December CET (2012/13 Competition)

[ISAAC]

-0.6c

Late and crazy, i know

[jonboy]

wonder what the outcome would be if tonights ECM verified?

[Relativistic]

wonder what the outcome would be if tonights ECM verified?

I know, just seen that.

[Methuselah]

wonder what the outcome would be if tonights ECM verified?

My guess of 4.4 would be a tad too high!

[jonboy]

I think mine at 1.2 might be a tad high too

[damianslaw]

Any idea what the CET wil be by the 7th?

Here are some cold December CETs up to the 7th

2010: -2.1

2008: 2.1

1998: 2.4

1976: 1.6

1962: 0.1

1957: 2.7

1952: 0.0

1950: 1.6

1947: 2.1

1933: 1.5

1925: -0.3

1916: 1.1

1903: 1.4

1902: 0.8

1894: 2.7

1892: 1.6

1890: 2.7

1889: 0.8

1886: 2.6

1882: 2.1

1879: -3.6

1878: 1.8

1875: 0.1

1874: 2.4

1871: 0.6

1870: 1.2

1869: 0.5

1867: 1.6

1846: 0.7

1844: -0.7

1839: 1.3

1837: 2.1

1816: 2.6

1807: 2.6

1804: 2.7

1803: 1.9

1801: 2.2

1800: 2.3

1796: -1.9

1791: 2.1

1788: 0.9

1784: 2.4

1782: 0.6

2010 stands out - it was an exceptional spell of weather especially so given the first 7 days if December on average are usually mild. Would be interesting to see stats of the mildest opening 7 days to the month, suspect a number of years achieved means close to double figures, the likes of 1985, 1988, 1994, 1997, 2000, 2004, 2006 and 2007 spring to mind.

1998 stands out, as it wasn't a particularly cold month in the end - indeed from memory it ended up above average. I do remember the cold northerly though and hoping for a decent winter ahead, but in the end it was a mild winter with little snow like many inbetween 1987/88- 2007/08.

I'm liking the way this December is potentially evolving, the early cold start now looks to be strengthening in potency as we move into the second third.. it isn't doing a 2010 but possibly a 2009 which felt so much more 'right'..

[Yozzer]

think I may have to amend my 3.1c to minus 3.1c if the ECM 12z verified even closely!!!

[Stu_London]

CET to the 5th - 3.0C

Last night was a chilly -3.3C, so a biggish drop likely today.

Pretty good model agreement on the next 10 days being below average, so the odds of an above average month are lengthening rapidly.

[Stu_London]

Based on the latest output, I would expect the next 10 days to average at about 1.5C.

That would bring the CET down to 2C by the 15th.

The remainder of the month would have to average 7.2C then just to get to the 61-90 average of 4.7C - so whilst not impossible, pretty unlikely as it would require 16 days of South westerlies, which doesn't look that likely at the moment.

[kold weather]

I suspect Stu once all is said and done this month will probably be in the 1-2.5C range. I don't think I'd like to nail down anymore than that because much depends on whether we get any reload. I think we will get probably a good week of milder temps in somewhere this month before the hole pattern reloads and temps drop through the floor again, but who knows!

I think its highly unlikely we reach average

[Thundery wintry showers]

I agree with the suggested range of 1 to 2.5C.

At present I consider it extremely likely that we're going to get a cold spell around the 10th-16th. There is still scope for a toning down of the cold 850hPa temperatures and amount of showery activity over the North Sea in my opinion, but I find it hard to see us not getting an airflow vectored from the eastern half of the compass with well below-average temperatures. From the 17th-21st we will most likely see an attack from Atlantic depressions to the SW which may bring us a mild interlude, but I can see a northerly outbreak setting in around or just before Christmas as highest pressure retrogresses to Greenland. Milder weather may then return towards the month's end.

The likelihood of the milder interludes coming off, at least for two or three days, makes the chance of a sub 1C December quite remote (though not outside the realms of possibility) while I doubt that any milder interludes will sustain for long enough to prevent a sub 2.5C December, especially given the cold start to the month.

[summer blizzard]

I suspect Stu once all is said and done this month will probably be in the 1-2.5C range. I don't think I'd like to nail down anymore than that because much depends on whether we get any reload. I think we will get probably a good week of milder temps in somewhere this month before the hole pattern reloads and temps drop through the floor again, but who knows!

I think its highly unlikely we reach average

It wouldn't surprise me if we ended up colder.

