Below Average CET spring months

[North-Easterly Blast]

I have noticed that when a winter is cold, dominated by north and or / east winds, it increases the chances that these patterns will be repetitive and cold spring months often follow:

Winter 1916-17: CET 1.5 March 3.2 April 5.4

Winter 1928-29: CET 1.7 April 6.8

Winter 1935-36: CET 3.0 April 6.3

Winter 1940-41: CET 2.6 April 6.4 May 9.4

Winter 1941-42: CET 2.2 March 5.2

Winter 1946-47: CET 1.1 March 3.6

Winter 1950-51: CET 2.9 March 4.1 April 6.8 May 10.1

Winter 1952-53: CET 3.5 March 5.6 April 7.3

Winter 1954-55: CET 3.5 March 3.2 May 9.7

Winter 1955-56: CET 2.9 April 6.9

Winter 1961-62: CET 3.5 March 2.8 April 7.7 May 10.5

Winter 1963-64: CET 3.5 March 4.3

Winter 1964-65: CET 3.3 March 5.2

Winter 1968-69: CET 3.2 March 3.3 April 7.4

Winter 1969-70: CET 3.3 March 3.7 April 6.7

Winter 1976-77: CET 3.4 April 7.2 May 10.5

Winter 1978-79: CET 1.6 March 4.7 April 7.8 May 10.0

Winter 1984-85: CET 2.7 March 4.7

Winter 1985-86: CET 2.9 March 4.9 April 5.8

Winter 1990-91: CET 3.0 May 10.8

Winter 1995-96: CET 3.0 March 4.5 May 9.1

So, from the above, it shows that a cold / colder winter certainly increases the chances of below average CETs during the spring months, and that most colder than average winters lead to one or two cold spring months.

Even many near average winters still often lead to colder spring months too:

Winter 1957-58: CET 4.2 March 3.7 April 7.4

Winter 1965-66: CET 4.4 April 7.2

Winter 1970-71: CET 4.4 March 4.9

Winter 1977-78: CET 4.1 April 6.5

Winter 1982-83: CET 4.3 April 6.8 May 10.3

Winter 1983-84: CET 4.2 March 4.7 May 9.9

Winter 2000-01: CET 4.4 March 5.2 April 7.7

Winter 2005-06: CET 4.2 March 4.9

It seems that most mild / milder winters rarely lead to colder spring months, the only examples I can think of were in the mid 1970s:

Winter 1974-75: CET 6.4 March 4.8 May 9.9

Winter 1975-76: CET 5.2 March 4.8

Also 1988-89: CET 6.5 April 6.6, but this was masked as this spring featured a cold April in between a mild March and a warm May, both of which were quite a bit above average.

Winter 1997-98: CET 6.1 April 7.7, although this was again masked as it was a rather cold April in between a mild March and warm May, both of which were well above average.

So my conclusion is that there is a correlation between average to cold winters and cold spring months, showing that once the winter weather patterns have become established, they often are repetitive during the spring months, so a colder winter is definitely the key to getting a lower annual CET and below 10*C. Without a cold winter it is very difficult to get the sort of yearly CET figures that we saw in years like 1996 and colder.

Again, there is certainly some truth in the warm September / mild winter correlation as well. Below are Septembers with CETs of 1*C or greater above average over recent decades and the winter that followed:

Sep 2006: 16.8 Winter 6.4

Sep 2005: 15.2 Winter 4.2

Sep 2004: 14.9 Winter 5.2

Sep 2000: 14.7 Winter 4.4

Sep 1999: 15.6 Winter 5.4

Sep 1998: 14.9 Winter 5.4

Sep 1991: 14.7 Winter 4.6

Sep 1989: 14.7 Winter 6.2

Sep 1985: 14.6 Winter 2.9

Sep 1980: 14.7 Winter 4.5

Sep 1961: 15.2 Winter 3.5

Sep 1959: 14.9 Winter 4.6

Sep 1958: 15.1 Winter 3.5

Sep 1949: 16.3 Winter 5.1

Sep 1947: 14.9 Winter 5.1

Sep 1934: 14.6 Winter 6.1

Sep 1933: 14.9 Winter 3.2

Sep 1929: 15.3 Winter 4.6

I have quoted Septembers 14.6 or above as the 61-90 average is only 0.1 below the 71-00 average and is also the average for the entire 20th Century, so little difference by 71-00.

