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Summer Sun

Met office Contingency planners forecasts

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April update

May to July

Temperature summary

For May-June-July, above-average temperatures are more probable than below-average. Overall, the probability that the UK-average temperature for May-June-July will fall into the coldest of our five categories is 10% and the probability that it will fall into the warmest of our five categories is 35% (the 1981-2010 probability for each of these categories is 20%)

Full update: http://www.metoffice.gov.uk/binaries/content/assets/mohippo/pdf/public-sector/forecast-temp-mjj-v2.pdf

Precipitation summary

For May-June-July, above-average precipitation is considered slightly more probable than below-average, on balance. Overall, the probability that the UK-average precipitation for May-June-July will fall into the driest of our five categories is 20% and the probability that it will fall into the wettest of our five categories is around 25% (the 1981-2010 probability for each of these categories is 20%).

Full update: http://www.metoffice.gov.uk/binaries/content/assets/mohippo/pdf/public-sector/forecast-precip-mjj-v2.pdf

Edited by Summer Sun

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May update

June to August

Temperature summary

For June and June-July-August above-average temperatures are more probable than below-average temperatures. Overall, the probability that the UK-average temperature for June-July-August will fall into the coldest of our five categories is 10% and the probability that it will fall into the warmest of our five categories is 35% (the 1981-2010 probability for each of these categories is 20%).

Full update: http://www.metoffice.gov.uk/binaries/content/assets/mohippo/pdf/public-sector/forecast-temp-jja-v1.pdf

Precipitation summary

For June, above-average precipitation is moderately more likely than below-average precipitation. For June-July-August the chances of above- and below-average precipitation are fairly balanced. The probability that UK-average precipitation for June-July-August will fall into the driest of our five categories is between 15% and 20% and the probability that it will fall into the wettest of our five categories is around 20% (the 1981-2010 probability for each of these categories is 20%).

Full update: http://www.metoffice.gov.uk/binaries/content/assets/mohippo/pdf/public-sector/forecast-precip-jja-v1.pdf

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June update

July to September

Temperature summary

For July and July-August-September above-average temperatures are more probable than below-average temperatures. Overall, the probability that the UK-average temperature for July-August-September 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 30% (the 1981-2010 probability for each of these categories is 20%).

Full update: http://www.metoffice.gov.uk/binaries/content/assets/mohippo/pdf/public-sector/forecast-temp-jas_v1.pdf

Precipitation summary

For July and July-August-September above-average precipitation is slightly more probable than below-average. The probability that UK precipitation for July-August-September will fall into the driest of our five categories is between 15% and 20% and the probability that it will fall into the wettest of our five categories is around 20% (the 1981-2010 probability for each of these categories is 20%).

Full update: http://www.metoffice.gov.uk/binaries/content/assets/mohippo/pdf/public-sector/forecast-precip-jas-v1.pdf

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Bit behind with this here's July's update

August to October

Temperature summary

For August-September-October above-average temperatures are more probable than below-average temperatures. Overall, the probability that the UK-average temperature for August-September-October will fall into the coldest of our five categories is around 5% and the probability that it will fall into the warmest of our five categories is between 50 and 55% (the 1981-2010 probability for each of these categories is 20%).

Full update: http://www.metoffice.gov.uk/binaries/content/assets/mohippo/pdf/public-sector/forecast-temp-aso-v2.pdf

Precipitation summary

For August-September-October below-average precipitation is slightly more probable than above-average. The probability that UK precipitation for August-September-October 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 around 20% (the 1981-2010 probability for each of these categories is 20%)

Full update: http://www.metoffice.gov.uk/binaries/content/assets/mohippo/pdf/public-sector/forecast-precip-aso-v2.pdf

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August update

September to November

Temperature summary

For September and September-October-November, above-average temperatures are more probable than below-average temperatures. Overall, the probability that the UK-average temperature for September-October-November 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 50% (the 1981-2010 probability for each of these categories is 20%).

