December CET

[Nick L]

A record cold December is certainly back on the cards!

http://www.wetterzentrale.de/pics/Rmgfs1684.gif

[BornFromTheVoid]

A record cold December is certainly back on the cards!

http://www.wetterzentrale.de/pics/Rmgfs1684.gif

Definitely. The 18z GFS would have the CET at about -1.2C to the 28th!

[Nights King]

Cold looks set to persist at least possibly first week of jan so record is back on the cards!

[Roger J Smith]

Wonder what the first winter of an ice age is like?

*ramp of the century*

[AderynCoch]

A record cold December is certainly back on the cards!

http://www.wetterzen...s/Rmgfs1684.gif

Those four digits at the end of the link... are you trying to tell us something?

This is going down to the wire. Some fascinating CET watching on offer in the coming days....

[summer blizzard]

Certainly interesting model ouputs with the war between the GFS and other models continuing.

Odds are against the record going, but a 30% chance is still significant.

[lukemc]

Certainly interesting model ouputs with the war between the GFS and other models continuing.

Odds are against the record going, but a 30% chance is still significant.

I do think that even though we might not get the coldest December ever we are certainly odds on to beat 1981 which would mean that we have the coldest December for over 100 years which would be an impressive record especially after all the mild winters we have endured and I do still think we will get a negative CET figure the first since 1986.

I also have a feeling and it is just a hunch at the moment that January is going to be a colder month than December and it is possibly going to be the coldest since at least 1963 would that mean that we get the coldest winter since 1963?

I think February might be too close to call at the moment but I think it will still be below average.

Luke

[kold weather]

I'd still advise against taking the 18z too seriously, the most likely solution by far is still for a breakdown, I'd say its still 80-20 in favour of a breakdown by the 27th...

However by then as others have said its an uphill struggle to get above 0C.

We will see, either way December 2010 is going down in the record books as being one of the msot severe ever...

[lukemc]

I'd still advise against taking the 18z too seriously, the most likely solution by far is still for a breakdown, I'd say its still 80-20 in favour of a breakdown by the 27th...

However by then as others have said its an uphill struggle to get above 0C.

We will see, either way December 2010 is going down in the record books as being one of the msot severe ever...

So would you see a sub zero month as being odds on KW even with a breakdown just after Boxing Day?

Amazing achivement especially considering we have not have had a subzero December for over 100 years! That is amazing in itself regardless of how the rest of the winter goes!

Luke

[Cymro]

What is different about the 18z however is the meto fax charts showing that potent high which would ensure some really cold minima and maxima!. And for the metoffice to go against the grain and boldly stick their necks out in comparison to ecm (wich is also showing more colder esembles later in the run) is quite something.

I wouldn't say it's nailed on or banked as things will change but there is no significant warm up forecast where some would have you believe. Even with the so called breakdown we would only see highs of around 3/4 and frosts early and late.

If that's the modern Mild then I will bank it with a long shot.

What's evident however is how interesting watching the CET has been this month probably as exciting as looking for snowy prospects IMO. I would sooner cold temperatures as much as snow.

[Stu_London]

I think we need cold or surface cold though to 28th, to be sure of sub zero. 27th might be ok- depends on how quick the transition to mild is and how mild we get

[Nick L]

Do you reckon we will get downward adjustments? I remember earlier in the month when we had some strangely high minima.

[paul tall]

Wonder what the first winter of an ice age is like?

*ramp of the century*

Only Terminal Moraine could have carried off that statement as well as you did there. +1.

[kold weather]

I think we need cold or surface cold though to 28th, to be sure of sub zero. 27th might be ok- depends on how quick the transition to mild is and how mild we get

Hmmm its going to be tight thats for sure, if the ECM is right then we'll probably keep a cold CET for the 26th but the 27th would be milder.

Its going to be a close run thing though, every bit lower we get now gives us more margin for error.

Of course we also have 0.2C above 0C to be the coldest December since 1890 I believe...combined with downward adjustments of a little bit may well make us go below Dec 81 even if we end up warming up on the 27th like most models do suggest...

[reef]

24th November-19th December CET: -0.3C

I cant speak for nationally, but the period 24th November - 20th December here has a 1971-2000 mean of 5.3C. This year its running at -0.1C which is an ridiculous anomoly of -5.4C.

Even February 1986 was -4.7C below average and I cant find such a prolonged negative anomoly anywhere else (it'd probably be 1963 if my records went back that far). Absolutely remarkable and it could drop even lower over the next few days.

[Roger J Smith]

Not sure if mentioned but a recent 30-day period very close to zero on CET was 22 Jan to 20 Feb 1991. With rounding it may have been right on zero, the average of daily means is about 0.17 C.

[West is Best]

I'd still advise against taking the 18z too seriously, the most likely solution by far is still for a breakdown, I'd say its still 80-20 in favour of a breakdown by the 27th...

