December CET

[AderynCoch]

Hadley down to 3.9 to the 22nd Dec

Exactly the same as 2008 at this point - now for the first time, 2009 will be cooler.

2008 rose to 4.2C at Boxing Day, before dropping to 3.5C at New Year's Eve to finish the month - surely 2009 will now beat this?

[Snowly does it]

Hadley now at 3.7 to the 23rd and last night down as -2.1 so a further fall today with supressed maxima in the western CET stations. Probably down to 3.6. If it gets cold tonight then a further fall Xmas day likely before 2 days of no or slight upward movement and then, perhaps, a slide down to New Year to finish low 3s.

In terms of corrections, Rothamstead, one of the CET sites, had the lowest minima in the East of -8.7 on the night of the 22nd, Pershore also got down to -5 or so in the early hours that day. One example of somewhere I would expect to see a fairly drastic correction.

It would be interesting to see where Manley sits right now, given where it was on the 20th, probably around the 3.2 or 3.3 mark.

[Guest]

5.4C

[Supercell]

5.4C

...

[kold weather]

Hadley now at 3.7 to the 23rd and last night down as -2.1 so a further fall today with supressed maxima in the western CET stations. Probably down to 3.6. If it gets cold tonight then a further fall Xmas day likely before 2 days of no or slight upward movement and then, perhaps, a slide down to New Year to finish low 3s.

In terms of corrections, Rothamstead, one of the CET sites, had the lowest minima in the East of -8.7 on the night of the 22nd, Pershore also got down to -5 or so in the early hours that day. One example of somewhere I would expect to see a fairly drastic correction.

It would be interesting to see where Manley sits right now, given where it was on the 20th, probably around the 3.2 or 3.3 mark.

Yep thats been the case quite a bit in this cold spell, I'd imagine there will be a fair few corrections being made to the December CET.

Still some uncertainties as to how quickly the cold air gets dragged down southwards into the CET zone, the GFS has cooler temps back in by the 28th again whilst the UKMO looks a bit slower in that regard. I'd suggest we will see 2-3 days where we get a CET mean upto 5C (so closer to average) but after that we will probably be back to the colder airflow yet again...

IMO we really could be looking at on of the coldest 30 days we've seen since 96-97.

[Weather-history]

Unfortunately, most of the cold has been concentrated in two months aswell! (January and December)

Not sure why unfortunately because I rather have the cold when it should be cold ie in the winter months rather than the summer months, if you see what I'm saying.

11th-23rd December CET: 1.6C

[Nick L]

Could we get a sub 3c December? Or will we need to have a substantial downwards correction (we seems pretty possible)?

[osmposm]

How could August possibly be mild?

At 16.6C it was 0.8C above the 1961-1990 August average of 15.8C

I think OP is referring to the English, not the temp. "Mild" is a term that's generally only used when describing something that is normally cold: a winter month can be 'mild' but not a summer one. "Warm", on the other hand, can be used for either.

5.4C

Mike, if you think you've just posted an entry in the January CET contest.....you're in the wrong thread!

[Optimus Prime]

It's gojng to be interesting to see how low the Scottish average temperature will drop. Very cold until the end of the month up there. Certainly looking like the coldest month of this century and likely to be the coldest December since 1995 which had an average temperature of 0.5c.

2008 2.3c (-0.8c)

2001 2.4c (-0.7c)

Average 71-000 is 3.0c

According to Manley Scotlands running about 2.2c.

[kold weather]

Yep OP, temps up there are really going to keep low thats for sure, esp with regards to those mins which stay very low.

Going to be very interesting to see what happens down here as well for that matter, with alot of uncertainty as to whether we get one last final cold day in December as the NE airflow starts to come back in again.

Looks quite possible that after adjustments we will be below 3.6C and therefore get a month that comes in 1.5C below normal.

[West is Best]

Manley 3.2C to 24th. As Hadley was 3.9C to 29th, looking at the synoptics which keep pushing the milder air away, a sub 3C month is looking increasingly possible. The coldest since 1996/7?

[Optimus Prime]

Manley to the 24th;

Mean Max; 5.7c (-2.2c)

Mean Min; 0.7c (-1.8c)

And yeah West a sub 3c is looking possible. I think 3.1c is quite likely and so the first 2.0c below normal month in 14 years!

Hadley is once again higher then Manley. I really don't understand this as it was always the other way around aside from the odd month here and there.

