Ag Weather Forum

El Nino Reaches Peak

Bryce Anderson
By  Bryce Anderson , DTN Senior Ag Meteorologist
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El Nino is a big topic. I fielded many questions about its status and the future of this event at the DTN/Progressive Farmer Ag Summit Dec 7-9. So, following are some comments about where this event is and what its expected longevity is. These comments are all from the December 6-10 time frame.

First--from the Australia Bureau of Meteorology:

"The strong 2015 El Nino event is near its peak. While sea surface temperatures remain close to record-high values, some El Nino indicators are now showing signs of easing. However, the current El Nino is likely to persist well into 2016.

El Nino indicators, notably sea surface and sub-surface temperatures, westerly wind anomalies in the central Pacific, and cloudiness near the (International) Date Line, remain well above El Nino thresholds. The Southern Oscillation Index (SOI) has eased back into neutral values, though this may be short-lived: the SOI tends to be more variable during the northern Australian wet season (October–April). Model outlooks and the strength of the current event suggest El Nino thresholds may continue to be exceeded well into the southern hemisphere autumn.

The 2015–16 El Nino is strong, and likely to rank in the top three events of the past 50 years. Presently, several key indicators fall short of their 1997–98 and 1982–83 values, both in the ocean (e.g. sub-surface temperatures, which have peaked around +8 degrees Celsius this year, compared to +12 deg C in 1997–98), and atmosphere (e.g. SOI, for which monthly values peaked around −20, while 1982–83 had several months at −30)."

And, here is the latest weekly description of El Nino conditions from the U.S. Climate Prediction Center:

"Synopsis: El Nino is expected to remain strong through the Northern Hemisphere winter 2015-16, with a transition to ENSO-neutral anticipated during late spring or early summer 2016.

A strong El Nino continued during November as indicated by well above-average sea surface temperatures (SSTs) across the central and eastern equatorial Pacific Ocean. The Nino-4, Nino-3.4 and Nino-3 indices rose to their highest levels so far during this event, while the Nino-1+2 index remained approximately steady.

The traditional and equatorial Southern Oscillation Index (SOI) values remained negative. These conditions are associated with enhanced convection over the central tropical Pacific and suppressed convection over Indonesia. Collectively, these atmospheric and oceanic anomalies reflect a strong El Nino episode that has matured.

Most models indicate that a strong El Nino will continue through the Northern Hemisphere winter 2015-16, followed by weakening and a transition to ENSO-neutral during the late spring or early summer. The forecaster consensus remains nearly unchanged from last month, with the expectation that this El Nino will rank among the three strongest episodes as measured by the 3-month SST departures in the Nino 3.4 region dating back to 1950. El Nino is expected to remain strong through Northern Hemisphere winter 2015-16, with a transition to ENSO-neutral anticipated during the late spring or early summer 2016.

El Nino has already produced significant global impacts and is expected to affect temperature and precipitation patterns across the United States during the upcoming months. Seasonal outlooks indicate an increased likelihood of above-median precipitation across the southern tier of the United States, and below-median precipitation over the northern tier of the United States. Above-average temperatures are favored in the West and northern half of the country with below-average favored in the southern Plains and along the Gulf Coast."


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