Full update: http://www.metoffice.gov.uk/binaries/content/assets/mohippo/pdf/public-sector/forecast-temp-son-v1.pdf

Precipitation summary

For September, the forecast for UK precipitation suggests that the chances of above- and below-average rainfall are fairly balanced. For September-October-November as a whole, above-average precipitation is considered slightly more probable than below-average precipitation. The probability that UK precipitation for September-October-November will fall into the driest of our five categories is 20% and the probability that it will fall into the wettest of our five categories is around 25% (the 1981-2010 probability for each of these categories is 20%).

Full update: http://www.metoffice.gov.uk/binaries/content/assets/mohippo/pdf/public-sector/forecast-precip-son-v1.pdf

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September update

October to December

Temperature summary

For October-November-December above-average temperatures are more probable than below-average temperatures. Overall, the probability that the UK-average temperature for October-November-December will fall into the coldest of our five categories is between 10% and 15% and the probability that it will fall into the warmest of our five categories is between 35% and 40% (the 1981-2010 probability for each of these categories is 20%).

Full update: https://www.metoffice.gov.uk/binaries/content/assets/mohippo/pdf/public-sector/forecast-temp-ond-v2.pdf

Precipitation summary

For October-November-December above-average precipitation is more probable than below-average precipitation. The probability that UK precipitation for October-November-December 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 around 30% (the 1981-2010 probability for each of these categories is 20%).

Full update: https://www.metoffice.gov.uk/binaries/content/assets/mohippo/pdf/public-sector/forecast-precip-ond-v2.pdf

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1 hour ago, Summer Sun said:

September update

October to December

Temperature summary

For October-November-December above-average temperatures are more probable than below-average temperatures. Overall, the probability that the UK-average temperature for October-November-December will fall into the coldest of our five categories is between 10% and 15% and the probability that it will fall into the warmest of our five categories is between 35% and 40% (the 1981-2010 probability for each of these categories is 20%).

Full update: https://www.metoffice.gov.uk/binaries/content/assets/mohippo/pdf/public-sector/forecast-temp-ond-v2.pdf

Precipitation summary

For October-November-December above-average precipitation is more probable than below-average precipitation. The probability that UK precipitation for October-November-December 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 around 30% (the 1981-2010 probability for each of these categories is 20%).

Full update: https://www.metoffice.gov.uk/binaries/content/assets/mohippo/pdf/public-sector/forecast-precip-ond-v2.pdf

Never really was a fan of the probability forecasts. How is anyone supposed to plan for that? If someone told you that you had a 10% chance of winning the lottery, you would be eagerly watching the next draw, but in Met Office speak, that seems to be more saying "Not gonna happen", but they still assign 10-15% to it...

Surely unless you can be more than 60% confident in something, better to say nothing? hmm

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25 minutes ago, jvenge said:

Never really was a fan of the probability forecasts. How is anyone supposed to plan for that? If someone told you that you had a 10% chance of winning the lottery, you would be eagerly watching the next draw, but in Met Office speak, that seems to be more saying "Not gonna happen", but they still assign 10-15% to it...

Surely unless you can be more than 60% confident in something, better to say nothing? hmm

Have a look up the page to their July update, covering  AUG/SEP/OCT. Their gonna need a record breaking warm October to rescue that probability forecast....

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1 minute ago, DAVID SNOW said:

Have a look up the page to their July update, covering  AUG/SEP/OCT. Their gonna need a record breaking warm October to rescue that probability forecast....

I guess my general whinge is that with probability forecasts you can never actually be wrong. At what point does not needing to be right influence how much effort going into the actual prediction? hmm.

 

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That's just the reality of forecasting. When there are knowns, uncertainties, unknowns, and unknown unknowns - probabilities are as good as you can really get.

"Forecasters" that tell you it will certainly be one way or the other months in advance are the ones that should be ignored. Better to give the probabilities as they are than to embellish for a false sense of certainty.

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9 minutes ago, BornFromTheVoid said:

That's just the reality of forecasting. When there are knowns, uncertainties, unknowns, and unknown unknowns - probabilities are as good as you can really get.

"Forecasters" that tell you it will certainly be one way or the other months in advance are the ones that should be ignored. Better to give the probabilities as they are than to embellish for a false sense of certainty.

Oh, I understand. I think I would rather just have the disclaimer at the front and then someone telling me what they think will happen and why, as opposed to giving me three options with different probabilities and then always being right....

