December CET

[Stu_London]

Provisional CET to 01.12.10

-1.6C

Last night was -2.1C, so a rise tomorrow likely before a big drop on the 3rd.

[kold weather]

Yeah a rise probably close to -1C tomorrow before the CET zone falls through the floor for Friday...

Then after that maybe slightly less cold for a few days as we pick up a more unsettled pattern again followed by a ridge of HP and likely another fall. If we can average another few days below -0.0C then this cold spell may well be more prolonged then even Jan 2010!

Hard to see anything above 3.5C right now...but the models can still shift loads.

[noggin]

http://hadobs.metoffice.com/hadcet/cet_info_mean.html

Current anomaly for December is minus 6.4.

Bit on the parky side, eh?

Edited December 2, 2010 by noggin

[Weather-history]

Coldest start to December for the CET since 1947 which recorded -3.0C

It also means 6 consecutive days of the CET mean below 0C and these have been very rare in the last 20 years.

[BornFromTheVoid]

The 12z GFS would have us at about -1.4C to the 10th, which would require 7.45C/day for the remainder of the month to reach the 61-90 average.

[kold weather]

whilst synoptically the 12z GFS doesn't look all that good, with HP nearby to the UK we keep the surface cold which would give some really impressive temps still, we'd be below 0C for the first 15 days

[AderynCoch]

It also means 6 consecutive days of the CET mean below 0C and these have been very rare in the last 20 years.

Looking back at your list of CET cold spells, this is the first time there have been five consecutive sub-zero days in November alone. Truly exceptional.

[damianslaw]

The start to December 2010 quite likely to be the coldest since 1962 - mmm ominuous signs here perhaps... Will certainly kick into touch Dec 2008 which I remember at the time thinking was an unusally cold start to December. I can't help but think had we not experienced the cold of last winter, this spell would be feeling exceptionally severe, alas many me included are all quite blase about it like it is normal... it is truely abnormal weather for the time of year on a par with the unusual lengthy heat we saw in April 2007.

[Weather-history]

I have combined the years with a cold last week of November (the first value) with those that then had also cold first week of December (2nd value). This list is not necessarily all the of the coldest 24th November-7th December periods, there could be a few which had a very cold opening to December but not that cold last week of November but overall that period was cold.

1782: 0.8; 0.6

1788: 2.4; 0.8

1801: 2.5; 2.2

1804: 2.8; 2.7

1807: 0.3; 2.6

1816: 2.6; 2.6

1874: 2.9; 2.4

1875: 1.3; 0.1

1878: 2.2; 1.8

1879: 1.2;-3.6

1890: 0.2; 2.7

1925: 0.8;-0.3

1947: 2.0; 2.1

1952: 0.5; 0.0

[Duane S.]

It does look like we could have a very cold December CET. To start a natural 'cooling month' on a -6.62 anomaly by day 3 is quite amazing really. I see RJS called it correct last month when his against the grain guess came up trumps! I must say I can't blame anybody for thinking 5.4 would have been unobtainable by day 10 of November. This month he has gone for a 1.8 month I think I saw? It would be an amazing figure to end up with and I can see where he is coming from, my (I don't know how it works but I guess it's too late to make it official) prediction would be 2.7

Edited December 3, 2010 by s4lancia

[Roger J Smith]

Actually I said 0.8 but there are a few lower guesses into the minuses, and you can't rule them out, if the Atlantic high retrogrades a bit faster than the GFS is showing, it could open up a direct northerly flow again, although the closer high would be cool enough with all this snow around. For me, the key will be what happens in a higher energy situation around the 20th-21st, if a potential storm there stays south and drops more snow or at least pulls down another blast of cold, then the month could end up minus (and that would be astounding after even larger teapot came and went).

This is turning out to be one mixed up La Nina because we're supposed to be cold and it's quite average here. There was some snow last week but it has all melted and we're just about at our normal December temperature, highs of about 7 degrees, lows just above freezing.

