AUSTIN (KXAN) — Despite months of anticipation, a long-awaited El Niño atmospheric pattern has yet to return. The Climate Prediction Center announced early Thursday El Niño conditions in the equatorial Pacific Ocean have not yet fully developed, though they are still likely this winter. Forecasters say conditions are “borderline” now, and predict a 58% chance the El Niño pattern will develop soon.
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 (opposite of El Niño) cycles formed.
The main thing holding this El Niño back is a lack of a solid response from the atmosphere. There have been some bursts of westerlies and associated shifts in rain patterns, but the signs just haven’t been strong enough to warrant an official declaration yet.
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. While not all El Niño months are big rain-makers for Central Texas, some have resulted in record rainfall and flooding, filling area lakes.
Rainfall across Central Texas over the past three days has definitely had a Pacific influence, as the remnants of Hurricane Vance provided a large amount of atmospheric moisture, resulting in 2-3 inches of rain across much of the KXAN viewing area. Flash flooding in September in the Austin area was also related to remnants of a Pacific Hurricane, Odile.
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.
If the El Niño does form soon, it will be in place for winter, when it has the biggest impact across the U.S. 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 this forms, the El Niño is expected to be a weak or moderate 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 (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 playing a part in quashing the Atlantic hurricane season.
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.
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Information from NOAA and Climate Central was used in this article.