ABILENE, Texas (KTAB/KRBC) – Today, National Oceanic and Atmospheric Administration (NOAA) announced that La Niña conditions have emerged in the Tropical Pacific for the second winter in a row. But what is La Niña, and what does that mean for winter here in the Big Country?
What is La Niña?
La Niña is one phase of climate phenomenon ENSO, or El Niño Southern Oscillation. ENSO is one of the most important climate phenomena on Earth because of its ability to change the global atmospheric circulation, which in turn influences temperature and precipitation across the globe. Usually the trade winds, which blow from east to west, push warm surface waters toward Asia.
However when the La Niña phase is in effect, we see a cooling of the ocean surface or below average sea surface temperatures in the central and eastern Tropical Pacific Ocean. The normal easterly winds that we see all year long for global circulation along the equator become even stronger. These winds push more warm water toward Asia, while off the west coast of North America upwelling increases. This upwelling brings cold and nutrient-rich water to the surface of the Pacific.
How does this impact the winter here in the Big Country?
But what does all of this mean for us here in the Big Country? The cooler waters in the Pacific push the jet stream northward. Due to this position of the Pacific jet, the majority of the state of Texas during La Niña tends to be warmer and drier than average in the winter months.
If Texas enters into an extended dry period this winter, some portions of the state are in better shape than others. In the Big Country, we have seen at least the first category of drought (abnormally dry) since August 10, 2021, so a drier trend in the winter months doesn’t look too good in the long run. However, it is important to remember that this is just an overall trend of the season from December through February. Individual cold fronts and low pressure systems will deviate from this trend at times.
La Niña by the numbers
As touched on before, this is the second winter in a row that La Niña will be present. The winter of 2019 was neutral, but last winter we had La Niña in effect. Looking at data from the last two years we can definitely see La Niña’s impact on precipitation.
|Winter of 2019 (Neutral)||6.03″|
|Winter of 2020 (La Niña)||3.04″|
|Normal Measured Precipitation for Dec.-Jan.||3.65″|
While the impact of reduction of precipitation was seen quite easily between the last two years, La Niña’s impact on temperature was not as obvious.
|Winter of 2019 (Neutral)||61.9 degrees|
|Winter of 2020 (La Niña)||56.7 degrees|
|Normal Average Max Temperature for Dec.-Jan.||60.33 degrees|
In a neutral year, the state of Texas can also see warmer winter temperatures as we see with La Niña. It just so happened that the trend was weaker for warm temperatures last winter compared to the trend seen in the winter of 2019.
Overall, it is important to remember that the warmer and drier conditions seen during La Niña winters are just a trend. This doesn’t mean we’ll see temperatures in the 80s throughout the season and never see a drop of rain. Individual weather systems will still impact our day-to-day conditions throughout the winter months. The warmer and drier trend is relative to what we normally see during the months of December through February.