Flood Disaster Likely Just Beginning Over Central U.S. with Troublesome Season Expected03/19/2019
Flooding will continue in waves and varying degrees of severity over the central United States, including a large part of the Mississippi River watershed, through the spring.
While high stream and river levels are common during the spring thaw, flooding that occurs is sometimes worse than other years.
This year will be one of the bad years for flooding in the Central states.
More flooding likely from central Plains to part of Midwest this spring
The combination of frozen ground, ice-clogged rivers and streams, a sudden thaw and heavy rain combined with a snow-eating wind contributed to the magnitude of the flooding from parts of the central Plains to the Upper Midwest thus far.
(Mike Bossman / Omaha Police Department)
Historic flooding in Nebraska left some roads completely washed out and scenes of widespread devastation, dramatic aerial photo showed.
River flooding has overtaken a highway in Columbus, Nebraska.
Hardest hit have been portions of Nebraska, Iowa and South Dakota. The flooding already experienced may not be the last for the region.
Most of the storms are likely to occur over the southern half of the nation, rather than over the northern tier during much of the spring. Some of these storms and their heavy rain will reach some areas hit hard.
“Since El Niño is likely to persist through the spring and not weaken like it usually does this time of the year, the main storm track may remain south of the northern tier states,” according to AccuWeather Lead Long-Range Meteorologist Paul Pastelok.
While the storms are not likely to be as intense as the recent bomb cyclone, there will remain the risk of strong storms during April, May and June.
This setup may keep the risk of major flooding elevated well beyond this week over the central Plains in areas that have been hit with record high water.
What about the flooding risk over the northern tier?
There is also the likelihood of flooding farther to the north over the northern Plains and the Upper Midwest in the weeks ahead, even if no major storms come through.
How severe the flooding is will depend on whether the thaw is gradual or sudden.
A few inches to a couple of feet of snow remain on the ground and rivers are still clogged with ice over the northern tier of the Central states.
There are 2-10 inches of water locked up within the snow. In some cases, this is more water than what was released farther south.
Even a gradual thaw is likely to lead to minor to moderate flooding.
Any sudden surge of warmth combined with heavy rain would likely lead to major and rapid flooding, perhaps on par with that of Nebraska and Iowa.
Through the end of March, the bulk of the major storms are likely to track across the Southern states of the heavy snowpack region.
At the same time, days with above-freezing temperatures and nights with below-freezing temperatures should allow a gradual thaw over the northern tier.
However, should a storm strengthen significantly over the southern or central Plains, it may track farther north toward the Canada border. Such a track could trigger a rapid and severe flood event.
Flood risk to extend through spring and into the summer
Following the thaw, areas throughout the Central states may be at risk for more localized flooding of streams and rivers, depending on the track and strength of clusters of thunderstorms.
Thunderstorm complexes produce heavy rain and are responsible for the bulk of the rainfall over the Central states during the late spring and early summer.
Many rivers in the area may remain above flood stage or near flood stage for many weeks.
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While evaporation rates increase exponentially during the spring, the ground may remain saturated in some areas setting the pace for more flooding. The soggy ground may also delay spring planting.
“At this time, we think the progression of thunderstorm complexes to the Canada border will be delayed a bit,” Pastelok said.
“This might help mitigate the flood potential for the northern tier, but perhaps not so over the central Plains and the middle Mississippi valley and farther south.”
As the spring progresses, the surge of water from the central Plains flooding and the snowmelt on the way farther north will work its way southward over the Missouri and Mississippi rivers.
One surge of flooding that was initiated by heavy rain over the Tennessee Valley and lower Ohio Valley areas earlier this winter is just now cycling through the lower end of the Mississippi River.
Backwater flooding covers stretches of farm lands near Yazoo City, Miss., Sunday, March 17, 2019, as seen in this aerial photograph. Various communities in the Mississippi Delta are combating both Mississippi River flooding and backwater flooding that are affecting homes, businesses and farm lands. (AP Photo/Holbrook Mohr)
A new surge of water and corresponding flooding is likely to extend from the upper Mississippi to the middle and lower parts of the river in the coming weeks and months.
Water levels on the Mississippi may have yet reached their peak during the event.
It is possible that many parts of the Mississippi River will remain above flood stage through the spring and into the first part of the summer in the slow-moving natural disaster.
Source: Alex Sosnowski, AccuWeather