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Met office Contingency planners forecasts

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This is the amalgam of the European models - ECM, UKMO, Meteo France and some input from NCEP. The thing to note, there are only the tiniest blobs of cold anomalies anywhere in the NH.

 

http://www.cpc.ncep.noaa.gov/products/NMME/current/IMMEtmp2m.html

 

I just don't see these charts as in any way realistic other than a reflection of an assumed warming world.

Edited by Gael_Force
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this link seems to suggest they do not start the model in any way different for months ahead to what they do for 5-6 days ahead or the 30 day outlook. What turns up then yes they have to compare the values shown with some standard but what other than the 71-2000 would you suggest?  Why do you feel that skews the result. 71-2000 is the period most of us remember so I cannot see the point of showing anomalies for T, 500mb or whatever on another period>

Genuinie question?

 

maybe, rather than showing anomalies for Europe, or larger areas, they should show what ht e temperature ranges are predicted to be for the same areas?

That way the results are what the model comes up with just as when it predicts at 1 day or 30 days the temperature for a given location, which is then given as above/below normal based on the 71-2000. If we accept the method for 1 day why not for 30 or 90 days?

Edited by johnholmes

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this link seems to suggest they do not start the model in any way different for months ahead to what they do for 5-6 days ahead or the 30 day outlook. What turns up then yes they have to compare the values shown with some standard but what other than the 71-2000 would you suggest?  Why do you feel that skews the result. 71-2000 is the period most of us remember so I cannot see the point of showing anomalies for T, 500mb or whatever on another period>

Genuinie question?

Maybe it's the staring point itself whic skews the results and maybe using a starting point which goes further back could effect the outcome, say from the 1950 - 2010. Would this if fed into the models make them more semi reliable for LRF in general?

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So, they have explained El Nino, eQBO as being blocking factors - so what are the other factors that override these? Why can't they be explained to as what they are instead of just leaving them as 'other factors'?

 

The cynic in me thinks that the GCM's are set up to the warm ocean - warm continent theory and that no matter what they will predict a positive NAO. As ever we shall see, but I would love to see the met office explain what these other factors actually are.

 

They said ENSO had no strong influence, as we don't have an official El Nino and the atmosphere isn't responding to the warm SSTs. The pattern we see in GCMs are emergent phenomena, nothing set or directly programmed in, such as the warm Arctic - cold continents pattern.

The Met Office forecasts work on probabilities, and even in years with SSW I'm sure plenty saw above average winter CET values.

 

 

I assume they start from a 71-2000 point John as they have to have a starting point per say?

 

I'm pretty sure the models start with the latest initial conditions, that is, they take as much of the current data about the state of the atmosphere, snow, ice, SSTs, etc, and run multiple model runs from now through winter, each with slight variations. Then based of the proportion of these model runs showing wet or dry, mild or cold, we get the probabilities of the different outcomes for winter.

 

In this particular instance, 25% show very mild conditions and 10% show cold conditions during winter 2014/15

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It's clear that their GCM's are predicting a +NAO period in general and that translates to a higher chance of above av temps. They are going for 25/10 above av against below av with a 65% probability of average. they seem to accept that their models, which must be programmed re -QBO etc are predicting a mean +NAO. Even with a -AO, that more than likely means above av temps for the far nw of Europe. as mathematicians, I am not surprised to see them stick with their models.

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They said ENSO had no strong influence, as we don't have an official El Nino and the atmosphere isn't responding to the warm SSTs. The pattern we see in GCMs are emergent phenomena, nothing set or directly programmed in, such as the warm Arctic - cold continents pattern.

The Met Office forecasts work on probabilities, and even in years with SSW I'm sure plenty saw above average winter CET values.

 

 

 

I'm pretty sure the models start with the latest initial conditions, that is, they take as much of the current data about the state of the atmosphere, snow, ice, SSTs, etc, and run multiple model runs from now through winter, each with slight variations. Then based of the proportion of these model runs showing wet or dry, mild or cold, we get the probabilities of the different outcomes for winter.

 

In this particular instance, 25% show very mild conditions and 10% show cold conditions during winter 2014/15

I suppose working on probabilities with all the relevant info at hand I can see why they've come to such a conclusion, it  would be fascinating to see how and what they program into their models.

