Motorists may want to consider starting their weekend early. Another snowstorm is expected Friday, primarily after 4 p.m. and during the evening, and possibly Saturday, the National Weather Service said on its website Thursday morning. The storm comes nearly two weeks after the blizzard that dropped over 13.5 inches of snow on Dover and Sherborn from Sunday, Dec. 26 to Monday, Dec. 27. The weather service cautioned that the next storm's track remained unclear Wednesday night. Dover-Sherborn Patch will continue to update this story.