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La Nina chances

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La Nina chances

Post by Ken »

Just a paste from an email I forwarded to some people re the recent talk of possible upcoming La Nina conditions. Thought some here may be interested:

Interesting to see EC's latest seasonal forecast run that came out today still seems to be suggesting a moderate probability/signal of above average winter rainfall (overall) for QLD/NSW and parts of SA with some stronger signals near the QLD east coast... although the actual forecast amounts aren't a huge margin above average at this stage. It's also still showing a strong signal of above average near-surface temps for much of Oz except northeast NT and around the central Qld coast, although again, not by that much according to the ensemble mean. The MSLP and 500hpa height fields show a belt of pretty big positive anomalies across the far south of the continent. CFS (US) and the multi-model EUROSIP forecasts look pretty similar with their precip and temp forecasts as well. Haven't had a chance to look at the others such as NASA/GMAO and this month's UK run hasn't been finished yet but noticed POAMA's winter rainfall suggestion was similar to the others. The important disclaimer here is that the forecast skill of dynamic models isn't too crash hot during autumn and spring.

So in a nutshell, they still seem optimistic for reasonable winter rainfall around inland and eastern Oz as well as parts of SA. Not sure if the overall warm temp anomalies for the rest of Oz would be due to warmer mins or warmer max's though. I'm guessing it might be partly due to the residual heat left in the system after the recent El Nino. If the eastern Oz rainfall eventuates, it seems consistent with the upcoming return to neutral or possibly even La Nina conditions - see below links:

P.S. JMA's ensemble run on the 13th suggests the areas for the peaking of frontal activity/cyclogenesis for Week 2 (20th to the 27th May) to be southwest of WA and near eastern/southeastern Oz before becoming a bit more zonal for Weeks 2 to 4.

Attachment 1 - SST anomaly forecasts for the NINO 3.4 region (central/eastern Pacific) from all the major dynamic and statistical models until early next year. Sustained strong negative values imply La Nina conditions. Many dynamic models have been going for a return to neutral or La Nina values by this winter since the end of last year:
Image


Attachment 2 - This forecast is created by combining different models and weighting the result towards the higher performing ones. It gives a handy picture of the probabilities of La Nina, El Nino and neutral conditions occurring this year:
Image

Ken.
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Re: La Nina chances

Post by johnno »

Updated today July 21st from the BOM

ENSO:

Computer Models:

All leading international climate models surveyed by the Bureau predict further cooling of the tropical Pacific, accompanied by La Niña conditions, during the coming southern spring.

Recent forecasts from the POAMA model, run daily at the Bureau of Meteorology, are predicting, on average, that ocean temperatures will remain within La Niña values throughout the remainder of 2010.


IOD: Indian Ocean Dipole:
The Indian Ocean Dipole (IOD) remains in a neutral phase, with the latest weekly value of the IOD index near zero.

Recent forecasts from the POAMA model, run daily at the Bureau of Meteorology, predict that the IOD index will fall during the coming months, and potentially reach levels typical of a negative IOD event in spring.

Negative IOD events are often, but not always, associated with above average rainfall over large areas of southern Australia during winter and spring and often coincide with La Niña events.
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Re: La Nina chances

Post by Karl Lijnders »

Thanks for the update John. Loving the info!!! :)

Predicting quite substantial rainfall over the western 2/3rds of the state. Gippsland may struggle this year.
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Re: La Nina chances

Post by Anthony Violi »

if we have favourable conditions from October onwards, expect records to be broken with regards to rainfall through to winter 2011..
http://www.therealworldweatherforum.com" onclick="window.open(this.href);return false;

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Re: La Nina chances

Post by johnno »

From Sintex model latest Monthly (August) update..


ENSO forecast: The La Nina condition has continued to develop quickly in July 2010. A fairly strong cold event would occur in following months and peak around the end of 2010. This La Nina condition would be long-lasting and persist till early 2012.