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Another vague and rather pointless LFR from the MetO, I think the main problem lies with these long range models is the warming bias they start from, no I'm not inferring climate change is the reason before someone brings that boring subject up. 

Its not a long range weather forecast .....  And it is not at all pointless for those to whom it is aimed and who understand it.

And no doubt if it suggested a higher probability for colder than average temps, you would be less scathing?  :p

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I suppose working on probabilities with all the relevant info at hand I can see why they've come to such a conclusion, it  would be fascinating to see how and what they program into their models.

 

http://www.metoffice.gov.uk/research/climate/seasonal-to-decadal/gpc-outlooks/user-guide/technical-glosea5

 

:)

Edit; obviously the Contingency Planners report is based on more than just their model though

Edited by Essan

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To repeat what I and others have said and perhaps someone could e mail to ask if they can confirm?

That ALL models no matter how far ahead they forecast, 1-5 days or 2-5 months ahead, start with the same data, that is what the atmosphere is at T00=T,Td, P, RH etc etc for every grid point used, they then switch the machine on and off it trundles until the appropriate htt or httt is reached.

Bit like cooking your dinner!

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A pretty dismal update from the Met Office but what will be will be.

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Its not a long range weather forecast .....  And it is not at all pointless for those to whom it is aimed and who understand it.

And no doubt if it suggested a higher probability for colder than average temps, you would be less scathing?  :p

I know it's not and I'll still be scathing as such down to the fact that I don't rate LRF from whatever source, though now with the benefit of hindsight I much prefer the MetO approach of probabilities  then something that is set in stone.

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To repeat what I and others have said and perhaps someone could e mail to ask if they can confirm?

That ALL models no matter how far ahead they forecast, 1-5 days or 2-5 months ahead, start with the same data, that is what the atmosphere is at T00=T,Td, P, RH etc etc for every grid point used, they then switch the machine on and off it trundles until the appropriate htt or httt is reached.

Bit like cooking your dinner!

I like your analogy, if I can find the time I'll email them  tomorrow John.

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I like your analogy, if I can find the time I'll email them  tomorrow John.

 

I'd be interested to read what they say, maybe they will suggest something different to my suggestion, long time since I did any forecasting for real!

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December updated Issued

 

January to March

 

For January near- to below-average temperatures are more probable than above-average, although there is a large degree of uncertainty. For January-February-March, predictability is low and the forecast does not differ significantly from climatology, with above-average and below-average temperatures equally probable. 12 Overall, the probability that the UK-mean temperature for January-February-March will fall into either of the warmest or coldest of our five categories is between 15% and 20% (the 1981-2010 probability for each of these categories is 20%). 

 

The tropical Pacific Ocean remains warmer than average, with sea surface temperatures exceeding El Niño thresholds for several weeks and the Southern Oscillation index (SOI), a measure of the pressure difference between Darwin and Tahiti, is negative. These two factors point towards El Niño conditions being already established. However other atmospheric indicators, such as trade winds, cloudiness and tropical rainfall, have yet to show sustained and widespread patterns consistent with El Niño. Additionally sea surface temperatures in the western Pacific remain warmer than usual, with the west to east temperature gradient normally associated with El Niño not yet established. Latest forecasts suggest little change to the current situation in the coming months, with the influence on weather patterns in Europe unlikely to be significant. 

 

In the Arctic, sea ice extent is close to average across the basin and is larger, at this point in time, than in the last few years. This factor is not expected to offer any useful predictability for Europe in the next three months.  The Quasi-Biennial Oscillation (QBO), an oscillation of the equatorial zonal wind in the stratosphere, is now firmly in an easterly phase. Typically, at this time of year, an easterly phase is associated with a weaker polar vortex. A weaker polar vortex can lead to a greater incidence of blocking patterns over the northern hemisphere, which would increase the probability of cold weather across northern Europe.

 

For January, there is a reasonably strong signal, from several models, for the strong positive North Atlantic Oscillation (NAO) phase, which has dominated the winter so far, to wane. This weakening of the westerly winds across the Atlantic leads to an increased chance of cold, blocking patterns developing across northwestern Europe, compared to earlier in the winter. However, this does not mean that a prolonged spell of cold weather is necessarily expected in the UK; indeed looking at the left hand curve in figure T2, there is only a slight shift to colder than average conditions and the chance of a severe spell of cold weather is similar to climatology. 

