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42 minutes ago, jvenge said:

La Nina, although only a medium one, showing on the CFSv2 last 10 runs. This is a movement from the neutral to weak La Nina from earlier runs

Captură de ecran din 2017.08.30 la 12.57.56.png

Captură de ecran din 2017.08.30 la 12.58.40.png

That's quite a change! I wonder how it will affect our winter prospects.

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8 minutes ago, karyo said:

That's quite a change! I wonder how it will affect our winter prospects.

I suppose those looking at previous correlation would have preferred if it had stayed neutral on the negative side.

I also don't have access to the other models to see how they see it, but CFSv2 was more interested in sending it neutral before the others some months ago. I guess the enso watch will be updated today/tomorrow though.

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45 minutes ago, jvenge said:

I suppose those looking at previous correlation would have preferred if it had stayed neutral on the negative side.

I also don't have access to the other models to see how they see it, but CFSv2 was more interested in sending it neutral before the others some months ago. I guess the enso watch will be updated today/tomorrow though.

As a general rule I agree but the long range models I have seen so far are unanimous in a mild late autumn and winter period. That was before the CFSv2 went for La Nina. At least it may help the global temperatures even if our winter ends up in the bin.

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2 minutes ago, karyo said:

As a general rule I agree but the long range models I have seen so far are unanimous in a mild late autumn and winter period. That was before the CFSv2 went for La Nina. At least it may help the global temperatures even if our winter ends up in the bin.

Agree, the global temperatures need to subside!

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2 hours ago, karyo said:

As a general rule I agree but the long range models I have seen so far are unanimous in a mild late autumn and winter period. That was before the CFSv2 went for La Nina. At least it may help the global temperatures even if our winter ends up in the bin.

Not sure. I'm not sure if any of the seasonal models are going to be even slightly trustworthy until October. Then keep in mind that they favoured the wrong scenario last winter ;-)

 

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ECM now also pointing to La Nina. CFSv2 modeling a stronger La Nina than just last week.

It looks likely we will be having La Nina conditions for the winter, although only a weak to medium one.

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1 hour ago, jvenge said:

ECM now also pointing to La Nina. CFSv2 modeling a stronger La Nina than just last week.

It looks likely we will be having La Nina conditions for the winter, although only a weak to medium one.

Interesting stuff - but am I right in thinking that La Nina has little effect on European weather? 

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Just now, Paul_1978 said:

Interesting stuff - but am I right in thinking that La Nina has little effect on European weather? 

Depends who you ask :-). Through correlation, technically speaking, cold lovers in the UK like to look for enso neutral to weak La Nina. There isn't any strong correlation for the UK in regards to La Nina and El Nino, but some other parts of Europe can see some differences.

Really good read at http://www.metoffice.gov.uk/research/climate/seasonal-to-decadal/gpc-outlooks/el-nino-la-nina/enso-impacts

La Nina usually brings the global average temperature down as well, which for the UK in winter, can't be a bad thing, one would have thought :-)

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6 hours ago, knocker said:

There is an increasing chance (~55-60%) of La Niña during the Northern Hemisphere fall and winter 2017-18.

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.shtml

Took me a while to figure it out but found it on fig 7,the same as what Michael ventrice has posted

 

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1 hour ago, Allseasons-si said:

Took me a while to figure it out but found it on fig 7,the same as what Michael ventrice has posted

 

Would be a tick  in the box for a cold December, just need more ticks in other boxes....Tis hard work for the uk.:cold::help:

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I'd not get too giddy about a cool start. The early winters of 2005 and 2011 were substantially different for example. 

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11 hours ago, summer blizzard said:

I'd not get too giddy about a cool start. The early winters of 2005 and 2011 were substantially different for example. 

Lol, giddy, far from it.

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On 9/14/2017 at 17:41, summer blizzard said:

I'd not get too giddy about a cool start. The early winters of 2005 and 2011 were substantially different for example. 

2010-11 was a strong la nina coincided with one of coldest Decembers on record but then again so was 2007-8 and 1974-75 both mild winters throughout..having looked at la nina winters there seems to be no correlation with either cold or mild winters in the UK for example both 1955-56 and 1988-89 were moderate to strong la nina one was cold one was mild.

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29 minutes ago, cheeky_monkey said:

2010-11 was a strong la nina coincided with one of coldest Decembers on record but then again so was 2007-8 and 1974-75 both mild winters throughout..having looked at la nina winters there seems to be no correlation with either cold or mild winters in the UK for example both 1955-56 and 1988-89 were moderate to strong la nina one was cold one was mild.

I think what we don't want to see is no Pacific forcing at all. Last winter we saw such a sluggish mid latitude HP scenario and I'm guessing that was, in part, caused by ENSO neutral. I also believe that a strong ENSO event is of detriment to UK winter chances. Weak to moderate events seem to be the most conducive to our winter chances.

