Snow Melt Likely to Cause Spring River Flooding

Feb 22, 2019

It's been a cold, snowy winter, so the chance of major flooding on the Mississippi and other rivers will be high.

The National Weather Service in the Quad Cities has released its first Spring Flood Outlook for 2019.

Hydrologist, Jessica Brooks, says the ground is saturated and frozen. When the snow melts over the next three months, it won't have anywhere to go except creeks and rivers. And to make matters worse, local rivers are already high.

One example is the spring flood forecast for the Mississippi at Rock Island Lock and Dam 15. She says normally there would be a 21% chance of major flooding for March through May. But with current conditions, the risk is a lot higher at an 85% chance of major flooding in the Quad Cities.

This shows the chances of the Rock River at Moline exceeding various levels for the entire period, roughly late February through late May. The black line is a "conditional simulation" (the forecast with current conditions), and the blue line is an "historical simulation" based on past data.
Credit https://bit.ly/2tz8GCT / National Weather Service Quad Cities

All the factors Brooks considers when creating the Spring Flood Outlook are coming together to create a higher risk of major flooding.

That includes a lot of snow that's fallen and on the ground in the upper Mississippi River basin to the north.

We can expect it to melt, flow into the river, and eventually arrive in our area.

The hydrologist also says ice jam flooding continues to be a threat on local rivers.

The next spring flood outlook will be released in two weeks.

Ideally, Brooks says the thaw would take three to four weeks, with snow melting slowly during the day but not overnight, with a lot less rain.

Spring Flood Outlook 1 Text... by on Scribd