You can clearly see from the above that in the last 100 years there has only on two occasions been a particularly cold winter (less than 3.5*C) that has followed a warm September (at least 1*C above average), in 1985-86, and that autumn also featured a very dry anticyclonic and rather warm October, and in 1933-34, although even that winter after a cold December, January and February were close to average. The only other two occasions that any winter was even anything below average after warm Septembers were in 1961-62 and 1958-59, although in 61-62 Dec was cold but Jan and Feb were average, and in 58-59 Jan was cold but Dec and Feb were average.

So, the above paragraph holds that it was a well known fact in the British Climate that even for the entire 20th Century a warm September meant that it would not be a brilliant winter for cold weather, and the vast majority of winters in the 20th century that followed a warm September turned out to be milder than average, and it is certainly true for recent years.

My conclusion to all the above is as cold winters often lead to cold spring months and that winter is rarely cold after a warm September, we certainly need to see a cool or at least average September before there will be much prospect or hope of a change of the weather patterns of recent years during the winter and spring, and even as long as the warm Septembers continue there will be little prospect of us getting away from the sort of yearly CET figures of the last ten years or so.

Another point to mention is that, the winter of 1991-92 was also characterised by a zonal pattern almost throughout with strong depressions running through the GIN corridor, but a mild winter like 88-89 was denied as a displaced Azores High became sat over the UK much of the time especially in Dec and Jan and temperature inversions developed at times and also cold dry continental air was able to cover the UK at times, preventing mild weather in the UK although there was still a strong zonal pattern in the GIN corridor, and the pattern that was observed in Dec 1991 / Jan 1992 was very similar to the pattern seen in the second half of December 2006.

[North-Easterly Blast]

I have noticed that when a winter is cold, dominated by north and or / east winds, it increases the chances that these patterns will be repetitive and cold spring months often follow:

Winter 1916-17: CET 1.5 March 3.2 April 5.4

Winter 1928-29: CET 1.7 April 6.8

Winter 1935-36: CET 3.0 April 6.3

Winter 1940-41: CET 2.6 April 6.4 May 9.4

Winter 1941-42: CET 2.2 March 5.2

Winter 1946-47: CET 1.1 March 3.6

Winter 1950-51: CET 2.9 March 4.1 April 6.8 May 10.1

Winter 1952-53: CET 3.5 March 5.6 April 7.3

Winter 1954-55: CET 3.5 March 3.2 May 9.7

Winter 1955-56: CET 2.9 April 6.9

Winter 1961-62: CET 3.5 March 2.8 April 7.7 May 10.5

Winter 1963-64: CET 3.5 March 4.3

Winter 1964-65: CET 3.3 March 5.2

Winter 1968-69: CET 3.2 March 3.3 April 7.4

Winter 1969-70: CET 3.3 March 3.7 April 6.7

Winter 1976-77: CET 3.4 April 7.2 May 10.5

Winter 1978-79: CET 1.6 March 4.7 April 7.8 May 10.0

Winter 1984-85: CET 2.7 March 4.7

Winter 1985-86: CET 2.9 March 4.9 April 5.8

Winter 1986-87: CET 3.5 March 4.1 May 10.1

Winter 1990-91: CET 3.0 May 10.8

Winter 1995-96: CET 3.0 March 4.5 May 9.1

So, from the above, it shows that a cold / colder winter certainly increases the chances of below average CETs during the spring months, and that most colder than average winters lead to one or two cold spring months.

Even many near average winters still often lead to colder spring months too:

Winter 1957-58: CET 4.2 March 3.7 April 7.4

Winter 1965-66: CET 4.4 April 7.2

Winter 1970-71: CET 4.4 March 4.9

Winter 1977-78: CET 4.1 April 6.5

Winter 1982-83: CET 4.3 April 6.8 May 10.3

Winter 1983-84: CET 4.2 March 4.7 May 9.9

Winter 2000-01: CET 4.4 March 5.2 April 7.7

Winter 2005-06: CET 4.2 March 4.9

It seems that most mild / milder winters rarely lead to colder spring months, the only examples I can think of were in the mid 1970s:

Winter 1974-75: CET 6.4 March 4.8 May 9.9

Winter 1975-76: CET 5.2 March 4.8

Also 1988-89: CET 6.5 April 6.6, but this was masked as this spring featured a cold April in between a mild March and a warm May, both of which were quite a bit above average.

