Weather patterns in Pacific trending toward higher precipitation, warmer winter

By Kyle Troutman [email protected]

A strengthening El Niño in the Pacific Ocean could bring a wetter-than-normal winter to southwest Missouri, with temperatures expected to be slightly warmer than average, according to the National Weather Service (NWS) in Springfield.

The weather pattern is already developing and could become one of the strongest El Niño events on record.

The NWS said Sept. 15 that there is a 93% to 98% chance El Niño will reach the “very strong” category from October through at least January. There is also a 75% chance the event could become stronger than previous El Niño events dating to 1950.

Despite the name, El Niño is not a storm or a single weather event. It is a recurring climate pattern caused by changes in ocean temperatures and atmospheric circulation across the tropical Pacific. During an El Niño, sea-surface temperatures in the central and eastern equatorial Pacific become warmer than normal as the trade winds weaken or reverse.

The current event is particularly strong, as the NWS reported that sea-surface temperatures in the eastern Pacific were more than 2 to 3 degrees Celsius above normal as of Sept. 15. Those unusually warm waters can alter the position and strength of the jet streams, changing the odds of different types of weather across North America.

The changes don’t mean El Niño dictates the weather on any particular day. Instead, it shifts the overall odds of certain conditions occurring over a season.

“The general patterns can be identified, but it does not guarantee a specific outcome,” the NWS said in its briefing.

For Barry County and southwest Missouri, El Niño’s potential effect is less straightforward than it is for some other parts of the country.

The region falls within what the NWS describes as a “transition zone” between areas where El Niño’s effects are more consistent. In general, El Niño tends to favor warmer and drier conditions farther north and cooler and wetter conditions farther south.

Southwest Missouri sits between those patterns, meaning conditions can vary considerably from one El Niño event to another.

Historical data from strong El Niño events provide some clues about what could happen this winter, the NWS said. The strongest signal for the Ozarks is precipitation.

The NWS said 8-10 of the 11 strong El Niño events on record, roughly 75% to 90%, produced above-normal precipitation in the region.

For the Ozarks, normal winter precipitation is about 7-8 inches. The current Climate Prediction Center outlook gives the area a 33% to 40% chance of receiving above-normal precipitation this winter.

That could be particularly significant following the region’s recent dry conditions, although the El Niño outlook does not guarantee that every month or individual storm will be wet.

Temperature trends associated with strong El Niño events are considerably less consistent.

The NWS said there is a “very slight preference” for above-normal temperatures in the Ozarks, but only six or seven of the 11 strong El Niño events on record produced above-normal temperatures. Four or five resulted in below-normal temperatures.

Normal winter temperatures in the Ozarks generally range from highs of 40-50 degrees to lows of 20-30 degrees.

So, while the odds lean slightly toward a warmer-than-normal winter, periods of significant cold are still possible.

The combination of somewhat warmer temperatures and increased precipitation could have an effect on what form that precipitation takes.

The NWS said the overall pattern favors above-normal precipitation but suggests a slight preference toward fewer snowstorms.

When snow does occur, however, historical strong El Niño events indicate that individual snowstorms could produce greater-than-normal accumulations. Only two to five of the 11 strong El Niño events produced above-average seasonal snowfall, according to the NWS.

Normal winter snowfall in the Ozarks is approximately 10-15 inches.

The NWS said the combination of above-normal temperatures and precipitation means much of the winter precipitation could fall as rain rather than snow. That, however, does not eliminate the possibility of significant snow or other winter weather. And, El Niño does not prevent severe weather from occurring during the winter.

An important distinction for area residents, the NWS said, is that an El Niño outlook is not a day-to-day weather forecast. A winter classified as “above normal” for temperature or precipitation can still contain periods of below-normal temperatures, dry stretches, snowstorms or other extremes.

The NWS emphasized that seasonal forecasts describe the overall average conditions expected across a period. They do not mean every day or every week will experience those conditions.

The strongest historical signal is for more precipitation, while temperatures have only a slight tendency to run above normal. Snowfall may be less frequent overall, but significant snow remains possible when the right conditions develop.

For now, forecasters are watching an El Niño that could become historic, the NWS said.

The Service’s latest assessment gives the event a 75% chance of exceeding the strength of previous El Niño events dating to 1950 — a development that could make its influence on the nation’s weather patterns significant heading into the 2026-27 winter.