August CET

[Guest Mike W]

Is that a result of climatic warming Thundery?

[Thundery wintry showers]

I don't know- all I can say is that the band from 65 to 80N seemed to be rather warmer than normal.

[shuggee]

Well after a record July - it's hardly surprising there there wasn't anything cooler around! So it's not a surprise really that the synoptics didn't deliver something even cooler at all!

[Scorcher]

It is very interesting that despite the very pronounced northerly element to the month, the CET has turned out around or fractionally above the 1971-00 average. I think we saw something similar last winter- maybe 20 years ago with the synoptics we witnessed during the winter, we would have seen more sub-zero temperatures and far more snow, but it certainly seems that air masses are getting warmer. As it happened, despite favourable synoptics for cold conditions during the winter, the winter was actually above average overall. It seems like the capacity for cold conditions has been dramatically reduced and to achieve a below average winter it is certainly going to take some exceptional synoptics.

[Bottesford]

Yeah an awful lot of very warm air got pumped northwards during June & July. It'll take quite a while to 'normalise' after that. If we get some more ex hurricanes coming up they'll pump even more heat up there knocking these cold pools out somewhere else (southwards probably thus moderating them in the still warm September Sun).

[Thundery wintry showers]

I'm not actually sure that last winter was a very good example of the right synoptics not providing the goods. Most of the time, the cold air sources were there, but the synoptics provided near-misses with the cold easterlies staying put out in the continent.

We had two northerlies in November, the second of which was quite potent for the time of year, and the easterly at the end of December produced sub-zero maxima for many on the 28th and 29th. As for the SE'ly at the beginning of January, SE'ly winds are traditionally an unreliable source of snow as mild Mediterranean air can easily get caught in the circulation. In March, north and east winds delivered the goods for many, and NW'ly winds likewise in April. The one exception was February, with a 36-hour northerly non-event, and a rather pathetic easterly at the end (in Cleadon the temperature never got below 2C during that easterly!)

2004/05, however, certainly was a good example, with northerly and NW'ly non-events in January and the first half of February, and then an easterly that, while snowy, was rather less cold than one would usually expect, meaning that for many the snow struggled to settle.

[johnholmes]

I'm not actually sure that last winter was a very good example of the right synoptics not providing the goods. Most of the time, the cold air sources were there, but the synoptics provided near-misses with the cold easterlies staying put out in the continent.

We had two northerlies in November, the second of which was quite potent for the time of year, and the easterly at the end of December produced sub-zero maxima for many on the 28th and 29th. As for the SE'ly at the beginning of January, SE'ly winds are traditionally an unreliable source of snow as mild Mediterranean air can easily get caught in the circulation. In March, north and east winds delivered the goods for many, and NW'ly winds likewise in April. The one exception was February, with a 36-hour northerly non-event, and a rather pathetic easterly at the end (in Cleadon the temperature never got below 2C during that easterly!)

2004/05, however, certainly was a good example, with northerly and NW'ly non-events in January and the first half of February, and then an easterly that, while snowy, was rather less cold than one would usually expect, meaning that for many the snow struggled to settle.

August CET!!

[Thundery wintry showers]

Maybe I should've quoted the post I was replying to- I can see the 'off-topic' argument there! It was in reply to a point that last winter was a good example of the right synoptics failing to deliver snow.

The August CET stuff bears out some of my earlier posts where people were posting that if the northerlies in the second week of August had happened in winter there would have been snow, and I didn't agree. Here was the analogy I used:

http://www.wetterzentrale.de/archive/2006/...00220060813.png

http://www.wetterzentrale.de/archive/1999/...00219991119.png

[Stratos Ferric]

Yeah an awful lot of very warm air got pumped northwards during June & July. It'll take quite a while to 'normalise' after that. If we get some more ex hurricanes coming up they'll pump even more heat up there knocking these cold pools out somewhere else (southwards probably thus moderating them in the still warm September Sun).

It's a convenient argument if people want to clutch straws, but it doesn't wash. Warm air moving poleward would be moderated anyway. Even if you build a pool of warm air, a cooler surface, with a much greater thermal capacity, will soon "correct" the boundary layer. Once the synoptics change, as they did more than three weeks ago now, you'd expect to see rapid corrections, even if the surface had been warmed slightly above normal. The argument might hold good for a few days, but not, I think, for three weeks. That degree of sustained moderation needs fuelling from a more permanent source.