 

For January-February-March as a whole, computer models begin to diverge; consequently no clear signals emerge and predictability is considered low. Additionally, apart from the QBO, most external forcing factors are weak. Overall, while there is no strong signal for cold weather, there is also little evidence to suggest a very mild season, as experienced last year. The right hand curve in figure T2 reflects this, being similar to climatology. Nevertheless, short spells of cold weather are still possible, with current predictions suggesting these are more likely to occur than last year. 

 

Temperature Summary

 

Summary precipitation

 

Latest predictions for UK-mean precipitation favour near- to below-average rainfall for January. For January-February-March as a whole, although uncertainty is large, there is a slight preference for near- to above-average precipitation. The probability that UK precipitation for January-February-March will fall into the driest of our five categories is between 15% and 20% and the probability that it will fall into the wettest category is around 20% (the 1981-2010 probability for each of these categories is 20%) 

 

As already mentioned in the temperature section, there is a fairly consistent signal from computer models for the current positive phase of the North Atlantic Oscillation (NAO) to wane by January, increasing the probability of blocking patterns developing across northwestern Europe. At this time of year, blocking patterns are typically associated with drier, colder conditions. However, it is worth noting that although the chance of drier episodes is higher than earlier in the winter, it is not significantly higher than climatology; this can be seen in the left hand curve of figure P2, where the shift towards drier-than-average conditions is only slight.

 

For January-February-March as a whole, although near- to above-average precipitation is slightly favoured, uncertainty is large; this is highlighted in figure P2, where there is broad range of outcomes. There is disagreement between models over which atmospheric pattern will dominate, although there is a slight preference in the majority of models for below-average pressure near the UK, which is generally associated with wetter-than-average conditions. The chances of the period being as wet as last year are very low.

 

Precipitation Summary

 

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A well balanced summary by all accounts, not swinging one way or the other in excess, which is pretty much how we are doing so far.

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Still, generally speaking, going against some 'considered' views amongst the NW 'stalwarts'.

Maybe some fleeting visits from cold and snow possible.

IMBY - would turn out to be a bulk standard average winter for these parts.

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January updated Issued

 

February to April

 

Summary Temperature

 

For February-March-April as a whole above-average temperatures are more likely than below-average. Overall, the probability that the UK-mean temperature for February-March-April will fall into the coldest of our five categories is around 15% and the probability that it will fall into the warmest category is around 30% (the 1981-2010 probability for each of these categories is 20%).

 

The tropical Pacific Ocean overall remains warmer than average. However, sea surface temperatures in the eastern Pacific have cooled in the past month, with the strongest positive anomalies remaining across central and western parts of the tropical Pacific Ocean. This change in the pattern of sea surface temperature anomalies suggests that we are now moving away from a possible weak El Niño event, with near-neutral conditions the most probable outcome in the coming months; this will offer little predictive value for conditions across Europe during the period of this forecast.

 

In the Arctic, sea ice growth has slowed and overall extent is now below average, particularly across the Bering Sea and Sea of Okhotsk. This factor is not expected to offer any useful predictability for Europe in the next three months.

 

The Quasi-Biennial Oscillation (QBO), an oscillation of the equatorial zonal wind in the stratosphere, is now firmly in an easterly phase. Typically, an easterly phase is associated with a weaker polar vortex. A weaker polar vortex can lead to a greater incidence of blocking patterns over the northern hemisphere in winter, which would increase the probability of cold weather across northern Europe. However, this is a transitional time of year with the QBO probably exerting some influence at the beginning of the season, but providing little known contribution by the end.

 

For February-March-April as a whole, initially computer models are in good agreement, suggesting a continuation of a positive phase of the North Atlantic Oscillation (NAO), with winds blowing frequently from the west or northwest. However as the season progresses models begin to diverge; consequently no clear signals emerge for the period as a whole and predictability is considered low.  Figure T2 reflects this, with the forecast curve closely resembling climatology. Nevertheless, there is still an increased probability of above-average temperatures.

 

Temperature Summary

 

Summary Precipitation

 

For February-March-April, predictability is low and the forecast does not differ significantly from climatology, with above-average and below-average precipitation equally probable. The probability that UK precipitation for February-March-April will fall either into the driest or wettest of our five categories is around 20% (the 1981-2010 probability for each of these categories is 20%).

