December CET

[damianslaw]

I keep pinching myself, is this really only the 7th December?, the cold over the past 10 days has been exceptional and the chances of a sub zero CET month our first since Feb 1986 are now looking quite a good bet - remarkable.

The 'milder spell' about to occur on Thursday, is hardly looking mild, indeed it is being toned down, and I doubt many places will see maxima higher than 4 or 5 degrees, in fact thursday will bring 2's and 3's to many, and Friday/Saturday probably 5 at the most and thereafter the CET will drop downwards. If anything it will be nightime minima in the coming days which will have a more marked pronounced affect on the CET, under cloudier skies much of central britain from thursday night will struggle to get below 0 degrees it would appear.

[West is Best]

Staggering synoptics.

I just wonder at what point in all of this we are going to begin considering that we may be heading for the coldest December ever recorded in this country? Staggering and exceptional.

[kold weather]

Whilst I still think its a little unlikely and will probably require the cold on the models to last the entire month more or less, it can't be ruled out!

Heck just going 1.5C would be utterly amazing and put this month up with in the same sort of league's as the all time bests...Jan 2010 was probably in the 2nd division of severe months however with the way this is going this December is going to end up right in the top rank, alongside Dec 81, 1890, etc...

We did managed a CET of about 0C back in 09-10 for a 30 day period so its clearly doable, just need to wait and see if it comes off.

One thing is for sure, we're heading towards a well below normal month which will likely pull in the biggest net anomaly since Feb 1986...

[Stu_London]

Staggering synoptics.

I just wonder at what point in all of this we are going to begin considering that we may be heading for the coldest December ever recorded in this country? Staggering and exceptional.

If I was laying odds on December 2010 CET, I would go as follows: -

Sub 3C - 1/5

Sub 2C - 1/2

Sub 1C - 11/10

Sub 0C - 4/1

Coldest Ever - 16/1

[kold weather]

Yeah I'd broadly agree with those sorts of figures Stu, though I'd say maybe 3/1 for a sub 0C month considering where we are and the fact the models are still suggesting another fairly lengthy cold spell is likely.

I think its highly likely we end up sub 2C now...I'd be surprised if we go as low as -1C which is whats required to be the coldest on record...remember those sorts of values weren't common even in the Little Ice Age!

Odds are we end up below December 1995 and have the coldest December since 1981...

[Weather-history]

24th November-6th December 2010 CET: -1.4C

24th November-6th December 1879 CET: -0.9C

By contrast 24th November-6th December 1979: 9.5C

The last fortnight has probably been the coldest such period on record.

[kold weather]

Yeah Mr.data I think thats highly likely, maybe 1879 is the only one that is close given its absurd first week?

Anyway the models are still good agreement of a pretty sustained cold spell, and interestingly most now drag in colder air again as soon as Sunday night/Monday so we will likely only have a few days that end up above say 1C on the CET, so we many well only gain 8-9C on the cumulative total before we start to see near freezing CET days again which will put a stop to the CET rising...

After that it seems quite probable IMO we end up with a stronger northerly towards the 17-20th and if that happens then sub zero CET days are highly likely, indeed shades of 81 in some of the output...if it was to occur then a sub zero month would be rather probable and not just possible...

If it doesn't come off, then I suspect somewhere between 0.5-1.5C is the outcome zone so still a severe month, but I'm actually thinking we have a real good chance of going sub zero now...

[VillagePlank]

The December CET this year looks to be staggeringly low. I also agree with those odds, Stu, but, perhaps, I'd reduce the odds of <1C. How long has it been since we've had an CET ice month (CET<=0)?

[Great Plum]

Feb 1986 I think...

[kold weather]

Yep indeed Feb 86, Ice months are very rare at the best of times without the globe being very warm in comprasion to normal...so if we do manage something close to 0C on average then that is probably one of the most exceptional months out there...

06Z GFS looks very cold though it does start to get milder right at the end, if that run came off something in the mid-high 0Cs would be probable....however thats a long way off!

Remember below 1.3C secures a sub 9C year...and I think thats increasingly probable now...

[Paul T]

-1.9oC to Dec 7th

Another cold night last night, with Mins @ -7oC; assuming a max of 2oC today, then it will drop to a mean of -2.0oC to the 8th.

Given the forecast, we will be at 0oC by the 15th. Then it will probably get COLDER!

Sub zero could happen.

[AderynCoch]

And there was me thinking I was sticking my neck out with 1.7C! Once the milder interlude is out the way we'll have a good idea of how cold it's going to get and a better picture regarding the end of the month.

Exciting times.