IOD forecast: Basin-wide sea surface temperature warming structure in the tropical Indian Ocean would persist up to the end of 2010. In early 2011, basin-wide cooling except a warming near the west coast of Australia would occur due to the La Nina influence.

Others: Associated with this strong La Nina influence, more rainfalls would occur in the Eastern Asia, Indonesia, Northern South America, Australia, and India in following boreal fall and winter seasons. During the winter, surface air temperature over many parts of the globe would be below-than-normal. Whereas, the Europe, northern Eurasian continent and southeastern North America would experience a warm winter.
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Re: La Nina chances

Post by Petethemoskeet »

I have a feeling that the next 15mths may well be the wettest(since 1974) across a large part of oz with the SOi touching +30 around the end of the year.Also with a quiet sun next winter IMO will be bordering on the ridiculous for very cold conditions and heavy snow.
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Re: La Nina chances

Post by Karl Lijnders »

Loving your prognosis athern!!!

I hope we can get a few 1974 events!!
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Re: La Nina chances

Post by Karl Lijnders »

Well back in August we were last talking about this and it seems we are in the midst of a serious La Nina. There is a chance we could go into a double dip La Nina also which could mean a very wet 18 months to come.

Spectacular turn around - mother nature showing us who is boss!!
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Re: La Nina chances

Post by Ken »

As far as model outputs go, most of them have been fairly consistent with suggesting a swing towards more neutral ENSO territory approaching next winter (indicated by the warming central/eastern Pacific SST's in the first graphic):

Image

Image
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Re: La Nina chances

Post by Karl Lijnders »

When was the last time we had a double dip La Nina??
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Re: La Nina chances

Post by johnno »

1998-99 & 1999-2000 Karl
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Re: La Nina chances

Post by Karl Lijnders »

With favourable IOD!?
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Re: La Nina chances

Post by johnno »

1998 was a wet year Australia wide close to how this Year has been so I think the IOD was in our favour, for some reason don't remember 99 that much it wasn't a stand out nor wet nor dry Nationwide but 2000 Australia wide was our 2nd wettest Year on record behind 1974 so IOD was in our favour
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Re: La Nina chances

Post by johnno »

Though this Year should rivarl all those 3 Years (74, 98, 2000) interms of rainfall Nationwide be interesting to see if it comes out wetter or not though


Heres a sample of rainfall for Winter and Spring 1998 (this doesn't take in Jan, Feb, Autumn and December but gives us some kind of an idea how 1998 was)

http://www.bom.gov.au/watl/about-weathe ... inaexample" onclick="window.open(this.href);return false;

Vic was mainly close to average apart from parts of the N and NE which were wetter but as you can see quite wet alot of Australia.



1974 Winter/Spring rainfall

http://www.bom.gov.au/climate/IOD/negative/1974n.shtml" onclick="window.open(this.href);return false;

Bit that suprises me here is how not so wet through these 6 months Queensland was and NE NSW
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Re: La Nina chances

Post by Ken »

Karl, http://www.bom.gov.au/climate/IOD/negative/#LaNiña is probably one of the better links out there to describe when they've happened in the past.
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Re: La Nina chances

Post by Karl Lijnders »

Appreciate it guys. Thanks John and Ken!! :D

Bit of a break over the country right now from the insane weather but it will be back in 10 days.
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Re: La Nina chances

Post by johnno »

Well looking back the 2 most accurate models that predicted this La Nina and its strength back in April last Year were JPN-FRCGC & NASA GMAO other models didn't even come close!

Interesting though these same 2 models that got the strength of this La Nina are at odds of how Winter and Spring will pan out this Year NASA GMAO are still saying El Nino conditions will develop by mid Winter while JPN-FRCGC is still sticking to La Nina type of conditions throughout the Year with further weakening during Autumn and Winter with a possible La Nina modoki occuring during this period before the La Nina conditons right across the Pacific return later in the Year.. Heres there prediction which was updated a week ago.


