(KWWL) – Ice jams aren’t something usually thought about if you don’t live along a river. However with an ice jam prompting evacuations in Illinois, KWWL looked into what’s behind these frozen hazards.
Meteorologists from the National Weather Service office in La Crosse, Wisconsin said ice jams are hard to predict when and where they’ll happen
“It’s really hard sometimes to know exactly where it’s going to occur. Sometimes they’ll flow right on through and other times they’ll back up, almost like a beaver dam,” said Todd Shea, Warning Coordination Meteorologist in La Crosse.
While frozen rivers may look pretty, all that ice can cause a mess as temperatures begin to warm up.
Shea said they’ve seen between five and ten so far this year for their service area, which covers much of northeast Iowa. He said they have seen them earlier than normal this year.
“What happened recently here was we had that real cold spell, so the ice really thickened up on these riverways. Then you follow up on that with 40 and 50 degree weather,” he said.
That warm up caused issues like the one in Illinois. Towns along the Kankakee River are preparing to evacuate as the ice jams have prompted flash flood warnings.
Shea said they haven’t seen anything quite that severe here quite yet.
“We have not had anything major occur with them, no major impact. We’ve had some roads temporarily closed, some water levels get into a technical flood stage and things like that,” he said.
While not really preventable, Shea said many cities have plans on how to deal with the big ones.
“City officials watch for that. I’ve seen cases where they might have to go out and push the ice along or break up an area that is starting to make the clog,” he said.
Shea said the usual timing for ice jams is later on in March and April as rivers begin to thaw.