Experts Credit Weather Patterns For Warmest Winter In Decades
MICHELLE WILLARD, Special to the Courier
Sunday, April 1, 2012 6:23 am
The midstate experienced its warmest winter since 1971, according to data collected by the National Weather Service.
“It’s been 40 years since Nashville had such a mild winter,” said Bobby Boyd, a meteorologist with the Weather Service’s Nashville office. “The two previous winters (2009-10 and 2010-11) were much colder than normal and some of the coldest in more than 30 years.”
The winter of 2011-12 was the 13th warmest on record in Nashville with an average temperature of 4.3 degrees warmer than normal.
The lowest temperatures in Murfreesboro was 16 degrees, recorded the night of Feb. 12-13.
“Nashville (and Murfreesboro) were only colder than 20 degrees on three days during the entire winter of 2011-12. Once in December and twice in February,” Boyd said.
This warm weather came on the heels of two very cold winters.
“The two previous winters (2009-10 and 2010-11) were much colder than normal and some of the coldest in more than 30 years,” Boyd said, adding the midstate recorded 12.5 inches of snow last year alone.
In comparison, snowfall totaled only 0.4 of an inch for the season.
And it looks like the beginning of spring could be a record-setter too.
“It looks like this March could end up the warmest on record,” Boyd said. “We are 10 degrees above normal at this point (Friday) in the month.”
Boyd said the warmest March on record was in 1907.
The scientific reason behind this year’s mild winter is a La Niña in the Pacific Ocean, Boyd explained.
La Niña is characterized by unusually cold ocean temperatures in the eastern equatorial Pacific, as compared to El Niño, which is characterized by unusually warm ocean temperatures in the Equatorial Pacific.
“In part the La Niña pattern kept the main branch of the polar jet farther north, with the more active southern branch across the southern United States throughout the winter months,” he explained.
He added the Arctic Oscillation and the North Atlantic Oscillation were both in a positive phase.
“So, the colder air over the arctic regions has remained bottled up in those areas with cold air dumps into Europe from time to time this winter,” he said.
As for the rest of the spring, Boyd said he doesn’t expect any more frigid temperatures this year, unlike 2007, which had the sixth warmest March on record and then had the coldest Easter when 23 degrees was recorded on April 8, 2007.
“I do look for near normal temps around the first week of April,” he said, “but overall, April 2012 should end up above normal.”