[reef]

Hadley is on -1.2C to the 2nd. Yesterday came in at -0.8C.

Last night's minima was -7.8C and today many places have seen an ice day. We could well be sub -2.0C on tomorrow's update.

[stewfox]

The 12z GFS would have us at about -1.4C to the 10th, which would require 7.45C/day for the remainder of the month to reach the 61-90 average.

Not often can you say by the 3rd of the month a lot of peoples forecasts will be way out

How many penalty points for a 'adjustment now'

[cooling climate]

Extremely late I know but ... -0.7c please.

Got caught up in the cold spell, only play the cet game in the winter months.

[BornFromTheVoid]

-1.8C to the 3rd

http://hadobs.metoffice.com/hadcet/cet_info_mean.html

The 06z GFS would have the CET at about -2.2C to the 10th.

If that was to verify then for the rest of the month we'd need...

7.8C/day to reach the 61-90 figure of 4.6C

8.6C/day to reach the 71-00 figure of 5.1C

5.5C/day to reach 3.0C

4.0C/day to reach 2.0C

2.5C/day to reach 1.0C

1.0C/day to reach 0.0C

[Thundery wintry showers]

Unusually I have a different guess in this thread to the one I went for in the month-ahead forecast- CET Competition 3.3C, month-ahead forecast 2.2C! Will be interesting to see which one is nearer the mark, although I think my 3.3 in the competition may end up a little high...

[Optimus Prime]

-1.8C to the 3rd

http://hadobs.metoff..._info_mean.html

I make the period 4th-10th at -1.7c. The CET would still be likely to be around -1.8c by the 10th. 7.7c below normal. Could well be 7.0c below normal by the 15th.

[North-Easterly Blast]

I really think that it is about as rare as a complete winter like 1962-63 to see such extreme cold this early in the season. There were no Decembers in the 1900s below 0*C; sub zero CETs occurred in three Januarys and four Februarys. The coldest December of the 1900s was 1981 at 0.3*C; after this the next in the line was 1950 with 1.2*C. This shows us that sustained and extreme cold was extremely rare in December at least during the 1900s, and many of the coldest winters reached their coldest peak in January and often even more so in February.

Even the extreme winter of 1962-63 didn't really start until December 22nd/23rd. Yes, up to that point there had been one or two cold spells but never anything like what we have had during the last ten days. The big freeze of 1947 didn't really start until January 20th, yes the first half of winter had been colder than average and there had been cold spells, but up until mid-late Jan the weather was not particularly extreme. The 1978-79 winter didn't really start until the back end of December, that had seen one or two cold snaps earlier but nothing like the current weather we have now. From what I know of, looking at the coldest first halves of December I believe it is something like 1981 (0., 1933 (1.1), 1916 (1.2), 1950 (1.6), 1952 (1.7). There may also be more that I have missed.

Looking at the two coldest Decembers in the 1900s neither of them were followed by anything special in the rest of the winter; OK there was a major cold spell from about 5th to 15th Jan 1982 but the rest of the winter was certainly nothing special. Only in the cold, although less cold Decembers of 1962 (1. and 1916 (1.9), was the cold of December sustained through the rest of the winter. This suggests to me that a cold December doesen't always mean that Jan and Feb will be up to much, and they are the months that have largely been the most devoid of cold weather in the 1990s and 2000s. OK, I know that in the mild 1990s and 2000s winters there has still been relatively little in the way of cold conditions in December at least from proper cold synoptics, it is clear that the lack of mild Decembers since 1988 (CET 6*C and above), has bucked the trend that Jan and Feb have followed. Compare only two 6+ Decembers since 1988 with five Januarys and six Februarys.

On top of this, the two coldest Decembers in the 1900s were both followed by a run of mild Decembers. After the very cold December of 1981 had passed there began a run of mild, mostly snow free Decembers in the UK. We went 11 years from 1981 without seeing a December even below 4*C, and even that was down to only a rex block in late Dec 1992. The same is true of 1950 as well, after that had passed the Decembers for the rest of the 1950s were largely mild and often snow-free.

