As cooler air drives into the sea of heat and humidity in the East, locally powerful thunderstorms will continue to develop into this evening.
Relief is coming for those with heat-sensitive health problems, but big thunderstorms are marking the transition.
There is a risk of strong to perhaps damaging thunderstorms this afternoon and evening along the I-95 corridor from Richmond to Washington, D.C., Baltimore, Wilmington, Philadelphia, Trenton, New York City, Hartford, Providence and Boston.
While the storms will not be severe in every neighborhood, they can bring a brief period of damaging wind gusts and blinding downpours to many locations.
A few communities can be hit with downed trees and power outages, frequent lightning strikes, urban flooding and hail.
Much cooler and drier air will work in aloft, while the air remains hot and humid at the surface into this evening.
This setup produces an unstable atmosphere that can be made acute by the approach of the cooler air at the surface.
Folks spending time outdoors into this evening should keep an eye out for rapidly changing weather conditions and seek shelter in a building away from windows as storms approach.
In addition to the heat, the approach of the storms could lead to delays at area airports and poor visibility on the highways, due to blinding downpours.
An unusually strong push of cool air for early September will move southward along the Atlantic Seaboard into the Labor Day weekend, before July-like heat returns by next week.
While lulls in tropical activity in the Atlantic will continue, a rapid end to the hurricane season in September does not always occur during an El Nino.
After heat has dominated headlines this summer, cool air has finally taken control of the northern half of Europe with no signs of departing anytime soon.
While Tropical Storm Kevin will stay well away from Mexico, its moisture will still lead to an increase in showers and thunderstorms from Baja California to the Four Corners region of the United States.
A stormy weather pattern will prevail through September across much of southern South America.
Steering winds could take Ignacio, as a remnant storm, into the southeastern arm of Alaska or British Columbia during the middle days of next week.
Denver, CO (1961)
Earliest snow on record; a total of 4.2 inches. A great storm raged at high elevations with 2-3 feet of snow closing roads on Labor Day weekend.
Coffeyville, KS (1970)
Hailstone 17.5/44 cm in circumference 1.671 lb/757 gm.
Long Island NY (1821)
Long Island hurricane of 1821 struck western Long Island. The storm affected a densely populated area where weather observers were common.