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El Nino And La Nina: How They Effect The North Atlantic And The Uk


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Posted
  • Location: Stanwell(south side of Heathrow Ap)
  • Weather Preferences: Thunderstorms, squally fronts, snow, frost, very mild if no snow or frost
  • Location: Stanwell(south side of Heathrow Ap)

    Please discuss these weather phenomenons, how they affect the north atlantic and the uk , how active are they now, in what way is the uk weather going to be affected over the coming months?

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    Posted
  • Location: Split,Croatia(ex yugoslavia)
  • Location: Split,Croatia(ex yugoslavia)

    If you ask me this is pretty stupid.Because some El nino episodes bring cool and wet and some dry and warm spells in UK...similar is for La nina,this is just one factor and it's not also dominant....more dominant is NAO,AO,QBO and sea temperatures west of UK...La nina and El nino can't control weather here in Europe.....

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    Posted
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet

    If you ask me this is pretty stupid.Because some El nino episodes bring cool and wet and some dry and warm spells in UK...similar is for La nina,this is just one factor and it's not also dominant....more dominant is NAO,AO,QBO and sea temperatures west of UK...La nina and El nino can't control weather here in Europe.....

    I disagree, along with the QBO it is the most dominant teleconnection on the planet, the AO and NOA are just by products of these two teleconnection patterns and probably dictate around 80% of the UK weather patterns on a monthly basis.

    The reason for the differences in weather observed is because of the interaction between the states of the MEI and QBO, you may get two strong El Ninos, but if one has a +QBO and one has a -QBO, you get two different affects on the AO which in turn means two differing effects on the NAO. On top of that, you have to take into the account whether the El Nino/La Nina is west or east based and whether we have a period of high solar activity or low, thus you never get exactly the same effect twice. Teleconnection interaction is extremely complicated.

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    So, assuming that we will get a fairly substatial La Nina winter along with subdued solar activity, what are the likely effects going into thw winter months and how are the other factors looking as regards to high latitude blocking and hence the NAO.

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    Posted
  • Location: Stourbridge
  • Location: Stourbridge

    So, assuming that we will get a fairly substatial La Nina winter along with subdued solar activity, what are the likely effects going into thw winter months and how are the other factors looking as regards to high latitude blocking and hence the NAO.

    well glacier point made a very good post yesterday i think it was, explaining how stratospheric cooling could occur this winter, and therefore a positive NAO and stormy winter look likely, perhaps after a cooler start.

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    Posted
  • Location: Stanwell(south side of Heathrow Ap)
  • Weather Preferences: Thunderstorms, squally fronts, snow, frost, very mild if no snow or frost
  • Location: Stanwell(south side of Heathrow Ap)

    Im studying meteorology and am very interested in how the oceans temperatures affect uk weather and also the atlantic ocean.

    la nina is believed to be linked to more tropical storms then usual in the north atlantic, but less storms during el nino ,the storm season so far looks normal but is it likely to increase during august?

    How active is LN/EN now?

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    Posted
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet

    well glacier point made a very good post yesterday i think it was, explaining how stratospheric cooling could occur this winter, and therefore a positive NAO and stormy winter look likely, perhaps after a cooler start.

    I would concur with that. If we are going to see stratospheric warming it will be during November or December, however the combination of a strengthening La Nina and +QBO will almost certainly mean a strong Polar Vortex during January.

    At the current moment in time, we have a strengthening weak La Nina combined with a weakening -QBO, this should lead to a cool Autumn.

    The Atlantic Hurricane season is currently predicted to be well above average, there is nothing so far to suggest that this will not occur, given that the main activity occurs in the August-October timeframe.

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    Posted
  • Location: Windermere 120m asl
  • Location: Windermere 120m asl

    Yes I think there are a number of factors which influence the british weather though El Nino and La Nina are big factors. I think many were caught out last winter mind with all the talk of a ramping El Nino which alone would be enough to kill any chances of sustained cold. I'm not what other factors came into play to prevent such a thing happening, but it shows that predicted El Nino and La Nina forecasts can easily be thrown out the window by other less believed influential factors.