Winter 1997-98: CET 6.1 April 7.7, although this was again masked as it was a rather cold April in between a mild March and warm May, both of which were well above average.

So my conclusion is that there is a correlation between average to cold winters and cold spring months, showing that once the winter weather patterns have become established, they often are repetitive during the spring months, so a colder winter is definitely the key to getting a lower annual CET and below 10*C. Without a cold winter it is very difficult to get the sort of yearly CET figures that we saw in years like 1996 and colder.

Again, there is certainly some truth in the warm September / mild winter correlation as well. Below are Septembers with CETs of 1*C or greater above average over recent decades and the winter that followed:

Sep 2006: 16.8 Winter 6.4

Sep 2005: 15.2 Winter 4.2

Sep 2004: 14.9 Winter 5.2

Sep 2000: 14.7 Winter 4.4

Sep 1999: 15.6 Winter 5.4

Sep 1998: 14.9 Winter 5.4

Sep 1991: 14.7 Winter 4.6

Sep 1989: 14.7 Winter 6.2

Sep 1985: 14.6 Winter 2.9

Sep 1980: 14.7 Winter 4.5

Sep 1961: 15.2 Winter 3.5

Sep 1959: 14.9 Winter 4.6

Sep 1958: 15.1 Winter 3.5

Sep 1949: 16.3 Winter 5.1

Sep 1947: 14.9 Winter 5.1

Sep 1934: 14.6 Winter 6.1

Sep 1933: 14.9 Winter 3.2

Sep 1929: 15.3 Winter 4.6

I have quoted Septembers 14.6 or above as the 61-90 average is only 0.1 below the 71-00 average and is also the average for the entire 20th Century, so little difference by 71-00.

You can clearly see from the above that in the last 100 years there has only on two occasions been a particularly cold winter (less than 3.5*C) that has followed a warm September (at least 1*C above average), in 1985-86, and that autumn also featured a very dry anticyclonic and rather warm October, and in 1933-34, although even that winter after a cold December, January and February were close to average. The only other two occasions that any winter was even anything below average after warm Septembers were in 1961-62 and 1958-59, although in 61-62 Dec was cold but Jan and Feb were average, and in 58-59 Jan was cold but Dec and Feb were average.

So, the above paragraph holds that it was a well known fact in the British Climate that even for the entire 20th Century a warm September meant that it would not be a brilliant winter for cold weather, and the vast majority of winters in the 20th century that followed a warm September turned out to be milder than average, and it is certainly true for recent years.

My conclusion to all the above is as cold winters often lead to cold spring months and that winter is rarely cold after a warm September, we certainly need to see a cool or at least average September before there will be much prospect or hope of a change of the weather patterns of recent years during the winter and spring, and even as long as the warm Septembers continue there will be little prospect of us getting away from the sort of yearly CET figures of the last ten years or so.

Another point to mention is that, the winter of 1991-92 was also characterised by a zonal pattern almost throughout with strong depressions running through the GIN corridor, but a mild winter like 88-89 was denied as a displaced Azores High became sat over the UK much of the time especially in Dec and Jan and temperature inversions developed at times and also cold dry continental air was able to cover the UK at times, preventing mild weather in the UK although there was still a strong zonal pattern in the GIN corridor, and the pattern that was observed in Dec 1991 / Jan 1992 was very similar to the pattern seen in the second half of December 2006.

[Weather-history]

Another point to mention is that, the winter of 1991-92 was also characterised by a zonal pattern almost throughout with strong depressions running through the GIN corridor, but a mild winter like 88-89 was denied as a displaced Azores High became sat over the UK much of the time especially in Dec and Jan and temperature inversions developed at times and also cold dry continental air was able to cover the UK at times, preventing mild weather in the UK although there was still a strong zonal pattern in the GIN corridor,

I think you've got that the wrong way round. Winter 1991-92 was pretty anticyclonic during December and January with some good inversions at times.

