December CET

[reef]

As mentioned above by TWS, months with cool zonality often show larger differences between Manley and Hadley.

Theres still a good chance of a result in the low 6s after adjustments if things turn milder than shown (possible as the GFS often underestimates maxima). Anything above 5.8C would make it the 3rd warmest December in the last 25 years and at least 1.2C above average.

[A Winter's Tale]

As mentioned above by TWS, months with cool zonality often show larger differences between Manley and Hadley.

Theres still a good chance of a result in the low 6s after adjustments if things turn milder than shown (possible as the GFS often underestimates maxima). Anything above 5.8C would make it the 3rd warmest December in the last 25 years and at least 1.2C above average.

At the moment December is currently below average in Scotland and may well end up being slightly below average. It just shows the sheer contrast between the south and north during zonality. No wonder that there were so many differences in opinions of the latter parts of last winter and this December as a lot of the south has seen nothing whereas the northern third has enjoyed quite a few nice snowfalls with some lying snow days.

[AderynCoch]

It certainly looks like we'll have the second highest annual CET on record, with only 5.2C or higher required this month. First place is out of reach though, requiring 7.4C.

[Weather-history]

Provisionally, Christmas Day 2011 was 14.7C warmer than Christmas Day 2010.

Looks like the warmest Christmas Day since 2003, provisionally

Edited December 27, 2011 by Mr_Data

[The watcher]

Provisionally, Christmas Day 2011 was 14.7C warmer than Christmas Day 2010.

Looks like the warmest Christmas Day since 2003, provisionally

Record warm here on christmas day so seems about right with maxs this year at 14.4c and last year close to 0c. What a contrast.

[North-Easterly Blast]

2011 has been the second warmest year on record, but has been largely due to two distinct exceptionally warm periods - the February to May period and the September to December period. We may not have broken any monthly extreme records over the past four months, but I can safely say that we will record the warmest final quarter of a year since records began in 1659. The previous record for the Oct to Dec period is 9.2*C, set in 2006. Dec 2011 would only need a CET of 5.5 to beat this, and before adjustments the Hadley CET will be above 6*C, though after adjustments we may not quite make 6*C, though we will still certainly beat the 5.5 needed for the warmest last quarter of a year ever. The warmest last third of a year is out of reach though, that is 11.1 for the Sep to Dec period in 2006, which would require a Dec 2011 CET of 6.9 to beat, and we are not going to reach that for this month's final CET.

I have not checked the records, but I am sure that 2011 has to have recorded the warmest February to April period on record, and even the warmest February to May period ever, can Kevin Bradshaw confirm this?

[North-Easterly Blast]

2011 has been the second warmest year on record, but has been largely due to two distinct exceptionally warm periods - the February to May period and the September to December period. We may not have broken any monthly extreme records over the past four months, but I can safely say that we will record the warmest final quarter of a year since records began in 1659. The previous record for the Oct to Dec period is 9.2*C, set in 2006. Dec 2011 would only need a CET of 5.5 to beat this, and before adjustments the Hadley CET will be above 6*C, though after adjustments we may not quite make 6*C, though we will still certainly beat the 5.5 needed for the warmest last quarter of a year ever. The warmest last third of a year is out of reach though, that is 11.1 for the Sep to Dec period in 2006, which would require a Dec 2011 CET of 6.9 to beat, and we are not going to reach that for this month's final CET.

I have not checked the records, but I am sure that 2011 has to have recorded the warmest February to April period on record, and even the warmest February to May period ever, can Kevin Bradshaw confirm this?

I think that pear shaped winters often lead into a very warm year, so it was always likely after the most pear shaped winter on record in 2010-11, that 2011 would be the warmest year ever or at least the second warmest year ever.

Regardless of what the rest of this winter brings, then at least 2011-12 is not going to join the list of pear shaped winters, like 2010-11, 1996-97, 1917-18, 1925-26, 1927-28 etc.

We can also say that a cold winter this year is looking almost impossible, certainly like 2009-10 that's for sure. It is looking as though a milder than average winter is likely at this stage, though there is a chance that it could still finish up as an average winter if there are some cold spells later in the winter, even if nothing extreme.