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    Posted
  • Location: W. Northants
  • Location: W. Northants

    All I'll say at this stage in relation to the coming winter is that to me theres a rather 1950's feel about the state of the various teleconnections at the moment. The strong La Nina's in 54-55 and 55-56 both co-incided with cold winters, however both had mild Decembers.

    So all this talk of early cold followed by a mild and stormy spell mid to late winter, could be barking up the wrong tree. :shok:

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    Posted
  • Location: hertfordshire
  • Location: hertfordshire

    I disagree, along with the QBO it is the most dominant teleconnection on the planet, the AO and NOA are just by products of these two teleconnection patterns and probably dictate around 80% of the UK weather patterns on a monthly basis.

    The reason for the differences in weather observed is because of the interaction between the states of the MEI and QBO, you may get two strong El Ninos, but if one has a +QBO and one has a -QBO, you get two different affects on the AO which in turn means two differing effects on the NAO. On top of that, you have to take into the account whether the El Nino/La Nina is west or east based and whether we have a period of high solar activity or low, thus you never get exactly the same effect twice. Teleconnection interaction is extremely complicated.

    I'm sorry but I have to disagree with your opening sentence. The AO and the NAO can be positive or negative regardless of the ENSO state.A colder subtropical stratosphere plus higher quantities of ozone in the northern hemisphere leading to a more disorganized polar vortex and a continuation of northern blocking (not necessarily a - AO) could lead to another very good winter. This is of course all speculation at present although I have been monitoring these indices and they look quite promising at the moment.

    The continued low solar activity, higher ozone levels due to a fairly active brewer dobson circulation and encouragement from a north Atlantic sst pattern which would help support a -NAO plus the IOD as GP mentioned is forcast to enter its negative mode which I have read can aid in the NAO being negative although how much if any correlation there is I don't profess to know.

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    Posted
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet

    I'm sorry but I have to disagree with your opening sentence. The AO and the NAO can be positive or negative regardless of the ENSO state.A colder subtropical stratosphere plus higher quantities of ozone in the northern hemisphere leading to a more disorganized polar vortex and a continuation of northern blocking (not necessarily a - AO) could lead to another very good winter. This is of course all speculation at present although I have been monitoring these indices and they look quite promising at the moment.

    The continued low solar activity, higher ozone levels due to a fairly active brewer dobson circulation and encouragement from a north Atlantic sst pattern which would help support a -NAO plus the IOD as GP mentioned is forcast to enter its negative mode which I have read can aid in the NAO being negative although how much if any correlation there is I don't profess to know.

    It is true that teleconnections in a certain state do not mean that the AO or NAO will be 100% positive or negative, all we can really do is use statistics to try predict what the effect will be. In general a positive AO in winter leads to above average temperatures and precipitation, and visa versa for a negative AO, however you can get a split vortex which in the right places can lead to cold weather over the UK such as in winter 1984.

    Gavin, the winter of 1955 saw a weak/moderate La Nina, and in 1956 a moderate strong La Nina. In both of these instances La Nina was weakening throughout the winter (you are correct in that both saw strong peaks at other times of the year), this resulted in the AO becoming more negative as winter progressed.

    http://www.esrl.noaa.gov/psd/people/klaus.wolter/MEI/table.html

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    Posted
  • Location: Yorkshire Puddin' aka Kirkham, Lancashire, England, United Kingdom
  • Weather Preferences: cold winters, cold springs, cold summers and cold autumns
  • Location: Yorkshire Puddin' aka Kirkham, Lancashire, England, United Kingdom

    On top of that, you have to take into the account whether the El Nino/La Nina is west or east based and whether we have a period of high solar activity or low, thus you never get exactly the same effect twice. Teleconnection interaction is extremely complicated.