 

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Just now, jvenge said:

Oh, I understand. I think I would rather just have the disclaimer at the front and then someone telling me what they think will happen and why, as opposed to giving me three options with different probabilities and then always being right....

 

I'm sure there is a lot more behind their forecasts that they don't release. Seeing as it's specifically for contingency planners, they're probably not too concerned with the detailed methodology, just the probability of different seasonal weather patterns occurring.
A bit frustrating for amateur enthusiasts though, I agree.

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Just now, BornFromTheVoid said:

I'm sure there is a lot more behind their forecasts that they don't release. Seeing as it's specifically for contingency planners, they're probably not too concerned with the detailed methodology, just the probability of different seasonal weather patterns occurring.
A bit frustrating for amateur enthusiasts though, I agree.

Well, even as a contingency planner, I'd be looking at those odds and I'm going to be thinking I have really good chances of being wrong and the people who told me about it can turn around and say "Well, we did warn you"

I guess it is just a whinge though. There is no perfect way.

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I think the contingency planners forecasts needle is well and truly stuck...warmer than average for November to January as well when the next update is issued by any chance?

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7 hours ago, BornFromTheVoid said:

I'm sure there is a lot more behind their forecasts that they don't release. Seeing as it's specifically for contingency planners, they're probably not too concerned with the detailed methodology, just the probability of different seasonal weather patterns occurring.
A bit frustrating for amateur enthusiasts though, I agree.

Probably a bit frustrating for those that pay money for a 3 month probability forecast , no sympathy though, as a 3 month forecast should be JFF. Even one month ahead is pushing the boundaries of accuracy.

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October update

November to January

Quote

 

Temperature

For November-December-January above-average temperatures are more probable than below-average temperatures. Overall, the probability that the UK-average temperature for November-December-January will fall into the coldest of our five categories is between 10% and 15% and the probability that it will fall into the warmest of our five categories is between 30% and 35% (the 1981-2010 probability for each of these categories is 20%).

Sea surface temperatures in the tropical Central and Eastern Pacific have now fallen close to La Niña thresholds. Long-range prediction systems indicate this cooling is very likely to continue in the coming weeks, leading to a full La Niña event over the next few months. La Niña slightly increases the chances of blocking patterns over the North Atlantic and Europe in late autumn and early winter, leading to increased chances of colder-than-average conditions. The Quasi-Biennial Oscillation (QBO), an oscillation of the equatorial winds in the stratosphere, is in an easterly phase. The QBO is linked to conditions over Western Europe during late autumn and early winter through an influence on the phase of the North Atlantic Oscillation (NAO) at the surface.

An easterly phase of the QBO tends to moderately increase the chances of a negative phase of the NAO, which in turn increases the chances of below-average temperatures. Sea surface temperatures in the North Atlantic are generally above average, consistent with the current high levels of warmth globally. West of the UK, however, temperatures are slightly below average. Nevertheless, warmth beneath the ocean surface, which is expected to have an increasing influence on surface conditions as the period progresses, favours higher-than-normal temperatures for the time of year. For November-December-January as a whole, long-range forecast systems generally show an increased chance of westerly air flow over the UK, although some show more likelihood of high-pressure patterns over the North Atlantic implying a greater likelihood of northerly or north-westerly winds.

Overall, the outlook shows increased chances of above-average temperatures in the 3-month period (see figure T2). Despite this, the risk of colder-than-normal conditions remains a significant possibility, with some of the drivers of UK winter weather, such as La Niña and the QBO, favouring weather patterns associated with colder-than-normal weather.

Precipitation

For November-December-January above-average precipitation is considered more probable than below-average precipitation. The probability that UK-average precipitation for November-December-January will fall into the driest of our five categories is around 15% and the probability that it will fall into the wettest of our five categories is between 25% and 30% (the 1981-2010 probability for each of these categories is 20%).

Autumn is a season when it is usual for Atlantic depressions to become more intense. These systems bring large amounts of moisture, often making it one of the stormiest and wettest parts of the year (see figure P1). As discussed in the temperature section, signals from the Met Office long-range prediction system and other systems from prediction centres around the world broadly show an increased likelihood of westerly or cyclonic weather patterns during the outlook period.

