How the Remnants of Gordon will Impact the Ohio River Valley and the Lower and Mid-Mississippi Valley (Photo Credit: NOAA Weather Prediction Center)
DISCUSSION: Tropical Storm Gordon made landfall near the Alabama, Mississippi state line just before midnight local time on Sept. 4th, 2018. Although Gordon is no longer classified as a tropical system, its remnants are still producing heavy rainfall and flash flooding. As Gordon slowly moved to the north, northwest into Arkansas and southern Missouri the tropical depression interacted with a stationary front, becoming a post-tropical system with frontal boundaries. As of 1800 UTC the Weather Prediction Center, or WPC, had the center of the now post-tropical system located over southern Illinois and are forecasting it to track east, northeast through the Ohio River Valley. 24 hour rainfall totals are expected to exceed two inches from central Indian to central Pennsylvania, with totals exceeding four inches over central eastern Ohio and western Pennsylvania.
The system has also prompted the WPC to issue numerous Mesoscale Precipitation Discussions, or MPD, with one currently focused over the Ohio River Valley, see above image. Within this region expect embedded regions of extreme rainfall, with rainfall rates possibly exceeding three inches per hour. Rainfall rates close to this have already been recorded in Mount Vernon, IL, where 2.41 inches of rainfall was measured in one hour. In addition to the embedded regions of extreme rainfall, prolonged rainfall is also a concern. The continuous rainfall could lead to three to four inches of rainfall occurring over the next six hours across the region. Such rainfall rates and totals could lead to localized flash flooding and rivers and streams overflowing their banks. Remember to be alert and if you see flooded road ways turn around and find an alternate route.
Although the immediate impact from the system is heavy rainfall and flooding near its center and to its east, another threat is the development of showers and thunderstorms along its cold front, across the Lower and Mid-Mississippi Valley. These storms are not likely to be severe, though there is a slight chance of localized strong winds. The largest threat will be flash flooding due in part to the already saturated conditions from the first round of rain from Gordon. Another factor is the effects the daytime heating will have in combination with the tropical moisture being supplied by the post-tropical system. Such a combination could lead to hourly rainfall rates exceeding two inches and has resulted in an additional MPD being issued for eastern Arkansas.
Aside from the flash flood threat, the rain from the remnants of Gordon has been and will continue to impact American Football games. Currently, none of the college games have been postponed due to the rain, though the wet conditions have resulted in dropped balls and missed kicks. The larger impact on the sport will likely be tomorrow, Sunday Sept. 9, when the Cleveland Browns play the Pittsburgh Steelers. Heavy rainfall is excepted across the Cleveland region, with winds gusting to 40 mph. These conditions could result in the postponement of the game, though currently the game is expected to start as scheduled.
To stay update with the rainfall associated with the remnants of Gordon go to https://www.wpc.ncep.noaa.gov
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© 2018 Meteorologist Sarah Trojniak