Southeast’s winter weather will likely swing from cold to warm to wet to dry.
The sea surface temperatures near the equator in the eastern and central Pacific Ocean are close to normal, meaning the region is in the neutral phase of the El Niño/La Niña cycle, natural phenomenon where the ocean temperatures in the tropical Pacific swing between warmer-than-normal and colder-than-normal every two to seven years, says David Zierden, Florida’s climatologist who keeps up with such.
Winter weather and climate patterns in Florida and the Southeast are heavily influenced by this weather cycle.
El Niño ushers in warm sea surface temperatures near the equator for six months to a year. This sets jet stream patterns in place that usher frequent storms and rain to the northern Gulf Coast, Florida and the Southeast Atlantic coast along with cooler temperatures.
The opposite phase, or La Niña, describes a colder-than-normal sea surface in the same region of the Pacific Ocean. La Niña brings warmer, drier winters to the Southeast, often leading to the development of drought.
Instead of the odds being heavily tipped towards wetter and colder or drier and warmer, all possibilities are equally likely in a neutral winter.
From south Florida to the Carolinas, the summer weather ranked among the wettest ever with many areas setting records. Even in the parts that have received a little less rainfall, saturated soils and standing water were a huge problem.
Many locations recorded more than 30 inches of rain in the three months, over half the annual average, he said. The rainfall was not only heavy, but widespread and fell nearly daily. In the month of July, many locations in Florida, Alabama and Georgia recorded rainfall on 25 of the 31 days in the month.
The Southeast can expect freezing temperatures nearly every winter as far south as Lake Okeechobee, Fla. Some years you see severe freezes and Arctic outbreaks that devastate citrus and vegetable production in Florida.
These "impact" freezes happen every 10 to 20 years. A dozen or so of these "impact" freezes have struck since 1894, including several in the very cold decade of the 1980's. Of these harsh freezes, nearly all have occurred during the neutral phase of the Pacific Ocean, the condition now in place.
During years with El Niño or La Niña, the jet streams seem to lock into preferred positions that block the intrusions of the coldest Arctic air masses.
“With neither El Niño nor La Niña in place this year, the jet streams are freer to meander over North America, leading to greater variability in temperature and rainfall from week to week,” he says.
The neutral phase does not guarantee a damaging freeze this winter, but a damaging freeze is twice as likely this winter than in other phases of the Pacific Ocean cycle.
More from Southeast Farm Press