12:15 PM (Wednesday) | ***Significant rain event now getting underway in the Mid-Atlantic region with localized flash flooding an increasing concern…severe thunderstorm threat on the table as well***
Paul Dorian
One ingredient that will increase chances for significant rainfall in the Mid-Atlantic region will be a strong upper-level disturbance that will grind to a halt over the Great Lakes/Ohio Valley. The slow movement of the surface cold front and upper-level disturbance will lead to an extended threat of rain in the Mid-Atlantic from early today to early Friday. Map courtesy NOAA, tropicaltidbits.com
Overview
A significant rain event is now getting underway in the Mid-Atlantic region and it will continue into early Friday as a cold front inches its way across the area. This cold front has support aloft from a strong disturbance that will center itself over the Great Lakes/Ohio Valley and there will be plenty of low-level moisture within a persistent and broad south-to-southeast flow of air that is forming on its front side. Showers have already pushed into interior sections of the Mid-Atlantic region and there can be an afternoon thunderstorm or two. The showers and thunderstorms will become more numerous on Thursday and Thursday night and some of the storms can reach severe levels with damaging wind gusts and even isolated tornadoes on the table. Flash flooding is an increasing concern in the Mid-Atlantic region given the already well-saturated grounds from recent significant rain events.
This upcoming weather event could result in more than 2+ inches of rainfall for the Mid-Atlantic region from today into early Friday. Given the already well-saturated grounds, any significant rainfall could raise the chance for flash flooding. Map courtesy NOAA, Pivotal Weather
Details
There was a heavy rain event in the Mid-Atlantic region earlier this month associated with the remains of Hurricane “Ida” and another significant rain event is now getting underway. In fact, the next 48 hours or so could feature 2+ inches of rainfall along and to the west of the DC-to-Philly-to-NYC corridor and flash flooding is certainly a concern given the already well-saturated grounds. The ingredients for the significant rain event include a slow-moving surface cold frontal system, strong wave of energy in the upper atmosphere, and a very moist low-level flow of air from the south-to-southeast.
One ingredient that will increase chances for significant rainfall in the Mid-Atlantic region will be an influx of high-levels of moisture as a broad and persistent south-to-southeast flow of air develops ahead of the slow-moving cold front. Map courtesy NOAA, tropicaltidbits.com
In addition to the threat of heavy rain, severe thunderstorms are a possibility on Thursday and Thursday night with damaging wind gusts on the table and there can even be isolated tornadoes. The strong wave of energy aloft will tend to sit and spin for awhile over the Great Lakes/Ohio Valley and the result of this lack of movement will be an extended period of rainfall in the eastern states from now into early Friday. The front should be oriented north-to-south through New Jersey by the time we get to Friday morning with rain possibly still lingering along coastal sections.
This unfolding weather event will include the possibility of severe thunderstorm activity in the Mid-Atlantic region on Thursday and Thursday night. Map courtesy NOAA/Storm Prediction Center
The surface front should then grudgingly push offshore by later in the day setting us up for a nice weekend with plenty of sunshine and comfortable temperatures for late September. Temperatures will likely be confined to the 70’s this weekend in the DC, Philly and NYC metro regions following the passage of the frontal system. Another upper-level trough is likely to form in the eastern states later next week and this can result in some cooler-than-normal weather.
Meteorologist Paul Dorian
Peraton
peratonweather.com
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