Edited December 4, 2010 by North-Easterly Blast

[Weather-history]

Last occasion the first 3 days of December were sub zero for the CET mean? 1879

Here is that list again but with those that were 2.0C or over eliminated.

December CETs up to 7th

1976: 1.6

1962: 0.1

1952: 0.0

1950: 1.6

1933: 1.5

1925: -0.3

1916: 1.1

1903: 1.4

1902: 0.8

1892: 1.6

1889: 0.8

1879: -3.6

1878: 1.8

1875: 0.1

1871: 0.6

1870: 1.2

1869: 0.5

1867: 1.6

1846: 0.7

1844: -0.7

1839: 1.3

1803: 1.9

1796: -1.9

1788: 0.9

1782: 0.6

[damianslaw]

I really think that it is about as rare as a complete winter like 1962-63 to see such extreme cold this early in the season. There were no Decembers in the 1900s below 0*C; sub zero CETs occurred in three Januarys and four Februarys. The coldest December of the 1900s was 1981 at 0.3*C; after this the next in the line was 1950 with 1.2*C. This shows us that sustained and extreme cold was extremely rare in December at least during the 1900s, and many of the coldest winters reached their coldest peak in January and often even more so in February.

Even the extreme winter of 1962-63 didn't really start until December 22nd/23rd. Yes, up to that point there had been one or two cold spells but never anything like what we have had during the last ten days. The big freeze of 1947 didn't really start until January 20th, yes the first half of winter had been colder than average and there had been cold spells, but up until mid-late Jan the weather was not particularly extreme. The 1978-79 winter didn't really start until the back end of December, that had seen one or two cold snaps earlier but nothing like the current weather we have now. From what I know of, looking at the coldest first halves of December I believe it is something like 1981 (0., 1933 (1.1), 1916 (1.2), 1950 (1.6), 1952 (1.7). There may also be more that I have missed.

Looking at the two coldest Decembers in the 1900s neither of them were followed by anything special in the rest of the winter; OK there was a major cold spell from about 5th to 15th Jan 1982 but the rest of the winter was certainly nothing special. Only in the cold, although less cold Decembers of 1962 (1. and 1916 (1.9), was the cold of December sustained through the rest of the winter. This suggests to me that a cold December doesen't always mean that Jan and Feb will be up to much, and they are the months that have largely been the most devoid of cold weather in the 1990s and 2000s. OK, I know that in the mild 1990s and 2000s winters there has still been relatively little in the way of cold conditions in December at least from proper cold synoptics, it is clear that the lack of mild Decembers since 1988 (CET 6*C and above), has bucked the trend that Jan and Feb have followed. Compare only two 6+ Decembers since 1988 with five Januarys and six Februarys.

On top of this, the two coldest Decembers in the 1900s were both followed by a run of mild Decembers. After the very cold December of 1981 had passed there began a run of mild, mostly snow free Decembers in the UK. We went 11 years from 1981 without seeing a December even below 4*C, and even that was down to only a rex block in late Dec 1992. The same is true of 1950 as well, after that had passed the Decembers for the rest of the 1950s were largely mild and often snow-free.

Good well written read. Yes it is notable how in the past 20 years, of the three winter months it has been December which has shown more consistent cold. What is very interesting about this December is that it is coming on the back of two cold Decembers, to get three cold decembers in a row is quite unusual.

This December is starting off on a very cold note, and with the likelihood of no real mild weather on the horizon, it is looking increasingly likely we could see our coldest since 1981.

Dec 2009 saw a mild first half and very cold second half, Dec 2008 a very cold first third, mild middle and cold end, could this month be our first true full calandar month since Feb 1986 to register cold right from the start to the end?

