Spring / Summer 2010

[Jezzer]

next week doesnt look half as bad as what i thought it might be. nice.

http://www.weatheron...MENU=Week-ahead

Hmmm, that's better than previously forecast although time will tell wish I wasn't stuck at work, may have to head outside in a bit. Gorgeous out there

[snowlover2009]

Hmmm, that's better than previously forecast although time will tell wish I wasn't stuck at work, may have to head outside in a bit. Gorgeous out there

yes, i won't say make the most of it, because many parts could still have pleasant enough days. I think people will be annoyed by how cool it is next week, but in fact, temps look average, particularly for the south. many areas got up to high 20s today, so i think it will feel really cool next week, but it is still only May too. i really wasnt expecting 28c in may! i thought that would have come in a mini type heatwave soemtime in june or july! let alone by tomorrow that will be 4 consecutive days over 25c and everyday of the week has seen temps in the 20s i think.

[Glacier Point]

Sea surface temperature anomaly plots are advertising some pretty big hints for the summer:

http://weather.unisy...e/sst_anom.html

1) The warm anomaly west of Africa wideley extends to +2C. That is a signal for low pressure in the tropical Atlantic which will have a strong probability for poleward displaced high pressure cells.

2) The normal displacement for high pressure would be the sub-tropical (Azores) ridge. However, look at the cold water anomalies extending right across the sub-tropical Atlantic. This is a negative North Atlantic Oscillation signal, reinforced by the warmer seas north of 50N in the Atlantic which will lead to a weak Azores ridge. We therefore should expect the presence of a strong mid to high latitude high pressure response this summer.

3) The increasing cold anomalies over the central / eastern equatorial Pacific indicative of a rapid transition to La Nina. If the atmosphere plays ball and responds to this forcing, angular momentum should also show falling tendency. This teleconnects to a mid Atlantic ridge.

4) The generally cold look of the northern Pacific Ocean, likely to put a lid on extratropical temperatures and further strengthen a negative tendency in angular momentum.

It is no suprise to me that we have seen, continue to see modelled a strong mid Atlantic ridge anomaly. This ridge will likely move around, positioned more towards Iceland during June, but overall high pressure to our west looks a strong probability for the season ahead.

Edited May 23, 2010 by Glacier Point

[summer blizzard]

Sea surface temperature anomaly plots are advertising some pretty big hints for the summer:

http://weather.unisy...e/sst_anom.html

1) The warm anomaly west of Africa wideley extends to +2C. That is a signal for low pressure in the tropical Atlantic which will have a strong probability for poleward displaced high pressure cells.

2) The normal displacement for high pressure would be the sub-tropical (Azores) ridge. However, look at the cold water anomalies extending right across the sub-tropical Atlantic. This is a negative North Atlantic Oscillation signal, reinforced by the warmer seas north of 50N in the Atlantic which will lead to a weak Azores ridge. We therefore should expect the presence of a strong mid to high latitude high pressure response this summer.

3) The increasing cold anomalies over the central / eastern equatorial Pacific indicative of a rapid transition to La Nina. If the atmosphere plays ball and responds to this forcing, angular momentum should also show falling tendency. This teleconnects to a mid Atlantic ridge.

4) The generally cold look of the northern Pacific Ocean, likely to put a lid on extratropical temperatures and further strengthen a negative tendency in angular momentum.

It is no suprise to me that we have seen, continue to see modelled a strong mid Atlantic ridge anomaly. This ridge will likely move around, positioned more towards Iceland during June, but overall high pressure to our west looks a strong probability for the season ahead.

I agree with you in regards to there being a strong signal for a mid to high lattitude mean ridge over the summer.

While i agree that during June the mean ridge will be centred to the west of the UK, with its most northern displacement during July, i believe that once the negative AO backs off in late summer (August), we should see the mean ridge over western Europe.

[damianslaw]

Strong mid atlantic ridging for the summer wouldn't be a bad thing for those wanting some dry weather. It suggests the atlantic will remain quiet and blocked. However, the ridge will not be a position to deliver much sustained warmth, plenty of northerlies would occur, so perhaps some showery spells at times - how long will the atlantic remain so quiet, it really has been unusually sluggish, the winter just gone has to have gone down as one of the least atlantic dominated in a long time.

I'd be very pleased if the signals verify, I'm not a great lover of intense heat, low 20's and sunny clear air suits me much better interspersed with some hefty showers to avoid drought conditions... mmm.. I'm quite liking these signals.

