December CET

[kold weather]

I think its looking increasing probable we will be below average, though there is a risk of a southerly flow once this whole set-up does break down but thats too far out to make thats sort of call for now.

Mr.Data, thats an impressive 15 day drop for december 1938, just backs up my feelings that we will see a sub-4C month...quite amazing how many December's have come in below average in 00s, the only real month IMO to do this, I do wonder why!

[reef]

Another mild day yesterday at 8.2C on Hadley, taking the mean to the 9th to 6.3C.

The mean required over the remaining 22 days to hit the following figures by months end:

2.0C 0.2C

3.0C 1.6C

4.0C 3.1C

5.0C 4.5C

[Optimus Prime]

The period 10th - 15th comes in at 3.7c on the 12Z run. CET to the 10th is 6.3c (1.3c above normal) By the 15th the CET would be at 5.4c.

[stewfox]

Another mild day yesterday at 8.2C on Hadley, taking the mean to the 9th to 6.3C.

The mean required over the remaining 22 days to hit the following figures by months end:

2.0C 0.2C

3.0C 1.6C

4.0C 3.1C

5.0C 4.5C

By the 30^th November it was clear there would be mild mush for the first week of December and then signs of colder weather.

Hence I reduce my CET value for December from 5c to 3.8c.

I'm happy with that at present.

We can discount today I feel the CET will still nudge up a bit , but depending on the overnight temps re Friday we start a downward trend as we get into the colder snap.

Much will depend of course on the extent ,intensity and duration of the forth coming cold snap.

Although the potential for a number of -0 CET days is there

Whats the coldest CET day on record ?.

My punt last 30 years would be one of those days in January 1982 ??

Edited December 10, 2009 by stewfox

[Thundery wintry showers]

There was a spell under an inversion in late January 1963 with a CET mean of -8.4 or thereabouts, beating anything in 1947, 1982 or 1987. I haven't checked to see if it's the lowest ever, though.

[Snowly does it]

By the 30^th November it was clear there would be mild mush for the first week of December and then signs of colder weather.

Hence I reduce my CET value for December from 5c to 3.8c.

I'm happy with that at present.

We can discount today I feel the CET will still nudge up a bit , but depending on the overnight temps re Friday we start a downward trend as we get into the colder snap.

Much will depend of course on the extent ,intensity and duration of the forth coming cold snap.

Although the potential for a number of -0 CET days is there

Whats the coldest CET day on record ?.

My punt last 30 years would be one of those days in January 1982 ??

Xmas Day 1796 was a -10.6 CET day!

Dec 12 1981 -8.5

Dec 13 1981 -6.5

The 1995 spell in December got down to -4.7 on the 28th

I think there are only 3 sub -5 December days since 1900 (cursory glance only)

A December day under -5 would be notably cold for the whole series back to 1772 (daily records held to here) under -3.5 notably cold for the post-war period

Winter generally, Jan 1987 got down to -7.7, Jan 1982 -7.6, Jan 1963 -8.2, Jan and Feb 1947 -6.4 and -6.7

Jan 20 1838 -11.9 is the lowest I have found so far

The first 27 days of Jan 1814 were sub zero (as were 27-31 Dec 1813)

[osmposm]

Actually - amazingly - 25/12/1796 was even colder than that...-10.8 !!!

But that, of course, was long before the...um...m*d*rn winter .

"December 2000 had a CET of 9.1 by mid-month and ended up as 5.8 whilst December 1979 was 8.7 mid-month also ended as 5.8 and December 1831 had a CET of 8.5 by mid-month and that too ended as 5.8......It is clear that this December will not be as mild as that by mid-month."

Which is a shame, really, since my guess for this December was....5.8 !

Edited December 11, 2009 by osmposm

[Weather-history]

Lowest CET daily means ©

-11.9: 20/1/1838

-10.8: 25/12/1796

-9.3: 4/1/1867

-9.2: 8/1/1841

-8.9: 25/1/1795

-8.9: 19/1/1823

-8.8: 9/2/1816

-8.5: 15/1/1820

-8.5: 12/12/1981

-8.4: 27/12/1798

-8.4: 23/1/1963

-8.3: 8/2/1895

-8.2: 28/12/1798

-8.2: 15/1/1838

-8.2: 24/1/1963

-8.1: 21/1/1881

-8.0: 15/1/1929

The 3rd one in the list is interesting, 4th Jan 1867, because 3 days later it was 9.8C!

Edited December 11, 2009 by Mr_Data

[Stu_London]

Suprisingly we squeezed another small rise out of the CET for the 10th.

Hadley now at 6.4C to the 10th

This will definately be the last rising day for a while and is almost certainly the peak value for December 2009.

GFS 06z suggests a CET of 4.1C by the 20th, although it may be a little lower as I think the GFS may be underdoing some of the minima, especially if the flow were to slacken with a little snow cover later in the period.

