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August 

 

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July 

 

I fear this could be the beginning of a very wet and stormy Autumn and winter..

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Would all that warm water in the Pacific encourage the development of high pressure to the west of the United States, for most of the winter? Wouldn't this affect the jet stream bringing yet another freezing winter to the NE of America and cold plunges of air into the North Atlantic? That usually strengthens the jet and lets the Atlantic dominate our winter. I suppose the position of the high will be crucial if it developed like it did during the last two winters.  Would the cooler North Atlantic prevent powerful storms from forming, or would the big contrast in  Atlantic temps fuel them? Whatever the answers,  another mild borefest is possible. :closedeyes:

Edited by lassie23
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Would all that warm water in the Pacific encourage the development of high pressure to the west of the United States, for most of the winter? Wouldn't this effect the jet stream bringing yet another freezing winter to the NE of America and cold plunges of air into the North Atlantic? That usually strengthens the jet and lets the Atlantic dominate our winter. I suppose the position of the high will be crucial, but another mild borefest is possible. :closedeyes:

 

Surface warmth is more likely to cause low pressure rather than high pressure.

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Would all that warm water in the Pacific encourage the development of high pressure to the west of the United States, for most of the winter? Wouldn't this affect the jet stream bringing yet another freezing winter to the NE of America and cold plunges of air into the North Atlantic? That usually strengthens the jet and lets the Atlantic dominate our winter. I suppose the position of the high will be crucial if it developed like it did during the last two winters.  Would the cooler North Atlantic prevent powerful storms from forming, or would the big contrast in  Atlantic temps fuel them? Whatever the answers,  another mild borefest is possible. :closedeyes:

 

If anything I would think cool air over cool water would lead to a pretty sluggish jet stream, either that or the jet being stronger along the cool/warm boundary which is further south this year. Autumn 2013 and 2014 both had higher than average SSTs did they not?

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Surface warmth is more likely to cause low pressure rather than high pressure.

Sure about that? As the previous poster suggested, the warm water that has been present off the West coast of the US has caused High Pressure in that region. Therefore helping to create the harsh winters in central and north eastern parts of the US for the last three winters.

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If we do get a Westerly driven Winter, perhaps the well below SSTs will allow for less modifcation of the upper air, and therefore an increased snow chance.

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If anything I would think cool air over cool water would lead to a pretty sluggish jet stream, either that or the jet being stronger along the cool/warm boundary which is further south this year. Autumn 2013 and 2014 both had higher than average SSTs did they not?

 

This is my theory the second part, 

 

You have a very distinct boundary of warm water and cool water.. You get a cold pool set up over North America and the jet will dive down south once you have that jet diving down drawing the very cool air down and hitting the warm water BANG hey presto you have the ingredients for a storms

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Sure about that? As the previous poster suggested, the warm water that has been present off the West coast of the US has caused High Pressure in that region. Therefore helping to create the harsh winters in central and north eastern parts of the US for the last three winters.

 

I'm not sure that it is correct to say the positive SST anomaly in the west Pacific caused the high pressure. Not according to this anyway.

 

 

A prominent mass of positive temperature anomalies developed in the NE Pacific Ocean during winter of 2013–2014. This development can be attributed to strongly positive anomalies in SLP, which served to suppress the loss of heat from the ocean to the atmosphere, and leads to a lack of the usual cold advection in the upper ocean. The extra mixed layer heat persisted through the summer of 2014 and may have represented a significant contribution to the unusually warm summer (in some locations record high temperatures) observed in the continental Pacific Northwest. The linkage between the upper ocean temperature and downstream temperatures over the coastal region of the Pacific Northwest may provide a secondary source of predictability for seasonal weather forecasts. In particular, it suggests that coupled atmosphere-ocean models such as NCEP's Coupled Forecast System model may need to properly handle the evolution of the upper ocean in the NE Pacific because of its regional influences.