I think it's also readily accepted by the pros that 2010-2011 could have been a record cold winter for the UK had La Nina not been so strong as it overwhelmed the background blocking signal throughout January and February. Without, I think 2010/2011 could have rivalled '62/'63. I can remember John Hammond doing a piece on the BBC news saying the atmosphere was in a blocked state and they expected it to stay that way so I think it was clear the strong La Nina affected the general NH state during the last half/two thirds of winter.

Edited by CreweCold

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2 hours ago, cheeky_monkey said:

2010-11 was a strong la nina coincided with one of coldest Decembers on record but then again so was 2007-8 and 1974-75 both mild winters throughout..having looked at la nina winters there seems to be no correlation with either cold or mild winters in the UK for example both 1955-56 and 1988-89 were moderate to strong la nina one was cold one was mild.

I was actually referencing 2011-2012 which was close in strength to 2005-2006. 

2 hours ago, CreweCold said:

I think what we don't want to see is no Pacific forcing at all. Last winter we saw such a sluggish mid latitude HP scenario and I'm guessing that was, in part, caused by ENSO neutral. I also believe that a strong ENSO event is of detriment to UK winter chances. Weak to moderate events seem to be the most conducive to our winter chances.

I think it's also readily accepted by the pros that 2010-2011 could have been a record cold winter for the UK had La Nina not been so strong as it overwhelmed the background blocking signal throughout January and February. Without, I think 2010/2011 could have rivalled '62/'63. I can remember John Hammond doing a piece on the BBC news saying the atmosphere was in a blocked state and they expected it to stay that way so I think it was clear the strong La Nina affected the general NH state during the last half/two thirds of winter.

Although i suspect we got a tad lucky with the severity i have always believed that the early cold of 2010-2011 was a kind of aftereffect caused by the winter of 2010 and the significant forcing of the seasonal wavelengths. I'm a strong advocate that events in one year can effect the next, nicely shown by the early final warming in 2016 leading to a struggling vortex last winter. 

...

With regards to La Nina i am personally now jumping on the moderate train. One of the great things about the hurricane season being August-Oct is that we are nicely able to take a hindsight look at the atmospheric indicator for the coming winter. As you see below, last season saw a more or less neutral state (though we did head to a weak Nina) with both the pacific and atlantic basins a little above average. This season however has a whopping La Nina signal with a subdued Pacific and well above average Atlantic. This for me indicates that the atmosphere right now is leading the ocean in terms of driving a deeper Nina to come. 

YnFQWz6.png

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12 minutes ago, summer blizzard said:

I was actually referencing 2011-2012 which was close in strength to 2005-2006. 

Although i suspect we got a tad lucky with the severity i have always believed that the early cold of 2010-2011 was a kind of aftereffect caused by the winter of 2010 and the significant forcing of the seasonal wavelengths. I'm a strong advocate that events in one year can effect the next, nicely shown by the early final warming in 2016 leading to a struggling vortex last winter. 

...

With regards to La Nina i am personally now jumping on the moderate train. One of the great things about the hurricane season being August-Oct is that we are nicely able to take a hindsight look at the atmospheric indicator for the coming winter. As you see below, last season saw a more or less neutral state (though we did head to a weak Nina) with both the pacific and atlantic basins a little above average. This season however has a whopping La Nina signal with a subdued Pacific and well above average Atlantic. This for me indicates that the atmosphere right now is leading the ocean in terms of driving a deeper Nina to come. 

YnFQWz6.png

So, given this, what do you expect early doors this year then?

I can only see anything more than a moderate nina being detrimental to our winter chances.

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47 minutes ago, CreweCold said:

So, given this, what do you expect early doors this year then?

I can only see anything more than a moderate nina being detrimental to our winter chances.

The danger with La Nina is always that you get tropical subsidence and stronger than average sub-tropical high pressure zones enhancing the westerly flow and pressure gradient. 

My personal thoughts are that the -QBO in combination with lower solar activity and the relaxation of the PDO (neutral or negative) will tip the balance towards a -AO/-NAO winter albeit i don't expect Oct-Dec to be especially cold. If we are going to get a <1C below average winter month then it will be Jan-March. 

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UKMET now also on board with the La Nina. I saw it behind a pay wall, so no idea if I'm allowed to post it. Very similar to CFSv2 though.

 

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Monster surge in the East Pacific now forecast. 

SOI is pretty positive too. 

u.anom.30.5S-5N.gif

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sst.daily.anom.gif

The anomaly pattern still seems oddly inconsistent across the region. Starting to see some values near -2*C now though and with that trades outlook these should expand. Will it be enough to prevent October from having the warmest troposphere on record for the globally? I was amazed to see that September managed this feat but the negative equatorial anomalies were less intense back then.

In our little part of the world, retracing ridge tendencies could make for some interesting weather patterns by late Oct, though this does not necessarily tie in with height rises far N. enough in the Atlantic to deliver much of wintry interest; for that the Arctic profile needs to behave nicely. That detail is still unclear at this range.

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