 

As already mentioned in the temperature section, there is a fairly consistent signal from computer models for the positive phase of the North Atlantic Oscillation (NAO), which has prevailed through the winter so far, to dominate initially. However as the season progresses models begin to diverge; consequently no clear signals emerge for the period as a whole and predictability is considered low.

 

For February-March-April as a whole, although near- to above-average precipitation is slightly favoured, uncertainty is large; this is highlighted in figure P2, where there is a broad range of outcomes. There is disagreement between models over which atmospheric pattern will dominate, although there is a slight preference in the majority of models, for below-average pressure near the UK, which is generally associated with wetter-than-average conditions.

 

Precipitation Summary

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February update issued

 

March to May

 

Summary Temperature

 

For March near- to above-average temperatures are more probable than below-average. For March-April-May although above-average temperatures are more probable than below-average, predictability is low. Overall, the probability that the UK-mean temperature for March-April-May will fall into the coldest of our five categories is around 15% and the probability that it will fall into the warmest category is around 25% (the 1981-2010 probability for each of these categories is 20%).

 

Much of the tropical Pacific Ocean remains warmer than average, but just below El Niño thresholds. Climate models suggest little change in the coming months, with near-neutral conditions the most probable outcome; this will offer little predictive value for conditions across Europe during the period of this forecast. Spring is a transitional time of year, with large-scale global drivers becoming less influential and predictability declining. Early in the season, the Quasi-Biennial Oscillation (QBO), an oscillation of the equatorial wind in the stratosphere, can still be a useful source of predictability.

 

Currently, the QBO is in an easterly phase which increases the probability of disruptions to the polar vortex. A weaker polar vortex can lead to a greater incidence of blocking patterns over the northern hemisphere in early spring, which would increase the probability of cold weather across northern Europe. However, models show no indication of the polar vortex being disrupted in the coming weeks, with the circulation pattern over northern Europe and the North Atlantic most likely to be similar to that seen so far this year, that is predominately westerly or northwesterly.

 

For March, there is a reasonably strong signal, from several models, for a continuation of a positive phase of the North Atlantic Oscillation, with winds blowing frequently from the west. Overall this pattern typically brings near- to above-average temperatures but, as seen in the winter, this does not preclude occasional spells of colder weather. The left-hand graph in figure T2 shows a shift towards milder conditions and the chance of a prolonged, severe spell of cold weather, such as in 2013, is reduced compared to climatology.

 

As already noted above, predictability in spring is lower than in the winter, with large scale global drivers less influential. For March-April-May as a whole no strong signals emerge from models for temperature; this is reflected in the right-hand graph of figure T2, with the forecast curve only slightly shifted towards above-average temperatures.

 

Temperature Summary

 

Summary Precipitation

 

The latest predictions for UK-mean precipitation favour below-average rainfall over above-average in March. For March-April-May, predictability is low and the forecast is largely indistinguishable from climatology, although with a slight preference for near- to below-average precipitation. 400 The probability that UK precipitation for March-April-May will fall into the driest of our five categories is around 20% and the probability that it will fall into the wettest of our five categories is between 15% and 20% (the 1981-2010 probability for each of these categories is 20%).

 

As already mentioned in the temperature section, predictability in spring is lower than in the winter, with large-scale global drivers not known to have a significant influence on weather patterns across northern Europe. During March there is a fairly consistent signal from computer models for the positive phase of the North Atlantic Oscillation (NAO), which prevailed through the winter, to continue. Also evident is a preference for pressure to be higher than average, particularly in the south, with low pressure systems tending to track between Scotland and Iceland, rather than across the UK; this type of pattern is often associated with below-average UK rainfall. However, a slight shift in the track of these systems could bring higher rainfall and this is reflected in the left-hand graph of figure P2 which shows a shift towards drier-than-average conditions, but also still a large range of outcomes.

 

For March-April-May as a whole, although near- to below-average precipitation is slightly favoured, uncertainty is large; this is highlighted in figure P2, where the range of outcomes is broad. There is disagreement between models over which atmospheric pattern will dominate, although there is a slight preference in some models for above-average pressure near and to the south of the UK; this is generally associated with drier-than-average conditions.

