December CET

[Snowyowl9]

My -0.9c may still be on,the lack of wind and clear nights with more severe frosts and ice days,can`t see much of an end to this for quite a while now.

The CET will drop once again after reaching 0.6c only 0.0c on climate UK but thats until the 15th.

The coldest december on record looks on.

December 1981 gave a severe 3 week cold spell with a mild beginning and mild end.

[The PIT]

Well the models can't decide whether to go for a Xmas breakdown, in which case something between 0.5-1C looks likely, or if we can shunt off the breakdown till close to New Years, in which case sub 0C is very possible still...

Today almost certainly will be a sub zero day in the CET zone with some places getting Ice Days from the looks of things...

Looks like sub zeros up to xmas at the moment.

[Stu_London]

The 06z would probably deliver something close to 0C final outcome as the christmas day breakdown is brief and followed by a cold slack period.

Edit

the 06z is actually an insanely cold run that delivers the coldest December week in CET history and lowers the CET to -1.3C by Christmas day.

I suspect it won't be quite as cold as is progged but even if it half verifies we will almost certain of a sub zero month

Edited December 17, 2010 by Stu_London

[summer blizzard]

Definitely below -1C to the 27th, 80/20 in favour of beating 1981 now, 60/40 in favour of recording the coldest December CET on record!.

My opinion.

[morfius]

12z would probably bring a below -1C month!

[Optimus Prime]

Definitely below -1C to the 27th, 80/20 in favour of beating 1981 now, 60/40 in favour of recording the coldest December CET on record!.

My opinion.

Your opinion is usually very good. I'd say those are good odds.

-0.9c would also give us an anual CET of 8.88c.

[paul tall]

What is the coldest December on record chaps?

[BornFromTheVoid]

What is the coldest December on record chaps?

-0.8C, 1890.

[kold weather]

The 12z GFS would indeed likely taker us VERY close to the record or maybe just beat it, not one day that gets above 0C on the mean on the 12z...even for the severe winters in the past this is becoming an exceptional cold spell...

Should get a 45 day period sub 0C if the 12z comes off...

[Roger J Smith]

I knew I left something out of my forecast -- the minus sign.

[BLAST FROM THE PAST]

Sub zero.....I think is nailed on. Looking at the signals and how the NH has responded this cold is NOT going away. Already I can see Jan being a lot colder than we predicted......and you know what...we haven't reached the grand minima yet....that's 20 years away!!!!

BFTP

Edited December 17, 2010 by BLAST FROM THE PAST

[❄️❄️❄️❄️❄️❄️❄️❄️❄️]

we haven't reached the grand minima yet....that's 20 years away!!!!

BFTP

Yikes! If we are just starting off of a cooling trend, we are all screwed!

Out of interest, is it a cooling trend the whole planet or just our part of the world?

[Cymro]

Quite dramatic if you think about it could this winter potentially be colder than the last? Am I putting the cart in front of the horse here?

[AderynCoch]

Quite dramatic if you think about it could this winter potentially be colder than the last? Am I putting the cart in front of the horse here?

This winter could easily be colder than the last one - December this year will be much colder than last time round, so January and February won't need to be as cold.

Edited December 17, 2010 by AderynCoch

[kold weather]

Sub zero.....I think is nailed on. Looking at the signals and how the NH has responded this cold is NOT going away. Already I can see Jan being a lot colder than we predicted......and you know what...we haven't reached the grand minima yet....that's 20 years away!!!!

BFTP

I'm still not sure its nailed on, only need a few days like we had before this cold spell to make us end up just above 0C...that being very cold month and obviously coming in below 1C...only the 2nd December to do so since 1900s began.

Still I've been in agreement with for a while about a flip in the global circulation since 2007 when the PDO signal actually flipped (the supposed start in 1998 was IMO a mask so to speak caused by the very long La Nina of 1998-2001) and its no shock that things are starting to move...

Reminds me alot of the 1950s at the moment in terms of the pattern, both major La Ninas in the 50s were very cold...

[Stu_London]

18z GFS looks to deliver -0.8C by the 25th

3.4C would be needed to get above 0C for the period 26th-31st.

Given the tendency for downward adjustment, I would say the odds for december are currently as follows: -

-0.5C to 0C - 2/1

0C to 0.5C - 5/2

-1C to -0.5C- 3/1

0.5C to 1C - 6/1

sub -1C - 10/1

above 1C - 20/1

Or Sub 0C - 4/7

Above 0c - 11/8

[Kentish Kiwi]

When was the last year in which we had an above average December? Decembers in the 2000's (I'm assuming this one will be counted with the 2000's) will surely come in as the coolest compared to average of all the months?

It truly is astonishing to think that we are now odds on to have a colder month than anything the 'historic' winter of 2009/10 could conjure up.

Has anyone got any likely figures for what the period Mr Data highlighted of 24 November to 23 December will possibly come in at?

