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La Niña/Winter 2016-17 Discussion


dmillz25

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the neutral and weak la nina winters after an el nino are listed below...1978-79 was the only true neutral winter with an oni of 0.0 for DJF...1992-93 and 2003-04 never hit negative numbers...I'm leaning towards an oni of -0.9 or higher at its lowest point and maybe an official weak la nina...the three weak la nina's listed below the neutrals came after weak el nino's...1966 and 1983 and 1995 are the lead analogs as of now...

season...DJF ONI...

1959-60....-0.1

1966-67....-0.4

1978-79.....0.0

1980-81....-0.2

1983-84....-0.5

1992-93.....0.2

2003-04.....0.3

2005-06....-0.7

...............................................................................................

1954-55....-0.6

1964-65....-0.5

1995-96....-0.9

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11 minutes ago, bluewave said:

It's an interesting question...maybe the models are looking at the narrow nature of the cold anomalies being focused only in 3.4 with warmer SST's to east and west and projecting from that. We'll know if the models are correct soon enough since they all show a slight warming going into October.


31AUG2016     20.9 0.3     24.6-0.3     26.0-0.7     28.5-0.1

 

The CFS is already wrong, shocking I know, region 3.4 is colder right now than what it had been projecting

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35 minutes ago, bluewave said:

The POAMA is right on the -0.7 mark but also slightly warms heading into October. I guess all the models showing the same short term

trend caused NOAA to back off.

The multi-model averages favor borderline Neutral-La Niña conditions (3-month average Niño-3.4 index less than or equal to -0.5°C) during the Northern Hemisphere fall, continuing into winter (Fig. 6). However, the more recently updated model runs from the North American Multi-Model Ensemble (NMME) more strongly favor ENSO-Neutral (Fig. 7). The forecaster consensus prefers this outcome, which is supported by the lack of significant anomalies in several indicators over the past month (winds, convection, subsurface temperatures). Overall, ENSO-Neutral conditions are slightly favored (between 55-60%) during the upcoming Northern Hemisphere fall and winter 2016-17 (click CPC/IRI consensus forecast for the chance of each outcome for each 3-month period).

 

20160830.poama_nino34.png

 

The other issue is the IOD. It has started to become more negative over the last week. In fact, now the new model runs have it taking a big drop this month. Strong -IOD supports further Niña development. NOAA jumped the gun here 

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I thought we'd get to -0.7 in the fall, before weakening to -0.5 or -0.4 for the winter. I am a bit surprised they removed the watch altogether, as we've actually had some +SOI days recently. But that just hasn't been consistent enough, and the trade winds never fully consistently transitioned into a Nina state. 

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3 minutes ago, Dsnowx53 said:

I thought we'd get to -0.7 in the fall, before weakening to -0.5 or -0.4 for the winter. I am a bit surprised they removed the watch altogether, as we've actually had some +SOI days recently. But that just hasn't been consistent enough, and the trade winds never fully consistently transitioned into a Nina state. 

Do you think we transition to at least a weak Nina state, and if so, what is your best idea about when that might happen?  I would assume anything later than November will have negligible effects on winter weather in the northeast.

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1 hour ago, snowman19 said:

The other issue is the IOD. It has started to become more negative over the last week. In fact, now the new model runs have it taking a big drop this month. Strong -IOD supports further Niña development. NOAA jumped the gun here 

 

I actually do think the -IOD will be strong enough for us to get a -0.7 trimonthly this fall. But with the trade winds never consistently establishing themselves, plus the fact that the IOD is still supposed to rise pretty sharply after this month does point to the fact that it should weaken towards neutral (-0.5 or -0.4) for this winter.

I am a bit surprised they removed the Nina watch altogether, though. 

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On September 8, 2016 at 11:45 AM, Dsnowx53 said:

 

I actually do think the -IOD will be strong enough for us to get a -0.7 trimonthly this fall. But with the trade winds never consistently establishing themselves, plus the fact that the IOD is still supposed to rise pretty sharply after this month does point to the fact that it should weaken towards neutral (-0.5 or -0.4) for this winter.

I am a bit surprised they removed the Nina watch altogether, though. 

We are in agreement here. Of course right after NOAA makes their announcement, we are about to have a major trade wind burst coming up and to top it off, the new run of the JMA is taking region 3.4 down to moderate La Niña levels, not that it will happen, but you know what I mean. New JMA: 

image.png

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On September 13, 2016 at 9:52 AM, bluewave said:

The BOM has kept there watch up for a possible late and weak La Nina. But there isn't than much difference between a La Nada cold neutral and weak La Nina in terms of sensible weather.

http://www.bom.gov.au/climate/enso/#tabs=Outlooks

In the Pacific Ocean, although some La Niña–like patterns are present, there remains limited connection between the atmosphere and ocean, and hence La Niña thresholds are yet to be met. A La Niña WATCH remains in place as some climate models indicate a late and weak La Niña is possible.

Outlooks from the eight international climate models surveyed by the Bureau have eased back slightly in terms of the chance of La Niña, compared to two weeks ago. However, many of the models continue to show borderline cool conditions to be likely and most models include ensemble members which exceed La Niña thresholds. Overall, only one of the surveyed models indicates a clear La Niña is likely to develop and persist across the outlook period.

If La Niña does form, models suggest it will be weak, potentially short-lived, and well below the strength of the significant 2010–12 event.

Even if it turns into a modoki cold-neutral/La Nada event, there will be the exact same tropical convective forcing as there would be if it was a weak La Niña. There would be no difference at all between the two (weak La Niña or cold-neutral) with their effects on the global longwave pattern

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34 minutes ago, bluewave said:

It looks like there was too much residual Nino forcing following the the two year event which ended with the super El Nino.

Notice how much more warmth there is now compared to the same time following the the 97-98 event. All the areas

now are much warmer outside of the immediate equatorial regions. So La Nada or weak La Nina is the best that

the Pacific can do against such a warm background state.

globe_oisst_anom_20160913.png

 

globe_oisst_anom_1998.png

 

 

well said Blue 

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2 hours ago, bluewave said:

It looks like there was too much residual Nino forcing following the the two year event which ended with the super El Nino.

Notice how much more warmth there is now compared to the same time following the the 97-98 event. All the areas

now are much warmer outside of the immediate equatorial regions. So La Nada or weak La Nina is the best that

the Pacific can do against such a warm background state.

globe_oisst_anom_20160913.png

 

globe_oisst_anom_1998.png

 

 

A lot of warmth sst wise yes. My argument is that some people are making a big deal about a cold-neutral vs a weak La Niña, as if there will be a major difference, when in fact there will not be. As far as atmospheric forcing and feedbacks, they are the same thing...

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2 minutes ago, snowman19 said:

A lot of warmth sst wise yes. My argument is that some people are making a big deal about a cold-neutral vs a weak La Niña, as if there will be a major difference, when in fact there will not be. As far as atmospheric forcing and feedbacks, they are the same thing...

That's true but that's a pretty big difference from when you were calling for a strong Nina.  We'll see how this unfolds.  It's always interesting.

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