Now that the El Niño is declining and on the way out, it’s worth taking a look at what is likely to come next and how that will impact the growing season and perhaps even 2017.
El Niño has been the dominating atmospheric pattern driving the weather and climate in the Southeast for the past few months. Normally, El Niño brings wetter conditions to the region, with cooler conditions caused by the persistent cloudiness. This year has not been a perfect example.
Though some areas of the Southeast saw well-above normal rainfall, the temperatures across the region have been above average due to conditions not associated with El Niño.
Spring is typically the hardest time of year to predict what will happen in the eastern Pacific Ocean and the atmospheric patterns associated with El Niño and La Niña. Climatologists call this the “spring predictability barrier” because it is very hard to determine what will happen in the next few months as El Niño dies away.
The computer models of what is likely to happen next are all over the place, with some indicating a second round of El Niño, some keeping conditions near neutral, and some predicting a swing to the opposite phase, a La Niña, in the next few months. We will need to wait for sure until around the August time frame to see how the ocean temperatures evolve; that will give us a clue as to whether La Niña will occur next winter.
May see a La Niña by late summer
So how do we determine what climate conditions are most likely going forward? Statistically, in five out of six years following a strong El Niño, the pattern has swung to a La Niña. This gives us some confidence that we may see a La Niña by late summer, although of course each event is unique and statistics are no guarantee of what will actually occur.
It will take time to see the pattern shift to a classic La Niña event, and I expect to see El Niño moisture continue to be a factor in the climate at least for the next two to three months. Cooler conditions are likely in the early part of April but above-normal temperatures are expected to return by the second half of the month. By early summer, neutral conditions are likely to occur, and there is little predictability with that pattern in the summer. If La Niña develops, we should start to see it by late summer.
In La Niña years, late summer is often associated with drier and warmer conditions than usual. That reduces disease pressure but can cause problems for dryland farmers, although harvest conditions are often excellent. The one fly in the ointment is that neutral and La Niña years are also associated with above-normal tropical storm activity in the Atlantic Ocean. The paths of the storm depend on weather conditions at the time the storm develops, so we can’t say anything at this time about where they are likely to go. However, areas that are in the path of the storms can expect to see rainfall of up to several inches, depending on the forward speed of the storms and exactly what their path is.
If La Niña develops this fall, I expect to see warmer and drier conditions than usual next winter across the Southeast. This is good for finishing harvest but reduces the recharge of soil moisture and ground water in the area over the winter months. That can set the stage for drought the following year, so we will have to watch carefully to see if drought redevelops in the region in 2017.
Read more by Knox at her Climate and Agriculture in the Southeast blog.