Looks like a big La Nina event about to start.

 

http://www.drroyspencer.com/2010/05/global-average-sea-surface-temperatures-poised-for-a-plunge

 

And the experts concur..,.

 

•A transition from El Niño to ENSO-neutral is underway.
•Sea surface temperatures are decreasing across much of the Pacific Ocean.
•Based on current observations and dynamical model forecasts, a transition to ENSO-neutral conditions is expected by June 2010, which will continue into the Northern Hemisphere summer 2010.
•Although many models predict ENSO-neutral conditions, there is a growing possibility of La Niña developing during the second half of 2010.

A La Nina is certainly possible later in the year they do frequently follow El-Nino conditions but it is important to follow the main ocean weather forecast models, at the moment the ensembles point to ENSO neutral being somewhat more likely. Remember the 'fring' were hopelessly wrong about the current El-Nino now ending.

Here is the forecast from last year at this same time.  Nino 3.4 made it to 1.9C in Mid-december so only the Nasa GMAO model and the COLA CCM3 was close from this point in the year.

 

 

While as time went on, last year's forecasts got more accurate, one has to look at these forecasts over time to see if they are accurate and they are not.

Last year at this time, I was already calling for an El Nino

http://wattsupwiththat.com/2009/05/13/la-nina-fading-el-nino-may-soon-return/

Here is the ensemble forecast for the ENSO today.  Nino 3.4 this week is already in the -0.7C territory so no model is accurate even for the date of publication for this forecast which was May 20th.

 

 But a La Nina is certainly coming/here now.

NOAA weekly update 24 May:

A transition from El Niño to ENSO-neutral is underway.
• Sea surface temperatures are decreasing across much of the Pacific Ocean and
have recently become slightly below-average in portions of the eastern half of the
basin.
• Based on current observations and dynamical model forecasts, a transition to
ENSO-neutral conditions is expected by June 2010, which will continue into the
Northern Hemisphere summer 2010.
• Although many models predict ENSO-neutral conditions, there is a growing
possibility of La Niña developing during the second half of 2010.

 

Latest ECMWF forecast seems to think so too:

 

 

 

http://www.ecmwf.int/products/forecasts/d/charts/seasonal/forecast/seasonal_range_forecast/nino_plumes_public_s3!3!201005!/

 

Doesn't look to be particularly strong though, but we'll see.

 

 

 

I had not realised that the correlation between the ENSO index and the global temperature indices was so strong.

For example take a look at the ENSO index for example Bill's figure above and compare it with
http://data.giss.nasa.go...emp/graphs/Fig.C.lrg.gif

You see peaks in 1998, 2002, 2006, 2010, dips in 1999/2000, 2007/8.
Has anybody plotted them on the same graph? Bill?

The Nino 3.4 Index came in at -0.03C in May and has fallen to -0.4C for the week ending June 2nd.

The Equatorial Upper Ocean Heat Anomaly in April was -0.06C, fell to -0.96C in May and is about -1.2C in the week of June 2nd. [These numbers lead the ENSO by about 1 month].

So the prediction of a Nino 3.4 being close to Zero in May was correct and my best estimate for June is about -0.9C.

There is more than enough cooler than normal subsurface water to drive a La Nina into the late fall.

-----------------

Here is a bunch of charts (all updated for the May data) which shows how the ENSO is part of one big system which includes the:

- Equatorial Upper Ocean Heat Anomaly,

- the Equatorial surface and subsurface ocean currents which flow east-west at the surface with the prevailing winds and then flow west-east at about 150 metres depth back underneath the ENSO regions to the beginning of the regions at the Galapogos Islands which then recirculates across the surface once again,

- the Trade Winds at the Equator which blow east-west and drive the east-west surface ocean currents.  When the Trade Winds slow down there is an El Nino.  The surface currents slow down, the water gets heated day after day by the equatorial Sun, warmer water from the Pacific Warm Pool area slosh backwards into the ENSO region, cooler waters from below cannot surface.  The Equatorial Upper Ocean Heat Anomaly plays a large role in the strength of the Trade Winds it seems.  Warm anomalies help slow down the winds (rising air currents), cool anomalies help speed up the Winds.   

- Atmospheric Angular Momentum which is driven by mid-latitude winds mostly but which provides an extra push/pull on the Equatorial Trade Winds, The Length of the day actually changes by a millisecond or so through the AAM.

