Models continue to show a big coastal storm to impact the Mid-Atlantic Region on Wednesday. There has been little change in model guidance, but some ensemble data has trended a bit colder due stronger high pressure and creating a classic “CAD” or “Cold Air Damming” east of the mountains.
Scenario #1 is mostly favored by the latest model guidance. We’ve been talking about two areas of low pressure, the first low will dive out of the Pacific Northwest into the Rockies, and then into the Mid-South and transfer it’s energy from a developing coastal low off the North Carolina coast. High pressure will remain in control across Eastern Canada and provide a significant amount of cold air. However, with the combination of low pressure weakening to the west and the surface low very close to the coast, a lot of mild air will move into the mid to upper levels of the atmosphere. With colder air trapped at the surface, this could mean significant icing west of Interstate 95 in the Virginia Piedmont. Sleet and freezing rain would slowly transition to all rain across Southwest Virginia and Southern Virginia. As the low intensifies off the coast, heavy snow will be likely in this scenario across the Northern and Central Piedmont and Valley.