Edited December 11, 2009 by Stu_London

[kold weather]

Today looks like being quite a cold one, as I expected fog seems to be holding temps back in quite a few places, struggling to get 3-4C in many locations and some are a good deal colder then that still.

Much depends on the exacts of the stations, going to be hit and miss with regards to the fog. Overnight mins were also much colder then the GFS suggested which doesn't really surprise me all that much either.

I'd imagine today will come out at 2-3C but could be higher or lower depending on fog, etc.

[Optimus Prime]

Yeah GFS and the BBC forecast did awful for predicting the temperatures last night. Predicted low was 3c and insead dropped to -1.2c.

CET will take a hammering today. Perhaps dropping by 0.5c.

[damianslaw]

Believe we have hit the maxim the CET will get too this month unless of course there is a ridiculous warm up in the latter parts - very much doubt it though.

Watch the CET take a tumble over the next few days, maxes in the CET zone will be below the average for the foreseeable future though mins not that so, but by middle of next week we could be seeing some low mins in the midlands.

[kold weather]

Yep the CET should drop away quite nicely.

Models still seem to be extending the cold spell at the moment and how much this continues will make a big difference to the CET. Looks like we will have a reasonable shot at the coldest December since 1996 but much depends on the exacts of this cold spell and whether we can muster any ice days, which is quite possible...

3.4C would beat December 2001...but even if we don't I'd have thought that a below average month is highly likely at the moment, yet another one to add to the 00s years that had a below normal December.

[Weather-history]

3.4C would beat December 2001...but even if we don't I'd have thought that a below average month is highly likely at the moment, yet another one to add to the 00s years that had a below normal December.

3.4C would beat December 2008 (CET: 3.5) which was the coldest December for the CET since 1996, December 2001 was 3.6

[summer blizzard]

Phillip Eden has the CET at 5.3C, 0.2C above average, looking at the models i would favour a outurn between 2C and 3C.

[osmposm]

Phillip Eden has the CET at 5.3C, 0.2C above average, looking at the models i would favour a outurn between 2C and 3C.

I certainly hope so, despite my 5.8 guess. A sub-3.0 month has been a long time coming.

3.0 please

Ah, 'the triumph of hope over experience' (as someone once said of second marriages).

And why not, indeed? Although it's been 13 years since the last 3.0 or below December, that's much the same gap as there was between 1981 & 1995. Trouble is, I suspect last year's 3.5 was our "cold" one for the decade....though we could, of course, always get a pair, like '95 & '96.

I shall also be very happy if my cynical comment above comes back to bite me, and my suspicion proves complete nonsense.

EDIT: just checked climate-uk where (unless I've got a cache problem) it's still showing 5.8 (not 5.3) to the 12th. From there to hit 2.9 we'd need the 19 days 13th-31st to have an av daily CET mean of scarcely more than 1.0, which I think is pushing it some.

[David-kig]

I certainly hope so, despite my 5.8 guess. A sub-3.0 month has been a long time coming.

I shall also be very happy if my cynical comment above comes back to bite me, and my suspicion proves complete nonsense.

EDIT: just checked climate-uk where (unless I've got a cache problem) it's still showing 5.8 (not 5.3) to the 12th. From there to hit 2.9 we'd need the 19 days 13th-31st to have an av daily CET mean of scarcely more than 1.0, which I think is pushing it some.

with the north sea nearly 0c i think its possible giving it stays cold

[Polar Gael]

I am cautiously optimistic about this month's guestimate if the "modern whatitsname" plays ball...

[Roger J Smith]

I think realistically from the models the colder period to come will average near 2.5 and not much lower, then there's the question of how mild it could get Christmas to New Years, I have a mild spike in my LRF on the last two days of the month. So I'm going to say that the current value will fall to about 3.5 at lowest (22nd?) then recover to 4.5 to 5.0 at month's end. The North Sea is closer to 8 C than 0 C by the way.

[Optimus Prime]

The 06Z is a very cold run. Period 14th - 20th averages 0.6c. With the CET at around 5.6c to the 13th the CET would be around 3.9c by the 20th.

A huge range is on offer. Between 2.8c and 5.5c.

[SteveB]

Hadley on 5.7 up to the 13th, +0.8.

[damianslaw]

Likely to be close to the 3's by Sunday I feel with widespread low maxes from Thursday onwards, could be on course to beat last year if we maintain the Greenland High through to the end of the month.

[Optimus Prime]

Likely to be close to the 3's by Sunday I feel with widespread low maxes from Thursday onwards, could be on course to beat last year if we maintain the Greenland High through to the end of the month.

To require the CET to be down to the 3s by Sunday would need every day from today to average 0.8c. Possible.

[Lettucing Gutted]

This year could see the biggest November to December cool down since 1995.

[damianslaw]

This year could see the biggest November to December cool down since 1995.

Yes it does have big potential to do this, a major cooldown over the next few days, fingers crossed the rest of the winter follows a similiar pattern to winter 95/96 albeit with a colder january.

Very high chance of the CET being below 4 degrees by Sunday.