[Stu_London]

Hadley has updated to the 24th and is 3.6 (rounded up from 3.56)

The GFS 06z suggests a final outcome of 3.2 - sub 3 still possible with some end of month adjustments.

Anyway - back to my parsnips!

Edited December 25, 2009 by Stu_London

[kold weather]

Given there should be decent adjustments if we can get down to 3.2C then I'd imagine either 3.0 or 2.9C would be the final outcome after adjustments...

[Optimus Prime]

Given there should be decent adjustments if we can get down to 3.2C then I'd imagine either 3.0 or 2.9C would be the final outcome after adjustments...

Well if there aren't any real adjustments (like January, 0.3c was taken of that month) then we'll have to start question Hadleys reasons why it's coming in so high these days.

[Stu_London]

Hadley down to 3.5C after yesterday came in at 2.8C

If the low goes north we can expect a slight uptrend overall to the end of the month.

If it goes south then we could get close to 3.0C, although a decent downward adjustment would be needed for that in all probability.

[snowlover2009]

if next week stays cold, anyone think that this december will have a colder cet than last years december.

[damianslaw]

Good chances of this December being the coldest since 1996, beating last year and 2001, it will be a very close call to see whether we record a sub 3 month- the first I believe of the whole decade? Jan 2001 being closest at 3.3 degrees, can anyone verify this...

I think this Dec has surprised many who were believing although unlikely to be significantly mild, it would be average at best.

[Weather-history]

Good chances of this December being the coldest since 1996, beating last year and 2001, it will be a very close call to see whether we record a sub 3 month- the first I believe of the whole decade? Jan 2001 being closest at 3.3 degrees, can anyone verify this...

January 2009 was 3.0 and was the coldest month of the 2000s....so far.

11th-25th December CET: 1.6C

Edited December 26, 2009 by Mr_Data

[AderynCoch]

if next week stays cold, anyone think that this december will have a colder cet than last years december.

Almost certainly.

[Optimus Prime]

Period 26th-31st comes in at 2.9c. Cuurent HADCET is at 3.5c. The final outcome would be 3.4c before any adjustments.

1946 3.1c

1962 1.8c

1978 3.9c

[AderynCoch]

Provisional CET for Christmas Day is 2.8C - that's still dragging the overall CET down (currently at 3.5C). Boxing Day may show up as over 3.5C, but it shouldn't really make a dent on the overall average. From then onwards it should be sub-3C days again until January, shouldn't it?

In short, the current CET is about the same as 2008 - and can't really get much higher.

[Snowly does it]

Hadley at 3.5 (3.54 rounded down) to the 26th, Boxing Day was 3.9 so well below average despite the milder conditions. However last night is a provisional 3.3 and today will come in around 6 or 7 for maxima in all likelihood so tomorrow will see us at 3.6, but should fall from there.

If tomorrow sees us update to a flat 3.6, we would need the last 4 days to average -1.6 or so to come in under 3 unadjusted. However given the discrepancy between Hadley and Manley, there may be a downward correction. If 0.3 were the correction like last Jan (for example) then an average of 0.8 over the last 4 days of Dec would be enough to see us home under 3. That being said, odds look against it now - I favour an unadjusted 3.4 and an adjusted 3.2

[shuggee]

This cold spell has certainly put the holy grail of a sub 3ºC CET into some perspective for me - indicating just what is required to get it down there...

We are now at day 11 of lying snow here in central Edinburgh, and it's only been the last 3 days that has seen anything but snow falling from the sky - with sleet. And this has included 4 ice days.

That makes for a cold spell Edinburgh average temp of 11 days at -2.54ºC, yet the month of December is still at 3.19ºC.

[Snowly does it]

Yesterday was 4.5 provisionally so Hadley has gone to 3.6 (3.58 rounded up).

Last night was -2.0 so todays fairly cool maxima will see us back down to 3.5 tomorrow. From there just three days remain in the month so at best with low minima and suppressed maxima we may find ourselves at an unadjusted 3.2 or 3.3. The next Manley update might give us an idea of how far apart the two figures are (still at 3.2 to 24th December)

I would guess we will see an adjusted final result of 3.1 or 3.2 - possibly the first month of the century to be 2 degrees below the 71-00 average and almost certainly the biggest negative anomoly versus the 71-00 this century (needs to be less than 3.5 for this)