Originally Posted by: Robertski

Originally Posted by: yorkshirelad89

Originally Posted by: Gavin P

Originally Posted by: John S2

Originally Posted by: jtwigge

Originally Posted by: jtwigge

Going down - now to (minus) -0.78

http://www.bom.gov.au/climate/enso/monitoring/nino3_4.png

and still possibly going a lot lower...

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/images3/nino34SSTMon.gif 

perhaps this might make it chilly - the forecast up(down)dated: http://www.cpc.ncep.noaa...images3/nino34SSTMon.gif

Does anyone know why such a strong Nina is being forecast? It would be particularly unusual for a second year Nina. What signal or driver is the basis for this?

Personally I don't believe a word of it. It would be very unusual for a La Nina to keep go on stregnthning after Christmas and to reach its peak in March.

I think CFS has lost the plot, but we'll see.

Indeed the only example of a La Nina that has continued strengthening after Christmas is 1893 and to a smaller extent 1950, I think they are overplaying it at this point, especially seeing as it's a double dip La Nina.

Im interested to know whet you mean by "they are overplaying it"? Do you mean the models are inaccurate?

 think we can all agree that there will be at least a weak/ moderate La Nina, I'm just confused as to what the CFS is picking up on to forecast such a strong La Nina, I don't think we could rule it out, but it would certainly be unusual given recent multi year ENSO events if one was to carry on strengthening after January.

If the CFS was correct this would rival 1893 and 1917 but we shall see

Edited by user 14 October 2011 13:26:02(UTC)  | Reason: Not specified

I think the problem with CFS is that once it sees the trend, it takes it to an extreme. This was something we saw last year when it was predicting the most intense La Nina ever recorded.

The JAMSTEC model has updated today and is forecasting a much weaker La Nina, with a minimum of -1 around Dec/Jan;

http://www.jamstec.go.jp/frcgc/research/d1/iod/ (click the seasonal predictions link in the sidebar)

This looks much more reasonable than CFS's mega event that keeps stregnthening into March.

Edited by user 14 October 2011 15:58:43(UTC)  | Reason: Not specified

Very cold anomalies starting to appear in region 1&2;

http://www.weather.unisys.com/surface/sst_anom.gif

Maybe CFS was right all along?

Originally Posted by: Robertski

Originally Posted by: Gavin P

Very cold anomalies starting to appear in region 1&2;

http://www.weather.unisys.com/surface/sst_anom.gif

Maybe CFS was right all along?

I will be honest, im not sure why anyone would really doubt it, as there is a consensus accross all the runs of a big drop. Just because it is a bit extreme, that does not mean it will be wrong. I accept it could still be wrong, but why would all the runs be so dramatic? 

The CFS-2 model is the only model predicting such dramtic La-Nina other models go for a much weaker event

see for example

http://www.bom.gov.au/climate/ahead/ENSO-summary.shtml

or

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf

This has been pointed out by Joe B'astardi, there is a CFS V2, which you can see here;

http://www.cpc.ncep.noaa...FSv2/CFSv2seasonal.shtml

Heres the ENSO forecast of the V2 model;

http://www.cpc.ncep.noaa...v2/images3/nino34Mon.gif

Still going for a strong La Nina, but doesn't reach the extreme depth of CFS V1;

http://www.cpc.ncep.noaa...images3/nino34SSTMon.gif

Notice the recent warmer members on the V2 ENSO ensemble as well? The model could well be starting to realise this La Nina is not going to be anywhere near as extreme as its been forecasting?

Yes, CFS is rapidly backtracking on its mega La Nina forecast.

In a week the ensemble mean has gone from dropping off the chart early in 2012 to bottoming out at -2.5. But most of the more recent member go for a peak of between -1.5 and -2.

I think it will continue to backtrack further over the next few weeks and the minimum will finish up somewhere around -1.

One interesting thing I'm noticing on the SST anomaly maps in the last couple of days is some warmer water just off the coast of Peru;

http://www.weather.unisys.com/surface/sst_anom.gif 

http://www.osdpd.noaa.gov/data/sst/anomaly/2011/anomnight.10.27.2011.gif

Wonder if that could actually be the first signs of some ENSO warming into early 2012? Keeping in mind the Beijing model this month appeared to be forecasting an El Nino this winter. That seems outlandish, but perhaps it has picked up on some warming taking place through the winter?

Edited by user 28 October 2011 15:56:03(UTC)  | Reason: Not specified

No problem.

The best part of the run up to winter for me, is trying to put all the clues together to come up with an idea of what might happen. Its like fitting a jigsaw puzzle together and ENSO is a big piece of the puzzle, so I get a lot of lot of satisfaction out of all this geeky stuff.

Originally Posted by: sunnyhighpressure

The way this is heading, the La nina will end up being weaker, than last year, with how the forecast members have flipped. The grey and blue ones are the new runs!

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/images3/nino34SSTMon.gif

I think we could be odds on for a major shift from very mild weather to very cold weather in the coming weeks. Watch this space. Something similar to November/December 1981. Looking in the archives, you would have never have guessed the December coming would be a record cold month. The pattern just suddenly shift. I don't know what you guys think.

I am not saying a repeat of last year of when the cold came early, but some forecasters are expecting the cold to come in the second part of winter. If this is the case, judging by the new cfs link above, I think the cold could come early as next month.

Hopefully the Nina will be nowhere near as strong as progged.

Difficult to say what will happen come Dec/Jan but a strong event looking more and more unlikely.May not even reach moderate.

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf

her is the latest more nuanced NOAA discussion on La Nina.