"We knew well in advance these storms were going to be quite dangerous," he told CNN. "The weather service was crystal clear, to stay off the roads after 4 p.m. yesterday."
In Moore, the storms affected residents still picking up the pieces from the previous disaster.
"There's damage everywhere," Mayor Glenn Lewis told CNN's Anderson Cooper.
'Overwhelmed' by rains, flooding
Most of Lewis' already devastated town blacked out Friday night, with flooded streets adding to the headaches.
"I can't even get home to see if my house is OK," the Moore mayor said Friday night.
Eight to 11 inches of rain hosed Oklahoma City, drenching the area, Yager said.
An inch of water pooled on the first floor of City Hall, and apartments in low-lying areas of town were hit harder.
"We've seen widespread flooding throughout the entire 621 square miles," she said.
Flooding stranded some motorists.
"We saw flooding in areas that we don't see flooding," said police Lt. Jay Barnett. "We were overwhelmed."
3 die by drowning in Missouri
The impact of the severe weather spread beyond Oklahoma.
A powerful storm caused major damage to a gymnasium of Gillespie High School in southwestern Illinois, with bricks piled up from what had been the gym's front now piled up on the school's lawn, Gillespie Mayor John Hicks said. Seven to 10 homes were destroyed, and more than 30 others suffered damage, in the storm.
Thankfully, though, no one died or was significantly injured in the town of about 3,400 people. Gillespie's mayor said things might have been much different had the storm struck next week, when hundreds were set to gather not far from the high school for a celebration called Black Diamond Days.
In Missouri, Gov. Jay Nixon declared a state of emergency, as the storm front moved into his state stripping sidings and roofs off homes and causing deadly flooding.
A tornado in St. Charles and St. Louis counties left a path "over 10 miles of significant damage ... that caused dozens and dozens of houses to be literally blown up," the governor told CNN affiliate KSDK on Saturday.
Aerial video from CNN affiliate KMOV showed the second floors of several homes ripped apart, with houses to the front and behind still standing. In one home, a man walked across the exposed second floor, walls and roof gone, at one point picking up what appeared to be a picture as he negotiated debris on all sides. Nearby, shirts still hung on one side of what used to be a closet.
Also damaged was the 10,000-seat Family Arena in St. Charles, county spokesman Colene McEntee told CNN. The damage led three high schools in the Francis Howell school district to cancel graduation ceremonies that had been scheduled for Saturday, KSDK reported.
No one was killed in that tornado, but three people drowned in the state, according to Nixon. Problems with high waters aren't necessarily going away, especially in the southern part of the state.
"Waters are rising, floods are still occurring, and we're asking people to be very safe," the governor said Saturday afternoon.
In Moore, the howls of civil defense sirens sent storm-weary residents scrambling again.
Candace Looper retreated to her windowless laundry room with her cat and stacked couch pillows on top of her.
"I've been praying, and I've been singing 'The Lord's Prayer' and singing 'Amazing Grace,' so I'm OK," she told CNN.