By Karen Graham
Published October 8, 2022
Dried up Little Washoe Lake in Nevada is seen in July 2021 after prolonged drought. — © AFP
La Niña is expected to be in place this winter for the third year in a row, making the phenomenon the third time in recorded history with three straight La Niña years.
The National Oceanic and Atmospheric Administration *NOAA) is already predicting a 93 percent chance La Niña continues from November through January next year.
During August, below-average sea surface temperatures (SSTs) persisted across the central and east-central equatorial Pacific Ocean. Not only have there been SST departures in the Tropical Pacific during the last four weeks, but SST departures globally have been significant,
During the last four weeks, equatorial SSTs were below average across most of the Pacific Ocean
and in the western Indian Ocean. Equatorial SSTs were above average around Indonesia and in
small parts of the Atlantic Ocean. Source NOAA Climate Prediction Center
New research led by the University of Washington suggests that climate change is, in the short term, favoring La Niñas. The study was recently published in Geophysical Research Letters.
El Niño and La Niña are the warm and cool phases of a recurring climate pattern across the tropical Pacific—the El Niño-Southern Oscillation, or “ENSO” for short. The pattern shifts back and forth irregularly every two to seven years, and each phase triggers predictable disruptions of temperature and precipitation.
Global Impacts of El Nino and La Nina
El Niño and La Niña have weaker impacts during Northern Hemisphere summer than they do in the winter. Summer impacts include warm conditions in northeastern Australia and cooler-than-average conditions across India and Southeast Asia.
Generally, the polar jet stream in a La Niña winter buckles north over the North Pacific, then sweeps into the Pacific Northwest, dislodging cold air from Alaska into the Northwest, the northern Rockies, and Northern Plains.
But in the Eastern part of the country, the jet stream tends to swing to the north, as high pressure dominates over the South and Southeast, pushing warmer air up the East Coast. This is a typical winter pattern during La Niña. The actual conditions can vary with La Niña’s strength and other factors influencing the weather on shorter time scales.
Here’s something interesting to think about – Global warming is widely expected to favor El Niños. The reason is that the cold, deep water rising to the sea surface off South America will meet warmer air.
and in the western Indian Ocean. Equatorial SSTs were above average around Indonesia and in
small parts of the Atlantic Ocean. Source NOAA Climate Prediction Center
New research led by the University of Washington suggests that climate change is, in the short term, favoring La Niñas. The study was recently published in Geophysical Research Letters.
El Niño and La Niña are the warm and cool phases of a recurring climate pattern across the tropical Pacific—the El Niño-Southern Oscillation, or “ENSO” for short. The pattern shifts back and forth irregularly every two to seven years, and each phase triggers predictable disruptions of temperature and precipitation.
Global Impacts of El Nino and La Nina
El Niño and La Niña have weaker impacts during Northern Hemisphere summer than they do in the winter. Summer impacts include warm conditions in northeastern Australia and cooler-than-average conditions across India and Southeast Asia.
Generally, the polar jet stream in a La Niña winter buckles north over the North Pacific, then sweeps into the Pacific Northwest, dislodging cold air from Alaska into the Northwest, the northern Rockies, and Northern Plains.
But in the Eastern part of the country, the jet stream tends to swing to the north, as high pressure dominates over the South and Southeast, pushing warmer air up the East Coast. This is a typical winter pattern during La Niña. The actual conditions can vary with La Niña’s strength and other factors influencing the weather on shorter time scales.
Here’s something interesting to think about – Global warming is widely expected to favor El Niños. The reason is that the cold, deep water rising to the sea surface off South America will meet warmer air.
La Nina weather pattern, Source – The Weather Channel
Anyone who’s sweated knows that evaporation has a cooling effect, so the chillier ocean off South America, which has less evaporation, will warm faster than the warmer ocean off Asia.
This decreases the temperature difference across the tropical Pacific and lightens the surface winds blowing toward Indonesia, the same as occurs during El Niño. Past climate records confirm that the climate was more El Niño-like during warmer periods.
But here we are today, stuck in a La Nina weather pattern that could be classified as a strong La Nina. This generally means that you will see much less snow from southern New England to the mid-Atlantic states, as well as in parts of the central Plains.
The Pacific Ocean off South America has actually cooled slightly, along with ocean regions farther south. Meanwhile, the western Pacific Ocean and nearby eastern Indian Ocean have warmed more than elsewhere. Neither phenomenon can be explained by the natural cycles simulated by climate models. This suggests that some processes missing in current models could be responsible.
According to the researchers, changes on either side of the tropical Pacific show that the temperature difference between the eastern and western Pacific has grown, surface winds blowing toward Indonesia have strengthened, and people are experiencing conditions typical of La Niña winters.
The researchers aren’t sure why this pattern is happening. Their current work is exploring tropical climate processes and possible links to the ocean around Antarctica. Once they know what’s responsible, they may be able to predict when it will eventually switch to favor El Niños.
Anyone who’s sweated knows that evaporation has a cooling effect, so the chillier ocean off South America, which has less evaporation, will warm faster than the warmer ocean off Asia.
This decreases the temperature difference across the tropical Pacific and lightens the surface winds blowing toward Indonesia, the same as occurs during El Niño. Past climate records confirm that the climate was more El Niño-like during warmer periods.
But here we are today, stuck in a La Nina weather pattern that could be classified as a strong La Nina. This generally means that you will see much less snow from southern New England to the mid-Atlantic states, as well as in parts of the central Plains.
The Pacific Ocean off South America has actually cooled slightly, along with ocean regions farther south. Meanwhile, the western Pacific Ocean and nearby eastern Indian Ocean have warmed more than elsewhere. Neither phenomenon can be explained by the natural cycles simulated by climate models. This suggests that some processes missing in current models could be responsible.
According to the researchers, changes on either side of the tropical Pacific show that the temperature difference between the eastern and western Pacific has grown, surface winds blowing toward Indonesia have strengthened, and people are experiencing conditions typical of La Niña winters.
The researchers aren’t sure why this pattern is happening. Their current work is exploring tropical climate processes and possible links to the ocean around Antarctica. Once they know what’s responsible, they may be able to predict when it will eventually switch to favor El Niños.
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