How El Niño Could Affect U.S. Weather: NPR

Much of the United States could see warmer than normal temperatures, NOAA said in an update on current forecasts calling for an El Niño climate model.

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NOAA

Much of the United States could see warmer than normal temperatures, NOAA said in an update on current forecasts calling for an El Niño climate model.

NOAA

As hot as Earth’s weather has been in recent years, it’s about to get hotter: El Niño is on the way, with warmer sea temperatures promising new weather extremes, according to US and international forecasters .

For several years now, a persistent La Niña pattern in the equatorial Pacific Ocean has dampened some of the worst temperature rises, as well as upended precipitation patterns. But the World Meteorological Organization says that’s all about to change.

“We have just had the eight hottest years on record, although we have had La Niña cooling for the past three years,” WMO Secretary-General Petteri Taalas said.

In the United States, the change promises relief in other forms, as the outgoing La Niña is associated with greater hurricane activity in the East and dryness in the West.

Here is a quick guide to these two influential climate models:

They affect hurricanes and other weather conditions

El Niño generally brings a calmer hurricane season in the Atlantic and more hurricane activity in the Pacific, while La Niña does the opposite — a dynamic the National Oceanic and Atmospheric Administration has likened to a seesaw.

Warmer El Niño waters may also push the Pacific jet stream south. When this happens, according to NOAA, “northern parts of the United States and Canada are drier and warmer than usual. But on the U.S. Gulf Coast and Southeast, these times are wetter. than usual and increased flooding”.

La Niña said goodbye in March; since then, American forecasters have mounted an El Niño watch.

“There is a 62% chance of El Niño developing during the May-July period, and more than an 80% chance of El Niño occurring in the fall,” according to Emily Becker of NOAA.

La Niña cools and El Niño warms

La Niña “acted as a temporary brake on global temperature rise,” Taalas said. This is because the pattern occurs when sea surface temperatures are unusually cold and are expected to remain so for several months.

We have been seeing La Niña conditions since late 2020, triggering forecasts of below normal winter temperatures for much of the northern United States and warmer temperatures for much of the south.

But due to the new trend towards warmer sea surface temperatures, Taalas added, “El Niño will very likely cause a new peak in global warming and increase the chances of breaking temperature records” that have not been set. established only recently.

It usually takes time for the changes to take full effect. The WMO says the biggest impact on global temperatures is not expected until 2024.

Patterns change regularly and irregularly

The rule of thumb is that El Niño patterns occur more often, but La Niña generally lasts longer, sometimes for years. Most cases of either model usually take just nine to 12 months.

“El Niño and La Niña events occur every two to seven years, on average, but they do not occur on a regular schedule,” NOAA says. In addition to the two models, ocean temperatures are sometimes considered “neutral”, meaning they are not abnormally warm or cold.

As confidence grows that a new pattern is taking hold, it is not yet clear exactly how strong this incoming El Niño might be.

Still, the World Meteorological Organization is urging people and governments to prepare for warmer and more volatile conditions, citing a possible repeat of 2016 – the hottest year on record, thanks to what the WMO calls a “double whammy” of a very powerful El Niño event and human-induced warming from greenhouse gases.”