National Weather Service United States Department of Commerce

Overview

The scenario for this event was set in the early morning hours of Monday June 21st as a weakening mesoscale convective system was tracking across northern OH and into northwestern PA. The line of showers and storms dissipated over northwestern PA laying mesoscale boundary over this area and setting the stage for additional convection later in the day. Aloft, a strong shortwave trough crossed the Great Lakes region with the assist of a strong jet streak for this time of year. This setup began to push a cold front southeast through the area through the coming day. Showers and thunderstorms developed across Ohio by noon and began to push east through the the area. The showers and thunderstorms quickly developed and organized into a strong line of showers and thunderstorms. The line pushed east through the forecast area through the day with certain segments of the line surging eastward with time. Along these surges were enhanced areas of straight line wind damage. The surge in northern Allegheny County went on to produce a short lived tornado with EF-0 damage. The line increased in severity in the north as well as it crossed the aforementioned boundary developed by convection earlier in the day. By the evening that day, storms continued to travel over the same locations in southwest PA and into northern WV. This created some flooding issues and several problems of flooding roadways and homes were reported.    

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