More rain during early June could push river levels higher, expand flooding in central US

As waters reach levels seldom seen along the Mississippi and Missouri rivers and reach new heights along portions of the Arkansas and Illinois rivers, the risk of more levee failures and flooding will continue in the coming days and weeks.

What much of the middle and lower Mississippi River Valley needs is several weeks of dry weather. However, that is not going to happen as the wet pattern featuring frequent rounds of showers and thunderstorms is forecast to continue.

Storms will fire over part of flood-stricken areas into midweek. Some of the storms over the High Plains will turn severe.

Through Wednesday alone, an average of 1-3 inches of rain is forecast in the swath from eastern New Mexico and western Texas to portions of Oklahoma and southern Kansas.

This amount of rain over a few days may not seem tremendous. However, due to the saturated state of the ground in much of this swath and streams and rivers already out of their banks, flooding will be renewed or made worse and can sprawl into areas yet untouched by problems so far this year.

What could make matters even worse is the potential for moisture becoming involved from a tropical disturbance over the southwestern Gulf of Mexico that could unleash even more rain on part of the same area, as well as areas farther to the east where rivers are still rising.

Even with this feature failing to gel into a depression or storm, tropical downpours are likely to be drawn northward over a swath of the South Central states from the middle of this week into this weekend.

Between the tropical downpours late this week and the rounds of severe and heavy thunderstorms occurring early this week, there can be an AccuWeather Local StormMax™ of 10 inches from northern Texas to southeastern Kansas, southwestern Missouri and western Arkansas.

There can be similar localized totals in southeastern Texas and the lower Mississippi Valley regardless of tropical development.

The rain will have a significant effect on the crop yields of many different plants over the summer growing season, including corn and soybeans.

This week's rain could end the time to plant corn over much of the southern Midwest. Corn that is planted this week will likely see a 30 percent drop in yield from the late planting, and the next chance to plant in mid-June will make it too late.

The southern Midwest will see some heavy rainfall through the end of the week. This will continue to delay planting of soybean crops, as another week of delays will be possible for the soybean region.

The onslaught of rain could also affect the wheat and cotton crop.

With the time to harvest wheat approaching, any significant rain can cause the wheat to sprout prematurely. This can substantially cut the yield and the quality of the wheat that is available.

Western and central Texas are areas likely affected by the rainfall with regards to cotton. The crop is collected in the late summer, and most damage from rainfall is likely to occur later in the growing season. However, cotton can still see damage if there is significant flooding of the fields during the growing season or possible damage to the seed with heavy rainfall.

Levees have been topped or breached along portions of the Mississippi, Arkansas and Missouri rivers and have prompted mandatory evacuations of several communities.

Because of the amount of rainfall, flat terrain and meandering nature of these rivers, flooding typically occurs over weeks and months, rather than days.

The duration of the flooding can cause earthen levees to become soggy, develop boils and fail.

The Mississippi River, above the confluence of the Illinois River in Missouri, Illinois and Iowa will be cresting within a few feet of levels achieved just a few weeks ago during the middle of this week.

Farther south in Missouri and Illinois, where the latest heavy surge of water from the Illinois and Missouri is just arriving, a crest is not likely until late this week.

The Illinois River at Valley City, Illinois, is forecast to match or exceed the record level of 27 feet this week.

At St. Louis, National Weather Service (NWS) hydrologists are anticipating the second highest flood on record with a forecast crest near 46 feet this week. Only during the summer of 1993 were water levels higher.

In the coming weeks, the surge of water will continue to flow slowly southward along the Mississippi River, picking up water from the Arkansas River, where record levels have been achieved.

The Arkansas River at Pendleton, Arkansas, reached record flood stage of 34.1 feet early Saturday and is forecast to crest near 37.3 feet late this week.

Officials opened the Bonnet Carre Spillway above New Orleans to mitigate levels on the lower end of the Mississippi River earlier in May.

Officials expect to begin to open the gates along the Morganza Spillway on June 6 in order to ease water levels along the Mississippi River near Baton Rouge, Louisiana. If the Morganza Spillway is opened, it will join 2011 and 1973 as the only times for such an occurrence.

It may take until mid- to late-June for the full scope of the current surge of water moving down the Mississippi River to reach southern Louisiana.

River level forecasts, especially those beyond a few days, are subject to change based on the amount of rain that falls locally and upstream.

Should the worst-case scenario of rainfall from a tropical disturbance become involved, levels on the lower Mississippi could approach that of the Great Flood of 1927.

As high as some of the rivers are now, the full scope of the flooding may not yet be realized as more rain is forecast to pour down on a significant part of the region already hit hard, as well as other areas in the Central states.

Download the free AccuWeather app to see when rain will fall on your area and to be alerted as flood advisories are issued.

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