Economic Collapse

[basserdan]

Stage is Set for Potentially Devastating U.S. Spring Floods

By Bob Henson
March 21, 2019, 7:11 PM EDT


A home is surrounded by floodwater on March 21, 2019, in Craig, Missouri. The town of Craig was completely surrounded by floodwater, with every building water-damaged. Image credit: Scott Olson/Getty Image

A rare set of preconditions has left some of the nation’s biggest river basins vulnerable to what could be widespread and historic flooding, NOAA warned in its spring flood outlook issued on Thursday. Upcoming weather will play a huge role in the outcome, which is far from a done deal, but the agency didn’t pull any punches on what could happen—especially now that rainfall is projected to be above normal yet again this spring over much of the nation (see below).

“The stage is set for record flooding now through May,” said Mary Erickson, deputy director of the National Weather Service, at a news conference. The disastrous floods that hammered Nebraska and Iowa this month—inflicting what may be billions in damage and taking three lives—may only be a “preview” of what’s to come, said Erickson: “In fact, we expect the flooding will become worse and more widespread.”

Ed Clark, director of NOAA’s National Water Center, painted a similarly grim picture in a news release: “The extensive flooding we’ve seen in the past two weeks will continue through May and become more dire and may be exacerbated in the coming weeks as the water flows downstream.…This is shaping up to be a potentially unprecedented flood season."


Figure 1. NOAA’s Spring Flood Outlook issued on March 21, 2019. The outlook depicts areas where the odds favor minor, moderate, or major flooding for the period from March through May. This period includes the time frame in mid-March when severe flooding occurred along and near the lower Missouri River. Image credit: NOAA.
[img]
pbs.twimg.com/media/D2Nb36mX0AAUjE5.jpg[/img]
Where the risk is greatest, and why

As shown in Figure 1 above, vast parts of the country are at risk of at least minor flooding this spring. Such floods could be excerbated regionally by major storm systems and locally by heavy showers and thunderstorms.

Based on current conditions, the largest-scale and most serious flood threat will affect three of the nation’s great river basins.

• Additional flooding is quite possible along and near the Missouri River from eastern South Dakota to northeast Kansas and northwest Missouri. "Several of the prior major floods along the Missouri River have occurred during the months of April through June," said soil physicist Tyson Ochsner (Oklahoma State University). "The current high soil moisture levels in Nebraska and northern Kansas likely increase the probability of additional flooding this spring."

The risk may be somewhat less than depicted in Figure 1 over some parts of eastern Nebraska, where large amounts of snow and ice have already been dislodged or melted and flowed downstream during this month’s catastrophic floods.

• Saturated soils over much of the Upper Mississippi River basin will hike the regional flooding risk, especially over southeast Minnesota, western Wisconsin, and eastern Iowa. As these waters flow downstream, flood risk will be heightened along and near the Mid- and Lower Mississippi River, especially if heavy spring rains develop in the region.



NWS La Crosse
@NWSLaCrosse

A great view from "above" this afternoon! Notice all that remaining deep snow just to our north. That snow is the reason we continue to have concern about additional flooding over the next 1-2 weeks. http://tinyurl.com/yympbd63

• An unusually large snowpack over the northern Great Plains and Upper Midwest could lead to major flooding across the Red River Valley of the North in eastern North Dakota and western Minnesota. The threat will be greatest if temperatures suddenly spike far above freezing during April, especially if the warmth is accompanied by heavy rain. Unusually cold conditions in late winter and early spring have frozen the soil to unusual depths, and that will limit the soil’s ability to absorb rain and snowmelt until thawing is complete.

Another important variable is how quickly warming and heavy rains translate north. The Red River of the North is the nation’s only major river that flows northward into Canada, which means meltwaters tend to pile up as they flow toward progressively colder conditions.

As of March 19, the Upper Midwest region was covered by an average of 11” of snow, holding an average 3” of water, according to snow analyses from the NWS National Operational Hydrologic Remote Sensing Center. These amounts easily top anything observed for the date in data going back to 2004, with one exception. There was an average of 12.2” of snow on March 19, 2013—but that snow held only 2.2” of water, on average. All other years had less than 2” of water held in snowpack.

Continues below...

https://www.wunderground.com/cat6/Stage-Set-Potentially-Devastating-US-Spring-Floods?cm_ven=cat6-widget