[Bottesford]

It's a convenient argument if people want to clutch straws, but it doesn't wash. Warm air moving poleward would be moderated anyway. Even if you build a pool of warm air, a cooler surface, with a much greater thermal capacity, will soon "correct" the boundary layer. Once the synoptics change, as they did more than three weeks ago now, you'd expect to see rapid corrections, even if the surface had been warmed slightly above normal. The argument might hold good for a few days, but not, I think, for three weeks. That degree of sustained moderation needs fuelling from a more permanent source.

It'd hold for more than a few days if so much of it had gone northwards and spread across such a large area. The more permantent source you mention was the warmer air being pulled up from the south via east Europe due to the low over scandi which then returned back to us via from the NE. A more direct, longer lasting northerly would have cooled things more quickly of course.

[Stratos Ferric]

It'd hold for more than a few days if so much of it had gone northwards and spread across such a large area. The more permantent source you mention was the warmer air being pulled up from the south via east Europe due to the low over scandi which then returned back to us via from the NE. A more direct, longer lasting northerly would have cooled things more quickly of course.

An airmass loses its heat rapidly; look what happens when the sun goes down! A warm airmass flowing north would not build up a heat trap; it's not like a blast furnace - spatially the system is not bounded and there would be a lot of flux away from the air mass in all direction. In any case, the main flow this month has not really been northerly, its been off the oceans to the W and NW. You can wrap it up however you like, I'm with Philip on this one now that he's pointed it out; given the overall synoptics for the month it's remarkable that August has come out above normal. As I posted in a thread elsewhere, the diurnal variation has been small and fairly consistent all month, almost irrespectve of where the air over the UK was coming from.

[snowsure]

An airmass loses its heat rapidly; look what happens when the sun goes down! A warm airmass flowing north would not build up a heat trap; it's not like a blast furnace - spatially the system is not bounded and there would be a lot of flux away from the air mass in all direction. In any case, the main flow this month has not really been northerly, its been off the oceans to the W and NW. You can wrap it up however you like, I'm with Philip on this one now that he's pointed it out; given the overall synoptics for the month it's remarkable that August has come out above normal. As I posted in a thread elsewhere, the diurnal variation has been small and fairly consistent all month, almost irrespectve of where the air over the UK was coming from.

Do I believe my eyes?

That is surely like me saying that I am suprised that July wasn't any warmer, what with GW and all (sic)

This rates, in my eyes, as a most bizarre defence of GW in the face of one of the greatest July-August temperature collapses. (3.6 oC from http://www.metoffice.gov.uk/research/hadle.../HadCET_act.txt )

Even more bizarre is the fact that it has come from one of the most erudite contributors on this site.

[Nick F]

Interesting how quick the MO are to put up their CET for the past month recently, and that it's 0.2C below Philip's final figure. Splitting hairs though IMO to what is a close to average outcome overall.

But there was a more 'marked' cooling trend after mid-month - just by looking at Philip Eden's breakdown for the month shows how the final third of August brought down the CET to 0.5C below average between the 21st-30th:

http://www.climate-uk.com/page2.html

[The PIT]

We clocked in at 0.1c above are normal. Courtesy of a lack of varition on the min's which were above normal while the max was below. Also an interesting differance between the Davis and the Stevenson average.

[Thundery wintry showers]

Do I believe my eyes?

That is surely like me saying that I am suprised that July wasn't any warmer, what with GW and all (sic)

This rates, in my eyes, as a most bizarre defence of GW in the face of one of the greatest July-August temperature collapses. (3.6 oC from http://www.metoffice.gov.uk/research/hadle.../HadCET_act.txt )

Even more bizarre is the fact that it has come from one of the most erudite contributors on this site.

Read the posts more carefully- it may sound like a "defence" of GW, but what it's saying is that on average, given the synoptics we had, one would expect a below-average month, possibly by in excess of 1C.

There were probably a number of contributory factors to the anomaly- on UKWW it was suggested that the exceptionally high SSTs around Britain, especially in the North Sea, may have had something to do with it as well. They would have modified the airmasses more than is usual. Our northerly winds weren't generally long-drag, mostly taking air from around 65-75N. However, the 65-75N band was nonetheless unusually warm.

[snowsure]

Read the posts more carefully- it may sound like a "defence" of GW, but what it's saying is that on average, given the synoptics we had, one would expect a below-average month, possibly by in excess of 1C.

There were probably a number of contributory factors to the anomaly- on UKWW it was suggested that the exceptionally high SSTs around Britain, especially in the North Sea, may have had something to do with it as well. They would have modified the airmasses more than is usual. Our northerly winds weren't generally long-drag, mostly taking air from around 65-75N. However, the 65-75N band was nonetheless unusually warm.

