Areas from New England through the Ohio River Valley will be at risk for damaging thunderstorms and flash flooding into Wednesday night.
This is the same storm system that brought thunder, hail and gusty winds to the northern Plains and some of the Midwest on Tuesday.
As a cold front swings through the region on Wednesday, two very different air masses will collide. The drier air arriving from the northern Plains will meet the steamy air hanging on over the eastern third of the nation.
The merge of dry air and very moist air will create favorable conditions for thunderstorms, some of which may be severe.
The main threats with these storms will be torrential downpours, damaging wind gusts in excess of 60 mph and a few incidents of large hail. A couple of the strongest storms can also produce a short-lived tornado.
Affected cities stretch from Cape Girardeau in Missouri, to Cincinnati and Pittsburgh, but also as far north as Syracuse, Albany and Hartford.
Pittsburgh received drenching downpours Wednesday morning, leading to flash flooding in the area. Another round of storms is forecast for the Steel City later Wednesday, which will extend the threat for more flooding.
Wednesday night the storms will continue to drift eastward and may reach New York City, Philadelphia, and Washington, D.C. before weakening.
Another area of the country will experience locally severe storms Wednesday evening. A corridor from eastern Wyoming to northwestern Kansas could be hit with gusty winds and hail.
Later in the week, the front will slowly drift to the east with the threat of torrential downpours near the coast.
This will bring a refreshing end to the oppressive humidity felt across much of the Northeast for the weekend. However, the muggy weather will likely still have a bit of a hold along the Atlantic Coast.
As temperatures rise through the weekend in the South, so will the risk for heat-related dangers.
While a tropical low is expected to brew into Tropical Storm Cristobal this weekend, the East Coast of the U.S. is being monitored for future impacts -- even if the storm remains well offshore.
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United States residents may pay higher heating costs this fall as colder air is expected to grip the Rockies and Plains at times and some quick-hitting chilly shots may impact the Northeast.
A swath of steady, soaking rain will slowly shift from the northern Plains to the Canadian Prairies this weekend, making people reach for their umbrellas.
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103 degrees, hottest ever in Puerto Rico.
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2-1/2 to 3 inches of rain in 45 minutes. 75 homes were flooded and one was washed off its foundation, ending up blocking a roadway in the community of Beauty (near the WV-KY line). Heavy damage was reported, there including a washed-out bridge.
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108 degrees -- new record high for this date, also the 56th day of the last 59 days that they have reached 100 degrees or more.