Although virtually no snow fell in the latter part of 2011 or early 2012, the previous winter season brought a white Christmas and several significant snow and ice events.
Christmas Day 2010 was filled with sparkle and holiday cheer. Area children searched for reindeer and sleigh tracks in fresh snow.
A transitional La Niña/El Niño provides some uncertainty to forecasters for long-range predictions.
“Compared to the past few months, the chance is reduced for El Niño to develop during Northern Hemisphere fall/winter 2012-13,” according to climatologists at the Climate Prediction Center.
“Due to the recent slowdown in the development of El Niño, it is not clear whether a fully coupled El Niño will emerge,” they indicated.
Officials are calling the El Niño Southern Oscillation, or ENSO, “weak” or “neutral.”
The snows of 2010-11 were attributed to a La Niña weather episode in the Pacific Ocean.
A La Niña system occurs when the waters in the Pacific are cooler than normal — the opposite of an El Niño.
“In the continental U.S., during El Niño years, temperatures in the winter are warmer than normal in the North Central States, and cooler than normal in the Southeast and the Southwest. During a La Niña year, winter temperatures are warmer than normal in the Southeast and cooler than normal in the Northwest. El Niño was originally recognized by fishermen off the coast of South America as the appearance of unusually warm water in the Pacific ocean, occurring near the beginning of the year. El Niño means The Little Boy, or Christ child, in Spanish. This name was used for the tendency of the phenomenon to arrive around Christmas. La Niña means The Little Girl. La Niña is sometimes called El Viejo, anti-El Niño, or simply ‘a cold event’ or ‘a cold episode,’” according to the National Oceanic and Atmospheric Administration information center.
According to NWS forecasters who issued a report this month, “There is an increased likelihood for above-median precipitation across the central and eastern Gulf Coast region based on the possibility that weak El Niño conditions could have an effect during this season across the Gulf Coast region. It is unclear at this time whether or not weak El Niño conditions will become established this winter across the U.S. and to what degree an extended subtropical jet stream may influence precipitation patterns across the Southeast.”
“This is one of the most challenging outlooks we’ve produced in recent years because El Niño decided not to show up as expected,” said Mike Halpert, deputy director of NOAA’s Climate Prediction Center. “In fact, it stalled out last month, leaving neutral conditions in place in the tropical Pacific.”
“When El Niño is present, warmer ocean water in the equatorial Pacific shifts the patterns of tropical rainfall that in turn influence the strength and position of the jetstream and storms over the Pacific Ocean and United States. This climate pattern gives seasonal forecasters confidence in how the U.S. winter will unfold. An El Niño watch remains in effect because there’s still a window for it to emerge,” forecasters noted.
Much uncertainty continues to exist about how the weather patterns will develop and affect Tennessee and Bradley County. Some areas of East Tennessee did experience an unusual October snowfall at higher elevations as Hurricane Sandy swept to the northeast.
“Whatever the winter weather future, we will be monitoring along with the Morristown office of the NWS to make sure we are prepared,” said Cleveland-Bradley County Emergency Management Agency Director and interim Bradley County Fire Chief Troy Spence.