Mississippi River expected to hit 20 feet in Rock Island
Flood predictions for the Mississippi River have been revised again. Current projections from the U.S. Army Corps of Engineers say the river is expected to reach 20 feet at Lock and Dam 15 in Rock Island by July 7. Major flood stage is 18 feet. Matt Wilson, senior service hydrologist with the National Weather Service in the Quad Cities spoke with Our Quad Cities News via Zoom to discuss why the prediction was adjusted.
“They did get rain up north but that is actually factoring in the rain that we’re going to get over the next 48 hours,” he said. “Normally between April and October in our river forecast, we use 24 hours of predicted rainfall. That’s because typically in that time period, we’re seeing a lot of convective storms. Those are the kind of things where you might get three inches at your house and your neighbor a couple miles down the road only gets half an inch. Those are really hard on our river forecasting because three inches that falls in a small basin, that could send it in the flood stage but three inches that might fall 20 miles away in a bigger basin like the Mississippi, it was just a drop in the bucket. We typically try to keep it in for that 24-hour time frame because it gives us our best chance to get an accurate forecast out.”
Even though residents are anxious about holiday plans, the weather service doesn’t make predictions too far in advance. “When we see a big system, like what we’re looking at over the next 48 hours, where the predicted rainfall has been pretty steady and the locations been pretty steady for the last couple days in the model run, we’ll extend that out for up to 48 hours so that we can capture that whole event in there and give everybody as much heads up notice as we can.” Wilson says this might mean some forecasts for tributaries might be a little less accurate. He says with bigger basins like the Mississippi, it matters a little less where rain falls because it comes in at the same rate, providing a much better long-range forecast.
The record is 22.7 feet at Lock & Dam 15, but Wilson doesn’t think the 2024 flood will break that record. “I think we’re going to be up there. I don’t see us really getting a chance to peck at that record. This is because we are looking at summer convective-driven flooding. We do have a dry period that’s coming up to the middle of the month, but it might turn wet again by the end of the month. Hopefully, we’ll have enough chance during that drier period to flush a lot of this water downstream before we start seeing adding any more additional rainfall on top of it.”
The rising waters are playing havoc on 4th of July plans, but it’s better to be safe than sorry, according to Wilson. “Unfortunately, this year the Mississippi is definitely not the place you want to be spending your 4th of July, either on the riverbank or if you’ve got a boat. When we talk about minor flood stage, that’s where it starts to go over land and into park land and agricultural land. Moderate to major flood stage is where it’s actually impacting infrastructure and buildings, roads, bridges, that sort of thing. Imagine all the kinds of things that those impacts could be picking up and pulling downstream. Those will be in the river, so it’ll be a fairly dangerous place to be. If the lock and dams are closing to the barge traffic, that’s commercial traffic, recreational traffic is probably also not advised.”
Predictions will be revised over the next several days. Click here to see the latest projections for several locations along the Mississippi and Rock Rivers.
Copyright 2024 Nexstar Media, Inc. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.
For the latest news, weather, sports, and streaming video, head to WHBF - OurQuadCities.com.
