Weather forecasters can get a bad rap for predictions which don’t always turn out to be as accurate as they are supposed to.
Systems shift and change. A great deal of forecasting depends on patterns and history … especially what happens at sea and to the west. And, a significant portion of Tennessee’s weather forms in the Gulf of Mexico.
What happens when warm Gulf moisture combines with cold Arctic air?
This year, forecasters are predicting at least four significant winter weather events.
A weak or more neutral El Nino, coupled with an active southern jet stream, could be one cause of snowfall in Southeast Tennessee.
Winter officially begins Dec. 21, at 12:11 p.m. … the darkest day of the year.
Officially, the Southeast, including Bradley County and most of the region, have equal chances for virtually any type of weather event this year.
Much will depend on that weak or neutral El Nino and the Gulf stream, as well as the typical winter jet of cooler air from the north.
Forecast maps provided by the National Oceanic and Atmospheric Administration (NOAA) indicate the area stretching across the nation from the west in California, throughout some of the Plains states, into the Mississippi Valley region and eastward into Virginia, then northward to Maine, will be the mixing bowl for the 50/50 chances of any possible event, according to data from NOAA.
“Possible” will be the key word and probability will be an elementary term as conditions become an equation in the mixing bowl.
In 2010, Bradley County and surrounds experienced a number of snow events — even a white Christmas and snows into the new year.
Warmer temperatures are predicted for the deep South, southern Plains and desert Southwest, reinforcing drought conditions there and possibly warmer temperatures locally from December through February.
“It’s a challenge to produce a long-term winter forecast without the climate pattern of an El Nino or a La Nina in place out in the Pacific, because those climate patterns often strongly influence winter temperature and precipitation here in the United States,” said Mike Halpert, acting director of NOAA’s Climate Prediction Center.
“Again, a forecast of a dry winter doesn't preclude occasional storms producing significant rain or snow in any area,” Halpert said.
“Without this strong seasonal influence (El Nino/La Nina), winter weather is often affected by short-term climate patterns, such as the AO, that are not predictable beyond a week or two, so it’s important to pay attention to your local daily weather forecast throughout the winter.”