The weather pattern will remain unsettled across much of the eastern US today as a cold front tracks east before stalling across the Southeast and Mid-Atlantic. Waves of low pressure will ride this stalled frontal boundary, allowing for numerous showers and thunderstorms to affect the region. Localized severe weather and flash flooding will also be possible, while a more widespread threat takes place in the Northeast this Wednesday.
To the south this Wednesday outside of the severe area, there will be numerous clusters of heavy rain and thunderstorms that will affect the Texas Gulf Coast through the Mississippi River Delta and up through the southern Appalachian Mountains. Storms will also be likely across much of the Mid-Atlantic. Coastal areas will remain dry until tonight, which is when the storms will track east over the DelMarVa and Tidewater of Virginia. Areas to the south should remain dry Wednesday into Wednesday night. The area of greatest concern for flash flooding will span from the Lower Mississippi River Valley through the southern Appalachian Mountains, according to the Weather Prediction Center.
Now on Thursday, the cold front will stall out over the Southeast and Mid-Atlantic, which is quite common this time of the year. The most widespread of rain and thunderstorms, some of which will dump heavy rainfall, will be across the eastern Ohio River Valley and the central Mid-Atlantic, especially around the Mason-Dixon Line. To the south there will also be storms that develop, especially in the afternoon, across the southern Appalachian Mountains and into the Gulf Coast states.
That area of rain over the Mid-Atlantic will then track to the north and east overnight Thursday, which means the rest of the Mid-Atlantic and all of New England will end up having to deal with the heavy rain and thunderstorms. We are especially concerned about the flash flood risk in the New York City Tri-State area because this region just experienced flooding on Tuesday. With a saturated group and high rivers and streams, additional inches of rain will likely lead to more flooding.
The model guidance, such as the NAM model, is suggesting an area of intense lift that moves through the New York City area Friday morning. This basically means that the atmosphere will be favorable to produce heavy rain given the high amounts of moisture already in place.
Thankfully by Friday, the front will advance toward the East Coast, allowing for drier weather and air to move in. The only exception will be across eastern and northern New England, where it will take as late as Friday evening for the wet and dreary weather to clear out.
Through Friday, generally less than 1 inch of rain is forecast across the Northeast and Mid-Atlantic, but remember it won’t take much additional rain to produce ponding on the roadways or even flash flooding. It’s not until you get into the southern Appalachians where over 3 inches of rain may add up.