[Lettucing Gutted]

Again, there is certainly some truth in the warm September / mild winter correlation as well. Below are Septembers with CETs of 1*C or greater above average over recent decades and the winter that followed:

If another warm September and an El Nino show their ugly faces this year, I am writing off winter 2007/2008 in September.

[Guest Mike W]

Personally speaking, I would write winter 07/08 off right now if I was you.

[Stratos Ferric]

Mmmm, not so sure about this NEB.

A scatter plot based on winters since 1950 shows a less clear picture. As ever with these analyses, you've got to look in both directions, i.e. don't just work forwards from cold winters, but work back from cold springs as well.

There have been 23 years with colder than average (71-00) spring + winter (this in part reflect the fact that the average has risen quickly in recent years so there is a slight negative skew in the whole data): 7 have a warm-cold / cold-warm combination, 18 have warm / warm. On this basis there are 23 years where the cold -> cold relationship holds up, and 14 where it doesn't. Certainly not a hard and fast rule.

What I'd tend to take from this analysis is actually that the seasons are more inclined to follow the current pattern in the climate, which has a wavelength longer than one season: in other words at times when the climate is warmer than normal the seasons tend to be warmer, when it's cooler they're cooler. And if you dwell on this for a moment you realise that this must be a reasonable truism otherwise time series for CET would tend to be fairly flat, even over short-ish periods, the tendency being for warm and cold to balance each other out more often than they actually do.

The pattern across the entire CET series is actually very similar.

[sundog]

is it true that if that nao is negative for much of may that during the next winter it could be negative for much of the winter? i wonder what is the nao forecast for may this year?

[Don]

If another warm September and an El Nino show their ugly faces this year, I am writing off winter 2007/2008 in September.

I totally agree with this, we need to lose these warm September's to get even a close to average Winter IMO. If this coming September is another warm one with heatwaves, then the writing is on the wall for Winter 2007/08 - mild to very mild!

[sundog]

if we lose the warm septembers it would at least be a start thats for sure, i hope and pray september this year will be a cool one

[damianslaw]

if we lose the warm septembers it would at least be a start thats for sure, i hope and pray september this year will be a cool one

Yes the next month which I will be hoping for definate is below is September, it will build my confidence as we head towards the winter.

[summer blizzard]

To be honest, i am not bothered whether or not we see an above average September, it is October and November which are the key months for me.

[summer blizzard]

I did a CET study of the precceding months before the coldest winters in the past centuary, and found that September had no bias to above or below average temperatures (there was a equal amount) however those winters were more often preceeded by below average Octobers and Novembers.

[Summer of 95]

I did a CET study of the precceding months before the coldest winters in the past centuary, and found that September had no bias to above or below average temperatures (there was a equal amount) however those winters were more often preceeded by below average Octobers and Novembers.

Indeed I noticed a while back the fairly reliable correlation Warm October=Cold December, which in 2006 failed to work for the first time since 1959.

1994 is the one that springs to mind for a cold September NOT followed by a cold winter.

[Bottesford]

To be honest, i am not bothered whether or not we see an above average September, it is October and November which are the key months for me.

Yes I agree. I see little correlation between warm Septs & mild winters. Besides, September can be a very pleasent month if it's warm - especially after this grim start to 'summer'!

[North-Easterly Blast]

Throughout the last 100 years, after the 18 warm Septembers with CETs of 14.5 or greater, there was only one that was followed by a particularly cold winter (1985-86), and only two other occasions where a warm 14.5+ September was followed by a winter that was below average at all (1958-59 and 1961-62). All the other 15 warm Septembers were followed by mild winters, or average at best.

So by this measure it is the truth that a warm September decreases the chance of the following winter being colder than average, and increases the chance of it being milder than average.

Whereas it is difficult to see any correlation the other way round (a cool September increasing the chance of the following winter being colder than average), it does not always work this way round. Whilst it is not uncommon to see a mild winter after a cool September, it is very rare to see a cold winter after a warm September.

