By Monday morning, forecasters at the National Weather Center, home of the storm lab and storm prediction center, knew "that any storm that formed in that environment had the potential to be a strong to violent tornado," he said.
"This is a pretty classic setup," Brooks said.
Tornadoes have two main ingredients: moist energy in the atmosphere and wind shear. Wind shear is the difference between wind at high altitudes and wind near the surface. The more moist energy and the greater the wind shear, the better the chances for tornadoes.
But just because the conditions are right doesn't mean a violent tornado will form, and scientists still don't know why they occur in certain spots in a storm and not others, and why at certain times and not others.
On Monday, the moist energy came up from the Gulf of Mexico, the wind shear from the jet stream plunging from Canada. "Where they met is where the Moore storm got started," Brooks said.
With the third strong storm hitting Moore in 14 years — and following roughly the same path as an EF5 that killed 40 people in 1999 and an EF4 that injured 45 others in 2003 — some people are wondering why Moore?
It's a combination of geography, meteorology and lots of bad luck, experts said.
If you look at the climate history of tornadoes in May, you will see they cluster in a spot, maybe 100 miles wide, in central Oklahoma, Houston said. That's where the weather conditions of warm, moist air and strong wind shear needed for tornadoes combine, in just the right balance.
"Central Oklahoma is a hot spot and there's a good reason for it," Houston said. "There's this perfect combination where the jet stream is strong, the instability is large and the typical position for this juxtaposition climatologically is central Oklahoma."