A large, well-developed storm system currently over the southern Plains will continue to traverse across the country, taking aim at the eastern US just in time for the weekend. We’ll then see a second, weaker low pressure form over the Appalachian Mountains as the first low moves offshore, keeping the showers around parts of the Mid-Atlantic and Northeast.
On Friday, all eyes will be on the Mid-Atlantic and the Appalachian Mountains as heavy rain moves over the region. The reason why we are concerned about this region for flooding, however, is because of the recent heavy snowfall. That snow has started to slowly melt, which is raising the water levels in the streams and rivers. With substantial rainfall in the cards, that will lead to the rapid melting of snow, putting additional water into the rivers, some of which that are already reporting minor to moderate flooding.
Much of the East in general will also be at risk for flooding with this next storm, not because of the snow and rain combination, but because of record rainfall. Some cities have measured or are approaching the 100 inch mark of precipitation for the year, which is a substantial amount for any location in the Eastern US.
According to our Chief Meteorologist Joshua Feldman:
There’s a bit of a cold air damning scenario, so I’m expecting a coastal front to dump very heavy rain from northeastern South Carolina northward through eastern North Carolina. Coastal areas could pick up 3-5 inches of rain, with locally heavier amounts likely. There will be another 3-5 inches zone of rain in the eastern panhandle of Florida and southeastern Georgia, where all global models (such as the European and American models) seem to agree that there will be frontogenesis (enhanced lift and greater favorability for heavy rain) between the coast and the Blue Ridge Mountains. Rain totals will steadily decrease on the eastern slopes of the mountains, which will pick up 2-3 inches.Joshua Feldman
In terms of the forecast, the chances are rather high that it’s going to be a washout of a day Friday if you’re in the Southeast, southern Mid-Atlantic region, and the Ohio and Mid-Mississippi River Valleys. A steady, moderate to heavy rain will be in the cards for millions as deep moisture feeds into this large storm system from the Gulf of Mexico and Atlantic Ocean. By late in the day, we’ll then watch that rain try to reach the New York City Tri-State area while dry air tries to keep New York State and most of New England dry Friday into Saturday.
Another component aside from the flooding on Friday is severe weather. Yes, intense, mesoscale storms can form in the wintertime, albeit they are not as common. Strong to severe storms will be possible from the Carolina coast and coastal/southern Georgia through northern and central Florida. The greatest risk will be across the northern half of the Florida Peninsula. Damaging winds will be the main threat associated with any of these storms, but spotty hail and even a tornado report or two is expected as an intense line of thunderstorms form in the afternoon.
As we get into Saturday, dryer air will work further into our occluded storm system, allowing for the Southeast and much of the Mid-Atlantic to dry out. At the start of the day, the Carolina coast and the Mid-Atlantic should still be dealing with the rain, but it will clear out as the day progresses. Meanwhile to the north, rain, some of which will be heavy, will continue from the Ohio River Valley through the central Mid-Atlantic and possibly into southern New England. That will be dependent on how strong the dry air coming in from the north will be.
As the first low moves offshore, a secondary (but thankfully weaker) low will form over the Mid-Atlantic, ushering in another round of rain showers to the region. This storm will have a bit more colder air to work with, so there will be a concern for some freezing rain along the northern extent of its precipitation from northern Pennsylvania through southern New England. Otherwise, generally light rain showers can be expected, but the flood threat will be much lower.
We’ll be sure to keep you updated on this flood threat as it evolves online and on social.