Flooding: How to prepare for life-threatening extreme flood events

CHICAGO (WLS) -- Flooding is the number one severe weather killer nationwide, and the Midwest is no stranger to extreme flooding events.

Major flash flooding and record-setting rainfall most recently hit the Chicago-area in May 2020. In just four days, more than 7 inches of rain fell, contributing to major flooding on roadways. On Lower Wacker Drive, 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 the wettest May in Chicago history, with 9.5 inches of rainfall. It was also the third consecutive year with record rainfall in May. Additionally, two of the last five years overall 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. Senior Service Hydrologist W. Scott Lincoln with National Weather Service Chicago has been tracking this data for years.

"We have definitely seen a change in the rainfall and the precipitation over the last several decades," Lincoln said. "So, if we look back to 1950 versus to today, we have about a 10% to 20 % increase in Northern Illinois. Why that doesn't seem like a big deal, just a small amount can change the water balance. And can change how much water ends up in our rivers, so that 10% to 20% increase has led to a 50% to a 100% increase in the average flow in rivers in Illinois."

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. The massive rainstorm dumped 5 to 9 inches of rain in just two days. Area rivers reached record levels in many locations. The floods destroyed homes, 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.

"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 tend to evaporate and larger portion tends to soak into soil. When it comes too heavy to soak into soil, or too heavy to evaporate, so it ends up in waterways. So very interesting how pattern of rainfall can make a big difference," Lincoln explained.

The Climate Prediction Center recently released its spring seasonal outlook and in terms of precipitation, areas across the Great Lakes and the Midwest look wetter than average.

River flooding could be a big concern this spring if frequent, heavy rain events hit the Chicago area.

Chicago's lakefront is also susceptible to flooding. Lake levels are projected to remain high this spring and summer. Record high lake levels in 2020 brought rounds of flooding and destruction up and down the Chicago shoreline. Lake Michigan's water level has dropped this winter, but with above average winter snowfall and a forecasted wet spring, water levels will remain high; high enough to potentially cause more significant flooding.

"Even though we may be below those record highs that occurred last year, we're still well above average," said Deanna Apps, physical scientist with the U.S. Army Corps of Engineers. "When we get those stronger storms to move through the region, that have really strong winds associated with it, really can drive some high wave heights along the shore and that can still cause a lot of impact from flooding to erosion as well."

Since 2018, more than 150 people in the U.S. 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.

If you're driving during a flood or flash flood event, it is important to turn around if you encounter a road covered in water. More than half of deaths associated with flooding happen in vehicles, and flash flooding causes $8.2 billion in damage per year.

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.

"Flooding is one of the most costly and deadly disasters, and one of the most frequently occurring. People don't take flooding as serious as other disasters like hurricanes, wild fires or tornadoes. But it really does make for a lot of devastation for the individuals who suffer it and their communities," said Joy Squier, Chief Communications Officer of the Chicago and Northern Illinois American Red Cross.

Squier said the best practice in flood and severe weather events is to know the conditions, and come up with a plan to be prepared.

"Know if you have to leave or if you'll be safe. Listen to emergency apps like the Red Cross emergency app. And if you do have to leave, have an emergency kit ready to go so that you have important items at the ready in case you experience significant flooding," she said.

Your emergency disaster supply kit should include: water, non-perishable food, and a week supply of medications. Also be 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.