[SP1986]

Strong mid atlantic ridging for the summer wouldn't be a bad thing for those wanting some dry weather. It suggests the atlantic will remain quiet and blocked. However, the ridge will not be a position to deliver much sustained warmth, plenty of northerlies would occur, so perhaps some showery spells at times - how long will the atlantic remain so quiet, it really has been unusually sluggish, the winter just gone has to have gone down as one of the least atlantic dominated in a long time.

I'd be very pleased if the signals verify, I'm not a great lover of intense heat, low 20's and sunny clear air suits me much better interspersed with some hefty showers to avoid drought conditions... mmm.. I'm quite liking these signals.

The thing is though if these northerlies that are being shown now, lasted into July (generally, just as an example), I dont think 20C would be a very frequent temperature at all, I think in that circumstance, you're looking in most places at 15-17C as maximum with dry air.. it wouldn't feel all that pleasant in northerly breezes, but of course one mans scurge is another mans heaven

[Optimus Prime]

Some very warm May spells in the 60s and 40s after those cold winters. Poor summers aside from 1947 followed.

May 1960; Very warm (12.8c)

May 1964 13.3c

May 1965 (11.7c) 29c London 14th

May 1966 (11.0c) 27c much of the south east at the very start

May 1940 12.5c

May 1941 (11.8c) 30c 15th

May 1944 (11.4c) 33c London 29th

May 1945 (12.2c) 31c London 12th

May 1947 (13.5c) Over 30c widely on the 29th and 30th, upto 32c London

May 1948 (11.5c) Widely over 27c on the 17th and 18th

[Gavin P]

Sea surface temperature anomaly plots are advertising some pretty big hints for the summer:

http://weather.unisy...e/sst_anom.html

1) The warm anomaly west of Africa wideley extends to +2C. That is a signal for low pressure in the tropical Atlantic which will have a strong probability for poleward displaced high pressure cells.

2) The normal displacement for high pressure would be the sub-tropical (Azores) ridge. However, look at the cold water anomalies extending right across the sub-tropical Atlantic. This is a negative North Atlantic Oscillation signal, reinforced by the warmer seas north of 50N in the Atlantic which will lead to a weak Azores ridge. We therefore should expect the presence of a strong mid to high latitude high pressure response this summer.

3) The increasing cold anomalies over the central / eastern equatorial Pacific indicative of a rapid transition to La Nina. If the atmosphere plays ball and responds to this forcing, angular momentum should also show falling tendency. This teleconnects to a mid Atlantic ridge.

4) The generally cold look of the northern Pacific Ocean, likely to put a lid on extratropical temperatures and further strengthen a negative tendency in angular momentum.

It is no suprise to me that we have seen, continue to see modelled a strong mid Atlantic ridge anomaly. This ridge will likely move around, positioned more towards Iceland during June, but overall high pressure to our west looks a strong probability for the season ahead.

Sounds like a cool and dry summer then? Thats a very unusual combination? The only one I can remember in the last twenty years would be 1993? 1998 would also fit except that summer had a very wet June. Anyway, a pretty unusual pattern, which of course follows from the very unusual winter pattern. If the summer does turn out generally cool we could see a VERY low yearly CET for 2010?

Edited May 23, 2010 by Gavin P

[Glacier Point]

.... The constructed analogue suite - 1958, 1960, 1962, 1963, 1969, 1970, 1978, 1988, 1998, 2005 - make more of the upper trough centred over NW Europe, and place more emphasis on above average precipitation as being more likely but I suspect that June will feature a continuation of the high pressure theme and July's pressure anomaly will be of a north-westerly flow which is not supportive of high rainfall amounts, more the cool and showery type. The shifting phases of tropical convection should also help to bring the ridge closer to western parts of the UK and Ireland during this time.

[summer blizzard]

.... The constructed analogue suite - 1958, 1960, 1962, 1963, 1969, 1970, 1978, 1988, 1998, 2005 - make more of the upper trough centred over NW Europe, and place more emphasis on above average precipitation as being more likely but I suspect that June will feature a continuation of the high pressure theme and July's pressure anomaly will be of a north-westerly flow which is not supportive of high rainfall amounts, more the cool and showery type. The shifting phases of tropical convection should also help to bring the ridge closer to western parts of the UK and Ireland during this time.

2005 was quite a strong anologue for the March-April period and as we all know was very dry with a warm first half and cool second, something the anologues i have looked at support, however my understanding of teleconnections would indicate more of the opposite, with July the worst month, but a swicharound in August with August as the best month, at least in terms of temperature relative to average.

