A major storm is headed towards the Mid-Atlantic region for the mid-week time period and it should bring significant snow to much of West Virginia, Virginia, Maryland and the DC metro region, and the chances for significant snow continue in southeastern Pennsylvania as well. Low pressure will drop southeastward tomorrow across the Ohio Valley reaching southern West Virginia by tomorrow evening. From there, the storm should move to the southeastern Virginia coast by around mid-day Wednesday and then intensify as it pulls slowly to the northeast. Precipitation should begin in the DC region late tomorrow and then in Philly by late tomorrow night probably in the form of rain or a mix of rain and snow before changing to heavy, wet snow on Wednesday.
The heaviest precipitation amounts from this storm continue to seem destined for the region between eastern West Virginia and the Delmarva Peninsula; however, there has been quite a battle going on between the US models (GFS, NAM) and the foreign models (Euro UKMET) with respect to how much precipitation makes it north of the PA/MD border. The US models have been farther north with their precipitation fields while models like the Euro have generally suppressed the heaviest precipitation amounts to south of Philadelphia. This discrepancy continues somewhat today with the latest model runs, but the Euro has actually nudged a bit to the north with its precipitation and there is enough information that leads me to believe that the Philly region is still in the game for some significant snow accumulations on Wednesday; especially, on its southern and western sides. In fact, I would be rather surprised if the National Weather Service does not come out with a “winter storm watch” for at least parts of southeastern PA later today or tonight for the day on Wednesday (already out for the DC region). Preliminary snow estimates for the DC metro region are 6-12 inches with the higher amounts in the western suburbs. Even more substantial snowfall is likely across eastern West Virginia, western Virginia and western Maryland. Beach erosion and coastal flooding is a real threat along the coast from New Jersey to the southern end of the Delmarva Peninsula. Stay tuned, still a close call, and it is an interesting, complex storm - even New York City could get in on some of the action with accumulating snows and strong winds.