Thanks for your comments TWS.

Please rest assured that I do read all posts. What I cannot do is comprehend all of what I read, especially when advanced concepts are introduced or if too much info is posted in one post. I read research documents frequently but, to be honest, they are more accessible than some of the long-winded posts on here.

My specialism is Astrophysics (Active Galactic Nuclei) but I do possess a Diploma in Natural Science which I hope allows me access to such debates as this.

I hope my point of a 3.6 oC temp change from July-August is not lost in some tangential debate regarding forum decorum.

That feels better!

[Thundery wintry showers]

Everyone is perfectly entitled to contribute to these debates- it's a public forum after all.

Interesting is that if all source areas had been at near-normal temperatures, the temp difference between July and August would probably have been greater, and almost certainly record-breaking, as much of the warmth of July could indeed be explained synoptically.

[snowsure]

Everyone is perfectly entitled to contribute to these debates- it's a public forum after all.

Interesting is that if all source areas had been at near-normal temperatures, the temp difference between July and August would probably have been greater, and almost certainly record-breaking, as much of the warmth of July could indeed be explained synoptically.

Which was the freak month then?

[Stratos Ferric]

Thanks for your comments TWS.

Please rest assured that I do read all posts. What I cannot do is comprehend all of what I read, especially when advanced concepts are introduced or if too much info is posted in one post. I read research documents frequently but, to be honest, they are more accessible than some of the long-winded posts on here.

My specialism is Astrophysics (Active Galactic Nuclei) but I do possess a Diploma in Natural Science which I hope allows me access to such debates as this.

I hope my point of a 3.6 oC temp change from July-August is not lost in some tangential debate regarding forum decorum.

That feels better!

Snowsure,

Your specialism may well be astrophysics, but you aren't filling me with much confidence regarding how absolutely talented you might be in that field if your response here is anything to go by.

Your observation regarding the change from July-August is a total and utter irrelevance to the point I was making, and is any case fatuous, bounding being so fatuous, in fact, that but for the fact that I'm like a dog with a bone sometimes I wouldn't bother responding, for all your generous comments regarding erudition otherwise.

To elaborate on the above. First - my thread picked up on Philip Eden's analysis of August's temperaure given its synoptics. August stands alone in this regard; what happened in July is no more relevant to the point you're trying to make about my post than was the price of a tin on beans in Sainsbury's this morning. His analysis has the month as the MOST NORTHERLY August in his 130 odd years of analysis. I'll say that again, the MOST NORTHERLY - that being the coldest soutrce at this time of year. Yet it was far from being the coldest August on record - so cold was it in fact that it came out about average I believe. In simple terms, we were, on average, under the sustained influence, in that data set, for this month, of the coldest available source, yet still couldn't muster a cold month. You may have a better explanation than the one I've offered, in which case I'm all ears. You can mutter about the warm spell at the start of the month, but even if you removed that it would still have been about average, not dramatically cold. There is a chance that in the way Philip calculates the average flow a slight skew has been introduced, but I have seen cross comparative analyses of the technique he uses and it seems reasonably robust.

One or two people have suggested that July's warmth warmed the pole and therefore in August we were receiving the residual effects of summer's heat. I've already repsonded to that argument, and in any case, if you check the 90 day anomaly for the pole then for this argument to stack up you'd be expecting to see a +ve anomaly up there in order to account for an unusually warm source: there is no such anomaly.

Secondly, reference the drop in temperatures from July-August as if this were proof of anything at all, irrespective of its irrelevance to my comment (there is none). You might as well tell a guy who won nothing on the lottery this week after having won the jackpot last week that he's unlucky. I cannot quite see what point you're trying to make. July was an exceptionally hot month, it would have been far more remarkable had there not been a significant drop TO NORMAL - which is, after all, EXACTLY what has happened. All the month-month change highlights is how unusual July was; it says nothing at all about August.

If there are any posts on here (away from the environment discussions perhaps and occasions when people cut and paste huge swathes) longer than research papers you're reading then you're probably not reading very good research papers.

[Weather-history]

Interesting how quick the MO are to put up their CET for the past month recently, and that it's 0.2C below Philip's final figure. Splitting hairs though IMO to what is a close to average outcome overall.

But there was a more 'marked' cooling trend after mid-month - just by looking at Philip Eden's breakdown for the month shows how the final third of August brought down the CET to 0.5C below average between the 21st-30th:

http://www.climate-uk.com/page2.html

Going off the Met Office's value that makes it the coolest August jointly with 1999 since 1998.

