Lower Mississippi River to fall below flood stage after nearly 7 months

By Alex Sosnowski, AccuWeather senior meteorologist

The lower Mississippi River is forecast fall below flood stage in early August in the south-central United States after a nearly seven-month ordeal.

AccuWeather meteorologists believe that while the tropics will remain a wild card, a lack of widespread heavy rain over the central United States should allow the Mississippi River to continue settle or generally remain below flood stage for the balance of the summer and the early autumn.

A few showers and thunderstorms are forecast to focus over the Southeastern states into the first part of August, according to AccuWeather Lead Long-Range Meteorologist Paul Pastelok.

"We suspect there may be a tropical system that brews in the western part of the Atlantic during the first week of August, but it is unclear if that system will ever reach the U.S. or not," Pastelok said. "It's possible it takes a curved path just offshore."

That feature will spread drenching showers and thunderstorms westward across the eastern and northern Caribbean through the middle of this week.

Long-running flood to come to a close on the Mississippi

There have been several periods of rising and receding waters on the Mississippi since flooding was set into motion late in 2018.

The roots of the historic flooding during the spring and summer of 2019 began last November when the first widespread heavy rain fell from northern Louisiana through the Ohio and Tennessee valleys.

"Rain that falls directly on the Mississippi Delta does little to contribute to non-storm surge flooding in that area," according to AccuWeather Senior Meteorologist Jim Andrews.

"It can be bone-dry in terms of rainfall in the delta, but flooding can still occur due to rainfall hundreds of miles away," Andrews said.

Ongoing rounds of heavy rain over much of the Mississippi Basin, as well as heavy snow, which then melted over the upper reaches kept the Mississippi River in the delta region at high levels during the winter, spring and the first part of the summer.

"There can still be complexes of thunderstorms that bring localized heavy rainfall and rises on some of the secondary rivers and their tributaries," Andrews said.

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"But, we are entering a drier part of the year for much of the Ohio and Mississippi basins, when river levels tend to fall," Andrews said. "The thunderstorm complexes are not widespread enough to aggravate the main stem rivers on a mass scale."

Record-shattering flood duration set at Baton Rouge

Each day the Mississippi River remains above flood state at Baton Rouge, Louisiana, sets a new record.

At Baton Rouge, which is in the delta region, the Mississippi first rose above flood stage on January 5, 2019, and has been above that level ever since, according to the National Weather Service. Flood stage at Baton Rouge is 35 feet.

During the first week of August, the Mississippi River is forecast to drop below flood stage. By then, the river will have spent a record-shattering 210 days above flood stage.

The prior record was 135 straight days during the Great Flood of 1927.

Except for a very brief time on April 17, the Mississippi River at Baton Rouge was at major flood stage from late February to the fourth week of July. Major flood stage is 40 feet or higher.

This period of major flood is longer than the stretch at minor flood stage or greater from 1927 at Baton Rouge.

At Vicksburg, Mississippi, the river will slip below flood stage, or 43 feet, by Monday morning, July 29.

At New Orleans, the Mississippi level was hovering near the 15-foot-mark during late July. This level is a couple of feet below flood stage. Slow recession of the river will continue into August.

Some of the flow water from the lower Mississippi River can be controlled and diverted at the Bonnet Carre and Morganza spillways.

The projected levels have allowed officials to close all of the gates at the Bonnet Carre Spillway, which is just above New Orleans.

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The release of fresh water into the brackish Lake Pontchartrain has affected wildlife in the waters as well as that of the saltier Lake Borgne. The magnitude of fresh water flowing from the Mississippi has also altered salinity and brought more contaminants into the Gulf of Mexico.

Other rivers in the region, such as the Atchafalaya and Yazoo are slowly receding as well.

The recent Hurricane Barry caused water to back up and rise on some of the rivers in the Delta Region due to storm surge. Flooding occurred in some communities in southeastern Louisiana as a result of the prior rainfall upstream and the reverse flow of rivers created by Barry.

Farther upstream, the Mississippi was below flood stage along much of Arkansas and Tennessee.

Recent rounds of rain caused some rises on the middle and upper portions of the Mississippi and its tributaries during July. However, these have not resulted in significant flooding of the Mississippi and waters are projected to recede in the coming weeks as well.

As waters continue to recede. Barge operations which have been hit hard during the long-running flood event will continue to ramp up.

However, the magnitude and duration of the high water and flow on the Mississippi has likely deposited silt and created new shoals in part of the main shipping channel.

As water continues to recede, these deposits will have to be dredged to reduce the risk of tugs and the barges they pull to run aground.

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