 

Precipitation Summary

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March update issued

 

April to June

 

Summary Temperature

 

For April above-average temperatures are more probable than below-average. For April-May-June temperatures near- to above-average are most likely. Overall, the probability that the UK-mean temperature for April-May-June will fall into the coldest of our five categories is 10% and the probability that it will fall into the warmest category is between 20% and 25% (the 1981-2010 probability for each of these categories is 20%).

 

Much of the tropical Pacific Ocean remains warmer than average and close to El Niño thresholds. In particular the ocean temperatures near the dateline are much higher than normal, affecting weather patterns across the tropical Pacific. The majority of climate models now suggest that sea surface temperatures will exceed El Niño thresholds in late spring or early summer. Even if El Niño conditions do develop fully, the influence on climate across northern Europe, at this time of year, is unlikely to be significant.

 

In the North Atlantic, sea surface temperatures remain below average across the eastern side of the basin; this cold anomaly has the potential to influence conditions across the UK if winds blow frequently from the west. The positive phase of the North Atlantic Oscillation (NAO) has dominated throughout the year so far. This is usually associated with wet, mild conditions in the winter months, but this year the overall pattern has been shifted slightly north allowing more settled conditions at times, especially in the south, and interludes of colder weather.

 

Computer models are in fairly good agreement for the positive phase of the NAO to continue into April. At this time of year, this pattern still tends to be associated with near- to above-average temperatures. However, as already noted, the colder-than-average sea surface temperatures in the eastern North Atlantic may act to suppress temperatures across the UK somewhat and increase uncertainty in the temperature forecasts for April. For April-May-June as a whole no clear signals emerge for temperature; this is reflected in the right-hand graph of figure T2, which is similar to climatology but does show a reduction in the probability of below-average temperatures.

 

 

Temperature Summary

 

Summary Precipitation

 

The latest predictions for UK-mean precipitation favour near- to above-average rainfall in April. For April-May-June, there is a slight shift away from climatology towards above-average precipitation but there is a wide spread of possible outcomes. The probability that UK precipitation for April-May-June will fall into the driest of our five categories is around 20% and the probability that it will fall into the wettest of our five categories is 25% (the 1981-2010 probability for each of these categories is 20%).

 

Predictability of UK precipitation is low during this season, with no known large-scale global drivers that might influence weather patterns significantly across northern Europe. Additionally, as we approach summer, precipitation becomes increasingly difficult to predict due to its convective and localised nature and there is often more regional variability. As already mentioned in the temperature section, there is a fairly consistent signal from computer models for the positive phase of the North Atlantic Oscillation (NAO) to continue in April.

 

Also evident is a slight preference for atmospheric pressure over the south of the UK to be higher than average, with low pressure systems tending to track between Scotland and Iceland. With this type of pattern above-average rainfall is more probable than below-average, but with a tendency for a larger proportion of this to fall across northwestern parts of the UK and a possibility that southeastern areas may end up being drier-than-average. For April-May-June as a whole, although near-to above-average precipitation is slightly favoured, uncertainty is large; this is highlighted in figure P2, where there is a broad range of outcomes. Having said that there is a slight preference, in the majority of models, for below-average pressure across northern Europe and the UK, which is generally associated with wetter-than-average conditions.

 

Precipitation Summary

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April update issued

 

May to June

 

Summary Temperature

 

For May near- to below-average temperatures are most likely. For May-June-July above-average temperatures are most probable but uncertainty is large. Overall, the probability that the UK-mean temperature for May-June-July will fall into the coldest of our five categories is between 15% and 20% and the probability that it will fall into the warmest of our five categories is 25% (the 1981-2010 probability for each of these categories is 20%).

 

Much of the tropical Pacific Ocean remains warmer than average and close to El Niño thresholds with significant warming in the past month across the eastern Pacific Ocean and especially near the coast of South America. The majority of climate models continue to suggest that sea surface temperatures will be above El Niño thresholds in early summer. However, even if El Niño conditions strengthen, the influence on climate across northern Europe, at this time of year, is unlikely to be significant.

 

There are few external forcing factors which influence weather patterns across Europe at this time. Sea surface temperatures to the south of Greenland are cooler than in recent years, but this is not
expected to significantly influence conditions across northern Europe until later in the year. Computer model signals are weak regarding the most probable atmospheric circulation types over Europe during late spring and early summer. However, there is a slight preference for lower pressure near and to the north of the UK during May; this circulation type, with winds blowing more frequently from the west or northwest,
lends some support to the increased likelihood of near- to below-average temperatures in May.