    Indeed Summer Blizzard an east based La Nina like 1995/1996 and an west based El Nino like 2009/2010 will often give us cool/cold winters and other seasons. This is because an east based La Nina and west based El Nino teleconnects to a cold east based -ve AO/NAO block (Cold Northerlies over UK) or cold zonality +ve AO/NAO (Cold Westerlies or Southerly tracking lows over UK). However a west based La Nina like 1974/1975 and an east based El Nino like 1997/1998 will often give use mild/hot winters and other seasons. This is because an west based La Nina and east based El Nino teleconnects to a warm west based -ve AO/NAO block (Warm Southerlies over UK) or warm zonality +ve AO/NAO (Warm Westerlies or Azores High ridging over UK).

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    Posted
  • Location: Redhill, Surrey
  • Weather Preferences: Southerly tracking LPs, heavy snow. Also 25c and calm
  • Location: Redhill, Surrey

    What one must look at IMO is what has caused the AO and NAO to act in the way they have in spite of la Nina or El Nino. The noticeable common denominator of the last two winters is that we observed a southerly tracking jet. And because of this we were destined to have widespread cold outbreaks in the NH mid latitudes despite AO/NAO or ENSO set up [winter 08/09 had no -ve NAO to speak of or -ve AO] yet we had cold spilling southwards. The major driving factor is the low solar activity and I don't mean the 11 year cycle minimum [for I believe we have entered a period where a grand minimum will occur like a Dalton or Sporer].

    ENSO IMO is also solar driven as in the perturbation cycle. We entered the Nina dominant phase in Feb 2007, this is a approx 36yr cycle. The last time we were in this phase was late 30s onwards so doing the maths since late 70s we entered the Nino phase [and we have seen the temp differences in winters]. The overall state of the NAO correlates very well with the perturbation cycle and it seems very coincidental that since Feb 2007 the jetstream has shown a wanton willingness to track south?

    ENSO for me sets up a pattern but how that pattern shapes up ie how far north or south it is, gets decided by other teleconnections [most feared for last winter with an El Nino rapidly developing] and we are in a phase where colder winter patterns will be more common place. Then there's PDO/AMO but for me its all about the solar [and lunar] pattern changing the behaviour of the jetstream.

    BFTP

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    Posted
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet

    What one must look at IMO is what has caused the AO and NAO to act in the way they have in spite of la Nina or El Nino. The noticeable common denominator of the last two winters is that we observed a southerly tracking jet. And because of this we were destined to have widespread cold outbreaks in the NH mid latitudes despite AO/NAO or ENSO set up [winter 08/09 had no -ve NAO to speak of or -ve AO] yet we had cold spilling southwards. The major driving factor is the low solar activity and I don't mean the 11 year cycle minimum [for I believe we have entered a period where a grand minimum will occur like a Dalton or Sporer].

    ENSO IMO is also solar driven as in the perturbation cycle. We entered the Nina dominant phase in Feb 2007, this is a approx 36yr cycle. The last time we were in this phase was late 30s onwards so doing the maths since late 70s we entered the Nino phase [and we have seen the temp differences in winters]. The overall state of the NAO correlates very well with the perturbation cycle and it seems very coincidental that since Feb 2007 the jetstream has shown a wanton willingness to track south?

    ENSO for me sets up a pattern but how that pattern shapes up ie how far north or south it is, gets decided by other teleconnections [most feared for last winter with an El Nino rapidly developing] and we are in a phase where colder winter patterns will be more common place. Then there's PDO/AMO but for me its all about the solar [and lunar] pattern changing the behaviour of the jetstream.

    BFTP

    While i agree with much of what you said, there are a few points i would like to make.

    1) In regards to the AO during the winter of 2009, February did actually see a negative AO, however you are right in that December and January saw neutral positive values which would normally have led to zonality.

    2) I believe the reason the Jet Stream was so supressed last winter was because El Nino correlates to a +PNA which leads to the Jet Sream exiting the USA on a southerly track, in this case we also saw a -QBO which kept the Jet Stream south instead of returning northward, El Nino does not always mean a warm winter

    3) I believe there may be some basis in what you say, we have entered a -PDO decadel fase, which could possibly mean a much higher chance of a -AO during winter because they are correlated.

