It appears increasingly likely some snow will accumulate on the first day of spring, but it is expected to be limited to grassy surfaces and higher elevations.
After more colder-than-normal weather Thursday, with highs in the upper 40s, a low pressure system is forecast to bring precipitation into the region early Friday morning. A mix of snow and rain is expected for most of the region, turning to all rain through Friday afternoon.
A winter weather advisory is in effect for western Howard County, Carroll County, northern Baltimore County and Harford County, with 2-4 inches of snow possible there. But to the south at lower elevations, there is more uncertainty over how long snow will mix in with rain, whether it will manage to change over to all snow, and how much of it will stick given that the ground has warmed over the past week or so.
"The snow with this system is most likely to be elevationally dependent in that the higher snowfall accumulations will be in the mountains and higher hilltops in the far northern and western suburbs of Washington and Baltimore," the meteorologists wrote in a forecast discussion.
The weather service is forecasting an inch or two along the Interstate 95 corridor, with an inch or less to the south and two to three inches to the north and west. As much as four inches is possible along the Mason-Dixon Line.
Eric Luebehusen, a meteorologist with the U.S. Department of Agriculture who operates a Maryland-focused weather email list for friends, family and other weather watchers, said he expects heavier accumulations. Luebehusen said he expects 2-5 inches across the region, though still only on grassy surfaces, with snow possible all day in northern Maryland.
Accumulating snow is difficult in March, however, as sunlight becomes more intense. In areas along and south of I-95, snow is less likely after sunrise.
Friday, of course, is the first day of spring. But the season doesn't technically begin until the equinox -- the moment the northern and southern hemispheres receive equal sunlight -- which arrives at 6:45 p.m.
There are numerous instances of snowfall on the first day of spring in Baltimore going back half a century or more.
"Winter went down fighting" in 1965 when about 4 inches of snow fell, the second year in a row snow was recorded on the first day of spring, according to Sun archives.
In 1958, as much as 2 feet of snow was blamed for five deaths and power outages across a wide swath of Central Maryland.
In 1944, a couple of inches of a mix of snow, sleet and freezing rain fell, causing scores of traffic accidents, accoring to Sun archives.
Baltimore Sun librarian Paul McCardell contributed to this article.