Downpours to trigger flooding in southern Plains, Ozarks
Heavy rain and a growing flash flood threat are headed for the south-central United States this week. The rain will fall on some areas that have already had two to three times the historical average for April.
AccuWeather Flood Expert Alex Sosnowski monitors the growing risk of flash flooding for several parts of the central U.S. due to severe weather expected to bring heavy rainfall this week.
Showers and thunderstorms will be frequent from northern Texas to western portions of Arkansas and Missouri through the middle of the week. AccuWeather meteorologists are forecasting enough rain to trigger flash flooding of urban areas and along small streams. Some surging water can be expected in the Red, Canadian and Arkansas river basins.
A front will press slowly across this region into Tuesday night then stall at midweek, setting the stage for repeating downpours.
A wide area is expected to pick up 1 to 4 inches of rain. Where 1-2 inches of rain drenches an area in 12-48 hours, it will not pose a significant problem. However, there is the potential for some locations to be deluged with 4 to as much as 8 inches of rain in 12 hours. That magnitude of rainfall is problematic and can quickly flood streets, farmland and low-lying areas along small streams. Low water crossings may be too dangerous to venture through.
While drought conditions persist over the southern High Plains and farther north over the lower Plains, the zone where the brunt of the rain is projected to fall into midweek from northern Texas to Missouri and Arkansas contains moist to saturated soil.
For example, Tulsa, Oklahoma, has picked up 7.24 inches of rain in April, which is 1.7 times the historical average of 4.37 inches. Meanwhile, Springfield, Missouri, has amassed 10.55 inches of rain this month, which is 2.25 times the average. Oklahoma City has an even bigger rainfall departure from the historical average, with 2.5 times the typical monthly rain. Farther south, Wichita Falls, Texas, which is typically drier than Oklahoma City, has picked up 7 inches of rain in April, or 2.8 times the average.
Because of the moist ground, much of the rain that falls will quickly run off into the area streams.
Farther to the northeast over the Ohio River Basin, the rainfall with this particular setup will tend to be more sporadic though localized flash urban and small stream flooding can still occur.
Severe thunderstorms will be a key component to the rainfall along with the likelihood of urban and small stream flooding. Storms capable of producing powerful wind gusts, large hail and even tornadoes will be on the prowl.
Risk of more heavy rain next week
Portions of the south-central United States could experience another heavy rain event next week.
"A storm moving out of the Rockies may stall over the southern and central Plains next week with a swath of drenching showers and severe thunderstorms likely," AccuWeather Senior Meteorologist Adam Douty said.
Where the downpours focus may not only renew urban and small stream flooding for parts of the southern Plains, but it could bring such a threat for the first time this spring in some places and trigger more significant river flooding in portions of the Red, Canadian and Arkansas basins.
The persistent rounds of rain can delay plowing and planting operations in the agricultural communities.
Mississippi River flooding
Meanwhile, a surge of water continues to work downstream along the lower Mississippi River.
Historic rain fell on the Ohio and middle Mississippi valleys in early April, and it took several weeks to cycle downstream. Portions of the lower Mississippi River in Louisiana and Mississippi will be at a moderate to major flood stage with a crest in early May.
The high water can negatively impact tug and barge operations, which are typically an inexpensive means of transporting grains and goods.
Some ports may be closed due to high water. It could take until mid-May before the whole stretch of the Mississippi River has dipped below flood stage. Additional rain in the Ohio and Arkansas basins could impact that, however.
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