STATEN ISLAND, N.Y. — The latest outlook by the National Weather Service’s Climate Prediction Center reveals decreased odds of a La Niña emergence and reinforces previous forecasts by calling for a weaker and shorter weather event.
For those unfamiliar with La Niña, the key is something called the ENSO cycle.
The El Niño-Southern Oscillation (ENSO) cycle is a recurring climate pattern pertaining to changes in the water temperatures out in the central and eastern tropical Pacific Ocean, according to the weather service.
La Niña’s cool waters push the jet stream northward over the U.S. During La Niña winters, the South sees warmer conditions while the North experiences cooler conditions. This graphic by the National Oceanic and Atmospheric Administration illustrates the conditions resulting from La Niña. (Courtesy of The National Oceanic and Atmospheric Administration)(Courtesy of the National Oceani
The surface waters over part of the Pacific tend to warm or cool over a period of time. That warming and cooling pattern is referred to by the weather service as the ENSO cycle.
ENSO-neutral, as defined by the weather service, is when neither of the extreme phases of the ENSO cycle (El Niño and La Niña) prevail. During this phase, sea surface temperatures in the Pacific Ocean are near normal. ENSO-neutral conditions held strong this summer and continue to persist even now into the end of November.
La Niña, unlike El Niño, is a cold event. During this phase of the cycle, trade winds are enhanced and direct warm water toward Asia, ultimately cooling Pacific waters off the U.S. coast, according to the National Oceanic and Atmospheric Administration (NOAA). When this happens and La Niña takes charge for the winter, temperatures are generally warmer than usual in the South and colder than normal in the North.
The latest on La Niña
While La Niña could carry some significant implications for weather when powerful, forecasts continue to show the development of a weak and brief weather event.
A National Oceanic and Atmospheric Administration graphic shows the percent chance of El Niño, La Niña or ENSO neutral conditions for different three-month periods. (Courtesy of the National Oceanic and Atmospheric Administration)(Courtesy of the National Oceani
The odds of emergence have slightly diminished compared to where they stood a couple of months ago. Initially, in September, La Niña had a 66% chance of emerging before the end of November; that figure dropped down to 60% in October.
Now, the Climate Prediction Center is giving La Niña a 57% chance of emerging sometime before the end of December.
If and when La Niña comes to fruition, it is expected to only last from January through March 2025. This “weak” and “short duration” event “would be less likely to result in conventional weather impacts,” as reported by the Climate Prediction Center.
During a typical La Niña, the weather event could influence the trajectory of storms, resulting in a more northerly track during the winter months.
Given that a weaker weather event is predicted, La Niña may not prove to have the steering power it would normally wield.