Edited December 8, 2010 by AderynCoch

[kold weather]

-1.9oC to Dec 7th

Another cold night last night, with Mins @ -7oC; assuming a max of 2oC today, then it will drop to a mean of -2.0oC to the 8th.

Given the forecast, we will be at 0oC by the 15th. Then it will probably get COLDER!

Sub zero could happen.

Its going to be a close run thing, as you say we'll probably be close to 0C either side by the 15th and there after it does look like becoming quite cold again. I've got a gut feeling we may see another attempted breakdown like the 06z GFS shows near Xmas which would then make things very 50-50 however at least we have a real shot.

Below 1.5C looking a good bet now so our 2nd severe winter month in 2010...we go 55 winter months without a Severe cold winter month and then we go and get 2 in the space of 3 months!

[BornFromTheVoid]

The max for yesterday is down as 0C. Surely that's wrong?

I don't remember seeing anywhere in the CET zone going above 0C and most were around -3C or -4C weren't they?

Maybe I'm losing it!

[Stationary Front]

That's right, here in the middle of CET land it was minus 1.8 yesterday as a max temp.

[damianslaw]

Carlisle recorded a maximum of -9 degrees, this can't be far off a december record?

Here I don't believe we saw more than -3 degrees after a low of about -12 degrees.

Two thirds of last years weather payments have been made already I've just heard.

[Optimus Prime]

Thought it would be a good time to do some GFS 2M temperature calculations for upto the 15th.

CET to the 8th, will be around -1.9c, 7.5c below average (assuming the mean max is 3.0c after this mornings low of -7.0c) CET for the period 9th - 15th comes in at 1.1c which is 4.5c below normal. CET by the 15th should be around -0.5c, 6.1c below normal.

[Paul T]

The max for yesterday is down as 0C. Surely that's wrong?

I don't remember seeing anywhere in the CET zone going above 0C and most were around -3C or -4C weren't they?

Maybe I'm losing it!

will probably be an adjustment at the end of the month....

[Optimus Prime]

Even during the intesne cold snap of Feb 1991 the lowest daily max was only -2.2c.

Compare that to January 1987 and the lowest was -5.7c.

Edited December 9, 2010 by Optimus Prime

[Stu_London]

CET to the 8th -2.0C

[BornFromTheVoid]

Going by the GFS 06z, it looks like we'll be at

-1.8C to the 9th

-0.9C to the 11th

-0.5C to the 13th

-0.3C to the 15th

-0.3C to the 16th

Edit: 13 day running mean since the 26th November is now -1.98C. 30 day running mean is now down to 2.0C

Edited December 9, 2010 by BornFromTheVoid

[kold weather]

Probably will continue to see a very slight drop this weekend as we are losing the milder days from the 30 days CET...

Anyway cold is moderating now but its looking increasingly likely we are going to see a cool down again, I suspect we will be back down to about -1C by the 20th with temps dropping away, esp if we are to get a slacker flow even like the ECM suggests...

Still in with a real shout of sub 0C providing the cold spell can keep going past Xmas...otherwise 0-1C range is probably a very solid estimate for now....

I just can't see it going above 1.5C whatever happens, so I think a severe month is just about odds on, and I think we are something like 1/3 on for a month below 1.3C which would take us below 9.00C for the whole year.

[Isolated Frost]

I'd say.

3C+: 1%

2C-3C: 10%

1C-2C: 20%

0C-1C: 39%

Below 0C: 30%

Right now, I'd say 0.5C looks a good bet, but it all depends on how we can limit any milder interludes, and the severity and longevity of the Cold Spell that the models are pointing out to occur from around 10 days before Christmas.

[kold weather]

Yeah I agree IF, the only thing which could shift things wouild be if we got an undercutting low near Xmas...I think we won't and we'll get back towards a more normal temps towards the last 3-5 days but too early to tell yet.

By the way if we were to continue like we did in December 2009 from the 9th of December we'd end up around 0.9C...any milder spell at the end of the month probably wouldn't be any milder then the period between 9-15th of December last year and the cold spell looks similar so I wouldn't be surprised if the outcome is colder then that figure above. Sub 1C looking increasingly possible now...

[Roger J Smith]

I've never seen anything quite like the spread of blue on the 18z GFS -- and the Baltic is so cold already that it will be affecting the North Sea later this month, if any of these model charts are underestimating the easterly component of the northerly flow, then this month could start heading towards -3 for a CET ... if the 18z GFS verified it would be heading for perhaps -1.5 and a new record. Anything past day 12, I would factor in that the GFS always tries to return to zonal flow as a default, and it would be more likely that a cold outbreak this massive would consolidate and lead to a storm, additional snow cover and the radiative cooling that would follow.