ATLANTA - A newly confirmed Super El Niño in the equatorial Pacific Ocean is expected to bring a wetter winter, heightened flood risks and potential snow chances to metro Atlanta and North Georgia, according to forecasters and the National Weather Service.
Metro Atlanta winter rainfall outlook
What we know:
Forecasters confirmed Thursday that ocean temperatures averaged across August through October reached the 2 degrees Celsius threshold required for Super El Niño status. An earlier evaluation covering July through September fell short of that mark.
Long-range computer models strongly agree that a strengthened subtropical jet stream will act like a conveyor belt, pulling storm systems and Pacific and Gulf moisture directly over Georgia for the next three months. NOAA’s Climate Prediction Center favors above-normal precipitation across the Southeast, which is expected to improve or end regional drought conditions by late January after every climate site in North and Central Georgia finished 3 to more than 7 inches below normal last winter.
Georgia temperature and snow chances
What we don't know:
While a wetter season is the most confident call, forecasters say winter temperatures and exact snowfall amounts remain uncertain. Extra clouds and rainy days typically hold temperatures near or slightly below normal from the Gulf Coast through the Carolinas, a pattern seen in five of the last six strong El Niño winters, though a cold snap can sneak in at any time.
Cold air is the missing piece needed to turn incoming Gulf Coast low-pressure systems into winter storms, and forecasters will not know if temperatures will drop low enough until each system is a few days out. Forecasters are also monitoring a potential early sudden stratospheric warming event above the North Pole, which previously shook loose Arctic air during the unusually cold 2009–10 winter.
Historical El Niño weather data
By the numbers:
8 of 9: Strong or very strong El Niño winters since 1950 that brought wetter-than-normal conditions across much of Georgia, with some areas running 6 to 24 inches above normal from September through March.
70-plus: River gauges out of more than 240 monitored by the National Weather Service that flooded in late December 2015 after 8 to 12 inches of rain fell during the last very strong El Niño.
100%: Strong or very strong El Niño winters on record that produced at least some measurable snow in metro Atlanta.
North Georgia severe weather preparation
What you can do:
Residents living near creeks, rivers or flood-prone areas should pay close attention to heavy rain forecasts this winter, according to the National Weather Service. For North Georgia and metro Atlanta, the agency's takeaway is simple: prepare for some winter weather.
Because the same active jet stream can fuel cool-season severe storms and tornadoes—similar to the spring of 1998 when damaging tornadoes struck Gainesville and Dunwoody following the 1997–98 Super El Niño—forecasters advise making sure you have more than one way to receive weather warnings, especially at night.
The Source: The information in this story was gathered from weather forecasters, long-range computer models, historical climate records since 1950, NOAA’s Climate Prediction Center and the National Weather Service.