Torrential downpours in northeastern US to ease heat wave, raise flash flood risk

By Alex Sosnowski, AccuWeather.com Senior Meteorologist

July 28,2016; 11:02PM,EDT

 

 

As July draws to a close, a couple of storm systems swinging up from the Deep South will bring downpours to the northeastern U.S. and break the back of an extended heat wave.
Downpours will extend northeastward from the lower Mississippi Valley into this weekend.
Into Sunday, there is the potential for enough rain to ease abnormally dry and drought conditions in part of the Northeast.
Cloud cover and downpours associated with the storm systems will cause high temperatures to drop from the 90s F to the 80s in most locations. Where the heaviest rain falls, temperatures may be held to the 70s. However, high humidity will accompany the rain and will make for very muggy conditions.

The storms will take a general path from the northwestern Gulf of Mexico coast to the Tennessee Valley, across the central Appalachians then off the New England coast.
"During the summertime, it is difficult to pinpoint which communities will be hit the hardest by thunderstorms and downpours," according to AccuWeather Senior Meteorologist Dave Dombek.
The first batch of rain will spread northeastward into Friday evening.
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The heaviest rainfall from the first round will extend from parts of Kentucky to southeastern Ohio, much of West Virginia, northern and western Virginia, northern Maryland, central and southeastern Pennsylvania, northern Delaware, New Jersey, southeastern New York state and southern New England.
"Enough rain can fall to cause travel delays from New York City to Boston during the Friday morning rush hour," Dombek said.
A break in the rain is in store for many areas from late Friday into Saturday.
"The Friday evening commute should be better for most areas, except eastern New England, where rain may linger for a time."

However, the second storm in the series will already be moving in from the Ohio Valley during Saturday.
The second round of rain is likely to be more extensive and may deliver drenching rain to much of the region. This second round of rain will spread from west to east across the region from Saturday to Sunday.
The two punches from the storms have the potential to bring more rainfall than that which occurred on Monday in parts of the Northeast.

There is the potential for a general 1-2 inches of rain with localized amounts of 3-4 inches from both storms combined.
"In some cases, 2 inches of rain could fall in a couple of hours and result in flash and urban flooding, despite the preexisting dry conditions," Dombek said.
Because of the random nature of thunderstorms, some locations could still get missed by the big rain.
At least for a couple of days following the rainfall, the moist ground will tend to prevent extremely high temperatures during the daytime. The air at night may tend to remain muggy.
"Despite a little edge taken off the high temperatures by early next week, it will still feel steamy in much of the Northeast," according to AccuWeather Lead Long-Range Meteorologist Paul Pastelok.
Factoring in highs and lows, temperatures may continue to average slightly above normal in most locations during the first week of August.
"We expect another surge of heat in the Northeast during the middle of August," Pastelok said.