Record flooding could affect the Quad-Cities this spring, depending on upcoming rainfall and how fast accumulated snow melts.
Rich Kinney, warning coordination meteorologist with the National Weather Service, Davenport, emphasized an updated outlook, while it is not a prediction, takes into consideration what might occur under certain conditions.
“Right now, we’re already looking at a high probability of major flooding in the Quad-Cities,” he said. “There’s a potential for record or near-record levels of flooding.“
"The scenario and conditions we're seeing now compare to 1965," Kinney said.
Historically, in any particular year, there’s about a 20 percent chance of hitting major flood stage.
Flooding of the Mississippi River in the Quad-City area could start the week of April 8-15, he said. On the Mississippi at Muscatine, there's a high probability of major flooding the last half of April, Kinney said.
Charts, which you can see at weather.gov/dvn/, take into consideration historical flooding as well as current conditions. Outlook considerations also include seasonal temperatures, frost depth, current river stream flows and weather forecasts.
Below-normal temperatures in January and February led the ground to freeze, kept ice in the rivers and allowed the snow pack to grow.
“The main unknown factors are how fast is existing snow cover going to melt, especially to the north, and additional amounts of heavy rain,” Kinney said.
The snow melt alone, he said, will cause rivers to rise near or above flood stage. The severity will depend on the rate of the snow melt.
According to the outlook, the frozen ground will prohibit runoff from soaking into the ground, thereby increasing runoff from snow melt or heavy spring rains.
A growing snow pack in the upper part of the Mississippi River basin has increased the probability for major flooding, with a potential for near-record or record flooding on parts of the Mississippi, he said. Local tributaries, likewise, have an elevated chance for flooding this spring.
The soil has been saturated across the region since the fall of 2018. The snow pack and its water content, the frozen ground, winter snowfall and other precipitation, high river levels and continued ice action have primed the area for “a potentially significant spring flood season,” he said.
On the Rock River, there’s an 80 percent chance of getting above major flood stage by middle-to-late March, he said. “Part of that is driven by the size of the rainfall we’re expecting this weekend.”
The best-case scenario is a slow-melting snow cover up north, with not a lot of heavy rainfall, he said.
Still, “People need to start planning now. And don’t wait until the last minute” for the possibility of flooding.
The potential for ice jams continues, especially with the rain anticipated this weekend. Warmer temperatures could heat up the ice, he said, and meteorologists will watch closely.
On Friday, the ice was fairly stable, with an ice jam on the Rock River in the Prophetstown-Lyndon area in Illinois.