BIRMINGHAM, Ala. (WIAT) -- You may have heard of La Niña and El Niño before, which is one of our climatological tools that meteorologists will use as a guide into the predicting the larger-scale weather pattern.
Scientists use the ocean water temperature anomalies in the Nino 3.4 region located off the coast of Peru and Ecuador in the Equatorial Pacific Ocean to determine which phase we're in.
When those ocean water temperatures are cooler than average, then we are in a La Niña. We are currently teetering the line between a very weak La Niña and a neutral-based ENSO (El Niño/Southern Oscillation) as we come out of winter and into spring. The ENSO forecast is to remain in this neutral/weak La Niña phase heading into the coming months. This does lead to implications to the weather pattern in North America.
During a typical and arguably stronger La Niña, warmer and drier conditions are found across the southern tier of the U.S. The jet stream gets shoved just to our north, taking the above average precipitation into places like the Ohio Valley.
In 2025, however, the La Niña is rather weak, having a slightly different influence on our spring pattern in terms of temperatures. In years with a similar climate pattern since the 1950s, the period of March through May actually had cooler and drier weather than normal across central Alabama.
One may assume with cooler and drier weather occurring in those years with similar patterns, then our severe weather risk is lower because it could lead to less moisture and less heat, both of which are ingredients for severe storms. That is not necessarily the case, however.
We found that since 1999, Alabama averages around 30 tornadoes from March through May. If we specifically look at those years with a weak La Niña to neutral-based ENSO, the number of tornadoes during the spring months still comes out to near average. This is likely because of our close proximity to the jet stream, which is the focus for storm systems, placing us in the warm sector and making central Alabama more vulnerable to severe storms and tornadoes.
Keep in mind, La Niña is just one of many variables that go into a long-range or seasonal forecast. This is just diving into one of those factors, and we have certainly seen some of our worst severe weather seasons during La Niña years. The CBS 42 Storm Team will have your back when any severe weather is looming over the coming months.
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