ENSO ~ El Niño-Southern Oscillation

[GordMay]

ENSO ~ El Niño-Southern Oscillation

El Niño and La Niña are opposite phases of a natural climate pattern across the tropical Pacific Ocean that swings back and forth every 3-7 years on average. Together, they are called ENSO (pronounced “en-so”), which is short for El Niño-Southern Oscillation.

The ENSO pattern in the tropical Pacific can be in one of three states: El Niño, Neutral, or La Niña. El Niño (the warm phase) and La Niña (the cool phase) lead to significant differences from the average ocean temperatures, winds, surface pressure, and rainfall across parts of the tropical Pacific. Neutral indicates that conditions are near their long-term average.

El Niño and La Niña alternately warm and cool large areas of the tropical Pacific—the world’s largest ocean—which significantly influences where and how much it rains there. The primary location of moist, rising air (over the basin’s warmest water) is centered over the central or eastern Pacific during El Niño and over Indonesia and the western Pacific during La Niña.

This shift disrupts the atmospheric circulation patterns that connect the tropics with the middle latitudes, which in turn modifies the mid-latitude jet streams. By modifying the jet streams, ENSO can affect temperature and precipitation across the United States and other parts of the world. The influence on the U.S. is strongest during the winter (January-March), but it lingers into the early spring.

During El Niño, the southern tier of Alaska and the U.S. Pacific Northwest tend to be warmer than average, whereas the U.S. southern tier of state—from California to the Carolinas—tends to be cooler and wetter than average. During La Niña, these deviations from the average are approximately (but not exactly) reversed.

The influence of El Niño and La Niña in some parts of the United States and the rest of the world can be so strong that they increase the odds of “extreme weather events”—phenomena that rank in the highest or lowest 10% compared to historical observations.

Within any given decade, the warmest years are usually El Niño ones, and the coldest are usually La Niña ones.

Generally, El Niño contributes to more eastern and central Pacific hurricanes and fewer Atlantic hurricanes while, conversely, La Niña contributes to fewer eastern and central Pacific hurricanes and more Atlantic hurricanes..
The continental United States and Caribbean Islands have a substantially decreased chance of experiencing a hurricane during El Niño and an increased chance of experiencing a hurricane during La Niña.
Both El Niño and La Niña influence where Atlantic hurricanes tend to form. During El Niño, fewer hurricanes develop in the deep tropics from African easterly waves. Conversely, during La Niña, more hurricanes form in the deep tropics from African easterly waves and, therefore, have a greater likelihood of becoming major hurricanes that may eventually threaten the Caribbean Islands and the United States.

More ➥ https://www.climate.gov/enso

[GordMay]

September 2020 ENSO update:
La Niña conditions are present and are likely to continue through the Northern Hemisphere winter (~75% chance)
More ➥ https://www.cpc.ncep.noaa.gov/produc...ensodisc.shtml

[GordMay]

'El Niño' Predictions for Winter 2023-2024:

As El Niño causes the warm water in the Pacific Ocean to move eastwards, the Pacific jet stream will move to the south of its neutral position.
As a result, the United States National Oceanic and Atmospheric Administration (NOAA) predicts that the Northern U.S. and Canada will have a milder and drier winter than they usually do.
In contrast, NOAA says the Southeast and Gulf Coast will experience a wetter winter than normal, increasing the chances of flooding.

Europe can expect a wetter-than-average winter in the south of the continent, and a drier and colder winter in the north.

Countries like Japan, Australia, New Zealand, and Indonesia will most likely experience hotter and drier weather towards the end of 2023 and the beginning of 2024.

El Niño has already affected winter in South America, which has experienced the hottest and driest winters on record. However, as spring turns into summer, El Niño will likely bring heavy rains to much of South America, which could lead to flooding.

Climate experts all agree there will be a higher chance of monsoons in India, heavy rains in East Africa, and flooding during the end of 2023 and the beginning of 2024. On the contrary, El Niño is expected to cause a substantial reduction in the amount of precipitation in South Africa.

Furthermore, the climate scientists at NOAA warn that El Niño makes hurricanes more likely in the Pacific Ocean, and islands such as Hawaii will be at high risk of experiencing tropical cyclones towards the end of 2023.

