The effects of La Nina were felt before NOAA declared the pattern’s start

NOAA has said a highly anticipated La Niña climate pattern is underway, but the event is somewhat unusual as regions of the world have experienced La Niña-like conditions for months.

According to the agency, weather conditions in the United States and other parts of the world since at least October have resembled patterns of previous La Niña events. These include rainy conditions in parts of the Pacific Northwest and Northern California, a rainy Ohio Valley and a drier East Coast.

Because La Niña is generally weak, conditions around the globe are not expected to change dramatically.

“It is very likely that this La Niña will be weak as the Niño 3.4 index is unlikely to reach -1.0°C for a season. This is based on computer model forecasts and how late in the year La Niña conditions occurred. ENSO events are peaking.” “The Northern Hemisphere winter is over, and La Niña simply doesn’t have much time to strengthen,” NOAA forecasters said.

The La Niña climate pattern is officially underway and is expected to last through winter

La Niña is considered the cool phase of the El Niño-Southern Oscillation (ENSO) and is characterized by below-average sea surface temperatures with anomalies of at least -0.5 degrees Celsius in critical parts of the central and eastern Pacific.

Satellite data showed the current event to be slightly below the required threshold, prompting NOAA to declare a La Niña in progress.

An average La Niña event typically lasts between 8 and 12 months, but can extend well over a year.

The expected length of ENSO’s current cooling cycle is another uncharacteristic feature, as its length is expected to last only a few short months. Long-term climate models show the world could emerge from La Niña as early as February, but more likely in the spring.

This would mean that neutral conditions will likely prevail again for much of 2025 as the planet decides which direction it wants to go.

Little-known weather pattern when El Niño and La Niña are no longer under control

So why did La Niña-like conditions occur before the actual event and why does ENSO not follow normal patterns?

“The short answer is, ‘We don’t know yet.’ However, the occurrence of La Niña-like atmospheric conditions prior to significant cooling of the tropical ocean surface was unusual. The global oceans have been much, much warmer than average for more than a year, which may have contributed to the delay of La Niña. If we calculate the Niño 3.4 index but take into account the temperature of the tropical oceans, we get an index that has been in La Niña territory for months. Just in the last year or so, the difference between the traditional and the relative Niño 3.4 index has already been so large, and we are still exploring this new measurement and all the implications for ENSO development and its impact in a warmer one world,” NOAA forecasters said in a monthly blog.

In other words, climate change may play a bigger role than thought, but until scientists have years and possibly decades of data to study and compare to ENSO state, you can’t expect concrete answers as to why the weather patterns do not comply with previous standards.

NOAA’s official names for “La Niña” and “El Niño” have not been around long, with their widespread use only dating back to the 1980s.

Original source of the article: The effects of La Nina were felt before NOAA declared the pattern’s start