Posts Tagged El Niño-Southern Oscillation

Dec 8 2014

NOAA: Don’t Count On El Niño To Bring Drought Relief In California


It’s less likely an El Niño event will bring rain to parched California farms next fall or winter.

The forecast released Thursday from the Climate Prediction Center (National National Oceanic and Atmospheric Administration) said the chance of El Niño is about 70 percent during the Northern Hemisphere this summer and is close to 80 percent during the fall and early winter.

But Michelle Mead, Warning Coordination Meteorologist with the National Weather Service in Sacramento said the chance of a strong El Niño is not favored and forecasters anticipate El Niño will peak at weak-to-moderate strength during the late fall and early winter.

She said for Northern California and the San Joaquin Valley, the best estimate is for a weak to moderate event. Mead said there is little correlation between weak-to-moderate El Niño events and above-normal rainfall.

“El Niño right now is not looking like a slam dunk as far as helping us with our drought scenario,” said Mead.

Mead said if there is a strong El Niño it would means an increased chance of rain for California, but mostly for Southern California. But she said, even that is unlikely.

“The latest forecast ensemble models are actually indicating that the type of El Niño that could develop would be weak to slightly moderate and there’s no guarantee that Southern California will see increased precipitation,” said Mead.


 UC Davis researchers say “the drought is likely to stretch to a fourth straight year, through 2015, if not longer – regardless of El Niño conditions.”

“El Niño only means potential for at or above normal precipitation and we are so far behind in precipitation that even if we get normal amounts for next year it would not end the drought,” said Mead.

But she said flooding can happen very quickly, even during drought.

“You can actually have a drought scenario where one or two strong Pacific storms move in and small creeks and streams can rise quickly,” said Mead. “There won’t be a big influx of moisture and people should continue to conserve water.”

The term El Niño refers to the large-scale ocean-atmosphere climate phenomenon linked to a periodic warming in sea-surface temperatures across the central and east-central equatorial Pacific (between approximately the date line and 120oW), according to NOAA.

El Niño represents the warm phase of the El Niño/Southern Oscillation (ENSO) cycle, and is sometimes referred to as a Pacific warm episode.

NOAA said the term originally referred to an annual warming of sea-surface temperatures along the west coast of tropical South America.

El Niño events can bring flooding to some countries and drought to other countries.


Read original post here.

Nov 7 2014

Meteorologist explains El Niño, likely to develop this winter

Republished with permission of SEAFOODNEWS.COM November 6, 2014
In 1997-1998 abnormally high ocean temperatures off South America caused a collapse of the anchovy fisheries. Anchovies are a vital link in the food chain, and shortages can bring great hardship. Weather extremes associated with the event caused 2,000 deaths and $33 million (€26 million) in property damage. One commentator wrote that the warming event had “more energy than a million Hiroshima bombs”.

As it is not uncommon for an ocean warming to commence around Christmas, the fisherman of Peru call it El Niño, the Christ child. El Niño occurs when the temperature of the equatorial ocean west of South America is above normal, but its effects are more widespread.

Weather patterns in Indonesia and Australasia and the monsoons of southern Asia are affected. East Africa and North America also feel its impact. The heavy rainfall of Indonesia ceases, and droughts and wildfires are common in southeast Asia and Australia. Meanwhile, the mid- Pacific suffers a deluge.

During El Niño, the trade winds – which normally blow towards the west – weaken, allowing warm water from the western Pacific to slosh eastwards. El Niño lasts from a few months to a year or more and occurs about twice each decade, but its period is very irregular. It is linked to a see-saw pattern in which pressure in Tahiti is high when it is low in Darwin and vice versa. Together, this gives us Enso (El Niño southern oscillation).

Since February of 2014, some atmospheric models have been predicting the onset of El Nino, but it never quite materializes.

At the moment, there is evidence of warming along the South American Pacific coast, but that has not yet reached El Nino thresholds, despite disrupting the anchovy fisheries.

The current NOAA forecast says “Similar to last month, most models predict El Niño to develop during October-December 2014 and to continue into early 2015. However, the ongoing lack of clear atmosphere-ocean coupling and the latest NCEP CFSv2 model forecast have reduced confidence that El Niño will fully materialize. If El Niño does emerge, the forecaster consensus favors a weak event. In summary, there is a 58% chance of El Niño during the Northern Hemisphere winter, which is favored to last into the Northern Hemisphere spring 2015.

In Australia the Bureau of Meteorology says  “Weather conditions similar to El Nino will continue amid warming of the Pacific Ocean as thresholds for the event that brings drought to Asia and heavier-than-usual rains to South America may be reached by early next year.

Three of eight climate models may reach El Nino thresholds in January and another two remain just shy of the levels, the Australia’s Bureau of Meteorology said on its website today, maintaining an Oct. 21 outlook. The forecaster kept a watch status, indicating at least a 50 percent chance of a weak to moderate event, it said.

The bureau has pushed back projections for the onset of El Nino as changes to the atmosphere have failed to develop consistently. A weak event will probably develop by year end, MDA Weather Services predicted last month. El Ninos can roil agricultural markets as farmers contend with drought or too much rain. Palm oil, cocoa, coffee and sugar are among crops most at risk, Goldman Sachs Group Inc. has said.

“Sea surface temperatures in the tropical Pacific Ocean have warmed over the past two months, and the Southern Oscillation Index has remained negative, but indicators generally remain in the neutral range,” the bureau said. “The existence of warmer-than-average water in the tropical Pacific sub-surface supports a continuation of the current near-El Nino conditions.”

While sea-surface temperatures are warmer than normal across most areas in the tropical Pacific ocean, it still doesn’t qualify as an El Nino, Kyle Tapley, senior agricultural meteorologist at MDA said in response to e-mailed questions. Some additional warming could lead to the development of a weak El Nino, he said.
Feb 22 2014

El Niño may make 2014 the hottest year on record

Hold onto your ice lollies. Long-term weather forecasts are suggesting 2014 might be the hottest year since records began. That’s because climate bad-boy El Niño seems to be getting ready to spew heat into the atmosphere.

An El Niño occurs when warm water buried below the surface of the Pacific rises up and spreads along the equator towards America. For nine months or more it brings rain and flooding to areas around Peru and Ecuador, and drought and fires to Indonesia and Australia. It is part of a cycle called the El Niño-Southern Oscillation.

It is notoriously hard to make a prediction before the “spring barrier” as to whether there will be an El Niño in a given year. “The El Niño-Southern Oscillation cycle more or less reboots around April-May-June each calendar year,” says Scott Power from the Bureau of Meteorology in Melbourne, Australia.

The problem is that there is so much background variability in the atmosphere and ocean that it is hard to see any signal amidst the noise, says Wenju Cai from the CSIRO, Australia’s national research agency in Melbourne. “Even if there is a developing El Niño, it is hard to predict.”

Read the full article here.