Heat and flood risk to hit Northeast before cooler air arrives
A big change in the weather pattern will arrive in the Northeast around the same time the calendar flips to August. But before the shift, millions will contend with high humidity and potentially flooding downpours.
July 25 was a stormy Friday in parts of the Northeast.
Heat and humidity are once again surging across the Northeast and will continue to do so into the middle of the week before a significant cool push moves into the region, AccuWeather meteorologists say.
With the jet stream positioned well to the north, hot and humid conditions are forecast for millions in the Northeast through Wednesday. Daily high temperatures will top out well above historical averages for the end of July. Record highs will also be challenged daily along the Interstate 95 corridor.
AccuWeather RealFeel® Temperatures are likely to surpass the 100-degree Fahrenheit mark in the hottest spots during the afternoon.
Nighttime relief will be limited, with temperatures barely getting into the upper 70s in some locations paired with humid conditions.
Risk for severe thunderstorms, flooding to return ahead of refreshing air
A more substantial break from the heat and humidity is expected across the Northeast from Friday to Sunday, but not before the threat of severe weather and flooding surges in the region.
The same front that drove the risk of severe weather across the Plains and Midwest through Tuesday night will gradually push south across the Northeast from Wednesday to Friday.
Interacting with the hot and mositure-rich air in the region, there will be a risk of severe thunderstorms Wednesday and Wednesday night.
Flash flooding will be the primary hazard. Drenching thunderstorms could also reduce visibility, pond on roads, and slow travel. There is also a risk of locally damaging wind gusts and lightning strikes.
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There is increasing concern for heavy rainfall, raising the risk of flash flooding as the front continues to dive southward later in the week.
"A stripe of torrential, repeating downpours may develop from northern Ohio to western and central New York from Wednesday afternoon to Thursday morning," AccuWeather Senior Meteorologist Alex Sosnowski said. "This will be dependent on a stripe of energy at the level in the atmosphere where jets cruise at as well as thunderstorm activity right along an advancing cool front."
A more broad zone of heavy rain is forecast to unfold from Thursday to Friday farther to the south and east.
Tropical moisture will surge in from the south, providing ample moisture for persistent downpours to set up from portions of Tennessee into southern New England. Rainfall amounts of 2-4 inches are expected from Thursday to Friday, where the most persistent rounds of downpours occur.
"The AccuWeather Local StormMax™ is 8 inches for this event," Sosnowski said. "If rainfall close to that amount is realized, there will be significant flash flooding in areas that approach that intensity."
Individuals are urged to have several reliable ways to receive flood-related watches and warnings at all hours. Residents and visitors should make a plan and be aware of the quickest means to get to higher ground should flash flooding occur.
"Roads that appear to only have a small amount of water running across them may be deceiving, especially at night when the visibility is reduced," Sosnowski warned. "Six inches to a foot of moving water can cause small vehicles to be pushed along. With 1 to 2 feet of water, larger SUVs can float. At the very least, vehicles can sustain severe water damage."
A refreshing change will be in place across the Northeast by Friday evening and on through the weekend. Temperatures will trend below the historical average for the end of July and early August.
The historical average highs for Washington, D.C., and Philadelphia are 89 and 87, respectively, for the beginning of August. Forecast highs for the weekend are the low 80s in this zone, but in the 70s over much of the balance of the Northeast.
Along with the drop in temperatures, humidity levels will also decrease significantly across the region, creating more comfortable conditions for outdoor activities into the weekend.
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