There was a sudden change from an El Niño phase to La Niña in July 2010 which led many forecasters to believe that there would be warm temperatures throughout the Southeast of America. However, the region has been experiencing an extremely cold winter, as a result of the interruption of the North Atlantic Oscillation.
“There is another ocean-driven actress in the house called NAO — The North Atlantic Oscillation, or the Arctic Oscillation,” said James O’Brien, emeritus Robert O. Lawton Distinguished Professor and former state climatologist of Florida.
“The ocean between Canada and Greenland was very cold, creating a blocking high pressure system. As a result, the Atlantic winter storms stayed further south over the Gulf Stream extension and got very strong. Their backside pulled very cold air down from Canada all the way to Florida.”
El Niño and La Niña events can be predicted up to six months in advance, but NAO changes are not so easily predicted, which naturally pose a problem for those attempting to forecast the future, at least in terms of what weather we should be expecting.
The La Niña did arrive, but so did the NAO, which brought lower temperatures for the Southeast.
Florida, while experiencing dry conditions, saw temperatures in December 9 degrees Fahrenheit below the 20th century average, which was the coldest on record for the month, according to the NOAA National Climatic Data Center. On top of that, several cities within the state, including Miami, West Palm Beach, Fort Lauderdale, Daytona, Orlando, Tampa and Tallahassee, experienced record cold temperatures in December.
Medium-range weather prediction models, however, suggest that there will be a break from the negative NOA pattern, allowing the stronger La Niña re-establish itself on the climate patterns in the Southeast.
“Warmer and continued dry weather is still the best forecast for the remainder of the winter and the transition to spring in the Southeast,” O’Brien said.