The National Weather Service has 20 active flash flood alerts spanning six states Sunday, with the heaviest concentration across South and West Texas, where slow-moving thunderstorms have already dumped 1 to 2 inches of rain in some warned areas.
Alerts are in effect across Alaska, New Mexico, New York, Pennsylvania, Texas and Utah, according to the National Weather Service. The bulk of the activity is centered on Texas, where warnings cover Culberson, Reeves, Webb, Goliad, Karnes, Val Verde and Dimmit counties. Radar has indicated additional rainfall of up to half an inch is possible on top of totals already on the ground, and the Weather Service says flash flooding is ongoing or expected to begin shortly in several of those counties.
The flooding threat in Texas isn’t limited to flash runoff. The Weather Service has extended a Flood Warning for the Rio Grande at Laredo and continued one for the Rio Grande at Columbia Bridge, both affecting Webb County, where moderate flooding is occurring and forecast to continue. Rivers, creeks and low-lying areas near the Rio Grande are expected to stay swollen as the warnings remain in force.
In New Mexico, a Flash Flood Warning covers the South Central Mountains region through this afternoon, driven by excessive rainfall rather than a river system. The Weather Service warns that creeks and streams in the area may rise out of their banks, and that runoff could quickly flood roads and other flood-prone locations. The warning runs from midday Mountain time through the afternoon hours.
The remaining alerts are scattered across Alaska, New York, Pennsylvania and Utah, reflecting a pattern of isolated but potentially dangerous thunderstorm cells rather than a single organized system moving across the country. The Weather Service’s standard flash-flood guidance applies broadly: most flood deaths occur in vehicles, and drivers are urged to turn around rather than attempt to cross flooded roads, with extra caution urged after dark when high water is harder to spot.
Forecasters advise residents in all six states to monitor updated bulletins through the day, since flash flood warnings can be issued with little advance notice once thunderstorms intensify. Texans along the Rio Grande corridor, in particular, should expect the river flood warnings to persist as moderate flooding continues to work through the system.