Excerpted by permission from THE ENVIRONMENTALIST:
2008 has seen a record outbreak of tornadoes in the United States from California to the Midwest, from the South through the central plains, to the Appalachian states.
In January, THE ENVIRONMENTALIST reported the University of East Anglia’s prediction for a strong 2008 La Niña event.
“The assessment for 2008 is that there will be a “strong La Niña” event in the Pacific, which will limit the warming trend for the year (whilst still being one of the warmest years).”
The La Niña phenomenon is an upwelling of colder waters resulting in a change in ocean temperature that causes a shift in the jet stream, reducing corresponding climate temperature. While this NOAA study from October, 1999, still referenced on their site, which uses data from 1950 through 1996, concluded there was no tornadic connection to the El Niño/La Niña event, Joseph Schaefer, Director of the National Storm Center, seems to have revised that position, according to this February MSNBC report:
Tornadoes do happen in February, but a study by Schaefer two years ago found that winter tornadoes in parts of the South occur more frequently and are stronger when there is a La Niña…
Full article, graphs, climate change considerations and links at THE ENVIRONMENTALIST