(Updated 4/17/2023 with most recent hydrograph for the Quad Cities. Previous version main image was the LaCrosse, WI map, below to the left.)
On Thursday, the Quad Cities National Weather Service updated its flood forecast, which is for moderate to major flooding.
Hydrologist, Matthew Wilson, says he talked with his colleagues in Minnesota and Wisconsin as their snowpack melted.
"In the first 48-72 hours, when they were expecting to see large rises, they actually didn't see those rises. And that's due to the fact that as soon as that snowmelt began, the ground thawed out very quickly and started to absorb a lot of that initial melt. So, what should have been run off was able to be absorbed into the ground. And that's actually kind of blunted and delayed our flood a little bit from coming down."
Wilson says that means the Mississippi will crest here a couple of days later than previously forecast. And the crest should be up to one foot lower than predicted.
"So, first week of May for the Quad Cites as well...I'm thinking that's probably...April 30th to May 2nd or so. That's probably when the Quad Cities will see its snowmelt crest." (See hydrograph below.) Click HERE for the most recent hydrograph for the river gauge at Lock & Dam in Rock Island.
This weekend, the weather service expects rain with the possibility of snow in Minnesota and Wisconsin. Wilson says it shouldn't cause significant changes in the flood forecast for moderate to major flooding in Iowa and Illinois.
Currently, the Mississippi at Lock and Dam 15 in the Quad Cities is more than one foot below flood stage, and it'll probably reach flood stage late next week.