- Outgoing Long-Wave Radiation which is actually opposite to that expected - OLR FALLS during an El Nino and rises during a La Nina, this is driven by clouds which greatly multiply during an El Nino and hold the heat-in in the atmosphere, During a La Nina, there is much less clouds and whatever heat the Equatorial Oceans have is quickly lost to space.

- The OLR effect is really how the ENSO transfers its heat or lack of it to the rest of the globe; the prevailing winds are east-west across the tropics so the entire tropics are warmed first through an El Nino.  Other winds flow toward the north and make it first to northern North America and the Arctic.  These are the regions which are most impacted by the ENSO. 

- the Southern Oscillation Index which is influenced by the OLR and the Trade Winds and the cloud patterns.  Pressure falls at Tahiti at the end of the Nino regions during a El Nino (rising air columns and clouds) while it rises at Darwin because there is less cloud cover there and less moisture delivered to the region from the Equator.

http://img691.imageshack.us/img691/7948/ensovseuohamay10.png

http://img707.imageshack.us/img707/5650/euohcjune2.png

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/ocean/anim/monxzteq.gif

http://i39.tinypic.com/2rd91m8.jpg

http://img541.imageshack.us/img541/2987/ensovsgrosstradesmay10.png

http://img59.imageshack.us/img59/8261/ensovstradewindsmay10.png

http://img16.imageshack.us/img16/7389/ensovsaammay10.png

http://img256.imageshack.us/img256/6079/ensovsolrmay10.png

http://img29.imageshack.us/img29/8497/ensovssoimay10.png

http://img697.imageshack.us/img697/1503/soivsenso1871.png

http://img200.imageshack.us/img200/9973/ensovsrsstropicsmay10.png

http://img294.imageshack.us/img294/913/ensovsrsstropglobalmay1.png

 

Edited by user 09 June 2010 03:09:26(UTC)  | Reason: Not specified

The cross-sections of the Equatorial Pacific show a strong La Nina is on its way very soon.

At 0 degrees in the Nino regions (from 165E to 90W), there is more cool anomalies than I have seen before.

If you want to see the staying power of the La Nina, these anomalies at 140W and 0N and 100 metres depth take about 3 to 6 months to make their way to 25 metres depth at 100W when they start to influence the surface temperatures (they never actually make it all the way to the surface). 

There are some areas which are -7.0C.  

Further staying power can be observed at 165E 0N at 200 metres depth (where La Ninas or El Ninos are born in my opinion), which take about 6 to 9 months to make their way to 100W 25 metres deep and start influencing the surface.   There are anomalies here which are -2C.  So there is enough cooler than normal water to extend a La Nina into the Fall at least.

[The warm anomalies on the side are typical after-affects of the past El Nino.  The ENSO waters recirculate at 8N to 10N and 8S to 10S as a countercurrent after the ENSO so these areas usually reflect the most recent ENSO event.  The deeper anomalies also circulate the opposite direction (east-west) to those at the Equator.   The surface currents at these latitudes also flow backwards to that at the Equator (west-east) and especially on the northern side - the North Equatorial Counter-Current which seems to be much stronger than its southern cousin. ]

  

All these charts look exactly opposite last year at this time in the lead up to the El Nino.     

The La Nina continues to strengthen.  The Nino 3.4 Index is about -0.6 right now.

One issue is there is still relatively warm water in the North Equatorial Counter-Current at 3N to 5N (which is technically the warm water left-over recirculated from the last El Nino).  So the cooler Equatorial La Nina waters are slowing cooling this warmer current off and it is creating little eddies (well little for the ocean but still very large) which have one side cooler and the other warmer which is why the cool water in the chart below has the spikes in it.

Some areas are as low as -2.2C in the Nino regions.  The North Atlantic, however, is very warm and I think it has a slightly bigger impact than the ENSO has.  

The Pacific cross-sections show that the ocean below is quite a bit cooler than it was 1 month ago and this La Nina could become a very long-lasting strong event.

 

At 140W, some of the 5S to 5N ribbon which circulates up into the Nino regions is as cool as -9C.

As much as I am not a fan of NASA GISS, the ENSO forecasting model run by the Goddard Space Flight Centre in Maryland [NASA GMAO] seems to best model based on the track record over time ...

... and they are now predicting this event will become the first Super-La Nina ever.     

 

 

Edited by user 24 June 2010 15:24:41(UTC)  | Reason: Not specified