The current strong El Niño event has matured and will finish ranked among the top three strongest since 1950, according to the latest monthly outlook released by NOAA on Thursday.

El Niño conditions are likely to last through the winter before finally easing up and transitioning to neutral conditions by late spring or early summer. This means sea surface water temperatures in the equatorial central and eastern Pacific Ocean will return to near-average levels from their current above-average state. El Niño is an anomalous, yet periodic, warming of the central and eastern equatorial Pacific Ocean. For reasons still not well understood, every two to seven years, this patch of ocean warms for six to 18 months, then cools.

NOAA reported that while subsurface water temperatures in the central and eastern equatorial Pacific Ocean have now cooled slightly, overall water temperatures remain well above average. On Tuesday, Australia's Bureau of Meteorology said that El Niño is now near its peak and that there are some indicators it may be showing signs of easing.

Even if this El Niño has neared its peak and begins to ease, we will likely continue to see impacts around the world through winter. A record active central Pacific hurricane season and dry conditions leading to devastating wildfires in Indonesia are among the impacts we've seen so far.

The current El Niño set a monthly record in November. Water temperatures near the ocean surface reached their highest positive anomalies on record in the zone of the equatorial Pacific Ocean defining either El Niño or its opposite, La Niña. This means the sea-surface water temperature was farther above average for the time of year than any previous month in reliable records dating to 1950.

Specifically, the water temperature in this region was about 2.35 degrees Celsius above average in November 2015, topping the previous record monthly anomaly from November 1997 by 0.02 degrees Celsius, in reliable records dating to 1950.

Pacing this record monthly anomaly was a first-on-record monthly sea-surface temperature of 30 degrees Celsius (86 degrees Fahrenheit) in the equatorial central Pacific well south and southwest of Hawaii, according to Colorado State University tropical meteorologist, Dr. Phil Klotzbach .

Record Strongest El Niño?

The seemingly straight-forward question of whether this El Niño is the strongest on record is, well, complicated.

"It depends on the measure," said The Weather Channel's senior director of weather communications, Stu Ostro .

For historical purposes, the most accepted method of categorizing the intensity of El Niños and their opposite La Niñas utilize the NOAA Climate Prediction Center's three-month running mean SST anomaly, known as the Oceanic Niño Index (ONI) , instead of looking at one week or even one month's worth of data.

Based on the latest available three-month (September-November) ONI, the 2015 El Niño is pacing ahead of the 1982-1983 event, but still behind the pace of the strongest El Niño of record in 1997-1998.

Year Sep-Nov ONI (degrees C) 1) 1997 +2.18 2) 2015 +2.04 3) 1982 +1.86

When comparing the current ONI value with the peak values reached in the two strongest El Niños, 2015 (soon 2016) still ranks third.

Year Peak ONI (degrees C) 1) 1997-1998 +2.26 (Oct-Dec) 2) 1982-1983 +2.12 (Nov-Jan) 3) 2015-2016 +2.04 (Sep-Nov)

Another variable used to examine not just the sea-surface temperature anomalies, but also the atmosphere's response, known at the multivariate ENSO index (MEI) also places 2015 behind 1997 and 1982 in October and November data, according to Klotzbach.

So, this El Niño ranks among the top three strongest on record, but not the strongest overall, so far.

Potential Winter/Spring Weather Impacts

What does all this mean for the winter and spring ahead?

Precipitation and temperature impacts in the U.S. from a strong El Niño are typically most noticeable during the colder months, from late fall through winter.

(MORE: 5 Things to Expect This Winter )

First, keep these two things in mind:

1) El Niño is not the sole driver of the atmosphere at any time. Day-to-day variability in the weather pattern, including blocking patterns, forcing from climate change and other factors all work together with El Niño to determine the overall weather experienced over the timeframe of a few months.

2) No two El Niños are exactly alike. The intensity matters for impacts.

(MORE: El Niño & Seasonal Snowfall | White Christmas? )

Looking at past moderate and strong El Niños, here are the upshots for temperatures and precipitation through winter in the U.S.:

- Wetter : Southern U.S. from California to the Carolinas then up parts of the East Coast

- Drier : Parts of the Ohio Valley, Great Lakes, Northwest and Northern Rockies

- Cooler : Desert Southwest, Southern Plains, northern Gulf Coast

- Warmer : Northern tier of states from the Pacific Northwest to the Northern Plains, Great Lakes, and Northeast

Keeping in mind no two El Niños are alike, when looking only at the five previous strong El Niños, there are some general commonalities to note headed into winter:

- California's heaviest precipitation has waited until January, continuing through March. In fact, a dry December has happened before in northern California.

- Wet Decembers in the Pacific Northwest are typical in strong El Niños, before a drier trend later in the winter and spring.

- The warm northern tier of states sets in by December, continuing through March, but April can be dramatically different.

(MORE: Coldest Time of Year | Winter Outlook )

Note these are impacts that are typically expected, but they aren't always the rule.

Residents of the western states may remember the flooding that struck California during the strong 1997-98 El Niño. In February 1998, a series of storms caused an estimated $550 million in damage and killed 17 people in California. A total of 35 counties were declared federal disaster areas. This fits into the bucket of the wetter-than-average winter you would typically expect in a moderate or strong El Niño.

Interestingly, during the previous winter there was also major flooding in California and it was even more costly with a total price tag of $1.8 billion, according to Jan Null, a consulting meteorologist in California . However, El Niño was not present that winter and rainfall for the season was near average. The flooding was the result of excessive rainfall that fell in a short time period combined with snowmelt from late December to early January.

So, those hoping for drought relief next winter in the Golden State shouldn't immediately draw a conclusion that significant rains are ahead in any El Niño year. The strength of the El Niño can play a role in the outcome. In addition, heavy rainfall can occur with or without El Niño present and that was the case in the winter preceding the strong 1997-1998 El Niño.

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