As we continue to thaw out from a brutal stretch of cold back at the end of January, conditions for ice jams, especially on the Rock River will remain favorable this week.
There are several factors we look at when assessing the risk for ice jams which includes a quick thaw. We’ve experienced a nearly 80°+ temperature jump just in the last week alone which is starting to break up the ice and move it downstream. During the night temperatures have also remained above-freezing which further promotes the ice to break up.
The Rock and Wapsipinicon Rivers tend to suffer from ice jams more compared to the Mississippi River simply because of the width. The wider patch of the Mississippi River allows the ice to flow more freely and it is less likely to become hung up on the sides of the river.
With the narrower flow, there is also a greater chance that ice will become caught on either the banks of the river itself or on bridge/overpass support structures.
Once the ice comes to a halt, water levels behind the jam will quickly begin to rise leading to flash flooding, while the water level upstream will quickly drop. Because ice jams are so unpredictable in terms of when they will break, the risk for flash flooding is usually greater downstream as higher water levels rush in once the jam comes apart.
These ice jams are nothing new. We usually experience a few or more each year and by now you are likely familiar with many of the problem spots located across the Quad Cities region, especially if you live on the river. The Rock River is notorious for sharp turns, particularly in parts of Whiteside County near Prophetstown and Erie where significant flooding due to ice jams has occurred within the last year alone.
The best thing you can do is be prepared for rapid fluctuations in river levels and never cross a flooded roadway should you approach one while the river is in flood. The ice will also likely grab onto tree debris from the banks damaging any property that you may have alongside the river.
Meteorologist Andrew Stutzke