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Gray-Wolf

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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

With the next MJO wave not due to try and penetrate until December we could see November producing the strongest values of this Nina if not January. With the massive drop in 3.4 it looks as though those sub-surface anomolies are now crushing all opposition with a background of strong trades in the region. 

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u.anom.30.5S-5N.gif

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Posted
  • Location: Lincolnshire - 15m asl
  • Weather Preferences: Frost and snow. A quiet autumn day is also good.
  • Location: Lincolnshire - 15m asl

Yes - continued concern on the depth of Nina. MetO forecast a few days ago caught the eye, and with region 3.4 already at -1.2 and forecast to fall further we could end up in -1.5 or lower territory. Hard to see much AAM coming from such a setup. A winter of topplers only?

Edited by Catacol
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Posted
  • Location: Marton
  • Location: Marton
1 hour ago, Catacol said:

Yes - continued concern on the depth of Nina. MetO forecast a few days ago caught the eye, and with region 3.4 already at -1.2 and forecast to fall further we could end up in -1.5 or lower territory. Hard to see much AAM coming from such a setup. A winter of topplers only?

December 2010 had a similar level and produced the coldest in over 100 years:good:

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Posted
  • Location: Crewe, Cheshire
  • Weather Preferences: Snow, storms and other extremes
  • Location: Crewe, Cheshire
6 minutes ago, Matthew. said:

December 2010 had a similar level and produced the coldest in over 100 years:good:

Yes but the strong Nina is the reason the HLB signal became overwhelmed and winter pretty much ended on the 27th!

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Posted
  • Location: Marton
  • Location: Marton
5 minutes ago, CreweCold said:

Yes but the strong Nina is the reason the HLB signal became overwhelmed and winter pretty much ended on the 27th!

Very true but I’d take 1 month like that over 3 of a little below average and no proper snow let’s say.

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Posted
  • Location: Brighton (currently)
  • Location: Brighton (currently)
13 hours ago, Matthew. said:

Very true but I’d take 1 month like that over 3 of a little below average and no proper snow let’s say.

Well, if La Nina favours early cold (like 2010) then it has to show up pretty soon given that half of November is already over.

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Posted
  • Location: Marton
  • Location: Marton
3 hours ago, karyo said:

Well, if La Nina favours early cold (like 2010) then it has to show up pretty soon given that half of November is already over.

Without clogging the thread up all I’ll say is look out for the 2nd half of December:)

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Posted
  • Location: Wakefield, West Yorkshire
  • Location: Wakefield, West Yorkshire
3 hours ago, Matthew. said:

Without clogging the thread up all I’ll say is look out for the 2nd half of December:)

What do you know that we don't? :)

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Posted
  • Location: Windermere 120m asl
  • Location: Windermere 120m asl
8 hours ago, karyo said:

Well, if La Nina favours early cold (like 2010) then it has to show up pretty soon given that half of November is already over.

Lets see how dominant La Nina might be this winter - it is just one factor after all, others could cancel it out. If it was that easy to predict a season based on ENSO we should all go home now. Too many other variable factors at play.

 

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Posted
  • Location: Brighton (currently)
  • Location: Brighton (currently)
18 minutes ago, damianslaw said:

Lets see how dominant La Nina might be this winter - it is just one factor after all, others could cancel it out. If it was that easy to predict a season based on ENSO we should all go home now. Too many other variable factors at play.

 

That's true especially if La Nina stays weak to moderate. 

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Posted
  • Location: Chisinau, Moldova.
  • Location: Chisinau, Moldova.
17 hours ago, damianslaw said:

Lets see how dominant La Nina might be this winter - it is just one factor after all, others could cancel it out. If it was that easy to predict a season based on ENSO we should all go home now. Too many other variable factors at play.

 

Yes, but I guess it is then "Despite a La Nina, ...." As opposed to "Because of a La Nina,..." or "With the help of a La Nina.."

I don't think anyone would pretend that an ENSO state of La Nina means you can't experience cold, as you would be then denying some fairly significant winters over the decades. Just more that you rely more on something overriding the La Nina influence and the longer that interference is not forthcoming, the less likely it is to have the desired impact....

And just to be super duper clear, just because you don't have the cold the netweather crowd want, doesn't mean it could be classed as mild, either.

I think an interesting phase is coming up. Entering low solar again and the last time this happened, the UK enjoyed some impressing winter weather. Just that in this particular season isn't presenting the most opertunistic circumstances to take advantage of it....yet.

 

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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
On 11/14/2017 at 19:57, Catacol said:

Yes - continued concern on the depth of Nina. MetO forecast a few days ago caught the eye, and with region 3.4 already at -1.2 and forecast to fall further we could end up in -1.5 or lower territory. Hard to see much AAM coming from such a setup. A winter of topplers only?