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    Posted
  • Location: W. Northants
  • Location: W. Northants

    What one must look at IMO is what has caused the AO and NAO to act in the way they have in spite of la Nina or El Nino. The noticeable common denominator of the last two winters is that we observed a southerly tracking jet. And because of this we were destined to have widespread cold outbreaks in the NH mid latitudes despite AO/NAO or ENSO set up [winter 08/09 had no -ve NAO to speak of or -ve AO] yet we had cold spilling southwards. The major driving factor is the low solar activity and I don't mean the 11 year cycle minimum [for I believe we have entered a period where a grand minimum will occur like a Dalton or Sporer].

    ENSO IMO is also solar driven as in the perturbation cycle. We entered the Nina dominant phase in Feb 2007, this is a approx 36yr cycle. The last time we were in this phase was late 30s onwards so doing the maths since late 70s we entered the Nino phase [and we have seen the temp differences in winters]. The overall state of the NAO correlates very well with the perturbation cycle and it seems very coincidental that since Feb 2007 the jetstream has shown a wanton willingness to track south?

    ENSO for me sets up a pattern but how that pattern shapes up ie how far north or south it is, gets decided by other teleconnections [most feared for last winter with an El Nino rapidly developing] and we are in a phase where colder winter patterns will be more common place. Then there's PDO/AMO but for me its all about the solar [and lunar] pattern changing the behaviour of the jetstream.

    BFTP

    So putting it all together, the Grand Minimum, the Nina phase, the -PDO and -AMO phase's basically things are gonna get pretty chilly out there over the next 30-50 years if your right? :good::shok:

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    Posted
  • Location: Hanley, Stoke-on-trent
  • Location: Hanley, Stoke-on-trent

    It's just another factor to take into account. Teleconnections are interesting. Sometimes they are a good guide sometimes not. If it was all so easy, don't you think that longer range forecasts would be much more accurate?

    As it is, we seem stuck in a particular pattern at the moment, but one ex-hurricane could "blow" the present pattern away.

    We've had cold & mild winters, warm & cool summers in both el nino & la nina conditions. certain patterns may be more likely, but by no means certain.

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    Posted
  • Location: Crewe, Cheshire
  • Weather Preferences: Snow, storms and other extremes
  • Location: Crewe, Cheshire

    In analysis of the current state of things what is your opinion on the upcoming winter Blast, and how do you think the la Nina will affect things? Until recently i was convinced of a cold winter a la last winter but with some of the experts of the forum now saying the opposite I am less sure.

    Aaron

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    Posted
  • Location: Redhill, Surrey
  • Weather Preferences: Southerly tracking LPs, heavy snow. Also 25c and calm
  • Location: Redhill, Surrey

    While i agree with much of what you said, there are a few points i would like to make.

    1) In regards to the AO during the winter of 2009, February did actually see a negative AO, however you are right in that December and January saw neutral positive values which would normally have led to zonality.

    2) I believe the reason the Jet Stream was so supressed last winter was because El Nino correlates to a +PNA which leads to the Jet Sream exiting the USA on a southerly track, in this case we also saw a -QBO which kept the Jet Stream south instead of returning northward, El Nino does not always mean a warm winter

    3) I believe there may be some basis in what you say, we have entered a -PDO decadel fase, which could possibly mean a much higher chance of a -AO during winter because they are correlated.

    SB

    With regards to 2, correct El Nino doesn't always mean a mild winter but it almost always did in last 3 decades prior to 2007. Over 20th century the El Nino correlation to cold, average or mild was almost even but it appears that during the El Nino perturbation phase mild was much more likely and vice versa. Why did we suddenly get a -ve QBO with an El nino? IMO the solar and lunar phasing and perturbation cycle. It kicked in Feb 2007, since then the jetstream has shown strong suppressed tendency.