[Stu_London]

Has anyone got any likely figures for what the period Mr Data highlighted of 24 November to 23 December will possibly come in at?

Barring a dramatic turnaround, almost certainly sub 0C, maybe pushing sub -1C

[Optimus Prime]

When was the last year in which we had an above average December? Decembers in the 2000's (I'm assuming this one will be counted with the 2000's) will surely come in as the coolest compared to average of all the months?

If it averages 0c the average for the period 2000 - 2010 will come in at 4.3c. 0.4c below 61-90 average and 0.8c below 71-000 average.

[kold weather]

Thats a stunning downward trend OP, I'm not sure there have been many if any downward motions that large in the CET before, 0.8C down from the previous decadal December CET...

I take it that may well lead to December being close to or maybe the coldest winter month?

Anyway going to be a hard ask to get above 0C providing the trends continue...most models keep at least Boxing day around 0C so that figure of 3.4C would probably need to be adjusted up for the 27-31st period which is the only real uncertain period at the moment.

Either way the strength of this cold spell should ensure we come in below 1C...for the first time since Jan 87...an historic month by any standards!

[Roger J Smith]

From that table I made back at the start of the month, adding in one very late entry on the 5th:

(Dec forecasts 2.0 or lower)

-1.1 . Trickydicky

-0.9 . Snowyowl

-0.7 . Cooling climate ****

-0.5 . Polar Continental *****

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

* = one day late entry per * symbol.

Not sure how the scoring works except for 10% penalty per day, but without the three marked late entries, I had a safe zone from 0.0 to 1.2 ... counting the late entries, that safe zone shrinks to 0.2 to 1.1.

Strange to have such a wide safe zone that close to the projected landing zone which I gather you're saying is close to 0-0.5 C ... I am still hoping to see a negative month even though my scoring would be better in the zero point something range. Stormmad26 who was late and didn't enter said he thought zero to one (on the 6th).

The rest of the guesses can be seen back at post #121. Craig had that premonition ...

[Duncan McAlister]

Just for fun.

I make it that the 00z would give -0.75 which would be rounded up to -0.7, just missing out on equalling the record.

I've got a feeling it could come as close as that!

Edited December 18, 2010 by Duncan McAlister

[Weather-history]

I think we have a couple of key ingredients for some very low minima, snow cover and slack gradients. If we get the 3rd, clear skies then we could produce some very low CET minima which maybe enough to counter somewhat a mild last week.

[North-Easterly Blast]

We will almost certainly slip back to 4.7*C for the 1981-2010 December CET average, which will be the same as for the 1961-90 average, as compared to the 5.1*C, or 5.06*C to be precise, for the 1971-2000 average.

December is a month that was generally very cold in the 1960s, then very mild in the 1970s and 1980s, then by a total mystery, in comparison to all the other months that have shown marked warming in the 1990s and 2000s, December has swung the other way and seen significant cooling back down to close to the average for the whole of the 1900s in the last 20 years or so.

Whilst up until this year and the one last year, December in the last two decades has not been noted for prolonged cold spells at least from proper cold synoptics, it is certainly clear that in comparison to how often January and February have been very mild in the last 20+ years, December has certainly struggled to be a particularly mild month, and has clearly bucked a mild trend that it saw in the 70s and 80s.

I think also that Rex blocks are more responsible for cold spells in December over the last 20 years. A Rex block in the second half of December 1992 was enough to bring the CET below 4*C. The cold of December 1996 was brought about by largely Rex blocking plus also a weak easterly later on; frequent Rex blocking was enough to do a sub 4*C CET in December 2001, plus some not especially cold northerlies later on. December 2006 failed to see record warmth due to a short spell of Rex blocking just before Xmas. December 2007 was also, in a mild winter, not especially mild due to a ten day plus spell of Rex blocking.

It is certainly strange that the very cold December of 1981 came in the middle of an unusual run of mild Decembers.

[AderynCoch]

I take it that may well lead to December being close to or maybe the coldest winter month?

December already has been the coldest winter month from 1988 to present. Here's a post I made not long back:

For the period 1988-2009 inclusive, December has actually been the coldest winter month (Dec = 4.82C, Jan = 4.94C, Feb = 5.06C). This is rather strange when you consider how January and February are supposed to be the "meat" of the winter.

Thanks to a cold January and February this year, December 2010 needs to come in at below 3.9C to be the coldest month for the period 1988-2010 (3.9C exactly will place it equal with January). However, for the period 1989-2010 it will need to be above 6.0C to not be the coldest month (6.1C exactly will place it equal with January), thanks to the very mild December of 1988 being wiped off the slate.

http://forum.netweather.tv/topic/64563-the-months-that-buck-the-trend/

I thought January (and to a lesser extent February) this year would have put December's lead under pressure, but now it's clear that December will open the gap even further!

Even if the milder predictions for month's end do win out, we're heading for an exceptionally low CET. I still can't believe my 1.7C has kicked the bucket at this stage!

Edited December 18, 2010 by AderynCoch