A rather robust storm system for late-summer continues to track across the eastern US, and will impact the eastern seaboard by tomorrow with risk for additional storm damage. The main feature that will trigger the showers and storms expected tomorrow will be the warm front out ahead of our main system. As it tracks to the north and east across the Mid-Atlantic, that will fuel the development of this precipitation, some of which may turn severe.
Several ingredients will be in place to promote the formation of intense thunderstorms tomorrow. Due to showers Tuesday night however, the leftover cloudiness Wednesday morning will keep instability at bay in most areas, therefore preventing the explosive development of convection we saw today. On the other hand, moisture will be plentiful, making soaking storms that may still cause issues still possible. Another ingredient will be the wind shear. 30 to 40 knots of shear will also aid in storm growth, and adds the risk for localized damaging winds. Large hail and a couple spin-up tornadoes also cannot be ruled out either given the atmospheric setup present.
Like in most thunderstorm setups, the main activity will occur during the latter half of the day. At the start, the most unsettled weather will take place in New England as a line of light to moderate rain moves northeastward before clearing out by noon for most areas. Across the rest of the Northeast and Mid-Atlantic, it should remain mainly dry, but a couple spotty showers still cannot be ruled out.
In the afternoon we’ll begin to see the strong to severe storms pop up. Precipitation will not be widespread but will instead be of the hit or miss variety. Several lines of scattered showers and storms are expected to track east across much of the region, but severe storms will thankfully be mostly isolated. The threat will then wind down after dusk as the approaching cold front kicks the unsettled activity off the East Coast.
Aside from the severe weather threat, there will also be the risk for flash flooding, especially in the Appalachian Mountains and eastern Ohio River Valley. Rainfall will generally amount to between half an inch and 1 inch in New England.