    We've had cold & mild winters, warm & cool summers in both el nino & la nina conditions. certain patterns may be more likely, but by no means certain.

    Correct not certain but more prevalent, NAO behavior correlates very well with the perturbation cycle. We have entered a phase where -ve NAO is likely to readily show its hand.

    In analysis of the current state of things what is your opinion on the upcoming winter Blast, and how do you think the la Nina will affect things? Until recently i was convinced of a cold winter a la last winter but with some of the experts of the forum now saying the opposite I am less sure.

    Aaron

    Even in favourable phases a cold UK winter is by no means guaranteed. I see at least an 08/09 winter and potential more towards last winter [i think this sudden switch since 07 is very similar due to the cycles to winters from 38/39 onwards]. Western Europe very cold, will it hit our shores......I think yes but this is a very early indicator. I forecast that last winter would be cold but I was taken back a bit by its coldness as I succumbed that the recent decadal warmth would take some edge off it. It didn't.

    BFTP

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    Posted
  • Location: Ireland, probably South Tipperary
  • Weather Preferences: Cold, Snow, Windstorms and Thunderstorms
  • Location: Ireland, probably South Tipperary

    At a glance it looks like the monthly drop in the MEI values has been the largest on record. LINK

    Will that have any particular differring effect on ENSO influenced weather patterns over a usual drop? Other than the obvious of getting in a La Nina weather pattern sooner?

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    Posted
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet

    SB

    With regards to 2, correct El Nino doesn't always mean a mild winter but it almost always did in last 3 decades prior to 2007. Over 20th century the El Nino correlation to cold, average or mild was almost even but it appears that during the El Nino perturbation phase mild was much more likely and vice versa. Why did we suddenly get a -ve QBO with an El nino? IMO the solar and lunar phasing and perturbation cycle. It kicked in Feb 2007, since then the jetstream has shown strong suppressed tendency.

    Correct not certain but more prevalent, NAO behavior correlates very well with the perturbation cycle. We have entered a phase where -ve NAO is likely to readily show its hand.

    Even in favourable phases a cold UK winter is by no means guaranteed. I see at least an 08/09 winter and potential more towards last winter [i think this sudden switch since 07 is very similar due to the cycles to winters from 38/39 onwards]. Western Europe very cold, will it hit our shores......I think yes but this is a very early indicator. I forecast that last winter would be cold but I was taken back a bit by its coldness as I succumbed that the recent decadal warmth would take some edge off it. It didn't.

    BFTP

    Blast i do agree that it is quite strange that we saw a -QBO in combination with +MEI conditions, however that may have just been a fluke because the QBO cycle does not look unusual, one year negative, another year positive, while EL Nino/La Nina seems to follow a more more random pattern, though no doubt connected to the Pacific Decadel Occilation which you are right, has entered a negative phase and should remain negative until around 2040. Looking at the QBO and MEI data, only 1992 and 2004 saw a similar pattern.

    Blast in regards to the solar pattern, we entered a subdued phase of solar activity in 2008 which should persist until around 2060 (Gleisenburg Minimum). What this means is that the current solar maxima will be much lower than normal and then there will be almost no solar activity present until around 2050, this is also what caused the Little Ice Age, so should test the man made global warming theory. I believe that the combination of a -PDO and low solar activity should also mean a period of supressed temeratures year round, peaking around 2030, so yes Gavin the forecast would be for a cooldown during the next 40 years dependant on just how much impact man has made upon the climate.

    At a glance it looks like the monthly drop in the MEI values has been the largest on record. LINK

    Will that have any particular differring effect on ENSO influenced weather patterns over a usual drop? Other than the obvious of getting in a La Nina weather pattern sooner?

    Indeed, the drop was the largest monthly drop in MEI values on record.

    In regards to the effect, it is already showing its hand now, La Nina during summer is strongly correlated to a mid-Atlantic Ridge and El Nino to an tlantic trough. It also means that anybody who was predicting a weak La Nina needs to up their prediction accordingly because we are already seeing weak La Nina conditions.