My prediction (which was slightly too low as looking at my method i should have gone for 4.1C) was based on the coolish first third, a mild second third as the troposphere let us down and then a cold last third. What we have seen however is that whilst the tropospheric vortex is regrouping, it is going to be heavily displaced and with the western CET bias (i think) we should expect some extremely low minima from any easterly to pull us down.

It's hard to see us approaching the records for December as that would require a CET of about -3C from our mid month point but we can't rule out a sub-zero second half.

[Harve]

GP seems to be hinting at a renewed cold attack in the very last days of December. While TWS' suggestion of a northerly following the breakdown seems very plausible, it's very possible that this will be simply a northerly toppler and be followed by a mild spell to see the year out, just like in December 2009 and 2010 (for the CET zone, less so or not at all for Scotland). With the CET starting low, it won't take much for it to rocket up. I wouldn't rule out a 3-4c CET just yet.

However without such a spell, and if it simply becomes less-cold, then I'm fully aboard the sub-2c train.

There's the usual caveat of 'it's too early to be talking about this when we have a potentially baltic spell beforehand!' but I fail to see the harm in speculating.

Edited December 6, 2012 by Harve

[SteveB]

2.7c to the 6th, -2.5c

[BornFromTheVoid]

Yesterday was 0.9C. Today's minimum is -0.8C while maxima should be around 5.5C, so remaining at 2.7C on tomorrows update.

After that, the 06z GFS has the CET near

2.6C to the 8th (2.3)

3.0C to the 9th (6.0)

2.9C to the 10th (2.3)

2.8C to the 11th (1.1)

2.5C to the 12th (-0.1)

2.3C to the 13th (-0.4)

2.1C to the 14th (-0.4)

Guesses above 5C looking very unlikely now.

Even if we end up at a rather conservative 2.5C by the 15th, we'd need to average about 7.4C/day for the remainder of the month to get above 5.0C.

[BornFromTheVoid]

2.9C to the 8th

http://www.metoffice..._info_mean.html

With a minimum of 1.9C today and maxima a little over 8C, we'll likely be at 3.2C on tomorrows update.

After that, the 12z GFS has the CET at

3.3C to the 10th (3.8]

3.1C to the 11th (1.3)

2.9C to the 12th (0.8]

2.7C to the 13th (0.3)

2.8C to the 14th (4.6)

3.1C to the 15th (6.5)

3.3C to the 16th (6.2)

Despite that change to a milder outlook, I'd still put the upper limit for this month at about 5.5C, with a below average outcome still looking most likely.

Edited December 9, 2012 by BornFromTheVoid

[damianslaw]

2.9C to the 8th

http://www.metoffice..._info_mean.html

With a minimum of 1.9C today and maxima a little over 8C, we'll likely be at 3.2C on tomorrows update.

After that, the 12z GFS has the CET at

3.3C to the 10th (3.8]

3.1C to the 11th (1.3)

2.9C to the 12th (0.8]

2.7C to the 13th (0.3)

2.8C to the 14th (4.6)

3.1C to the 15th (6.5)

3.3C to the 16th (6.2)

Despite that change to a milder outlook, I'd still put the upper limit for this month at about 5.5C, with a below average outcome still looking most likely.

The odds of a below average month are still very high, the upcoming colder spell followed by the projected milder spell will likely cancel each other out, but we will still have a good 2 weeks to go and if the second half of the month is just average we would still end up appreciably below average.

[DR Hosking]

3.2c to the 9th

[DR Hosking]

3.2c to the 10th

[damianslaw]

CET should comfortably drop in the next 2-3 days, a number of places could see a couple of ice days before an upward turn from Friday- but not a particularly sharp rise, uppers over the weekend won't be that high and maxima will probably be in the high single digit figures for many. So at the half way stage we are likely to be around the 3 degree mark which is a preety low figure for the half way stage in December.

The second half of December is very much up in the air at present, but the odds of a below average month I say are still higher than an above average month.

[Harve]

Many places in the CET zone are still at -5/4c. Today could be a chilly one.

[DR Hosking]

2.9C to 11th

[Optimus Prime]

Lol at dat rise in CET coming up!

[The PIT]

Well if the GFS is right shouldn't alter much after Friday until a mild end of the month. A the moment a landing of 3.1C to 3.5c is possible.

[Methuselah]

I've a feeling that the upcoming warmer nights (3-6C) might cause quite a jump in the overall CET value?