Monday, March 24, 2014

Digging Deeper For Signs Of The Next El Nino

After reading several posts which posed the question of whether a "Super El Nino" will develop this summer, I wanted to find more data to shed light on what to look for in the upcoming weeks. These articles have sited sea surface temperature comparisons to 1997 both on the surface and below, ocean heat content, the building Kelvin Wave and subsequent changes in atmospheric winds.  All seem very valid. Let's review:

Comparing the sea surface temperatures on March 24th of this year to 1982, 1997 and 2002 (a weak El Nino year), each shows some warming in different locations at least on the surface. I circled the area in question in red. This is why we can't use a two dimensional sea surface temperature map as the only El Nino indicator.
 
Ocean Temperatures have been climbing in the western Pacific over the last 30 days. Notice the bubble of warmth between 100 and 200 meters.















Sub surface heat continues to build since the beginning of the year (see above). It compares very well to the onset El Nino of 1997. The Australian Bureau of Meteorology shows this very well.




HUGE spike in near surface ocean heat last 4 weeks

2002 was a weak El Nino year. The subsurface heating was nowhere as warm.


Comparing the sea surface temperatures on March 24th of this year to 1982, 1997 and 2002 (a weak El Nino year), each shows some warming in different locations at least on the surface. I circled the area in question in red. This is why we can't use a two dimensional sea surface temperature map as the only El Nino indicator.


The Southern Oscillation Index (Pressure index comparing sea level pressure at Darwin, Australia to Tahiti--30 day monthly moving mean) suddenly dropped into heavy El Nino territory.

Yet one index that blends together BOTH the changing ocean characteristics and the atmospheric conditions above it hasn't caught onto the idea...at least yet. Interestingly I haven't found much mention of this. This is called the Multivariate ENSO Index. The index includes several elements into its index: Sea surface temperatures, wind speed and direction, sea level pressure and temperature along with total cloud cover/fraction of the sky. Details are here on ESRL SITE.  Similar to the ONI Index, the MEI Index is calculated using overlapping 2 month periods. Since it takes into account many other atmospheric variables, the El Nino or La Nina signature may lag a bit compared to the others But in my opinion, it gives a better overall representation of the ENSO state even though it might be late to the party.

So far, the MEI is far ahead of 1982 and 1997, yet no positive numbers have shown up. Remember that The MEI is an overlapping bi-monthly indicator. So when the April update comes out (probably the first week of April), it will illustrate the conditions (ocean and atmospheric) for the FEBRUARY-MARCH overlap. If a  significant El Nino is truly developing, a SIGNIFICANT JUMP in the MEI would indicate it THIS SPRING as it did in 1982 and 1997. Check out the chart below for the past trend.

Be careful, the 1986 and 2002 MEI trends were SIMILAR to this year. Those years were weaker El Nino years.

Notice the MEI trends in 1986 and 2002.  Where will the MEI end up this summer?






So what's going to happen? Will the MEI match up with the MEI indices of the past El Ninos circled in black above. Will it mirror 2002 or 1986?

How will this effect out summer weather? 

The next 6 weeks will tell us a great deal.

6 comments:

Robert Ivancic said...

If we were to have a full blown El Nino, as is for 82,97 years will it prolong the onset the fall to winter season of 2014?

Robert Ivancic said...

If we were to have a full blown El Nino, as is for 82,97 years will it prolong the onset the fall to winter season of 2014?

Robert Ivancic said...

If we were to have a full blown El Nino, as is for 82,97 years will it prolong the onset the fall to winter season of 2014?

Robert Ivancic said...

If we were to have a full blown El Nino, as is for 82,97 years will it prolong the onset the fall to winter season of 2014?

Scott Sabol, Meteorologist said...

IF--big if--it develops into a 1997 or 1982 El Nino, the effects would continue into late 2014, early 2015 for sure. Not sold on the Super El Nino idea just yet. Ask me in another month when more data is available.

Dennis Boylan said...

if it does develop and the temperatures are lower, what will this do to overall weather stability?
Will we have more clear but cooler days? Will there be less storms, less windy days?