With once-in-a-lifetime rainfall and potentially widespread effects, historic flash floods are increasingly likely across the country's region until Saturday, driven by repeated storms accompanied by rare, high levels of severe weather threats, predictors warn.
A strong storm system took shape in central America on Wednesday, bringing a wide range of thunderstorms with rainy rain. A surge in moisture and instability refueling along a slow moving front increases the risk of flash flooding.
“The forecast for heavy rain at this event will have a return interval between 25 and 100 years,” said the National Weather Service in Little Rock, Arkansas. “In other words, heavy rain events of this size within four days are events that occur at one time in a lifetime. It has historical rainfall and impacts.”
The biggest concerns range from the Mississippi Valley to Ohio and Tennessee Valley. Repeated storms are likely to result in significant rainfall in local volumes up to one foot by the end of the weekend, the Fox Prediction Center said. Three to five inches of rain can only be Wednesday through Thursday, leading to early flash flood concerns.
Currently, Level 3 of the four flash flood risks have been introduced on Wednesday, with slower fronts expected to stall by Thursday, with longer durability in many of the same region.
This is why the highest levels of flash flood risk were issued on Thursday in parts of West Kentucky, a bushel in Missouri, West Tennessee and northeastern Arkansas.
Fox Forecast Center said there are concerns that a storm, a process known as “training,” will travel over the same area multiple times. Computer predictive models show the total number of inches of rainfall into western Kentucky, particularly across Arkansas. There, 24-hour totals are possible, ranging from 5-8 inches in some locations. This is on the few inches of rain that had already fallen the day before.
“This is an increasingly important setup with impact and the potential for life-threatening flash floods over a course of several days,” NOAA's Weather Forecast Centre (WPC). “If you live in a flood zone that runs through Arkansas, Northeast, or Ohio/Tennessee Valley, be sure to prepare.”
The uncertainty pattern continues through Friday and Saturday, with heavy rains and heavy storms potentially persisting. By the end of the week, the total rainfall may be nearing or exceeding feet.
The National Weather Service in Padoca, Kentucky, says total storm rainfall currently ranges from 8 to 12 inches in the Quad, with the highest amount spanning the Ohio River and the lowest in the northwest and southeastern areas.
“If we reach places close to these amounts, it is likely that the historic flash flood will be largely in four directions,” the agency warned. “There could also be widespread river flooding.”
Flood clocks have been issued from northeastern Texas to central Ohio, covering more than 900 miles and affecting more than 20 million Americans.
