Forecasters are warning for the possibility of ice jams and flooding on multiple Chicago-area rivers amid a prolonged string of cold weather.
According to a “Hydrologic Outlook” released by the National Weather Service, the risk of ice jams and flooding is rising on the Rock, Fox, Des Plaines and Kankakee rivers, and that risk will continue to increase for several days.
The NWS blames the prolonged cold in the Chicago area in recent weeks, with temperatures failing to rise above the freezing mark for most of the month of January.
That cold has been even more pronounced in recent days, with highs in the teens and low temperatures in the single digits each night, and as a result river ice is rapidly forming on those rivers.
Minor ice jams have already been reported on several rivers, but those jams could become more numerous and more serious in coming days, leading to an increased risk of associated flooding behind the jams as water has more difficulty flowing on the waterways.
While warmer temperatures are in the forecast for Thursday and Friday, with highs in the upper-30s and low-40s across the area, the weather likely won’t be warm enough to sufficiently melt ice and mitigate the risk of ice jams, forecasters say.
Those temperatures are also expected to plummet again beginning Sunday, with highs in the single digits on Monday and Tuesday, according to longer-range forecast models. Overnight lows could also plunge below zero, allowing for rapid forming of ice.
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Forecasters warn that the rapid formation of ice can cause river levels to change quickly, leading to flash flooding in vulnerable areas. Residents in flood-prone areas are urged to check forecasts frequently and to be ready to take mitigation or evacuation measures when necessary.
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