Also that makes it 0.1 below the 1971-2000 average.

The result of this makes summer 2006, the 5th warmest summer on record, 4 of the 5 warmest summers on record have occurred in the last 30 years.

As well as the drop in the CET between July and August equaling the record of 3.6 between July and August 1737.

Its remarkable that such a hot summer, should contain a month that was below the 30 year average albeit only slightly.

[Stratos Ferric]

I hope my point of a 3.6 oC temp change from July-August is not lost in some tangential debate regarding forum decorum.

That feels better!

What is your point. Are you suggesting that this drop means we're headed for 0C by December and -9 by March?

Its remarkable that such a hot summer, should contain a month that was below the 30 year average albeit only slightly.

Although, viwed another way, it's remarkable that a summer with two such hot months didn't go on to break the record for summer. That's period averaging for you.

[Stratos Ferric]

Read the posts more carefully- it may sound like a "defence" of GW, but what it's saying is that on average, given the synoptics we had, one would expect a below-average month, possibly by in excess of 1C.

There were probably a number of contributory factors to the anomaly- on UKWW it was suggested that the exceptionally high SSTs around Britain, especially in the North Sea, may have had something to do with it as well. They would have modified the airmasses more than is usual. Our northerly winds weren't generally long-drag, mostly taking air from around 65-75N. However, the 65-75N band was nonetheless unusually warm.

I have to say, which is why I make the point in my response to our snowy friend, that part of the apparent "anomaly" might be explained by the calculation. Your point also aligns with the instinct I mentioned previously, which is that describing the month as "northerly" is at odds with my recall of generally westerly - with occasional mP® or mP feeds. In testing for a pressure differential across a line only direction of flow at the line is indicated, not original source. When the typology used by Philip talks about "northerliness", it doesn't necessarily mean that the air is polar origin therefore, and I think what we actually had in August was more a pronounced absence of southerliness. We might need Philip - and I'm sure he will in time - to comment on whether the method might be slightly flawed on this occasion when used inferentially (I am certainly not sggesting any flaw in the application of the method to arrive at his indeces for this month and others, purely in MY [and it is "my"] search for explanation), or whether on more detailed analysis of the charts the net flow this August was, indeed, from the furthest poleward within the 130 year data set.

I hadn't noticed that SSTs were exceptionally high generally, however, whichever way you carve it, for a month with no real heatwave to come in close to average (even if you net off the warm 3-4 days start of month it was still close to average) suggests that some heat is entering the system somewhere.

[Weather-history]

Just looking at the figures out of the top 10 hottest summers, it is the summer that has the lowest CET value for the August, infact you have to go to the 18th hottest summer on record to find an August that has a lower CET value than August 2006.

[Scorcher]

Do I believe my eyes?

That is surely like me saying that I am suprised that July wasn't any warmer, what with GW and all (sic)

This rates, in my eyes, as a most bizarre defence of GW in the face of one of the greatest July-August temperature collapses. (3.6 oC from http://www.metoffice.gov.uk/research/hadle.../HadCET_act.txt )

Even more bizarre is the fact that it has come from one of the most erudite contributors on this site.

4 of the 5 warmest summers on record in the last 30 years? The highest ever temperature and the warmest ever month occurring within 3 summers of each other? Surely something has changed. Regardless of whether there was a 'temperature collapse' between July and August, July was the warmest month on record. June was the warmest since 1976. Even with an average August, it's still been the 5th warmest summer which shows how exceptional the June/July combination was. I'm pretty sure that September is also going to be considerably above average which would suggest August was a blip in the run of above average months.

[cheeky_monkey]

Read the posts more carefully- it may sound like a "defence" of GW, but what it's saying is that on average, given the synoptics we had, one would expect a below-average month, possibly by in excess of 1C.

There were probably a number of contributory factors to the anomaly- on UKWW it was suggested that the exceptionally high SSTs around Britain, especially in the North Sea, may have had something to do with it as well. They would have modified the airmasses more than is usual. Our northerly winds weren't generally long-drag, mostly taking air from around 65-75N. However, the 65-75N band was nonetheless unusually warm.

no has mentioned the fact the the ground would have retained suffuiceint heat through the warm june and hot july to have moderated daytime and particularly night time temperatures through august.. iknow this does happen in autumns with hot summers in terms of frosts or lack of them with the right synoptics when frost would normally occur....so it is possible that residual warming omiited from the ground could have prevented a cooler august than we got.