[GordMay]

U.S. Winter Outlook: Wetter South, warmer North
➥ https://www.noaa.gov/news-release/us...h-warmer-north

[GordMay]

NOAA’s Climate Prediction Center [CPC] issued an El Niño advisory, in its monthly update, on Thursday, a formality, that makes official what we’ve long known. El Niño is here, it’s strong, and it could affect our winter weather.

CPC Forecasters give a 35% chance of this El Niño growing “historically strong,” with average temperature anomalies of 2.0°C, or warmer. This change represents a slight uptick, in the odds of a high-end El Niño, compared to the agency’s October update.

Since 1950, only three winters have seen average temperatures, in this part of the Pacific, rise more than two degrees above normal: 1982-83; 1997-98; and 2015-16. All three of those seasons saw highly impactful shifts in weather patterns, around the world.

Some complicating factors will likely make this winter unique, including a far-reaching warmth across the Pacific, as well as the exceptional warmth, that remains present throughout much of the Atlantic Ocean.

Past data indicates that El Niño winters tend to be relatively mild, across most of North America, particularly during strong El Niño events, like the one anticipated for this winter

“El Niño Advisory - November 9, 2023" ~ by NOAA’s Climate Prediction Center [CPC]
➥ https://www.cpc.ncep.noaa.gov/produc...ensodisc.shtml

[GordMay]

El Niño ➛ La Niña?

There is a 58 per cent probability of a La Niña event, starting in July to September, according to the Columbia Climate School’s International Research Institute [IRI] for Climate and Society, in a report published Jan. 19. [1]
There is a 73 per cent chance that ENSO-Neutral will occur between April and June, according to the IRI. [1]

La Niña also tends to follow a relatively strong El Niño event, which has been occurring since June last year.

There is also a weather period, where neither event occurs, called El Niño-Southern Oscillation, or ENSO-neutral, where sea level temperatures are close to average. This year, it appears as though El Niño will transition into ENSO, during the spring, according to the National Oceanic and Atmospheric Administration’s (NOAA) Climate Prediction Centre. [2]

[1] “ENSO Forecast” [January] ~ by IRI
➥ https://iri.columbia.edu/our-experti.../enso/current/

[2] “EL NIÑO/SOUTHERN OSCILLATION (ENSO) DIAGNOSTIC DISCUSSION” ~ by NOAA’s Climate Prediction Centre
➥ https://www.cpc.ncep.noaa.gov/produc...ensodisc.shtml

[GordMay]

Last week, Berkeley Earth, a non-profit, independent climate analysis organization, released its March 2024 update [1], and forecast that 2024 had a 59 per cent chance of being the warmest year on record, and a 41 per cent chance it would come in at second place.

[1] “March 2024 Temperature Update” ~ by Robert Rohde, Berkeley Earth
➥ https://berkeleyearth.org/march-2024...rature-update/

"...
El Niño Outlook

March 2024 saw a significant weakening of the current El Niño event. The current CPC/IRI analysis [2] suggests that El Niño conditions will dissipate around Northern Hemisphere Summer in 2024. The current El Niño has weakened to a moderate intensity (after being roughly the 3rd strongest of the last 30 years) and is likely to continue dissipating over the next several months.

The current El Niño is likely to moderately boost global average temperatures during 2024. Due to the lag between the development of El Niño and its full impact being felt on global temperatures, it is plausible that the current El Niño will have a greater impact on global temperatures in 2024 than it did in 2023. If a La Niña event develops in late 2024, as now appears likely, this will generate moderately cooler conditions late in 2024. The interplay between the current El Niño, the possibility of a late 2024 La Niña, and unusual conditions in other regions (e.g. warmth in the Atlantic) will contribute to whether 2024 is or is not ultimately warmer than 2023...

... Estimated Probability of 2024 Annual Average final rankings:
1st – 59%
2nd – 41%
3rd or lower – <1%
...”

[2] “ENSO Forecast” ~ by the Climate Prediction Center/NCEP/NWS [Updated April 11, 2024]
➥ https://iri.columbia.edu/our-experti...nso-cpc_update

“Synopsis:
A transition from El Niño to ENSO-neutral is likely by April-June 2024 (85% chance), with the odds of La Niña developing by June-August 2024 (60% chance)...”