Some systems suggest a greater likelihood of high-pressure patterns over the North Atlantic Ocean, however, and there are global factors that favour weather patterns bringing colder and drier weather (see temperature section). Overall, the outlook for November-DecemberJanuary shows slightly increased chances of above-average rainfall compared to normal (see figure P2). The outlook also implies that the risk of impacts from high rainfall and strong winds is moderately greater than usual. Despite this, the likelihood of dry conditions, of concern for some parts of the UK following last winter’s low rainfall, remains only slightly less than normal.

 

 

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I like this bit @Summer Sun:

"Despite this, the risk of colder-than-normal conditions remains a significant possibility, with some of the drivers of UK winter weather, such as La Niña and the QBO, favouring weather patterns associated with colder-than-normal weather"

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November update

December to February

Temperature summary

For December, below-average temperatures are more likely than above-average temperatures. The likelihood of impacts from cold weather is greater than normal.  For December-January-February as a whole, above-average temperatures are more likely than below-average temperatures. Impacts from cold weather remain possible, but they are less likely than normal.  
 
Overall, the probability that the UK-average temperature for December-January-February will fall into the coldest of our five categories is between 5% and 10% and the probability that it will fall into the warmest of our five categories is around 30% (the 1981-2010 probability for each of these categories is 20%).

Full update: https://www.metoffice.gov.uk/binaries/content/assets/mohippo/pdf/public-sector/forecast-temp-djf-v1.pdf

Precipitation summary

For December, below-average precipitation is slightly more likely than above-average precipitation. For December-January-February as a whole, above-average precipitation is more likely than below-average precipitation. The likelihood of impacts from heavy rainfall and high winds is greater than usual.
 
The probability that UK-average precipitation for December-January-February will fall into the driest of our five categories is between 10% and 15% and the probability that it will fall into the wettest of our five categories is between 30% and 35% (the 1981-2010 probability for each of these categories is 20%).

Full update: https://www.metoffice.gov.uk/binaries/content/assets/mohippo/pdf/public-sector/forecast-precip-djf-v1.pdf

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7 hours ago, Summer Sun said:

November update

December to February

Temperature summary

For December, below-average temperatures are more likely than above-average temperatures. The likelihood of impacts from cold weather is greater than normal.  For December-January-February as a whole, above-average temperatures are more likely than below-average temperatures. Impacts from cold weather remain possible, but they are less likely than normal.  
 
Overall, the probability that the UK-average temperature for December-January-February will fall into the coldest of our five categories is between 5% and 10% and the probability that it will fall into the warmest of our five categories is around 30% (the 1981-2010 probability for each of these categories is 20%).

Full update: https://www.metoffice.gov.uk/binaries/content/assets/mohippo/pdf/public-sector/forecast-temp-djf-v1.pdf

Precipitation summary

For December, below-average precipitation is slightly more likely than above-average precipitation. For December-January-February as a whole, above-average precipitation is more likely than below-average precipitation. The likelihood of impacts from heavy rainfall and high winds is greater than usual.
 
The probability that UK-average precipitation for December-January-February will fall into the driest of our five categories is between 10% and 15% and the probability that it will fall into the wettest of our five categories is between 30% and 35% (the 1981-2010 probability for each of these categories is 20%).

Full update: https://www.metoffice.gov.uk/binaries/content/assets/mohippo/pdf/public-sector/forecast-precip-djf-v1.pdf

Looks like they are expecting a bit of a front loaded winter with a colder than average December followed by a milder than average January and February, leading to a mild winter overall.  A typical La Nina winter?

Edited by Don

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8 minutes ago, Don said:

Looks like they are expecting a bit of a front loaded winter with a colder than average December followed by a milder than average January and February, leading to a mild winter overall.  A typical La Nina winter?

1

Pretty much if everything goes as predicted wouldn't rule out a colder spell in early spring

La Nina winters do tend to bring a front-loaded winter 

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25 minutes ago, Summer Sun said:

Pretty much if everything goes as predicted wouldn't rule out a colder spell in early spring

La Nina winters do tend to bring a front-loaded winter 

Yes, they do with 2010 being an extreme example!

