MEMPHIS, Tenn. — The global weather pattern known as El Niño is officially over; according to NOAA as of last week. El Niño is when waters off of the South American coast are warmer than average and can drive large-scale weather patterns, especially in our Winter months. Now that this warmer water has eroded away, what could this mean for the months ahead, and what can we expect?
As of mid-June, the Climate Prediction Center has put a 65% chance that La Niña develops going into the rest of Summer. Looking at ocean temperatures, there is already an area of cooler waters that are forming off of South America. This is expected to grow over the months ahead.
During the Winter El Niño and La Niño have very large influences on our weather patterns. During the Summer months this is not entirely the case, but, they can still cause some changes. Looking at every La Niña year since 1970, the Summer months tend to trend warmer, especially in the central US. This hot pattern often results in drier weather across the Eastern US.
Looking at the historical data in Memphis, our El Niño Summers tend to be cooler and wetter while La Niña years tend to be warmer and drier. There isn't a huge difference between the two patterns overall though which highlights the limited influence it has on the season.
One place where La Niña can make a huge difference in the Summer months is when it comes to the tropics. La Niña often lowers winds that often work against the formations of systems in the Caribbean, this typically leads to above-average activity in the tropics. With experts predicting a very active hurricane season this year, it is easy to see how La Niña is playing into this forecast. Systems that form in the Gulf of Mexico can often bring heavy rain inland toward the Mid-South which could impact rainfall but also lower temperatures due to increased cloud cover.
While any impacts from the switch to El Niño over to La Niña won't be immediate, this something we will have to keep an eye on especially towards the later Summer months.