The present analysis does not focus on the cause(s) of the anomalous atmospheric forcing. A broad region extending from the North Pacific across North America is known to be subject to the effects of teleconnections from the tropical Pacific in association with El Niño–Southern Oscillation (ENSO) events, i.e., the “atmospheric bridge†[e.g., Alexander et al., 2002; Lau and Nath, 1996]. But such an explanation fails to account for the winter of 2013–2014 since ENSO was in a neutral phase. On the other hand, SST anomalies in the far western tropical Pacific, and accompanying deep cumulus convection, appear to account for a significant portion of the anomalous circulation [Seager et al., 2014; Hartmann, 2015; Lee et al., 2015] that occurred in the winters of both 2012–2013 and 2013–2014, with intrinsic atmospheric variability probably an additional important factor.

 

Causes and impacts of the 2014 warm anomaly in the NE Pacific

http://onlinelibrary...15GL063306/full

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Would all that warm water in the Pacific encourage the development of high pressure to the west of the United States, for most of the winter? Wouldn't this affect the jet stream bringing yet another freezing winter to the NE of America and cold plunges of air into the North Atlantic? That usually strengthens the jet and lets the Atlantic dominate our winter. I suppose the position of the high will be crucial if it developed like it did during the last two winters.  Would the cooler North Atlantic prevent powerful storms from forming, or would the big contrast in  Atlantic temps fuel them? Whatever the answers,  another mild borefest is possible. :closedeyes:

Cold Winter fans need to hope the sst's just off the eastern seaboard of the US cool rapidly this Winter. Warm waters here react rapidly with the frigid air coming off the northeastern US and Canada to create powerful cyclogenesis. Cold water here will nullify cyclogenesis and hence increase the chances of a blocked atlantic, in turn increasing the chances of a colder than average UK winter.

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The biggest cooling occurred in the 1960s when The North Atlantic Sea Temps cooled rapidly, largest in the Sub Polar Zone. Lots of theories made, however non definitely proved. During this cooling period of the vast ocean ( a largely cold decade of winter temperatures occurred in much of Europe with some fairly average summers ) The present cooling would need to be prolonged for several years to see if a trend is made to change seasonal forecasting. However, just look at this summer gone in much of NW Britain this year, cold and wet , whereas much of continental Europe has been baking hot with one of the hottest and driest summers ever in places. Whether another theory awaits for this cause including that of the present N .Atlantic lower than normal temps , we will have to wait and see and more than likely wonder why !

 C

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Cold Winter fans need to hope the sst's just off the eastern seaboard of the US cool rapidly this Winter. Warm waters here react rapidly with the frigid air coming off the northeastern US and Canada to create powerful cyclogenesis. Cold water here will nullify cyclogenesis and hence increase the chances of a blocked atlantic, in turn increasing the chances of a colder than average UK winter.

 

As far as I'm aware cyclogenesis has nowt to do with negative SSTs or Atlantic blocking and cooler than average winters in the UK.

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I am one to believe it has an effect and its been a while since I've seen such a cyclonic signal.

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I see a few of you talking about the pacific affecting our winter weather but would strong easterlies from Siberia/Russia or a northerly flow outweigh any jet effect?

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I'd expect the depth of N Atlantic depressions is more a function of the atmospheric temperature gradient than of the SST?

Edited by Ed Stone
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I see a few of you talking about the pacific affecting our winter weather but would strong easterlies from Siberia/Russia or a northerly flow outweigh any jet effect?

I would think so, is that not what we saw in winter 09/10 when the NAO was extremely negative.

The long range seasonal models are showing extensive blocking over Canada and this pulling in cold air from the Atlantic to make the southern US cold. If that pattern develops, I don't see the jet stream on a northerly path over the ocean. I think that is an el Nino driven pattern but we have yet to see if it works that way or not, every situation will have different configurations.

Knocker posted a new piece of research about Arctic ice melt giving indications for winter time circulations: I put the link in the snow and ice thread.