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1 hour ago, Summer Sun said:

Pretty much if everything goes as predicted wouldn't rule out a colder spell in early spring

La Nina winters do tend to bring a front-loaded winter 

This happened following the La Nina winter in 2008.  January and February were mild, but there were some cold wintry snaps in March and April.

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December update

Jan to March

Temperature summary

For January, above-average temperatures are slightly more likely than below-average temperatures. Weather patterns are likely to be changeable, suggesting a chance of cold weather during some parts of the month. For January-February-March as a whole, above-average temperatures are more likely than below-average temperatures. Impacts from cold weather remain possible, but they are less likely than normal.  Overall, the probability that the UK-average temperature for January-February-March will fall into the coldest of our five categories is between 10% and 15% and the probability that it will fall into the warmest of our five categories is between 35% and 40% (the 1981-2010 probability for each of these categories is 20%).

Full update: https://www.metoffice.gov.uk/binaries/content/assets/mohippo/pdf/public-sector/forecast-temp-jfm-v1.pdf

Precipitation summary

For January, and January-February-March as a whole, above-average precipitation is more likely than below-average precipitation. The likelihood of impacts from heavy rainfall and high winds is greater than usual. The probability that UK-average precipitation for January-February-March will fall into the driest of our five categories is 15% and the probability that it will fall into the wettest of our five categories is 30% (the 1981-2010 probability for each of these categories is 20%).

Full update: https://www.metoffice.gov.uk/binaries/content/assets/mohippo/pdf/public-sector/forecast-precip-jfm-v1.pdf

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January update

February to April

Temperature

For February-March-April above-average temperatures are more likely than below-average temperatures. Overall, the probability that the UK-average temperature for February-March-April will fall into the coldest of our five categories is around 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%).

La Niña conditions continue in the Tropical Pacific. While this event is likely to be close to its peak, it will still influence global weather patterns over the coming months. In late winter La Niña increases the chances of the positive phase of the North Atlantic Oscillation (NAO), which in turn increases the likelihood of milder-than-average conditions. Conversely, predicted patterns of rainfall in the Tropical Atlantic Ocean increase the likelihood of a negative phase of the NAO. The negative phase of the NAO usually brings colder-than-average conditions to the UK. The Madden-Julian Oscillation (MJO) is an area of enhanced thundery activity that moves eastwards through the tropics over a period of several weeks. It has recently been active and is forecast to enter a phase that frequently leads to negative NAO.

This implies an increased chance of colder-than-average temperatures in early- to mid-February. The Stratospheric Polar Vortex (SPV) is currently stronger than usual and forecasting systems show little likelihood of a sudden stratospheric warming (SSW) in February. This supports a positive phase of the NAO and an increased likelihood of milder-than-usual conditions, at least in the first half of the 3-month period. For the February-March-April period, predictions from long-range forecasting systems show a normal spread of potential weather patterns. The chances of above-average temperatures are slightly greater than the chances of below-average temperatures. The small shift towards above-average conditions (see figure T2) is consistent with the observed increase in UK temperatures compared to the long-term average.      

https://www.metoffice.gov.uk/binaries/content/assets/mohippo/pdf/public-sector/forecast-temp-fma-v2.pdf

Precipitation

For February-March-April as a whole, the chances of above- and below-average precipitation are close to normal.  The probability that UK-average precipitation for February-March-April will fall into the driest of our five categories is 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 discussed in the temperature section, forecast systems show a normal range of potential weather patterns for February-March-April.  The chances of above- and below-average precipitation are close to normal

https://www.metoffice.gov.uk/binaries/content/assets/mohippo/pdf/public-sector/forecast-precip-fma-v2.pdf
 
 

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February update

March to May

Temperature summary

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

Full forecast: https://www.metoffice.gov.uk/binaries/content/assets/mohippo/pdf/public-sector/forecast-temp-mam-v2.pdf

Precipitation

For March-April-May as a whole, above-average precipitation is slightly more likely than below-average precipitation. The probability that UK-average precipitation for March-April-May will fall into the driest of our five categories is between 15-20% and the probability that it will fall into the wettest of our five categories is between 25% and 30% (the 1981-2010 probability for each of these categories is 20%).

Full forecast: https://www.metoffice.gov.uk/binaries/content/assets/mohippo/pdf/public-sector/forecast-precip-mam-v2.pdf

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