With more storms predicted, rescue crews desperately searched for survivors in the rubble of flattened communities Tuesday, a day after a 2-mile-wide tornado carved a path of destruction in the Oklahoma City area.
At least two dozen people were reported killed. Earlier estimates were much higher, but the Oklahoma Medical Examiner's Office revised the estimate down.
Gov. Mary Fallin told CNBC on Tuesday that she's "instructed everyone to make sure first and foremost, we are looking under every single piece of debris we find in all the homes and buildings ... to find anyone that might still be alive and injured."
(Slideshow: Killer Tornado: Scenes From Oklahoma )
(Read More: NBC News Breaking News Coverage of Midwest Tornadoes)
The Storm Prediction Center in Norman, Okla., forecast more stormy weather for Tuesday, predicting golf ball-sized hail, powerful winds and isolated, strong tornadoes for parts of Texas, Arkansas, Louisiana and parts of Oklahoma other than the Moore area.
"Severe weather is all about contrast ... cooler, drier air next to warmer, moist air," Chuck Watson, director of research and development at Kinetic Analysis, told CNBC Tuesday. "Seeing that moisture moving up from the Gulf [of Mexico] in the Midwest, we're probably in for a few pretty tough weeks here."
Kinetic Analysis uses computer modeling and analysis to predict losses from natural disasters, Watson said in a " Squawk Box " interview. "We're still trying to piece together what the track and intensity it was, but the early computer model estimates are $1.2 billion to $2 billion."
He added that he'd be surprised if the damaged topped $2 billion.
The governor said, "It's going to take a long time to get all this cleaned up, to rebuild the structures. We have five schools that were hit with this storm and we lost several schools totally. The hospital was hit. A huge movie theater was hit. Many different buildings, the bank was destroyed."
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