The National Weather Service had 40 active flood alerts posted Monday, up from 37 a day earlier, as fresh thunderstorm clusters over the Midwest and Ohio Valley added to a threat that a day earlier had concentrated in the Northeast.
The most urgent new warnings are in northwestern Ohio, where the Weather Service’s Cleveland office issued a Flash Flood Warning for northeastern Lucas County and Ottawa County until 2 p.m. EDT Monday. Radar indicated 1 to 3 inches of rain had already fallen there by 7:56 a.m., with rainfall rates of 1 to 2 inches per hour still possible. A separate warning in the same region reported 2 to 4 inches already down, with storms lessening in intensity but flash flooding still ongoing or imminent. The Weather Service is warning of flooding in small creeks and streams, urban areas, highways and underpasses.
In Iowa, river flood warnings remain in effect for the Iowa River near Tama, affecting Tama and Poweshiek counties, and the South Skunk River at Colfax, affecting Marion, Polk and Jasper counties, with minor flooding forecast into Tuesday.
The geographic spread is now the widest of the week: alerts span Ohio, Iowa, Illinois, Kentucky, Louisiana, Missouri, Wisconsin, Florida, Massachusetts, New York, New Jersey and the Washington, D.C., region, plus a broad swath of Virginia counties from Shenandoah and Frederick east to Fairfax, Arlington, Stafford and Prince William, and a heavy concentration of Pennsylvania counties running from Elk and Clearfield through Centre, Cambria, Blair, Bedford, Franklin, Lancaster and York.
The most notable new addition is far outside the continental footprint: a flood alert now covers Guam and the Northern Mariana Islands — Rota, Tinian and Saipan — marking the first time this week the story has extended into the Pacific.
While the national count is up only modestly from Sunday’s 37, the shift shows the threat broadening rather than concentrating, with the Ohio Valley and Iowa emerging as the most active zones even as Mid-Atlantic warnings from the weekend persist. The Weather Service says small streams, urban low spots and highway underpasses remain most vulnerable, and continues to warn that most flood deaths occur in vehicles, urging drivers to turn around rather than cross flooded roads.
Forecasters expect the Ohio and Iowa warnings to expire through midday and afternoon as storms move east, but additional flash flood warnings are likely wherever training thunderstorms redevelop over already-saturated ground through Monday evening.