Delaware officials say the winter storm is now expected to dump up to 18 inches of snow on the southern part of the state and up to 8 inches in the north.
The Level One state of emergency means drivers are discouraged from taking to the roads unless it's absolutely necessary for safety, health or business reasons. The warning is expected to last at least through Sunday evening.
Markell says drivers run the risk of getting stuck in snowdrifts and impeding plowing operations.
The governor has deployed Delaware National Guard troops to operate heavy equipment and to help state police with emergency response. The state's emergency operations center has been activated.