Probably worth saying that it's likely to peak in November or January (based on the next MJO wave being due in December) so although this weekly value is a shock (lowest since 2011 in 3.4?) it's not guaranteed to be a monthly value and the weather is not so fickle that it responds on a whim. 

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Posted
  • Location: Roznava (Slovakia) formerly Hollywood, Co Wicklow
  • Weather Preferences: continental climate
  • Location: Roznava (Slovakia) formerly Hollywood, Co Wicklow

Can I ask what are the atmospehic responses that prevent blocking occurring during very strong LA Nina events? Are there any scientific research papers on this?thanks

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Posted
  • Location: Lytchett Matravers - 301 ft ASL
  • Weather Preferences: Snowy Winters, Torrential Storm Summers
  • Location: Lytchett Matravers - 301 ft ASL
On 15/11/2017 at 15:14, Matthew. said:

Without clogging the thread up all I’ll say is look out for the 2nd half of December:)

 

On 15/11/2017 at 18:29, Paul_1978 said:

What do you know that we don't? :)

Yes .... Matthew please do clog away... it's what we are here for after all. That's a fairly bold statement.

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Posted
  • Location: Lincolnshire - 15m asl
  • Weather Preferences: Frost and snow. A quiet autumn day is also good.
  • Location: Lincolnshire - 15m asl
On 17/11/2017 at 12:07, jules216 said:

Can I ask what are the atmospehic responses that prevent blocking occurring during very strong LA Nina events? Are there any scientific research papers on this?thanks

In simple terms the equatorial Pacific is the engine room of the entire global weather system. In a Nina the cooler waters encourage less convection and hence less storm activity and this in turn means there is less energy transferred to the northern hemisphere circulation. With less energy this tends to suggest waves of lower amplitude circling the earth... and without sufficient amplitude we end up with a flatter pattern. For us at 55 degrees we are then in a poor position because the normal position of the jet stream will tend to fire systems straight across the Atlantic at us in winter. For a higher lat block to be encouraged to take hold we need a more “wobbly” wave pattern courtesy of Pacific energy and atmospheric momentum.

The current Nina pattern is centred in the eastern Pacific. Pacific convection begins in cycles much further west than this. Those who are forecasting opportunities for cold later in the season are hoping that convection anomalies in Indian Ocean and central Pacific will produce forcing that will be sustained as the convection pattern moves east despite the cold waters in situ currently off Peru. Others think those cold waters will neutralise the pattern just when it hits the crucial eastern Pacific sector which is particularly important for blocking in our part of the world.

I am hoping Nina may fade just as the next cycle (MJO) begins, allowing a crucial input of energy into the system in the heart of winter. The next MJO cycle ought to begin in mid/late December, perfect timing for impacts in mid Jan. But if Nina strengthens.. and the atmosphere has already coupled to the Nina signature that will encourage flat westerlies across the Atlantic, then we will struggle to get blocks high enough. Azores High, or Euro High, influence will likely grow and then our winter sags.

The same Pacific forcing also has an impact on the stratosphere via potential vertical wave breaking of warm air upwards. This is another complex situation, but to maximise the benefits of the next Pacific cycle it wouldn’t be w bad thing to see an aleutian low in the North Pacific coupled to a Siberian High. These 2 features, properly positioned, can encourage vertical wave activity by adding energy to the atmospheric circulation via mountain torque and also disrupting the intensity of the vortex by firing broadsides of warmer air into the vortex as part of the torque event. I struggle to visualise the mechanics of this in all situations because these warm air attacks can disrupt the vortex in what seems to be a myriad of different ways, but once disrupted lower zonal wind speeds can also aid in blocks becoming established at high latitude.

Long and short of it is that the Pacific is absolutely key to patterns of weather in the North Atlantic. The obvious final point is that an incorrect seasonal assessment of Pacific patterns means any seasonal forecast for the UK ends up inaccurate. The reality is that the Nina forecast is not carved in stone and therefore, if the starting pacific conditions are incorrect in model calculations, then no matter how great the computer power the resultant forecast is damaged. UKmet forecasts of Nina are on the strong side compared to ECM at the moment, and I think this is important when considering Glosea output. But the last 3 Glosea runs have sequentially suggested less mild and more potential for cold... though the probability maps still suggest mild more likely than cold form the coming season. My interpretation, for what it is worth, of that trend is that all models are seeing a relaxing of the Nina signature as we hit January and so chances for blocking in mid to late winter may be gently increasing. However this is all conjecture at this stage really... but to finish with a direct Nina comment: if we want decent chances of proper cold in mid winter it will help if Nina doesn’t drop too deep. 

