New study suggests tornadoes are happening earlier in parts of the U.S.

Tuesday, September 16, 2014, 4:59 PM - A new study by the American Geophysical Union suggests that peak activity in tornado alley in the U.S. is starting and stopping up two weeks earlier than it did 60 years ago.

Researchers examined records from Nebraska, Kansas, Oklahoma and northern Texas to draw their conclusion.

Peak activity typically occurs in this region between early May and early July. On average, high season is showing up about a week ahead of schedule, but “if we take Nebraska out [of the data], it is nearly a two-week shift,” John Long, a research scientist at Montana State University and lead author of the new paper, says in a statement.

The findings could have implications for emergency planners.

“From a public safety perspective, if this trend (of an earlier tornado season) is indeed occurring, then people need to begin preparing for severe weather earlier in the year,” says Greg Carbin, the warning coordination meteorologist at the Storm Prediction Center in Norman, Oklahoma.

RELATED: Everything you need to know about Canadian tornadoes

Scientists aren't sure why activity appears to be shifting. Tornado data only dates back to the 1950s, making it difficult to identify long-term trends.

Earlier studies suggest that a warming climate may be a contributor.

“If winters are not as cold, or if spring times are warmer, the location of the jet stream is most likely displaced north of where it has been in the past,” Carbin says, adding that this could be causing activity to peak earlier in the year.

The full paper was published in last week's edition of Geophysical Research Letters.