TULSA, Oklahoma - The National Weather Service is defending the decision not to sound tornado sirens in Tulsa.

The Weather Service says the tornado was so unexpected, by the time they realized it was happening and issued the warning, the dangerous part of the storm was already moving out of Tulsa.

At the National Weather Service, Chief forecaster Steve Piltz replayed the radar data to see if they should have seen it coming.

“This storm just happened so quickly and it was ahead of our warning a little bit,” Piltz explained.

The warning was a couple of minutes behind, and Piltz says with Tulsa's emergency managers on the phone, the delay figured into the decision that it was too late to sound the sirens in Tulsa.

"And basically, in the coordination, it's moved so quickly, it's already out of the city, so it was sort of a joint decision not to blow the sirens,” he said.

“Within a mile of where the storm started, it was considered an EF2,” he said.

Piltz says the tornado appeared on radar about 90 seconds before it hit this restaurant.

“It takes about that long to issue a warning, and activate sirens,” he said. “But because forecasters weren't expecting a tornado, there was a minute or two of consideration about what the radar was showing.”

He added, “Every decision, every move is magnified, so if you say, ‘Hey come look at this data and tell me what you think,’ that 30-40 seconds, it's moved another mile almost; it just goes fast."

The situation was different in Broken Arrow where sirens sounded based on the same radar image of the tornado in Tulsa.