[Roger J Smith]

I was going to list the predictions below 2.0 but figured, might as well be a good sport and list them all. Check this out, one or two people use the - symbol without meaning minus, but they may come back later and claim it was a minus. I'm not sure for example if Snowfest (one of the earlier entrants) meant 2.8 or -2.8, have listed at 2.8

-1.1 . Trickydicky

-0.9 . Snowyowl

-0.7 . Cooling climate ****

0.8 .. Roger J Smith

1.5 .. Gavin P *

1.7 .. AderynCoch

1.8 .. Terminal Moraine

1.9 .. Midlands Ice Age

1.9 .. Nimbilus

2.0 .. Optimus Prime

2.0 .. Polar Gael

2.1 .. BARRY

2.1 .. Stormforce 10

2.2 .. White Xmas

2.3 .. Chionomaniac *

2.4 .. Sunlover

2.4 .. Fozfoster

2.4 .. Snowstorm1

2.4 .. Coram

2.4 .. Polarside

2.5 .. Tonyh

2.5 .. Themusicland

2.5 .. Born from the Void

2.6 .. Frozencanals

2.7 .. Stu London

2.7 .. Virtualsphere

2.7 .. Sundog

2.7 .. S4lancia ***

2.8 .. Snowfest

2.8 .. Steve B

2.8 .. Blast from the Past

2.8 .. AtlanticFlamethrower

2.8 .. ChrisHell

2.9 .. Ben Cambs

2.9 .. Isolated Frost

2.9 .. NorthNorfolkWeather

2.9 .. Jack Wales

2.9 .. Jonboy

2.9 .. DAVID SNOW *

3.0 .. Norrance

3.1 .. Snow Scotland

3.1 .. Milhouse

3.1 .. Glacier Point

3.1 .. JACKONE

3.1 .. Great Plum *

3.2 .. Damianslaw

3.2 .. Stewfox

3.2 .. Duncan McAlister

3.2 .. Rain Rain Rain

3.3 .. sufc

3.3 .. shuggee

3.3 .. Kentishman

3.3 .. Thundery winter showers *

3.4 .. Mark Bayley

3.5 .. Paul T

3.6 .. Summerblizzard

3.6 .. Mr Data

3.6 .. Adam Jones

3.7 .. Pete Tattum

3.7 .. Picog

3.7 .. Koldweather

3.7 .. Don

3.8 .. The Watcher

3.8 .. Reef

3.9 .. Koppite

3.9 .. Stationary Front

4.0 .. Jonathan F

4.0 .. The PIT

4.0 .. Stargazer

4.0 .. DR Hosking

4.1 .. Thunderman24

4.2 .. Davehsug

4.3 .. Bullworker *

4.8 .. Mullender83

4.9 .. Tom D

5.0 .. Keithlucky

6.0 .. Craig Evans

6.5 .. RichardR

7.4 .. Backtrack

Each * represents one day late ... I don't know if the *** and the **** can play or not.

I believe this is the first time Craig Evans has predicted less than record warmth, you are really in for it now.

[West is Best]

I really think that it is about as rare as a complete winter like 1962-63 to see such extreme cold this early in the season. [...]

Looking at the two coldest Decembers in the 1900s neither of them were followed by anything special in the rest of the winter; OK there was a major cold spell from about 5th to 15th Jan 1982 but the rest of the winter was certainly nothing special. Only in the cold, although less cold Decembers of 1962 (1. and 1916 (1.9), was the cold of December sustained through the rest of the winter. This suggests to me that a cold December doesen't always mean that Jan and Feb will be up to much, and they are the months that have largely been the most devoid of cold weather in the 1990s and 2000s. OK, I know that in the mild 1990s and 2000s winters there has still been relatively little in the way of cold conditions in December at least from proper cold synoptics, it is clear that the lack of mild Decembers since 1988 (CET 6*C and above), has bucked the trend that Jan and Feb have followed. Compare only two 6+ Decembers since 1988 with five Januarys and six Februarys.

