Friday, May 22, 2015

How Does This Early El Nino Start Compare To Others? Implications.

Last year at this time (Spring 2014) the talk of a "Super El Nino" was at the forefront of weather circles. The resultant El Nino later in the year surely didn't fit the hype for a variety of reasons.  This year's close El Nino cousin is a little different.  I believe the "hype" is more warranted this go-around.

Here is a great El Nino animation from NASA showing its evolution.

Using the ONI (Oceanic Nino Index), I logged all El Ninos since the early 1900s.  The ONI is a 3 month overlapping sea surface temperature anomaly index of the Nino 3.4 region, the area used in defining the ENS state.

In determining how different this evolving El Nino is compared to past events, I used the actual NON-OVERLAPPING monthly Nino 3.4 sea surface temperatures anomalies for each early stage El Nino event starting in March and continuing through December. My goal was to see any slight variation in ocean temperature that was smoothed by the 3-month overlapping ONI.  Note: Many of these El Nino events continued into the following year not shown here.

The first chart below shows El Nino events from 1982 to early 2015.

Some key points:  This year's event has started MUCH FASTER and earlier than the historic El Nino events in 1997 and 1982. 

The 1986-87 event peaked in summer then slowly dropped by fall after a similar start.

The current El Nino is well ahead of all of the events from the early 1950s through the late 1970s. Some of these El Ninos were weak. 1965 and 1972 was strong.

The El Ninos of the late 1920s, 30s and 40s were late bloomers showing little sign of El Nino until mid fall.

The early 20th century El Ninos had more erratic evolutions. Even the strong El Nino of 1918 struggled until fall/early winter.

Of all 23 El Ninos I charted, only the El Nino of 1905 had WARMER ocean temperatures in May compared to this year's event. That year peaked at 1.5 in September.

So in summary...

*  El Nino headlines need historical perspective.  Don't be quick to compare this event to the 1997 event per the model projections.

*  The 2015 El Nino is building faster than any El Nino since 1905

* The rapid rise in ENSO 3.4 ocean temperatures this early in spring historically usually means the El Nino will sustain itself through the summer. The major El Ninos of 1997, 82 and 72 started off slower. A big start doesn't necessarily mean 2015 will be another 1997 or 1982.  In fact, the warmth is more centralized. The warmth in '82 and '97 sloshed eastward by summer.

Warmth so far this year has two lobes, one central near dateline and another eastern closer to South America.

* The moderate El Ninos (SST 3/4 between 1.0 and 1.5) in 1987, 72, 65, 57, 30, 25, 23, 18, 05 and 1902 all sustained El Nino status through December per the ENSO 3/4 ocean temperatures.

What does all of this mean for the summer, fall and upcoming winter?

* The next 2-3 months will be critical in determining how this El Nino will impact our (US) weather this summer and especially fall.early winter.  The position of the warmth will be a big factor.

*  How much cool water near Australia relative to the ENSO 4 and 3/4 region temperatures will be HUGE in driving the westerly wind bursts necessary in sloshing more warmth to the east keeping the El Nino machine going.

Next week, we'll dive more into why the COOL WATER NEAR AUSTRALIA is so critical in the development of El Nino