The tornado that ripped through southwest Missouri will likely be rated an EF3 or greater, a forecaster with the National Weather Service said. The tornadic storm killed at least 13 people in southwest Missouri and seven in Oklahoma.

Jason Schaumann, a meteorologist with the National Weather Service in Springfield said an official determination will not be made until later this week after a National Weather Service Quick Response Team (QRT) evaluates the damage.

QRT's are called in to an area when tornado damage could potentially be EF4 or EF5. Tornadoes are rated on a scale from the weakest, EF0 to the strongest, an EF5 where winds are in excess of 200 miles per hour. The teams consist of researchers and meteorologists from different branches of the National Weather Service from across the country.

Schaumann said several local teams investigated the damage early Sunday morning.

"They (the assessment team) found at one point a damage path that was one mile wide. This was a large wedge tornado," Schuamann said. "We had framed houses completely swept off their foundations."

He also said the tornado appeared to have been on the ground for "several miles."

The tornado killed at least 20 people in Oklahoma and Missouri. The hardest hit community was Racine in Newton County where most of the fatalities occurred.

The National Weather Service issued a Tornado Warning for Newton County prior to the tornado touchdown.