Don't really know where you get those odds from Darren. The chances of a quick breakdown are slim, and the models are moving increasingly in favour of prolongation of cold.

Record cold December now looking distinctly possible. One might almost say 'probable'.

[Isolated Frost]

Anyone think -1C to the 27th?

If so, even a less cold breakdown of 4 days would add very little to the figure, considering we are at the back end of the month, and 4 days of 5C mean would hardly make it touch 0C!

I predict -0.4C for now...

[reef]

Hadley is on -0.4C to the 20th. Yesterday came in at -6.9C.

Today's min is down as -8.3C and its particularly cold in the north of the zone, so perhaps another 0.2C fall on tomorrows update.

The remaining days need to have a mean of -1.7C to break the December record.

[kold weather]

WWB, odds have REALLY increased in the last 12hrs, firstly the models seem to have underestimated the depth of cold for the enxt 2-3 days and secondly any breakdown now shunted to the 27-28th, which would probably mean even if we were to see a warm up its going to be too little too late.

Sub zero now pretty nailed on given those two factors.

Still think we will breakdown before the end of the month given the rather decent agreement on the synoptics at last (though UKMO is still keen on not breaking down the pattern) but I don't think its a long lasting set-up.

[West is Best]

There's no agreement for anything of the sort Darren. In fact, the opposite.

I predict a December CET of below -1C.

What's the record lowest month for anomaly below the 1961-1990 mean? This month could be around 6C below anomaly. If I get a mo' I'll try and work out the records. Where's Mr Data?!

[BornFromTheVoid]

Going by the GFS 06z, we'll be around

-0.6C to the 21st (-4.55)

-0.7C to the 22nd (-2.0)

-0.8C to the 23rd (-3.5)

-0.9C to the 24th (-4.6)

-1.2C to the 25th (-7.5)

-1.3C to the 26th (-4.5)

-1.2C to the 27th (+1.1)

-1.1C to the 28th (+4.0)

[kold weather]

There's no agreement for anything of the sort Darren. In fact, the opposite.

I predict a December CET of below -1C.

What's the record lowest month for anomaly below the 1961-1990 mean? This month could be around 6C below anomaly. If I get a mo' I'll try and work out the records. Where's Mr Data?!

I think i'd call the ~ECM+GFS+Ensembles from both+GEM+GME (though it doesn't run quite far enough to know exactly!) pretty strong agrement...the UKMo and Nogaps go for something longer lasting perhaps. (I think the ~UKMO would eventuallym breakdown aws well, that secondary low looks at totally the wrong angle!)

surface cold won't shift very far and either way sub zero pretty much certain now...we need to keep the cold till the bitter end to break the record...not impossible but I'm stioll pretty sure we do get a brief breakdown before a cold high re-establishes itself.

[West is Best]

People see what they want to see, so we'll just have to beg to differ Darren. UKMO is very much not on board, and nor is GFS. The ensembles don't show any support for any such thing, and I think you are being rather disingenuous to suggest it. The scatter is immense with a clear trend away from a quick breakdown (previously you and the other mild ramper Ian Brown said it was 'nailed on' for Dec 25th, then 26th). The trend is towards height rise both over the UK and Scandinavia and, concomitantly, a much greater mild vs cold battle. Anyone who has studied models knows that this illustrates the point admirably:

Massive scatter = no agreement.

So that's

UKMO + GFS Ensembles vs some of the minor models (ECM is no longer a big player)

Edited December 21, 2010 by West was Best

[kold weather]

West mate the GFS ensembles do go for a breakdown, look at the average:

http://91.121.84.31/...-21-1-144.png?6

Trust me you don't get that sort of average (975mbs low!) without strong agreement from the GFS ensembles. In fact its actually even more agressive then the GFS operational...Pressure rises because we actually drag in a SW airflow with pressure rising over Europe...not because of a developing Scandi high...probably 75% go Euro, 25% go Scandi.

Oh and here is the indivdual runs:

http://www.wetterzentrale.de/pics/senspanel1681.gif

ECM is still the best model statistically out there...its been rocky I grant you but you can't just brush it aside, the GFS ensembles DO breakdown, so does the GFS op run, as does various other models...

On the other hand I'm not saying the models are right, just that at the moment there is clearly strong agreement for a breakdown...plus I've never once said a breakdown was nailed on for a date, jsut that the models were breaking the pattern down. I always thought the models were being overprogressive with the Atlantic..hence why I've been saying I don't think the Atlantic lasts long even if it does breakdown.

Either way its still going to be an exceptionally severe month...the record is very much breakable IF we do manage to keep the cold till say the 29-30th...

Anyway why should be be debating anyway, we should all be happy that we are going to get the holy grail...a sub zero month. Afterall many (I'm sure you and me would both be in the same boat) back in 06-07 thought we may not ever see a sub zero winter month again...