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ooo:

 

I have been studying long term patterns/trends for 20 years now & archiving the data in an attempt to see if thers a deeper link to our suns cycles & the trending of global climate. 
One thing i have noticed in that time. Is when we have that warm body
 of water in the pacific like this. The UK's winter weather go's batty. 
Ive noticed the swings to be much more extreme because of the stronger larger Atlantic lows coming in spanning a much greater temperature range on the forward & backwards sides of these depressions. 
Its still next to impossible at present to gauge if it will be warmer or colder than average. 
But with that much energy available pacific side bleeding into the Atlantic system, one thing i can say with some certainty based of the data. 
Is that we will be in for fascinating one for sure. I just hope those super-storms of 2 winters ago stay away. My hill was leveled that year, the damage still remains from that season here. It is interesting to not that we have started Autumn here in the UK with a northern blocking high not normally seen so persistent this early with some very chilly night temperatures for the time of year.

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More info pouring in slowly...

 

Global sea surface temperature anomalies - those are some serious values! Notice how Pacific is extremely warm this year, moderately strong El Nino on going. But also impressive anomalies towards the Arctics and especially around Europe - could result in destructive flooding events this coming autumn. We will be covering all these potentially dangerous setups, so stay tuned.

 

What I will say is that the sea of the east coast has under gone some serious warming in the last month wtf?

Edited by Surrey
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As far as I'm aware cyclogenesis has nowt to do with negative SSTs or Atlantic blocking and cooler than average winters in the UK.

Your post does not corelate at all to what I explained in my post. Unless you are claiming that arctic air colliding with warm waters does not cause cyclogenesis?

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Maybe of interest - Meteo-France have just published their forecast for Autumn (Sept, Oct, Nov). This seasonal forecast is a collaboration (called EUROSIP) with ECMWF, Met Office and NCEP and in it they have included some interesting charts including 3 month probabilistic forecasts for global SST and 2m temp anomalies, and also the forecast Autumnal temp anomaly for Europe.

 

It highlights the current El Nino event plus the cool Atlantic and ends with a forecast of a warmer mainland Europe but cooler UK this autumn. Extracts:

 

Forecast for the quarter September, October and November 2015
 
El Niño is the major element of the current state of the global climate system. Ocean SST anomalies which are now reaching 2 ° C in the eastern basin. If this anomaly were to continue at this level over the next 3 months, the threshold of a strong El Nino event would be reached. All seasonal forecast models predict it will continue to strengthen over the next quarter. The expected evolution follows a traditional time scheme, with a maximum intensity at year end and could lead to an event of the most powerful seen since 1950.
 
Atmospheric circulation is deeply and lastingly influenced by these ocean temperature anomalies and anticipated impacts are very significant on temperatures, especially in tropical regions.
 
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Above Figure: SST forecast anomaly for the next quarter (September-November). Average models of all EUROSIP (Météo-France Weather Forecast European Centre Medium Term, Met Office, National Centers for Environmental Prediction). 
 
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Above Figure: 2m temperature forecast anomaly for the next quarter (September-October-November), the average of all models EUROSIP (Météo-France, European Centre for Medium-Term Weather Forecasting, Met Office, National Centers for Environmental Prediction). 
 
On Europe and mainland France
Europe is one of the least directly affected by the consequences of El Niño regions. However, in a global context favorable to warm anomalies, a warmer than normal scenario also seems to be quite likely in our continent, the exception is the British Isles.
 
post-20040-0-56386200-1441219657_thumb.p
Above Figure: Summary for temperatures probabilistic forecasts from the models of all EUROSIP.
 

 

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Your post does not corelate at all to what I explained in my post. Unless you are claiming that arctic air colliding with warm waters does not cause cyclogenesis?

 

No I'm not saying that but it needs to be qualified. Cyclogenesis iis an umbrella term that covers more than one process. If you are using it in it's primary definition, that of depression development, then I would say, put very simply, that the main components were the poleward movement of warm air and the eastward movement of cold air.

 

But if you are talking rapid cyclogenesis along the eastern seaboard of the US then yes sea temps can play a vital role. This mainly applies in winter in association with major baroclinic zones and close to strong gradients of SSTs.

 

But what I have a problem with is generalised statements linking one process to a definitive statement such as downstream blocking when there are many other factors to be considered.