One thing that does concern me, is that in every May/June there is the "European Monsoon", even if it not long lasting, this does lead me to suspect that June could be quite unsettled.

[damianslaw]

I'd be very suprised if June continues in the similiar vein of April and May in terms of sustained dry weather. Whilst I don't foresee a washout June, I do expect some quite unsettled wet conditions at times which though may be short-lived could be quite potent.

[Weather-history]

Sounds like a cool and dry summer then? Thats a very unusual combination? The only one I can remember in the last twenty years would be 1993?

Actually summer 1993 was just above average rainfall for England and Wales but its the closest we have come to it.

1981 was the last real one, that was a dry summer and temperatures on the whole were a little below par.

1972 is an even better example.

Hi,

I am intrested to here about the statistical link that a cold winter makes a cool and/or wet summer likley as I would dispute it in some respects for example we know that some cold winters were followed by quite mediocre summers like 1963, 1982 and 1985 but there were the cold winters of 1946/47, 1954/55, 1968/69 and to some extent 1995/96 which where followed either by a hot summer or quite a respectable summer with several noteable heatwaves. So I would say that a cold winter does not always mean a cold and/or wet summers and also it seems to be that cool and/or wet summers are just as likely to follow mild winters than cold ones for example the washout of 2007 followed an exceptionally mild winter, similar for 1998 and 1993 was a classic example in this respect as the cool summer that year came on the back of a very mild winter so that further disputes that thier is a link between the winters weather and the weather the following summer.

As I said before, there is some evidence that a severe winter (sub 2C for the CET) is less likely to be followed by a warm summer. You mention 1947, well that was an exception, the bulk of such winters were followed by cool summers.

.... The constructed analogue suite - 1958, 1960, 1962, 1963, 1969, 1970, 1978, 1988, 1998, 2005 -

The best summers in that list are 1969 and 2005 overall.

1960 and 1970 had very warm Junes but the other two months were less impressive and July 1960 saw the start of a prolonged wet spell.

1958, 1978, 1988, 1998: the curse of the "8" summers

Edited May 24, 2010 by Mr_Data

[Gavin P]

I knew MR D would have the answer.

[Methuselah]

Based upon my ability to forecast seasons from a few months ahead, my only honest expectations are: who knows?

[Weather-history]

For England and Wales, spring 2010 looks like being the driest spring since probably 1997 and drier than November 2009 by a margin.

[AderynCoch]

Some very warm May spells in the 60s and 40s after those cold winters. Poor summers aside from 1947 followed.

May 1960; Very warm (12.8c)

May 1964 13.3c

May 1965 (11.7c) 29c London 14th

May 1966 (11.0c) 27c much of the south east at the very start

May 1940 12.5c

May 1941 (11.8c) 30c 15th

May 1944 (11.4c) 33c London 29th

May 1945 (12.2c) 31c London 12th

May 1947 (13.5c) Over 30c widely on the 29th and 30th, upto 32c London

May 1948 (11.5c) Widely over 27c on the 17th and 18th

It didn't start with a cold winter, but 1922 deserves a special mention - it contained one of the best May heatwaves on record, with 32.8C in London on the 22nd being the earliest in the year 90F has ever been breached. 30C was reached in London on four consecutive days from the 21st to the 24th.

What followed however was a terribly cold summer, with all three months coming in at below 14C - in fact, I believe the combination of July and August is the second coldest in the entire CET series, beaten only by 1695.

EDIT - I've just checked and July/August 1725 was also marginally cooler.

Edited May 24, 2010 by AderynCoch

[Weather-history]

Harry Kershaw is predicting a poor summer but a warm and dry autumn.

http://menmedia.co.uk/manchestereveningnews/news/s/1240974_weatherman_harry_kershaw_predicts_a_damp_summer?all_comments=1

Despite that report, Harry Kershaw is not uncannily accurate and some of the info looks dodgy.

His summer forecast for last year was not brilliant, despite that report. Last July was a washout, he did not predict that.

Coldest and dullest July since 1944? The last 3 recent Julys all had a CET lower than July 1944

Warmest October since 1969? Has he forgotten about the recent Octobers of 2001, 2005 and 2006?

Mildest November since 1938? Has he forgotten about November 1994?

Edited May 26, 2010 by Mr_Data

[Gavin P]

Harry seems to be confused with many of his years however, I would say that with the rapid transition to La Nina now taking place, he may well end up being accurate with his prediction of another poor summer.

