Because a tornado is part of a severe convective storm, and these storms occur all over the Earth, tornadoes are not limited to any specific geographic location. In fact, tornadoes have been documented in every state of the United States, and on every continent, with the exception of Antarctica (even there, a tornado occurrence is not impossible). In fact, wherever the atmospheric conditions are exactly right, the occurrence of a tornadic storm is possible. More on the conditions necessary for tornado formation can be found at the NOAA National Severe Storms Laboratory Tornado Page.
Between April 25 and April 28, 2011, a record-breaking total of 362 tornadoes tore through the southeastern and central United States. Could climate change fuel such an unprecedented cluster of twisters? A number of commentators have addressed the question, but the most concise answer I’ve heard yet comes in the 36th minute of an On Point interview with NOAA tornado expert Harold Brooks.
On Point: When you look at the architecture of the weather that produced these storms can you tie it to global climate change? We’ve seen warning after warning saying that we may see an increase in storm conditions because of climate change.
Brooks: Well, the planet has undoubtedly warmed in the last 50 to 100 years. And it will undoubtedly continue to warm as greenhouse gases play a greater role. It’s not really clear what the connection is between tornadoes [and climate change] in particular. Some of the ingredients we look for in the production of supercells, such as the warm moist air at low levels, are going to increase in intensity and frequency and be supportive of supercell storms. On the other hand, one of the main predictions of climate change is that the equator to pole temperature difference will decrease because the poles will warm more than the equator. That’s related to the change of the winds with height term, which is one of the things that helps organize storms and make them more likely to produce tornadoes. That’s predicted to lessen as we go along. So we’ve got some ingredients that will be increasing in intensity and some that will be decreasing. If we look historically at the record and try to make some adjustments over the last 50 years for what we know is changes in reporting, we really see no correlation between occurrence and intensity and global surface temperatures or even the US national temperature.