Edited December 27, 2011 by North-Easterly Blast

[reef]

I have not checked the records, but I am sure that 2011 has to have recorded the warmest February to April period on record, and even the warmest February to May period ever, can Kevin Bradshaw confirm this?

1779 (8.40C), 1945 (8.37C) and 1961 (8.37C) all had a warmer February to April period than this year (8.30C).

Its the joint second warmest February to May period on 9.28C along with 1779. The warmest was 1945 on 9.33C.

Another big increase on Hadley which is now 5.9C to the 26th. Still a distinct possibility of ending in the 6s even after adjustments.

[damianslaw]

Not surprised to see the CET figure close to the 6 degree mark. Temps in the coming days look slightly above average so can't see the CET figure changing much. As a whole 2011 has been a very mild year indeed, with no significant cool/cold weather at any stage, yes we did see some notably cold minima during the summer but daytime maxima never fell to very low levels at the same time due to the dry clear sunny/bright conditions. Quite notable how we have endured two very mild long lasting periods from Feb - Mid May and from mid Sept - end December, reminding me of 2006 when we saw very lengthy sustained mild conditions most notably between May - Dec 2006 - the mild lasting right through to the following May.

I do believe next year should see much more normal temps as a whole thanks to no super la nina in charge. What are the ENSO forecasts for the year as a whole - are we entering a near neutral period surely la nina has to weaken markedly now and we had a very strong el nino just two years ago.

[J10]

As mentioned above by TWS, months with cool zonality often show larger differences between Manley and Hadley.

Theres still a good chance of a result in the low 6s after adjustments if things turn milder than shown (possible as the GFS often underestimates maxima). Anything above 5.8C would make it the 3rd warmest December in the last 25 years and at least 1.2C above average.

GFS tends to overestimate temps around coasts, and underestimate them inland.

If there is such a discrepancy between the 2 series, a larger than usual drop may be likely. perhaps all the way to 5.2c :lol:

Seriously a drop of 0.4-0.5c is possible, when there is such a discrepancy between the 2 series

[A Winter's Tale]

Okay I'd like to know what's the difference between Hadley and Madley, what the current CET is, what's the average and what the final CET is likely to be. And also, can anyone find me a link to the Scottish mean temperature [ so far ].

[Harve]

Probably a CET of around 6c, and yet here there's been 13 days of sleet or snow falling*, which is actually more than last December.

*At my location, of course.

Edited December 28, 2011 by Harve

[leicsnow]

The CET currently stands at exactly 6C.

[A Winter's Tale]

The CET currently stands at exactly 6C.

How Did You Get That? Do you have a link?

[leicsnow]

How Did You Get That? Do you have a link?

http://www.netweathe...action=cet;sess

Edited December 27, 2011 by Tellow

[reef]

Hadley is now 6.0C to the 27th, yesterday came in at 9.5C.

Another increase on tomorrow's update as today's min temp is down as 7.3C.

[BornFromTheVoid]

Last few days looking much milder now, and so a likely finish of 6.3C, or maybe 6.2C to the 31st. With a large downward correction looking likely, 5.7- 6.0C should be result after corrections.

[Scorcher]

Can anyone reveal what the mildest second half to December was? The 2nd half of this month must rank up there I imagine!

[Roger J Smith]

I posted a thread in the "Historic weather" sub-forum on the subject of half-monthly CET extremes and averages.

According to that, the warmest second half of December was 8.8 C in 1974. My half-month definitions for 31-day months are 1-16 and 17-31. If you prefer 16-31 as the second half, then 1974 reduces slightly to 8.6 C. The period 20-29 Dec averaged 9.7 C in that month and six of those ten days achieved a CET above 10 deg.

[North-Easterly Blast]

I posted a thread in the "Historic weather" sub-forum on the subject of half-monthly CET extremes and averages.

According to that, the warmest second half of December was 8.8 C in 1974. My half-month definitions for 31-day months are 1-16 and 17-31. If you prefer 16-31 as the second half, then 1974 reduces slightly to 8.6 C. The period 20-29 Dec averaged 9.7 C in that month and six of those ten days achieved a CET above 10 deg.

