Police in Tulsa, Oklahoma, are going through neighborhoods near a dam encouraging residents to get out of there in case the area floods due to release of water meant to keep the structure from failing.
The Army Corps of Engineers is releasing 215,000 cubic feet of water per second at the dam at Keystone Lake because the water is 29 feet above its normal level.
Tulsa Mayor G.T. Bynum tweeted that 215,000 cfs is the minimum rate they can release to keep the water in the reservoir from topping the floodgates. If the floodgates don't work, the dam could fail, Bynum said.
While that dam is about 20 miles from the city, Tulsa authorities were telling people to be ready to leave their homes quickly if the situation deteriorates.
"If you live an area along a river, creek or stream, we ask that you prepare now in case you are asked to evacuate. Have a GO KIT ready -- clothes, medication, important documentation, baby supplies. Charge your digital devices now," the city tweeted.
The warnings came as thunderstorms popped up Wednesday in Oklahoma, Missouri and Kansas.
The western portion of Tulsa was under a severe thunderstorm warning and CNN meteorologist Brandon Miller said storms are capable of dropping heavy rain in a short amount of time, worsening the flood situation quickly.
The showers are part of a deadly spring storm system that has unleashed drenching rain, flash flooding and hail in the central United States -- along with more than 130 reports of tornadoes in five days.
The storms have been a factor in at least four deaths.
And there is more bad news for Wednesday as the US Storm Prediction Center has taken the rare step of issuing two tornado watches with warnings that these event are each a "particularly dangerous situation." Forecasters are concerned over the possibility of violent, long-track tornadoes on Wednesday night.
Missouri couple dies in traffic accident
A husband and wife in Missouri were killed Tuesday when their SUV skidded across the center lines of US highway 160 and the vehicle struck a semi.
At least one person drowned in Oklahoma after driving around a barricade on a road in Perkins, the city's Emergency Management office announced.
And in Iowa, a tornado apparently destroyed a home early Wednesday near the city of Adair, killing a woman and seriously injuring a man, officials said.
The extreme weather is not just limited to tornadoes.
Parts of Oklahoma, Kansas and Missouri had more than three inches of rain in the past 24 hours, and are still under flood warnings, the National Weather Service said.
After the drenching rain, rescuers such as those in the Broken Arrow Fire Department in Oklahoma posted harrowing videos of people being pulled out of gushing flood waters and warned people to avoid flooded roads.
Firefighters responded to a car swept off the roadway Tuesday and found a man clinging to a fence post, unable to get out of the water, CNN affiliate KOKI reported.
The rescue team deployed a life safety rope and got in the water to climb to the victim. They gave him a flotation device and pulled him to safety.
Officials suspect a tornado killed a woman and injured a man in Iowa
In west-central Iowa, a home was destroyed by what is believed to have been a tornado early Wednesday, killing a woman and injuring a man inside, the Adair County sheriff's office said.
Linda Lee Brownlee, 74, was found dead in her destroyed home near the city of Adair after someone called 911 just before 2 a.m., CT the sheriff's office said.
Harold Brownlee, 78, was taken to a hospital, where he was in critical condition late Wednesday morning, according to the sheriff's office.
The weather service said a tornado -- up to 150 yards wide -- struck the area with peak wind speeds of up to 130 mph. Many trees were down, and a couple of other homes in the area sustained minor damage, authorities said.
The tornado touched down at 1:29 a.m. CT and appeared to dissipate eight minutes later, having traveled nearly 5 miles on the ground in the rural area, the weather service said.
Storms have repeatedly hit the same areas recently, making the Plains and the Midwest more vulnerable to flooding.
Serious river flooding -- including along the already swollen Mississippi River -- is expected in the central US as more rain falls over the region in the next few days.