Hundreds of miles apart, but connected by the same weather system, urban St. Louis and rural Appalachia have experienced devastating flash flooding.
At least 37 people have been confirmed dead in Kentucky, Gov. Andy Beshear said Monday afternoon, and the death toll will continue to rise as the flood waters and debris recedes.
Gov. Beshear described "widespread damage" that displaced thousands of people, including power outages for thousands as well as washed-out roads, destroyed homes, and flooded schools. More than 600 people have been rescued by aircraft and boat since the flooding began, Beshear said.
President Joe Biden approved funding to support disaster relief efforts in Kentucky amid the deadly flooding. Biden declared a major disaster in Kentucky Friday morning and directed federal aid for recovery efforts in the state.
In Missouri and Illinois, the first batch of downpours Tuesday and Wednesday, July 26 and 27, 2022, dropped a foot (30 centimeters) of rain in some places, up to 10 inches (25 centimeters) in others with another 2 to 4 inches falling Thursday, July 28. In eastern Kentucky, 8 to 10.5 inches (20 to 27 centimeters) fell.
“It’s not just how much rain fell, but where it fell, how exposed people were, how close the infrastructure is to where the heavy rainfall falls or where the channels rise,” said Kate Abshire, flash flood services lead at the National Weather Services’ Water Resources Branch.
In urbanized St. Louis, rainfall that would normally seep into the ground like a sponge ponded and flooded, Abshire said. In Appalachia, the people who live in the region, the roads, the buildings and the rainfall all were concentrated by river channels that flooded, she said.
As the world warms, scientists expect more frequent and intense downpours — warmer air holds greater amounts of water that it can then dump. Both flood disasters were spurred by 1-in-1,000-year rain events. Triggered by the same atmospheric setup, they exemplify the type of dangerous weather scientists project will become more common as the Earth warms.
NOAA satellites monitored the storms that produced the catastrophic flooding. GOES-16 imagery captured detailed information about cloud properties in near real-time, including the presence of overshooting tops and gravity waves, which indicate a storm may be severe. Infrared imagery provided information on the temperature of the cloud tops. The colder the cloud top, the more likely the storm is producing heavy rain and severe weather.
GOES-16 also captured significant lightning activity within the storms. Large lightning flash rates indicate areas of active convection, and frequently these parts of the storm are producing the heaviest rainfall.
The ATMS instrument on the NOAA-20 satellite measured the temperature and water vapor of the storm, helping forecasters make predictions on the storm’s direction and intensity. The VIIRS instrument also observes floodwaters, allowing for high-resolution flood maps.
During a major flooding event, local forecasters and first responders rely on satellite data, along with other tools like aerial mapping, to understand the extent of damage. NOAA flood products help identify where flooding may be occurring and aid officials in determining where to employ often limited resources during a flood. Data from NOAA’s geostationary and polar-orbiting satellites are merged to create detailed and comprehensive flood zone maps. These maps help FEMA and first responders determine where to focus their efforts. They also allow for insight into where water is receding. This highly valuable information is given to community officials to help them determine, in combination with other critical resources, when it is safe for people to return to their homes.
When storm systems develop with the potential to cause flash flooding, NOAA satellites will be watching.