On top of this, the two coldest Decembers in the 1900s were both followed by a run of mild Decembers. After the very cold December of 1981 had passed there began a run of mild, mostly snow free Decembers in the UK. We went 11 years from 1981 without seeing a December even below 4*C, and even that was down to only a rex block in late Dec 1992. The same is true of 1950 as well, after that had passed the Decembers for the rest of the 1950s were largely mild and often snow-free.

Very interesting writing Fred.

One of the most curious winters to me is 1985-6. November 1985 was really cold: 4.1C CET despite a very mild start to that month. I remember it well and it was bitterly cold. Even then the cold didn't match what we've just had, and it was followed by a very mild December, then a real dip in January (3.5C) followed by a bitterly cold February at -1.1C: one of the three coldest months of the C20th.

Here's what T.A. Hartley writes about November 1985:

'Cold (4.1C CET) and wintry. There were a few mild days early on, with Guernsey seeing 18C on the 8th. There was a severe frost in the southeast on the 14th (-8C). Snow in the south on the 18th. The 19th was a cold day, with temperatures close to freezing in easterly winds. 2-5 cm of snow were laying in Kent and east Sussex by the 20th. Even Jersey had a cover of 12 cm of snow on the 20th. It was then less cold, then very wintry in Scotland at the end of the month, and a particularly cold spell from the 27th to 29th. Snow showers moved north: 12 cm on Shetland by the 27th. The 27th was a very cold day, with temperatures beneath freezing all day in Lincolnshire with snow. There was a minimum of -14C across central Scotland on the 28th/29th, with a maximum the following day of only -8. -20.9 at Kinbrace in the Highlands on the 30th. The month ended with very mild air spreading north during the evening of the 30th, where the temperature got up to 14C in the southwest. This was month saw the second lowest November temperatures of the century (after 1919), and was the coldest November since 1919. Altogether snow fell on five days in London, and 19 days in the more vulnerable parts of Scotland.'

[North-Easterly Blast]

Good well written read. Yes it is notable how in the past 20 years, of the three winter months it has been December which has shown more consistent cold. What is very interesting about this December is that it is coming on the back of two cold Decembers, to get three cold decembers in a row is quite unusual.

This December is starting off on a very cold note, and with the likelihood of no real mild weather on the horizon, it is looking increasingly likely we could see our coldest since 1981.

Dec 2009 saw a mild first half and very cold second half, Dec 2008 a very cold first third, mild middle and cold end, could this month be our first true full calandar month since Feb 1986 to register cold right from the start to the end?

It was only the first ten days of December 2009 that were mild and colder weather was starting to develop by the 11th. The CET up to Dec 10th 2009 was 6.6*C. It may have been mild but it still was a fair bit short of some of the other mild starts to December in recent years. The first third of December 2008 was cold but it didn't see a real major cold spell. The last few days of Dec 2008 were the coldest of that month but it was due to a Rex block and surface cold.

I wouldn't entirely say that December has shown consistent cold in the last 20 years. The main point that I would say is that over the last 20 years, December has shown consistency to not be a particularly mild month as compared to how often January and February have been particularly mild. Only two 6+ Decembers since 1988 when you compare this to five Jans and 6 Febs, and even the two 6+ Decembers, 1994 and 2006, were still a good bit short of the record and still not in the top 20 warmest ever.

Very interesting writing Fred.

One of the most curious winters to me is 1985-6. November 1985 was really cold: 4.1C CET despite a very mild start to that month. I remember it well and it was bitterly cold. Even then the cold didn't match what we've just had, and it was followed by a very mild December, then a real dip in January (3.5C) followed by a bitterly cold February at -1.1C: one of the three coldest months of the C20th.

