Storm Trackers Say Comparing Advance Warning Times Is Difficult

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HUNTSVILLE, Ala.(WHNT)-Local weather experts say it's hard to compare advance warning times for the deadly tornado that struck Texas Wednesday and what we typically see here in north Alabama.

Residents in the small town of Granbury, Texas, had roughly 25 minutes to find shelter from the killer twister, more than double the national average. However, forecasters at the National Weather Service in Huntsville said there really is no reliable average for north Alabama that they go by since average warning times in our area fluctuate wildly from year to year.

National Weather Service Meteorologist David Nadler said the 2013 storm season has been relatively light so far in the Tennessee Valley with advance warning times averaging just five minutes. That may not seem like a lot of time when compared to the national average of ten to twelve minutes.  But, Nadler said those times are directly connected to the size and intensity of an incoming twister.

The mostly minor tornadoes that have struck north Alabama this year are sometimes hard to detect on radar, leading to shorter notices. Compare that to just two years ago during the historic outbreak of 2011, when average warning times in north Alabama fell just shy of twenty minutes, quadruple the current season average. But hundreds of people also died, many from long track EF4 and even EF5 tornadoes that were easily picked up by radar.

"Every event is different," said Nadler, who has been tracking tornado patterns for years. "Sometimes we may have only four or five minute lead time on those events, so it just really depends on the type of event."

Nadler said average warning times in north Alabama will continue to fluctuate from year to year, making comparisons to Texas, or anywhere else, impossible.

"I think it [Granbury tornado] is just a clear indication that no matter how much lead time or advance technology you have, you still can't control what mother nature can do."

Even though averages for advance warning time may swing drastically from year to year, there is a standard that the National Weather Service in Huntsville shoots for. Meteorologists said a warning window of at least thirteen to fourteen minutes is what they always aim to hit when severe weather strikes.