AUSTIN (KXAN) — Despite recent winter storm systems originating in the Pacific, a long-awaited El Niño atmospheric pattern cannot be blamed — as time is running out for the pattern to form. The Climate Prediction Center announced early Thursday conditions in the equatorial Pacific Ocean and atmosphere have not yet met the criteria for an El Niño, and the odds of the pattern developing this winter have been lowered to 50-60 percent. And, scientists say, even if the pattern forms, it only has the next two months to do so, won’t last long, and will be a weak version.
An El Niño forms when unusually warm ocean temperatures begin to influence weather patterns. That connection last developed in Central Texas during the winter of 2009-2010. Since that time, historic drought conditions developed across Texas as two consecutive La Niña cycles, opposite of El Niño, formed.
The El Niño cycle typically brings Central Texas wetter and colder than normal winters, as the southern jet stream becomes energized when the warming ocean destabilizes the atmosphere above. Historically, many El Niño seasons have brought wet and stormy weather, producing flooding rains, but filling area lakes. While El Niño-like wetter and colder than normal weather is still forecast for the coming winter into spring, the anticipated influence of the ocean/atmosphere coupling is diminishing.
To officially declare an El Niño, both the ocean temperatures and how the atmosphere reacts to them are critical. For NOAA’s Climate Prediction Center to make that declaration, the sea-surface temperature in an eastern-central segment of the ocean called the Nino 3.4 must be 0.5°C (0.9°F) above normal for at least a month – and be forecasted to last that way for at least three months. But the atmosphere also needs to show those wind shifts, and associated changes in precipitation and convection patterns across the region.
The most reliable effect of an El Niño — observed in 80 percent of El Niños in the past 100 years — is the wetter-than-normal conditions that affect the southern tier of states, from Southern California through Texas and on to Florida, thanks to a shift in the jet stream. One kink in that connection, though, is that wetter conditions in the Southwest only seem to appear with strong El Niños. If El Niño forms this winter, it is expected to be a weak event.
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). El Niño represents the warm phase of the El Niño/Southern Oscillation, or ENSO cycle, and is sometimes referred to as a Pacific warm episode.
The term El Niño, Spanish for “the Christ Child,” was originally used by fishermen along the coasts of Ecuador and Peru to refer to a warm ocean current that typically appears around Christmastime and lasts for several months. Fish are less abundant during these warm intervals, so fishermen often take a break to repair their equipment and spend time with their families.
NOAA has a list of some state-by-state impacts, but these localized impacts are, of course, less robust statistically than broader regional-scale impacts.
Even though the El Niño hasn’t technically formed, the warmer state of the Pacific is still having some impacts, including having played a part in quashing the Atlantic hurricane season, and energizing occasional storm systems that have moved into Texas in recent weeks.
NOAA’s Climate Prediction Center, which is part of the National Weather Service, declares the onset of an El Niño episode when the 3-month average sea-surface temperature departure exceeds 0.5oC in the east-central equatorial Pacific [between 5oN-5oS and 170oW-120oW].
- La Niña or El Niño Watch: conditions in the equatorial Pacific are favorable for the development of La Niña or El Niño conditions in the next three months.
- La Niña or El Niño Advisory: La Niña or El Niño conditions have developed and are expected to continue.
These watches and advisories are now part of the ENSO Diagnostic Discussion, which is issued by the Climate Prediction Center on the Thursday falling between the 5th and 11th of every month. It is available online.
Click here to visit the Climate Prediction Center’s ENSO site.
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NOAA and Climate Central contributed to this report