Here's what T.A. Hartley writes about November 1985:

'Cold (4.1C CET) and wintry. There were a few mild days early on, with Guernsey seeing 18C on the 8th. There was a severe frost in the southeast on the 14th (-8C). Snow in the south on the 18th. The 19th was a cold day, with temperatures close to freezing in easterly winds. 2-5 cm of snow were laying in Kent and east Sussex by the 20th. Even Jersey had a cover of 12 cm of snow on the 20th. It was then less cold, then very wintry in Scotland at the end of the month, and a particularly cold spell from the 27th to 29th. Snow showers moved north: 12 cm on Shetland by the 27th. The 27th was a very cold day, with temperatures beneath freezing all day in Lincolnshire with snow. There was a minimum of -14C across central Scotland on the 28th/29th, with a maximum the following day of only -8. -20.9 at Kinbrace in the Highlands on the 30th. The month ended with very mild air spreading north during the evening of the 30th, where the temperature got up to 14C in the southwest. This was month saw the second lowest November temperatures of the century (after 1919), and was the coldest November since 1919. Altogether snow fell on five days in London, and 19 days in the more vulnerable parts of Scotland.'

December 1985 was very mild up until Christmas, with the CET at 8.1 up to the 24th, and after mid-month many would have been talking about a possible record month, but a potent cold northerly in the final week produced severe frosts and some very cold days, which was intense enough to shave 1.8 off the CET in the last week. I think that one difference then compared to most of the last 20 years, is that during the very mild period in December 1985, pressure was still often high over Greenland, but unlike much of the rest of that winter, it was unable to influence the UK's weather and bring cold weather to Britain, until it finally succeeded in the last week.

[AderynCoch]

February 1986 was actually the fourth coldest CET month of the 20th century (January 1963, February 1947 & January 1940 were all colder) and November 1985 was the coldest since 1925. Trevor Harley's site is wonderful, but there are a few inconsistencies here and there.

The talk about very cold Decembers being followed by runs of mild Decembers is interesting, but then there were five Decembers below 1C in the period 1870-1890.

[West is Best]

With no let-up on the overnight model outputs we could be looking at a record-breaking cold December at this rate.

Thanks for the pointer that February 1986 was the 4th not 3rd coldest month of the C20th. I totally agree with T A Hartley that this is the forgotten month of the C20th. It was astonishingly cold, but often bone dry until 01st March:

February. Very cold (-1.1C CET), with frequent light snowfalls. The second coldest February of the century (after 1947), and third coldest month [edit. fourth]. The month was similar to January 1963 in being a completely blocked month, with a high centred over north Russia bringing some very cold air east. Winds were easterly for 23 days, and were of virtual calm for the remaining days. Easterly winds had already set in by the end of January. Snow cover was widespread in the east, where it was very dull: Cupar (Fife) registered only 41 hours sunshine all month. In the west it was very dry and sunny (144 hours sunshine on Anglesey; with no measurable rain at all in some western coastal sites). The lowest temperature was at Grantown-on-Spey, where it reached -21.2C on the 27th. The lowest temperature around Birmingham was -11.0C, at Elmdon, on the 21st, and the highest, just 3.8C on the 28th. Freezing rain in the north Midlands. Up to 50 mm of glaze was recorded on broken power lines at Buxton on the 2nd. Widdybank Fell, at 513 m above sea level in County Durham, remained beneath freezing all month, and had a total of 32 consecutive days beneath zero - probably a record for a habited area. This was our last exceptionally cold month (average beneath zero). I remember our toilet freezing and a six inch icicle growing out of the cistern overflow. I reckon this is the last time I experienced a temperature beneath -10C. The cold persisted into early March. For some reason I find that February 1986 is often "the forgotten month" when one talks about extreme winters in Britain. Perhaps this is because there wasn't any widespread serious disruption due to heavy snow over a wide area, perhaps because there weren't any record-breaking low temperatures, and perhaps because the rest of the winter was unexceptional. Indeed, some parts of the country had no snow at all. Nevertheless, it was, and remains, the coldest month since January 1963.

Edited December 5, 2010 by West was Best