For now, yes. But Congress would like to change that.
For those caught in the path of the EF 4 tornado in Oklahoma last week, 16 minutes were all they had to prepare themselves for the 200 mph winds that would flip cars, twist steel, and all but complete destroy a 1.3 mile-wide swath of the town.
Sixty or so years ago, they would have been lucky to have any warning at all. A form of the National Weather Service has been issuing tornado warnings only since 1938. Previously, the word "tornado" had been banned by the Army Signal Corps, which used to monitor the weather. To the corps, tornadoes were much too unpredictable to track, and the word incited more panic than meaningful response.
The House Environment Subcommittee is drafting a bill to spur forecasting research and technology procurement in the National Weather Service, in part, to extend lead times for tornado warnings. The National Weather Service had previously received $23.7 million in funds for forecasting in the Sandy Relief bill. The current bill would seek spur forecasting research investments (there's no specific dollar figure yet), and to replace satellite systems that will degrade over the next few years.
For the rest of the story: http://www.nationaljournal.com/domesticpolicy/is-16-minutes-the-best-we-can-do-for-tornado-warnings-20130529