Flooding and extreme flooding events

Flooding is the number one severe weather killer nationwide, and the Midwest is no stranger to extreme flooding events.

Video Transcript

CHERYL SCOTT: Flooding, it is the number one severe weather killer nationwide. And the Midwest is no stranger to extreme flooding events. Torrential downpours, flooded impassable streets, homes and properties damaged and destroyed. Major flash flooding and record setting rainfall recently hit the Chicago area in May 2020. In just four days, over 7 inches of rain fell, contributing to major flooding on roadways, including Lower Wacker Drive, where several people and trapped motorists had to be rescued by boat.

The Chicago River rose high enough that the Metropolitan Water Reclamation District had to reverse the flow to Lake Michigan. May 2020 was our wettest May in Chicago history, with over 9 and 1/2 inches of rain. It also marks the third consecutive year with record rainfall in May. In addition, two of the last five years, 2019, 2018, were some of our wettest on record.

Extreme flooding events in the Midwest have increased in frequency and intensity and are projected to increase through this century.

W SCOTT LINCOLN: So we've definitely seen a change in the rainfall and the precipitation over about the last several decades. So if we look back to the 1950s versus today, we do have, oh, it's about a 10% to 20% increase in precipitation in Northern Illinois. And while that may not seem like a huge deal, just a small amount of precipitation can change the water balance and can change how much water ends up in our rivers.

So that 10% to 20% increase in precipitation has led to anywhere from a 50% to 100% increase in the average flow in rivers in Northern Illinois.

CHERYL SCOTT: Intense rain and thunderstorm events play a huge factor in river flooding. April 2013 brought one of the worst flooding episodes to Chicago and Northern Illinois. This massive rain storm dumped 5 to 9 inches of rain in just two days. Area rivers reached record levels in many locations. The floods destroyed homes and businesses and caused numerous power outages.

Intense prolonged rain events are the grounds for major flooding. When there is too much rain or it happens too fast, there is nowhere for it to go. The result, scenes like this, disastrous flooding.

W SCOTT LINCOLN: Even if we had the same amount of precipitation as we did 50 years ago but more of it was falling in thunderstorms and less of it in light rain, that would also change the hydrology. Because when you have it in light rain events, more-- a larger portion of that tends to evaporate, and a larger portion of that tends to soak into the soil. So when it comes down heavy, it's just coming down too heavy, soaking the soil.

And it's coming down too heavy to get evaporated. So it ends up, you know, in the waterway. So very interesting how those small changes in the pattern of rainfall, how much can make a big difference.

CHERYL SCOTT: The Climate Prediction Center recently released its spring seasonal outlook. In terms of precipitation, areas across the Great Lakes, the Midwest looking wetter than average. River flooding could be a big concern this spring if frequent heavy rain events hit the Chicago area.

W SCOTT LINCOLN: That is the increase in precipitation. And so if the rivers are averaging higher than they used to, that's less room for more water. So it takes less rainfall, less precipitation, less snowmelt for rivers to get to flood stage.

CHERYL SCOTT: Chicago's lakefront, beautiful yet fragile, and also susceptible to flooding. This video shows the fury of Lake Michigan. High lake levels with strong winds caused high waves to pound the Chicago shoreline back in November. You can see the dangerous waves here knocking a person off their bike on the Lakefront Trail and nearly dragging them into Lake Michigan. Lake levels are projected to remain high this spring and summer.

Record high lake levels in 2020 brought flooding and destruction up and down Chicago's shoreline. Now Lake Michigan's water level has dropped this winter. But with above average winter snowfall and a forecasted wet spring, lake levels will remain high, high enough to potentially cause more significant flooding.

DEANNA APPS: Even though we may be below those record highs that occurred last year, we're still well above average. So when we get those stronger storm systems that move through the region, and they have that really strong winds associated with it, that can really drive some high wave heights along the shore. And that can still cause a lot of impact from flooding to erosion as well.

CHERYL SCOTT: Since 2018, more than 150 people in the US have died from flooding. Flood effects can be local, impacting a neighborhood, or very large, affecting entire river basins and multiple states. Some floods develop slowly over a period of days. But flash floods can develop quickly, sometimes in just a few minutes. Flash floods often have a dangerous wall of roaring water that carries rocks, mud, and other debris and can sweep away most things in its path.

Flash flooding, it can occur quickly and without warning. If you are traveling around and encounter a road covered in water, do not travel through the flooded area. The motto is turn around, don't drown. Take, for instance, your average car or SUV, six inches of water can cause a car to stall, stranding you in the middle of floodwaters. A foot of fast moving water can carry away a small car. 18 to 24 inches of fast moving water can carry away most large SUVs.

Water moving at about 10 miles per hour can carry the same force as winds up to 200 to 300 miles per hour. So remember, when traveling and you run into a flooded road, turn around, don't drown. If you're in an area that could be affected by flooding, it's important to be prepared. Preparing ahead of time for extreme storms and floods will make your family more resilient.

JOY SQUIER: Flooding is one of the most costly and devastating disasters. It's also one of the most frequently occurring. People don't really take flooding as seriously as they do other disasters, like hurricanes or wildfires or tornadoes. But it really does make for a lot of devastation for the individuals who suffer it in the communities.

CHERYL SCOTT: Joy Squier with the American Red Cross knows firsthand the importance of being prepared.

JOY SQUIER: Illinois is always impacted across the state when it comes to spring flooding and spring storms. I worked in Louisiana on flooding a couple of years ago. And I remember people, you know, being rescued by boat. I remember a man telling me his three dogs were outside. And he couldn't get to them. Someone else telling me, you know, she was in water up to her neck in her home, which is just shocking, you know, that that kind of situation can happen.

We always see flooding across the country. And Illinois is no exception. And people need to take it seriously.

CHERYL SCOTT: In terms of flooding in general, what can people do to prepare now before extreme flooding hits.

JOY SQUIER: What people can do is to know the conditions, have their pets and family members prepared. Know if you have to leave or if you'll be safe in your area. Listen to emergency apps, like the Red Cross Emergency app, which you can download on your phone, which will tell you if there's a warning in your-- if you're in the immediate area. And then if you do have to leave, to have an emergency preparedness kit with you so that you have important items at the ready for you should you experience significant flooding.

CHERYL SCOTT: Your emergency disaster supply kit should include water, non-perishable food, and a week's supply of medications. Make sure to create a household evacuation plan and don't forget your flood insurance if you live in a flood prone area. Lastly, know the difference between a flood watch and a flash flood warning. A flood watch means be prepared. A flash flood warning means it's time to take action. So make your preparations now before severe storms and flooding strike again.

[THUNDER]