Edited May 26, 2010 by Gavin P

[Gavin P]

I've been doing some digging into summers that saw a developing La Nina since 1949 and the corresponding CET's for June, July and August. The results come out as follows:

1954 - June 13.4 July 14.2 August 14.6

1964 - June 13.8 July 16.1 August 15.5

1970 - June 16.4 July 15.2 August 16.0

1973 - June 14.8 July 15.6 August 16.5

1988 - June 14.4 July 14.7 August 15.2

1998 - June 14.2 July 15.5 August 15.9

2007 - June 15.1 July 15.2 August 15.4

As you can see, June seems to show the most variation with very cool Junes in 1954 and 1964, but a hot June in 1970. July tends to be the most disappointing month of the three, with pretty much all years except 1964 showing below average . August also tends to be disappointing.

However, just to prove that even when you've got a developing La Nina all may not be lost check out these other two years:

1949 - June 15.3 July 17.4 August 16.8

1995 - June 14.3 July 18.6 August 19.2

Now check out the SST profile from May 1995;

http://www.osdpd.noaa.gov/data/sst/mean_anom/May.95.anomaly.gif

And compare to the SST profile from today;

http://www.osdpd.noaa.gov/data/sst/anomaly/2010/anomnight.5.27.2010.gif

Not a bad match overall, particularly in terms of the Atlantic tripole and the developing La Nina signature.

Now check out the SST profile from May 1988

http://www.osdpd.noaa.gov/data/sst/mean_anom/May.88.anomaly.gif

May 1998

http://www.osdpd.noaa.gov/data/sst/mean_anom/May.98.anomaly.gif

And May 2007

http://www.osdpd.noaa.gov/data/sst/anomaly/2007/anomnight.5.28.2007.gif

And you can see all three years (which all resulted in poor summers) have a very differant look in the Pacific and Atlantic. The closest match to now really does seem to be 1995.

Conclussion: If we had a positive NAO set up in the Atlantic, coupled with the switch to La Nina, I'd be very confident of a cool and wet summer. However, the closeness of the pattern to 1995, particularly in relation to the tripole gives me pause for thought. We could just be on the verge of a cracker of a summer?

Edited May 27, 2010 by Gavin P

[Harry]

Harry seems to be confused with many of his years however, I would say that with the rapid transition to La Nina now taking place, he may well end up being accurate with his prediction of another poor summer.

I thought for a minute I was being accused for sloppy maths lol

[johnholmes]

Conclusion:We could just be on the verge of a cracker of a summer?

which, if you read the post by Stewart in the technical thread is not that far off the idea suggested by him there. Probably the nearest so far to what seems likely in my view. Not a cracking summer but not the 'poor' version which others and other methods seem to be suggesting?

Seasonal predictions do seem to have their best hope of success by linking the various teleconnections.

[Eugene]

We could just be on the verge of a cracker of a summer?

Yes and similarily we could just be on the verge of a stinker of a summer, that more likely IMO, wasn't you going for a sub 10C even sub 9C year the other week well sounds like you've changed your mind surely a 1995 summer would mess that up unless you are counting on a cold autumn which is unlikely too.

Edited May 28, 2010 by Eugene

[AderynCoch]

There was indeed a significant La Niña event in 1995, so I wouldn't look into the phenomenon too much. There's a strong link between a La Niña episode and an active Atlantic hurricane season (conversely, El Niño stifles hurricane activity in the Atlantic), but I don't see how the oscillation has that much of an effect on these shores: even if any domino effects make it this far around the world, surely there are far more significant factors closer to home which dictate our weather patterns.

[lukemc]

Yes and similarily we could just be on the verge of a stinker of a summer, that more likely IMO, wasn't you going for a sub 10C even sub 9C year the other week well sounds like you've changed your mind surely a 1995 summer would mess that up unless you are counting on a cold autumn which is unlikely too.

What make you think a poor summer is likely? IMO even if we do get a poor summer a decent summer is equally likley as after 3 poor summers in succesion a good summer could be considered likley on the law of averages and also consider the fact that we are overdue a really warm month (16C CET or more) as we haven't had one of them since 2006.

Luke

[Methuselah]

which, if you read the post by Stewart in the technical thread is not that far off the idea suggested by him there. Probably the nearest so far to what seems likely in my view. Not a cracking summer but not the 'poor' version which others and other methods seem to be suggesting?

Seasonal predictions do seem to have their best hope of success by linking the various teleconnections.

Hi John,

'Method' does sound somewhat more persuasive than 'guess' though?? :lol: