By Pam Knox
This year's near-average sea surface temperatures in the eastern Pacific Ocean show the tenacity of the current neutral phase of ENSO, or the El Niño Southern Oscillation, over the last few months. While the ocean and overlying atmosphere often oscillate between warmer than usual (El Niño) and cooler than usual (the opposite phase, La Niña), this year ocean temperatures have stayed near their long-term average values. When neutral conditions like this occur, winter temperatures in Georgia tend to swing wildly between cold and warm conditions.
That is exactly what we have seen this year. In addition to the swings in temperature, precipitation has also varied substantially across the state. Earlier this winter, the atmosphere was locked into a pattern which caused flooding in northwest Georgia but left the southern half of the state high and dry. More recently, the axis of the storms has shifted to central Georgia, dumping excess rain across areas in exceptional drought. The rain has been a mixed blessing, improving soil moisture conditions and raising the levels of farm ponds, but making it difficult to get into the fields to prepare for the coming growing season.
Neutral conditions are forecast to continue through April. One of the consequences of neutral conditions is an increased chance for killing frost late in the season, or spring, as the swings in temperature continue. Another is the increased chance for tropical storm activity and rain during the June-November period. By next fall, we could see either an El Niño or a La Niña return, or neutral conditions could continue. Current forecasts show us most likely to continue in neutral conditions at least into next winter, but if we switch to a different phase, La Niña is twice as likely as El Niño to occur. If La Niña comes back, we can expect to see a return to drier and warmer than normal conditions next winter.
Climate predictions are increased chance of above-normal temperatures to continue through August, but no predictable pattern in precipitation. Once we get into the tropical season, then the rainfall will depend critically on exactly where the storms go, something no climatologists can predict at this point.
Knox is the University of Georgia College of Agricultural and Environmental Sciences agricultural climatologist.