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Central US threatened by up to 4 months' worth of rain in less than a week. What to know
In extreme cases, there could be rainfall rates of up to a few inches per hour, which can subsequently cause flash flooding.
AccuWeather has said that there could be up to four months' worth of rain in five days along portions of a 1,000-mile-long swath in parts of the Central US. The amount of rainfall may be hard to handle for small streams and drainage systems in urban areas. In extreme cases, there could be rainfall rates of up to a few inches per hour, which can subsequently cause flash flooding.
“Should the amount of rain occur that we anticipate over the middle of the nation, it would exceed the 500 to 1,000-year average," AccuWeather Senior Storm Warning Meteorologist William Clark said, "Truly, the potential is there for a historic flash flooding event."
Residents have been asked to remain vigilant, especially those travelling on roads near small streams in hilly terrain. Rapidly rising water can sweep vehicles and homes away.
Rivers that are most likely to see significant water level rises include the Ohio, Miami, Scioto, Wabash, White, St. Francis, Kentucky and Tennessee. The lower portion of the Mississippi River can also witness a surge. Not just flooding, the rapidly-moving water could also affect tug and barge operations as April progresses. It can take many weeks for the surge to cycle through to New Orleans.
Motorists who use secondary roads in the zones where heavy rainfall is likely should be prepared to look for alternative routes to travel. Property owners should have the means to take preventative action as the rising water could prompt evacuation in some communities.
Additionally, a swarm of tornadoes could hit a portion of the Mississippi and Ohio valleys Wednesday evening and night. This could lead to certain communities being under both a tornado warning and a flash flood warning at the same time.
Parts of US threatened by flooding, storms
Meanwhile, a firehose of moisture is likely to produce repeating thunderstorms along with torrential downpours over the middle of the US through this week, AccuWeather reported. Over a foot of rain may pour down from portions of Arkansas to Kentucky and Ohio, which likely trigger major and historic flooding, meteorologists have warned.
Intense rainfall is likely to affect more than 46 million people over the central US, of which at least 13 million will be within a high- to extreme-flood risk zone. There is also a risk of catastrophic flooding in some communities within the higher-risk zones.
From Wednesday night, March 2, heavy rain and flooding could start escalating. The downpours’ normal west-to-east or northwest-to-southeast path will be blocked by a building zone of high pressure from midweek on, over the Southeast states that is expected to evolve into a heat dome.
The setup will lead to the formation of a conveyor belt of moisture Wednesday night and continue into Saturday night. This will bring several hours of heavy rain over many days from the Ozarks in Arkansas to the middle portion of the Mississippi Valley to much of the Ohio Valley.
“That moisture plume, known as an atmospheric river, will be tropical in nature and originate from the Caribbean,” Clark said. “Tropical moisture raises the risk of excessive rainfall.”
According to the National Oceanic and Atmospheric Administration, “Atmospheric rivers are relatively long, narrow regions in the atmosphere – like rivers in the sky – that transport most of the water vapor outside of the tropics. While atmospheric rivers can vary greatly in size and strength, the average atmospheric river carries an amount of water vapor roughly equivalent to the average flow of water at the mouth of the Mississippi River.”
