relaxed their ticketing policies in advance of the storm, BWI officials said.
Nearly four dozen flights to and from BWI had been canceled as of 11 a.m., while about two dozen had been delayed, according to the airport website. Most of the canceled flights were to and from Southeastern cities like Atlanta, Charlotte and Raleigh, N.C.
More than 2,700 U.S. flights were canceled and hundreds more delayed early on Wednesday, according to flight-tracking website FlightAware.com.
A quarter to three-quarters of an inch of ice was expected in a broad section of Georgia, including metropolitan Atlanta. Some areas could see more than 1 inch.
The wintry mix has already caused two weather-related traffic deaths in Mississippi, and three in northern Texas, authorities said.
Reuters contributed to this report.Copyright © 2015, The Baltimore Sun