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    Posted
  • Location: Redhill, Surrey
  • Weather Preferences: Southerly tracking LPs, heavy snow. Also 25c and calm
  • Location: Redhill, Surrey

    Blast in regards to the solar pattern, we entered a subdued phase of solar activity in 2008 which should persist until around 2060 (Gleisenburg Minimum). What this means is that the current solar maxima will be much lower than normal and then there will be almost no solar activity present until around 2050, this is also what caused the Little Ice Age, so should test the man made global warming theory. I believe that the combination of a -PDO and low solar activity should also mean a period of supressed temeratures year round, peaking around 2030, so yes Gavin the forecast would be for a cooldown during the next 40 years dependant on just how much impact man has made upon the climate.

    Yes Gleissburg minima with two peaks [bottoms] around 2030 and 2080, possible 3rd in 2100. This is Sporer, Dalton or even Maunder standard. Jetstream pattern to remain surpressed 'overall'. This is for me the issue....quite a few 'cold' patterns are merging with the grand minima around the corner. You are correct it is the low activity during solar maxima periods within the 11 yr cycle which determines the depth of a grand minima......something folk should/need to be aware of.

    BFTP

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    Posted
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet

    Gleissburg Minima should be similar to the Maunder Minimum with two troughs, it is the one after in the 2200's which should have three. The Dalton Minimum was a single trough event and thus was not quite as sever as the Maunder Minimum.

    In regards to La Nina and the QBO this winter, 1984 looks to be quite similar, though both La Nina and the QBO look to have more amplitude, that winter saw the following CET values..

    5.2, 0.1C above average

    0.8, 3.4C below average

    2.1, 2.1C below average

    Lets hope the data at the end of July backs this up.

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    Posted
  • Location: Redhill, Surrey
  • Weather Preferences: Southerly tracking LPs, heavy snow. Also 25c and calm
  • Location: Redhill, Surrey

    Gleissburg Minima should be similar to the Maunder Minimum with two troughs, it is the one after in the 2200's which should have three. The Dalton Minimum was a single trough event and thus was not quite as sever as the Maunder Minimum.

    In regards to La Nina and the QBO this winter, 1984 looks to be quite similar, though both La Nina and the QBO look to have more amplitude, that winter saw the following CET values..

    5.2, 0.1C above average

    0.8, 3.4C below average

    2.1, 2.1C below average

    Lets hope the data at the end of July backs this up.

    Well spotted SB re troughs....but this is interesting from Landscheidt

    My linkhttp://www.schulphysik.de/klima/landscheidt/Fig11e.jpg

    2 triple troughs

    BFTP

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    Posted
  • Location: Liphook
  • Location: Liphook

    I think we are looking at a very potent La Nina, such a strong La Nina peaking in November/December will lead to a very zonal jet stream, with a strong Azores high pattern, but of course if we were to get any decent -ve AO pattern then the Azores High may well lead to a pretty good cold spell at some point this winter.

    The whole comprasion to the 54-56 Ninas is a very good one IMO, it came towards the last part of the warm Phase in the Atlantic and I believe the PDO had flipped negative by then....the AMO came 10-15 years later.

    We are now just about ready to dive downwards globally in terms of average, the 2010s should be cooler then the 2000s globally and this probably will be the high point we reach for a while yet....and once the Atlantic tropics cooldown as well, then things will get real interesting, esp as it should come at the same time as the next solar Min down the line, the combo of the -PDO/AMO and a very low solar min will tell I'm sure...

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    Posted
  • Location: Ireland, probably South Tipperary
  • Weather Preferences: Cold, Snow, Windstorms and Thunderstorms
  • Location: Ireland, probably South Tipperary

    MEI continuing to tank, now down to -1.166, the 9th lowest on record for this time of year MEI

    The latest CPC ENSO forecasts here link

    Looking good for a moderate-strong La Nina at this stage

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