I thought that the warmest second half of December ever was 1987.

It is clear that this December will be the warmest since 2006 overall, and will see the warmest second half to December since at least 1991. The second half of Dec 1991 averaged about 7.1*C I believe. As mentioned above, the warmest second half of December on record was 1987 at 8.7*C (correct me if I am wrong). Dec 1988 also saw a very warm second half averaging at around 8.2 I believe. Dec 1983 also was mild through the second half, at around 7.4 overall. So, there were some very warm second halves of December 20-30 years ago, but it has been quite a rarity since. In the last 20 years, only the Decembers of 1997, 2002, 2008 and 2011 saw a warmer second half than the first half.

[damianslaw]

I thought that the warmest second half of December ever was 1987.

It is clear that this December will be the warmest since 2006 overall, and will see the warmest second half to December since at least 1991. The second half of Dec 1991 averaged about 7.1*C I believe. As mentioned above, the warmest second half of December on record was 1987 at 8.7*C (correct me if I am wrong). Dec 1988 also saw a very warm second half averaging at around 8.2 I believe. Dec 1983 also was mild through the second half, at around 7.4 overall. So, there were some very warm second halves of December 20-30 years ago, but it has been quite a rarity since. In the last 20 years, only the Decembers of 1997, 2002, 2008 and 2011 saw a warmer second half than the first half.

Dec 2008 is an interesting case. The first half of the month was I believe the coldest first half to dec since 1978, beating even Dec 81 am I right on this one?. However, we then saw a very mild interlude from mid month through to christmas before things turned notably colder as we headed into the New Year. Quite an unusual month it has to be said.

Dec 87 saw a contrasting first and second half, the first half was quite cold thanks to anticylonic conditions. Dec 88 was very mild throughout.

[Roger J Smith]

Sorry, that's correct, it was 1987 ... 1974 had similar values about 0.1 lower and did have the ten-day mild spell that I mentioned. So it was Dec 1987 with the 8.8 for 17th-31st and 8.6 for 16th-31st.

[North-Easterly Blast]

Dec 2008 is an interesting case. The first half of the month was I believe the coldest first half to dec since 1978, beating even Dec 81 am I right on this one?. However, we then saw a very mild interlude from mid month through to christmas before things turned notably colder as we headed into the New Year. Quite an unusual month it has to be said.

Dec 87 saw a contrasting first and second half, the first half was quite cold thanks to anticylonic conditions. Dec 88 was very mild throughout.

Dec 1991 was similar in many respects to Dec 1987 - a slightly colder version of it - cold and anticyclonic first half, then a very mild second half.

No, the first half to Dec 2008 wasn't as cold as the same period in 1981 - the first half of Dec 1981 was around 0.8*C; the first half of Dec 2008 averaged 2.3*C, around the same as the first half of Dec 1991, then it turned mild for a week up to Christmas, then it was cold and anticyclonic towards the end. It was an interesting month for temperature, one of the colder Decembers in recent years; watching the CET rise rapidly after mid-month and then fall away again. On the negative side, despite how interesting it was watching the CET progress; although the first half was cold it never produced anything that was extreme, and snowfalls were short lived, just frequent frosts. Then the cold spell at the end was from surface cold under a Rex block and not deep cold Arctic air.

[Kentish Man]

Hadley on 6.1C today (Dec 1 - 28).

Interestingly Climate UK (Manley) is now on 5.7C (Dec 1 - 28) so the gap between the two has reduced sharply possibly due to the prevalence of TM air recently (Continual cold zonal PM flows earlier this month seemed to have exacerbated the difference according to TWS above). Manley incidentally has moved from being bang on the running mean to 0.6C above in just 3 days so it shows how mild the last 3 days have been.

[reef]

Hadley is 6.2C to the 30th, yesterday was mild again at 7.6C.

Today needs to come in at 9.0C for us to finish at 6.3C before adjustments. 5.8-6.1C looks pretty likely after adjustments, which is 1.2-1.5C above the 1981-2010 average - so pretty mild really.