Edited by Catacol
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Posted
  • Location: Roznava (Slovakia) formerly Hollywood, Co Wicklow
  • Weather Preferences: continental climate
  • Location: Roznava (Slovakia) formerly Hollywood, Co Wicklow
8 hours ago, Catacol said:

In simple terms the equatorial Pacific is the engine room of the entire global weather system. In a Nina the cooler waters encourage less convection and hence less storm activity and this in turn means there is less energy transferred to the northern hemisphere circulation. With less energy this tends to suggest waves of lower amplitude circling the earth... and without sufficient amplitude we end up with a flatter pattern. For us at 55 degrees we are then in a poor position because the normal position of the jet stream will tend to fire systems straight across the Atlantic at us in winter. For a higher lat block to be encouraged to take hold we need a more “wobbly” wave pattern courtesy of Pacific energy and atmospheric momentum.

The current Nina pattern is centred in the eastern Pacific. Pacific convection begins in cycles much further west than this. Those who are forecasting opportunities for cold later in the season are hoping that convection anomalies in Indian Ocean and central Pacific will produce forcing that will be sustained as the convection pattern moves east despite the cold waters in situ currently off Peru. Others think those cold waters will neutralise the pattern just when it hits the crucial eastern Pacific sector which is particularly important for blocking in our part of the world.

I am hoping Nina may fade just as the next cycle (MJO) begins, allowing a crucial input of energy into the system in the heart of winter. The next MJO cycle ought to begin in mid/late December, perfect timing for impacts in mid Jan. But if Nina strengthens.. and the atmosphere has already coupled to the Nina signature that will encourage flat westerlies across the Atlantic, then we will struggle to get blocks high enough. Azores High, or Euro High, influence will likely grow and then our winter sags.

The same Pacific forcing also has an impact on the stratosphere via potential vertical wave breaking of warm air upwards. This is another complex situation, but to maximise the benefits of the next Pacific cycle it wouldn’t be w bad thing to see an aleutian low in the North Pacific coupled to a Siberian High. These 2 features, properly positioned, can encourage vertical wave activity by adding energy to the atmospheric circulation via mountain torque and also disrupting the intensity of the vortex by firing broadsides of warmer air into the vortex as part of the torque event. I struggle to visualise the mechanics of this in all situations because these warm air attacks can disrupt the vortex in what seems to be a myriad of different ways, but once disrupted lower zonal wind speeds can also aid in blocks becoming established at high latitude.

Long and short of it is that the Pacific is absolutely key to patterns of weather in the North Atlantic. The obvious final point is that an incorrect seasonal assessment of Pacific patterns means any seasonal forecast for the UK ends up inaccurate. The reality is that the Nina forecast is not carved in stone and therefore, if the starting pacific conditions are incorrect in model calculations, then no matter how great the computer power the resultant forecast is damaged. UKmet forecasts of Nina are on the strong side compared to ECM at the moment, and I think this is important when considering Glosea output. But the last 3 Glosea runs have sequentially suggested less mild and more potential for cold... though the probability maps still suggest mild more likely than cold form the coming season. My interpretation, for what it is worth, of that trend is that all models are seeing a relaxing of the Nina signature as we hit January and so chances for blocking in mid to late winter may be gently increasing. However this is all conjecture at this stage really... but to finish with a direct Nina comment: if we want decent chances of proper cold in mid winter it will help if Nina doesn’t drop too deep. 

Thanks for your opinion on this matter Catacol,I thought that LA Nina has no great temperature impact in Europe in Winter, apparently it promotes SouthEastern USA ridge,I have seen it on met office website some time ago,Europe was neither cold or warm, what you present above is far more complex, I don't know why then Metoffice present those maps to public,probably CP LA Nina and EP La  Nina neutralise each other and yield average figures,it seems like one gets far more access to interesting findings  by private individuals rather then official sources like UK Met,Met.ie  etc,wonder how do they spend tax payers money appart  from presenting simple data that we can decipher from the likes of meteociel,americanwx etc.For fact I know that our own most respected Climatologist in Slovakia has no idea about GLAAM,EAMT,GWO.lol 

la-nina-temp.jpg

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Posted
  • Location: Chisinau, Moldova.
  • Location: Chisinau, Moldova.
7 hours ago, jules216 said:

Thanks for your opinion on this matter Catacol,I thought that LA Nina has no great temperature impact in Europe in Winter, apparently it promotes SouthEastern USA ridge,I have seen it on met office website some time ago,Europe was neither cold or warm, what you present above is far more complex, I don't know why then Metoffice present those maps to public,probably CP LA Nina and EP La  Nina neutralise each other and yield average figures,it seems like one gets far more access to interesting findings  by private individuals rather then official sources like UK Met,Met.ie  etc,wonder how do they spend tax payers money appart  from presenting simple data that we can decipher from the likes of meteociel,americanwx etc.For fact I know that our own most respected Climatologist in Slovakia has no idea about GLAAM,EAMT,GWO.lol 

la-nina-temp.jpg

This is in relation to averages. If you imagine all the possible combinations of ENSO, QBO, Solar, MJO, plus whatever other two dozen things you look at, plus throw in SSW, when you average just La Nina or El Nino, you end up with no signal over the seasonal period for the UK with the 70 years or so of ENSO data they use.