Dear Sensei and colleagues,> > Please find the attached PDF for RIGC/JAMSTEC seasonal forecasts> initiated from 1 March 2011. The current forecasts are basically> similar to the forecasts issued last months.> > Temporary highlights (to be finalized later):> > ENSO forecast: The current strong La Nina has started to weaken and> would decay further in following boreal (Northern Hemisphere) spring and> summer seasons. The decaying La Nina would show a Modoki> pattern. The cold La Nina condition might rebound in> fall and persist up to early 2012.> > IO forecast: Cold sea surface temperature anomalies in the equatorial> Indian Ocean and warm anomalies along the west coast of> Australia, in association with the La Nina impact, would> persist in the following season. In the second half of> 2011, a weak negative IOD would occur probably.> > Regional forecast: The flooding condition in Australia, northern> Brazil, and southern Africa, due to the La Nina> influence, would weaken but tend to persist in the> following season. Southeastern China, southwestern Japan,> US and Europe would have warm and dry condition during> boreal spring-summer seasons. While, Northeastern> China-Korea-northern Japan would have cool and wet> spring-summer seasons.
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Re: La Nina chances

Post by Anthony Violi »

I cant see an El Nino at all developing, Neutral then back to La Nina is my tip..
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Re: La Nina chances

Post by Ken »

Anthony Violi » Tue Mar 15, 2011 3:59 pm wrote:
Anthony Violi wrote:I cant see an El Nino at all developing, Neutral then back to La Nina is my tip..
Once the Pacific Ocean makes up its mind on what it wants to do later this year (usually by around late autumn/early winter in most years), we should have a better idea. Meanwhile, here's some food for thought:

Latest update of the graph comparing the current easing La Nina with similar past events (in terms of central/eastern Pacific SST anomalies). Strong negative values represent La Nina conditions while strong positive values represent El Nino conditions. Past events have typically seen a return to more neutral conditions by winter before another slight dip later in spring - this is where they start to diverge:
Image

Plume forecast of central/eastern Pacific SST anomalies from all the leading dynamical models (black line = observed). Like past similar events, most models suggest a return to more neutral territory by winter before some suggest another dip later in spring - which again is where they start to diverge. Incidentally, CFS was upgraded to Version 2 at the end of last month but its outlook for another dip later in spring still hasn't changed from its predecessor:
Image

Forecast probabilities of La Nina/Neutral/El Nino from the IRI:
Image
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Re: La Nina chances

Post by johnno »

Latest Jamstec forecast for June updated Today...

Dear Sensei and colleagues, Please find the monthly mean maps as attached below. Your comments are very appreciated. Best regards,Jing-Jia > Dear Sensei and colleagues,> > Please find the attached PDF for RIGC/JAMSTEC seasonal forecasts> initiated from 1 June 2011. Please note that certain uncertainties exist in> the June forecasts. > > Temporary highlights (to be finalized later):> > > >

ENSO forecast: The current La Nina condition has decayed during the> past months and showed a Modoki-type pattern. Although the> possibility of an El Nino development cannot be excluded> (if surface westerly wind bursts in the equatorial western> Pacific would happen in following months), our model> forecasts continuously show that the La Nina condition> would return back in fall and persist up to early 2012.> >

IO forecast: Large uncertainty exists for the IOD forecasts; neither> strong positive IOD nor strong negative IOD would occur> this year. Warmer seas surface temperature would persist> west of Australia.> >

Regional forecast: The cool/wet condition in southern Africa would> continue in following austral winter but weaken in spring.> Most of Australia would have a dry austral winter and> normal spring. Japan would have a dry condition in> July-August 2011; seasonal mean temperature would be almost> normal this summer but with strong intraseasonal> fluctuations. Northeastern China would have flooding> condition in July-August 2011. Most of India would have> good rains/flooding associated with the La Nina influence.> > > > If you have any comments/suggestions/requests, please kindly inform> us. Thank you very much.> > Best regards,> Jing-Jia
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