 

For May-June-July as a whole no clear signals emerge for temperature; this can be seen in the right-hand graph in figure T2 which, although it shows a slight shift towards above-average temperatures, also has a large spread of possible outcomes.

 

Temperature Summary

 

Summary Precipitation

 

Latest predictions for UK precipitation favour a slight shift towards above-average rainfall for both May and May-June-July as a whole. The probability that UK precipitation for May-June-July will fall into the driest of our five categories is around 20% and the probability that it will fall into the wettest of our five categories is 25% (the 1981-2010 probability for each of these categories is 20%)

 

Climatologically the period through late spring and early summer is the one of the driest times of year across the UK, as can be seen in figure P1. At this time of year, predictability of UK precipitation is low, as there are few large-scale global factors that might influence weather patterns significantly across northern Europe. As discussed in the temperature section, there is a slight preference early in the season for below-average pressure near and to the north of the UK; this circulation pattern is typically associated with wetter-than-average conditions and this is reflected in the left-hand graph of figure P2, which shows a
shift towards above-average precipitation during May.

 

It is worth noting that as we approach summer precipitation becomes more convective and localised in nature and there is often more regional variability. For May-June-July as a whole, although above-average precipitation is slightly favoured, uncertainty is large; this is highlighted in figure P2, where there is a broad range of outcomes.

 

Precipitation Summary

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I wonder what they mean with this quote....

 

"There are few external forcing factors which influence weather patterns across Europe at this time. Sea surface temperatures to the south of Greenland are cooler than in recent years, but this is not
expected to significantly influence conditions across northern Europe until later in the year."

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I wonder what they mean with this quote....

 

"There are few external forcing factors which influence weather patterns across Europe at this time. Sea surface temperatures to the south of Greenland are cooler than in recent years, but this is not

expected to significantly influence conditions across northern Europe until later in the year."

 

Suppose there are few teleconnections have have known strong influence on our summer weather. Factors such as ENSO or the the sub polar gyre SSTAs are believed to have a stronger effect in Autumn/Winter than Spring/Summer

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May update issued

 

June to August

 

Summary Temperature

 

For June near- to above-average temperatures are most likely. For June-July-August, although above-average temperatures are more probable than below-average, uncertainty is large. Overall, the probability that the UK-mean temperature for June-July-August will fall into the coldest of our five categories is around 10% and the probability that it will fall into the warmest of our five categories is around 20% (the 1981-2010 probability for each of these categories is 20%)

 

Over the past few months there has been a trend towards El Niño with further warming of sea surface temperatures in the tropical Pacific Ocean, particularly near the coast of South America. Other factors such as weaker trade winds and increased cloudiness near the International Date Line have been observed. This suggests that the ocean and atmosphere have started to couple and reinforce each other, indicating El Niño is likely to persist in the coming months. Climate models continue to suggest that sea surface temperatures are likely to be above El Niño thresholds throughout summer and that at least a moderate event is now likely. However, El Niño is not known to have a significant influence on the climate across northern Europe at this time of year

 

In the North Atlantic, sea surface temperatures to the south of Greenland are cooler than in recent years; this pattern of sea-surface temperatures is thought to increase the probability of above-average pressure over northern Europe in summer. At this time of year such a pressure pattern is often associated with above-average temperatures. Computer model signals are weak regarding the most probable atmospheric circulation types over Europe this summer, although there is a slight preference for higher-than-average pressure across northern Europe. This lends support to the increased likelihood of above-average temperatures during June and June-July-August as a whole, which can be seen in the graphs in figure T2; however, uncertainty is large and there is still a broad range of possible outcomes.

 

Temperature Summary

 

Summary Precipitation

 

The latest predictions for UK precipitation favour near-average rainfall for June. For June-July-August uncertainty is large but, on balance, below-average seasonal rainfall is more probable than above-average. The probability that UK precipitation for June-July-August will fall into the driest of our five categories is between 20% and 25% and the probability that it will fall into the wettest of our five categories is 15% (the 1981-2010 probability for each of these categories is 20%).