If a La Nina influence firmly establishes, doesn't weaken and the next MJO cycle isn't particularly amplified, even this doesn't mean the UK will be mild, as you can still be on the cooler side of zonal and also tap into polar maritime flows. Therefore ending up in that no signal chart.

What it generally means is that you won't see blocking establish over Greenland, Scandinavia, Arctic, etc, which means that deep prolonged cold is unlikely.

The Met Office know about all of this. Their models and then forecasters will be trying to determine all these influences.

It is worth saying that the MetOffice Contingency forecast is for a more or less "average" winter.

Most forecasters putting out the cold western Europe forecasts know about it. They then study past years and decide all those things Catacol mentioned as influences are likely during the conditions we have now. I'm personally a big fan of analog years, but it is a frought and often bias process. You never find an exact match and you will always find some years that completely go against others.

 

 

 

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Posted
  • Location: Lincolnshire - 15m asl
  • Weather Preferences: Frost and snow. A quiet autumn day is also good.
  • Location: Lincolnshire - 15m asl

 6 consecutive days now of SOI index >10. Running averages also on the way up. Atmosphere beginning to respond to Nina signature?

 

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Posted
  • Location: Netherlands
  • Location: Netherlands

Seems to me the MJO gets alive.

The Madden-Julian oscillation (MJO), also known as the 30–60 day oscillation, is the strongest of the intraseasonal climate oscillations in the tropics and has significant derivative effects on extratropical circulation and intraseasonal climate. It has recently been shown that the stratospheric quasi-biennial oscillation (QBO) modulates the amplitude of the boreal winter MJO such that MJO amplitudes are larger on average during the easterly phase (QBOE) than during the westerly phase (QBOW). A major possible mechanism is the decrease in static stability in the lowermost stratosphere under QBOE conditions resulting from relative upwelling associated with the QBO-induced meridional circulation. Here evidence is presented that tropical upwelling changes related to the 11 year solar cycle also modulate the boreal winter MJO. Based on 37.3 years of MJO amplitude data, the largest amplitudes and occurrence rates, and the weakest static stabilities in the tropical lower stratosphere, occur during the QBOE phase under solar minimum (SMIN) conditions while the smallest amplitudes and strongest static stabilities occur during the QBOW phase under solar maximum (SMAX) conditions. Conversely, when the QBO and solar forcings are opposed (QBOW/SMIN and QBOE/SMAX), the difference in occurrence rates becomes statistically insignificant. During the coming solar minimum, at least one additional winter in the QBOE/SMIN category should occur (possibly as early as 2017/2018) during which especially large MJO amplitudes are expected and an initial test of these results will be possible. http://www.geo.fu-berlin.de/en/met/ag/strat/produkte/winterdiagnostics/index.html

Interesting to follow this winter.

ensplume_full.gif

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Posted
  • Location: Marton
  • Location: Marton
On 17/11/2017 at 12:13, karlos1983 said:

 

Yes .... Matthew please do clog away... it's what we are here for after all. That's a fairly bold statement.

 

On 15/11/2017 at 18:29, Paul_1978 said:

What do you know that we don't? :)

Hi Karlos and Paul. All it is is from previous analogues from years with similar patterns. From this I’ve noticed the higher than normal frequency of the second half of December being colder than average. Therefore there’s a higher chance of snow and frost this December.

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Posted
  • Location: Lytchett Matravers - 301 ft ASL
  • Weather Preferences: Snowy Winters, Torrential Storm Summers
  • Location: Lytchett Matravers - 301 ft ASL
Just now, Matthew. said:

 

Hi Karlos and Paul. All it is is from previous analogues from years with similar patterns. From this I’ve noticed the higher than normal frequency of the second half of December being colder than average. Therefore there’s a higher chance of snow and frost this December.

Hi Matthew

Since I read your comment I have done some digging, had a couple of chats with other members, I have a feeling you could well be correct. Certainly going to be a roller coaster week for those who model watch daily, plenty of swings to come, but I do now believe a cold start to December (at least) is more likely than a mild one. I fear for the festive period however.

Cheers

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Posted
  • Location: Chisinau, Moldova.
  • Location: Chisinau, Moldova.
2 hours ago, Summer Sun said:

 

Maybe @Tamara can correct, but I don't think the MJO phases of December 2010 were responsible for the severe cold in that month. Wasn't it amplification that took place in October/early November, which lead to a very cold start to December, which was responsible for the November/December cold spell and wasn't it then the La Nina influence that put an end to it?

 

So, maybe it is just me, but I find his December comparison to be way off the mark and the linking of the analog also off the mark.

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