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El Niño Tracker - Dec 2015 | CLIMAS

 SW Climate Outlook

El Niño Tracker - Dec 2015

El Niño 2015-2016

We spent 2014 and the first part of 2015) waiting in anticipation for an El Niño event that was forecast to be one of the stronger events on record. By early 2015, the event in question had not yet materialized, and some questioned whether El Niño would ever arrive. Eventually it did, and has been going strong for months, with most forecasts indicating that it will remain a strong event through the winter. There are numerous impacts we expect to see across the Southwest over our cool season (approximately Oct - Mar). In the coming months, CLIMAS will aggregate news, information, and commentary about the possible and expected impacts of El Niño, from the perspective of what is most relevant and applicable to the Southwest. This will include things we learned from past events, and what forecast models can tell us about planning for this event.

For more information, please visitño-southern-oscillation, our repository for El Niño related materials, which we will update with timely and relevant information about El Niño throughout the winter.

2015 El Niño Tracker

El Niño conditions continued for a 10th straight month, and models continue to forecast a strong El Niño event that will last through spring 2016 and remain strong through the early part of the year. Forecasts focused on the persistence of sea surface temperature (SST) anomalies (Figs. 1–2) and weakened trade winds, enhanced convective activity in the central and eastern Pacific, and El Niño-related ocean-atmosphere coupling. Notably, the SST values in the Niño 3.4 region were at or above the record values in November. Climate scientists have been quick to point out that numerous factors contribute to the overall strength of El Niño, but we are certainly seeing one of the strongest events on record.

Image Source - Australian Bureau of Meteorology

Image Source - NOAA/NWS - Climate Prediction Center

On Dec. 8, the Australian Bureau of Meteorology maintained its tracker at official El Niño status, with the event having likely reached its peak. On Dec. 10, the Japan Meteorological Agency identified ongoing El Niño conditions as having reached their “mature stage” in the equatorial Pacific and “remarkably above-normal” SST anomalies and atmospheric convective activity. The agency projected that El Niño would remain in place through spring 2016 before transitioning to ENSO-neutral by summer. Also on Dec. 10, the NOAA-Climate Prediction Center (CPC) extended its El Niño advisory and identified the current atmospheric and oceanic anomalies as reflecting a strong El Niño event that will be one of the three strongest events on record. CPC models indicate the El Niño event will persist through winter, with a transition to ENSO-neutral conditions by late spring or early summer. On Dec. 17, the International Research Institute for Climate and Society (IRI) and CPC forecasts indicated that all oceanic and atmospheric variables were indicative of a strong El Niño event, with consensus centering on strong El Niño conditions that will persist through spring 2016 (Fig. 3).   The North American multi-model ensemble currently shows a strong event extending into 2016 with gradual weakening heading into spring (Fig. 4).

Image Source - International Research Institute for Climate & Society

Image Source - NOAA/NWS - Climate Prediction Center

So what does this mean for the region? Seasonal forecasts and past events suggest we should see well above-average cumulative precipitation totals throughout our cool season, but we should also expect periods of inactivity between storms. Past events also suggest the best bets for seeing above-average precipitation will be in February and March, and perhaps later in January. Looking at the 1997–1998 event—the strongest El Niño event on record—most of Arizona and New Mexico received above-average precipitation in December but below-average rain and snowfall for all of January before returning to normal or above-normal precipitation in February and March (Figs. 5–8). At this point, we know a strong El Niño event is underway, and it will likely have a number of projected impacts on the Southwest (and the world), but we will need to wait until seasonal totals are in to accurately gauge the impact of El Niño.

Image Source - Western Regional Climate Center - WestWide Drought Tracker

Image Source - Western Regional Climate Center - WestWide Drought Tracker

Image Source - Western Regional Climate Center - WestWide Drought Tracker

Image Source - Western Regional Climate Center - WestWide Drought Tracker

To provide data and analysis regarding possible impacts of El Niño on the Southwest, CLIMAS created an El Niño hub:ño-southern-oscillation

Please contact Dan Ferguson or Ben McMahan for more information