 

There are fewer external factors which influence weather patterns across Europe during the summer. However, the pattern of sea surface temperature anomalies now seen in the North Atlantic is believed to increase the probability of
below-average rainfall across central and western parts of Europe. For June-July-August as a whole, computer models have a weak preference for higher-than-average pressure close to the UK; this is often associated with drier-than-average conditions. The right hand graph in figure P2 reflects the shift towards below-average rainfall, but also shows a large spread of solutions, with the probability of wetter-than-average only slightly lower than climatology

 

Precipitation Summary

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June update issued

 

July to September

 

Summary Temperature

 

The latest predictions for UK-mean temperature for July-August-September as a whole are largely indistinguishable from climatology. Overall, the probability that the UK-mean temperature for July-August-September will fall into the warmest of our five categories is between 20 and 25% and the probability of falling into the coldest of our five categories is 20% (the 1981-2010 probability for each of these categories is 20%

 

During recent months El Niño conditions have become established across the tropical Pacific Ocean. Further warming of sea surface temperatures has taken place during recent weeks with the largest anomalies near the coast of South  America. Other factors, such as weaker trade winds and increased cloudiness near the International Date Line, suggest that the atmosphere and ocean have coupled and are reinforcing each other leaving El Niño significantly more likely than not to both intensify and persist through the rest of this summer onwards into the autumn.

 

At the very least a moderate El Niño event with the largest anomalies over the eastern Pacific is expected. However, it is worth noting that El Niño is not known to have a significant influence on weather conditions across northern Europe during the summer and early autumn. Closer to home, sea surface temperatures across the northeastern Atlantic south of Greenland and Iceland and west of Scotland remain below average. Persistent sea surface temperature anomalies in this area can have some impact on weather conditions over parts of Europe and Africa during the summer: cooler-than-average sea surface temperatures are thought to increase the probability of above-average atmospheric pressure which at this time of year often leads to above-average temperatures, at least by day.

 

Computer model signals are remarkably consistent in showing higher-than-average pressure likely dominating across a large part of Europe through the rest of this summer and the early autumn. This leaves a strong signal for above-average temperatures across central and southern Europe for July-August-September as a whole. However, for the UK things are less clear-cut; the position of the British Isles in relation to areas of high pressure is key to the magnitude of temperature. High pressure centred south of Britain would allow an Atlantic influence to be exerted and leave temperature in many regions lower than if high pressure was centred over northern Europe allowing higher temperatures from central and southern Europe to spread into the UK.

 

This uncertainty leaves southern and eastern UK with the best chance of seeing spells of above-average temperatures during the rest of this summer. This uncertainty is reflected in the graphs for mean temperature shown in T2 which show a relatively broad forecast distribution which is similar to climatology. It is also worth noting that even average or below-average mean temperatures could come about as a result of colder-than-average nights and warmer-than-average days. This means that average temperatures should not be taken as a sign of an absence of spells of pleasantly warm weather

 

Temperature Summary

 

Summary Precipitation

 

The latest predictions for UK precipitation favour near- or below-average rainfall for July-August-September as a whole. The probability that UK precipitation for July-August-September will fall into the driest of our five categories is close to 25% and the probability that it will fall into the wettest category is approximately 15% (the 1981-2010 probability for each of these categories is 20%)

 

As discussed in the temperature section, there is a clear model signal, potentially influenced by negative sea surface temperatures over the northeastern Atlantic Ocean, for higher-than-average atmospheric pressure to dominate across a large part of Europe through the rest of this summer and the early autumn. This in turn reduces the risk of wetter-than-average conditions and, instead, suggests near- or below-average rainfall is more likely. This is reflected in the difference between the probabilities for the driest and wettest categories shown in figure P2

 

It is worth noting that at this time of year the often convective nature of rainfall can lead to quite marked local or regional variations in rainfall totals relative to average. This can particularly be the case during warmer-than-average conditions when high daytime temperature can trigger isolated heavy showers and thunderstorms. This also makes UK-wide average rainfall more difficult to predict than during autumn and winter when the precipitation signal is dominated by larger-scale storm systems. This means that during any given summer month it is quite possible for the UK as a whole to be drier-than-average but locally higher-than-average rainfall totals could have occurred

 

Precipitation Summary

Edited by Summer Sun

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At the very least a moderate El Niño event with the largest anomalies over the eastern Pacific is expected.

 

So this suggests the Met Office currently does not expect a Modoki type El Nino to develop?

Edited by Don

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