[ribster]

Throughout the last 100 years, after the 18 warm Septembers with CETs of 14.5 or greater, there was only one that was followed by a particularly cold winter (1985-86), and only two other occasions where a warm 14.5+ September was followed by a winter that was below average at all (1958-59 and 1961-62). All the other 15 warm Septembers were followed by mild winters, or average at best.

So by this measure it is the truth that a warm September decreases the chance of the following winter being colder than average, and increases the chance of it being milder than average.

Whereas it is difficult to see any correlation the other way round (a cool September increasing the chance of the following winter being colder than average), it does not always work this way round. Whilst it is not uncommon to see a mild winter after a cool September, it is very rare to see a cold winter after a warm September.

Blimey, thats it then, 'the truth'. There are so many counter-arguments and counter-claims that can be made against this, indeed SB has already given you one. But I sense in reality, someone is doing a bit of fishing......

[summer blizzard]

I only used the ten coldest winters in the past centuary, and only used the average as a base however the statistical link between September and the following winter is low.

[Guest Daniel]

The future for cold is looking very good. Here why. the sun is forcast to go quite soon and that would mean a strong cooling trend for us which could take us straight back to a new 17th style climate. Now in the last 10 years since 1997 on the most part summers and Atumns have been very warm. this has lead to mild winters. Infact there been no severe winter or even a freeze in the last 10 years and subzero ice days have all but gone. However that is likerly to change soon. when the cooling begins we are likerly to get cooler summers which would lead to much colder winters. Now in the 17th century there were a high number of warm summers but nothing as hot as now and Atumns were cooler. this prcoess of cooling could even be starting now. this summer so far has been much cooler and wetter than the ones we are used to. The result of this since may lows have been taking a much more southerly track aross the. U.K Thus preventing the southern highs from forming. Now why this is occuring is ruther strange because in warming lows should take a much more northerly track and this year it not happing. I think the sun has a lot do do with it. If this trend continues throught the rest of summer and we get a cooler Autum. There a real chance next winter will be cold to severe. There also a small chance next winter could be one of the coldest in history. Even a much colder winter with blizzrds freezing winds and frozen rivers will be a huge shock to us who have become use to mild weather and global warming. If the forcast of the sun is right we could well be heading for an age of very severe winters in the comming years and cooler summers as well.

[Stu_London]

The future for cold is looking very good. Here why. the sun is forcast to go quite soon and that would mean a strong cooling trend for us which could take us straight back to a new 17th style climate. Now in the last 10 years since 1997 on the most part summers and Atumns have been very warm. this has lead to mild winters. Infact there been no severe winter or even a freeze in the last 10 years and subzero ice days have all but gone. However that is likerly to change soon. when the cooling begins we are likerly to get cooler summers which would lead to much colder winters. Now in the 17th century there were a high number of warm summers but nothing as hot as now and Atumns were cooler. this prcoess of cooling could even be starting now. this summer so far has been much cooler and wetter than the ones we are used to. The result of this since may lows have been taking a much more southerly track aross the. U.K Thus preventing the southern highs from forming. Now why this is occuring is ruther strange because in warming lows should take a much more northerly track and this year it not happing. I think the sun has a lot do do with it. If this trend continues throught the rest of summer and we get a cooler Autum. There a real chance next winter will be cold to severe. There also a small chance next winter could be one of the coldest in history. Even a much colder winter with blizzrds freezing winds and frozen rivers will be a huge shock to us who have become use to mild weather and global warming. If the forcast of the sun is right we could well be heading for an age of very severe winters in the comming years and cooler summers as well.

Where is the sun going exactly?

Whilst the future for cold may be very good, it probably leaves the future for life hanging very precariously! <_<

[Nick F]

The Ice age commeth, because we are having a wet summer so far!? TBH I'm not sure it's much cooler, although it's wet, there nothing to suggest there's a cool down with the CET 1.3C above average and every month above average so far this year, so nothing pointing to a cool down going on atm.

[Lettucing Gutted]

Spot on Nick. I also think that Daniel is forgetting the Anthrogenic Enhanced Greenhouse Effect which will at least dramatically offset any Sunspot Minima cooling if not offset it completely...