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If they're right,not looking good for snow cover advance in November.

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The quite prominent cold anomaly in the Atlantic will certainly help in any marginal situations, meaning the air isn't warmed so rapidly on its journey across the water. If the cold anomaly can last into November then we may start to see some more interesting conditions than would be expected for the time of year if any north westerlies can set up. To be honest given its state now we are into September, it seems pretty inevitable that some sort of cold anomaly will exist throughout the early autumn. Whether it is in a weakened form by December who knows but I would definitely say the chance of wintry precipitation from a north westerly could be at its highest for some years at least for late autumn. Too early to judge winter yet - wasn't some modelling a few weeks ago suggesting the anomaly will start to ease soon or in the winter?

 

Nonetheless, the weather is fascinating re: cyclogenesis. One factor that seems to enhance something always seems to be possibly counteracted by another. That is the fascinating and interesting thing though. Whether it is mild and stormy or colder and more wintry, I would say things favour a more varied and interesting season than last year thus far. However, much water to pass under the bridge before making more concrete assumptions about winter yet.

 

 

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The quite prominent cold anomaly in the Atlantic will certainly help in any marginal situations, meaning the air isn't warmed so rapidly on its journey across the water. If the cold anomaly can last into November then we may start to see some more interesting conditions than would be expected for the time of year if any north westerlies can set up. To be honest given its state now we are into September, it seems pretty inevitable that some sort of cold anomaly will exist throughout the early autumn. Whether it is in a weakened form by December who knows but I would definitely say the chance of wintry precipitation from a north westerly could be at its highest for some years at least for late autumn. Too early to judge winter yet - wasn't some modelling a few weeks ago suggesting the anomaly will start to ease soon or in the winter?

 

Nonetheless, the weather is fascinating re: cyclogenesis. One factor that seems to enhance something always seems to be possibly counteracted by another. That is the fascinating and interesting thing though. Whether it is mild and stormy or colder and more wintry, I would say things favour a more varied and interesting season than last year thus far. However, much water to pass under the bridge before making more concrete assumptions about winter yet.

 

CDF...

 

Reading your post above, I realised that last winter we had a lot of North-West winds, mainly coming down from Greenland and Iceland.

However the temperatures in the eastern Atlantic were not too cold at that stage, so the precipitation that fell was rain/sleet rather than snow..

 

As I understand it the cold anomaly was present last winter, but as a much smaller area south of Greenland, and  cyclogenisis seemed to form depressions on the left hand edge of the colder waters before moving up to the Icelend area and then plunging down over the UK. 

 

The colder sst's  seems to have expanded now and includes the Atlantic just west of Ireland. It certainly will be interesting to see how these depressions move this year. It could be that the depressions will form further east also, in the eastern Atlantic and then it could be a thoroughly wet and miserable winter with the temperatures fluctuating wildly, Or if they form in the western Atlantic, as per last year, then it could get very interesting with a lot of snow.

 

However the El Nino effect could send one depression after another barrelling across the Atlantic with rapid deepening and we all know what that means!!

 

All in all an interesting period ahead, and that is without considering any blocking anticylones which may be caused by the cooler waters, possibly causing a very cold winter for us.

 

It seems like the pattern has set up an almost infinite number of options are perfectly possible (even more so than usual).

 

The two drivers (El Nino and abnormally low sst's in the North Atlantic) are not a usual set of conditions (in measurable history) and we will have to see which affects us the most.

 

MIA

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Following on from the above, it seems as though north west winds have also had a higher  preponderance this summer and this has caused the very low temps in Scotland and Ireland.

 

 

So the question is has the northwesterly element to our weather caused the low sst's, or is it that the northwesterly's are caused by the plunging sst's?

 

If its the latter and the sst's are associated with a colder period (cycle) of the NAO, then we could be in for a severe correction of the CET in the next few years !!

 

MIA 

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The cold pool seems to have weakened a tad to my eye and one musn't forget the positive anomalies in the western Atlantic and Davis Strait

 

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