C.E.T. forecasts for December 2015 (start of 2015-16 competition year)

[Roger J Smith]

Summer Sun, you might want to add a third line to your daily updates, comparing to previous highest values. The table looks like this:

 

11th ___ 9.7 __ 1898, 2000. (overtaken by 9.8 in 2015 but perhaps a three-way tie after adjustments?)

12th ___ 9.9 __ 2000 __ (9.8 in 1898)

13th ___ 9.7 __ 2000

14th ___ 9.4 __ 2000

15th ___ 9.2 __ 1898

16th ___ 9.0 __ 1898, 1918, 1934

17th ___ 9.1 __ 1898

18th ___ 9.2 __ 1898

19th ___ 9.0 __ 1898

20th ___ 8.8 __ 1934

21st ___ 8.6 __ 1934

22nd ___ 8.4 __ 1934

23rd ___ 8.3 __ 1934

24th ___ 8.2 __ 1934

25th ___ 8.1 __ 1934

26th ___ 8.0 __ 1934, 1974 (8.04 vs 7.96)

27th ___ 8.0 __ 1934, 1974 (8.03 vs 8.04)

28th ___ 8.2 __ 1974 __ 1934 was 8.0

29th ___ 8.2 __ 1974 __ 1934 was 8.1

30th ___ 8.1 __ 1934, 1974 (8.05 vs 8.13)

31st ___ 8.1 __ 1934, 1974 (both 8.09)

 

[reef]

If we're at 9.5C to the 21st, then the record is probably all but gone. We'd only need the remaining 10 days to average 5.4C to give a finishing value of 8.2C.

We were probably overdue an exceptionally mild December, but to potentially have one so much higher than the existing record is surprising to say the least.

It's worth noting aswell that an 8.2C December would only require the rest of the winter to average 6.1C for this to be the mildest winter on record. A long way to go yet until we contemplate that though!

[Roger J Smith]

Then again, Dec 1985 managed to climb as high as 8.3 on 21st before falling over 2 deg and eventually that winter produced a subzero month (Feb 86). The last GFS run I saw had some signs of much colder weather at times near the holiday week and I don't think a record-breaking December is anywhere near carved in stone yet. Would say the current output suggests a 7.5 to 8.0 finish for a new third (about how November went).

Anything under 6.5 will take a major revision of the model runs plus significant cold in last week of December.

Another record under threat this month would be the number of 10.0 or higher days, I believe the record was eight, and five consecutive. Will post something on that perhaps after the month is over because so many days this month will be subject to revision out of this category so not much point in speculating too much.

I counted 257 days in 243 previous years that made 10.0, sounds like an average of one every December but it works out more like two or more days in 30% of years, just a few managed one day, and the majority do not achieve one at all. A handful have exceeded five such days.

[Summer Sun]

9.6c to the 12th

4.7c above the 61 to 90 average

4.5c above the 81 to 10 average

0.3 below the daily record of 9.9 set in 2000

[peborant]

Station here is reading 5.8 for the month - very happy to have moved to Scotland tbh, despite the whole crazy CET's it feels quite wintry with snow in the hills pretty often, settling above 200-400m 

Tonight's min. 

[Summer of 95]

Are we looking at 9 consecutive months at 9C or above? I remember noticing in Nov 2009 that we were heading for 8, which had never happened before in 300 years. Now 9???

[BornFromTheVoid]

Min today is 2.9C, while maxima should be something close to 8.5C, so a drop to 9.3C is likely on tomorrows update.

The 12z GFS has the CET at:

9.1C to the 14th (6.8: +2.4)
9.2C to the 15th (10.2: +5.6) [Record High: 11.2C]
9.3C to the 16th (10.7: +6.1) [Record High: 10.8C]
9.5C to the 17th (13.3: +8.9) [Record High: 11.6C]
9.6C to the 18th (10.5: +6.1)
9.6C to the 19th (10.1: +5.8)
9.7C to the 20th (11.4: +7.7) [Record High: 11.1C]
9.5C to the 21st (6.8: +2.6)
9.5C to the 22nd (8.1: +3.6)
 

Odds now in favour of recording a record mild December methinks. That forecast value of 13.3C on the 17th would be the warmest December day on record, and the first to exceed the 13C mark, so definitely on to keep an eye on.

Edited December 13, 2015 by BornFromTheVoid
mistake...

[reef]

7 minutes ago, BornFromTheVoid said:

Min today is 2.9C, while maxima should be something close to 8.5C, so a drop to 9.1C is likely on tomorrows update (possible low point of the month?).

The 12z GFS has the CET at:

9.1C to the 14th (6.8: +2.4)
9.2C to the 15th (10.2: +5.6) [Record High: 11.2C]
9.3C to the 16th (10.7: +6.1) [Record High: 10.8C]
9.5C to the 17th (13.3: +8.9) [Record High: 11.6C]
9.6C to the 18th (10.5: +6.1)
9.6C to the 19th (10.1: +5.8)
9.7C to the 20th (11.4: +7.7) [Record High: 11.1C]
9.5C to the 21st (6.8: +2.6)
9.5C to the 22nd (8.1: +3.6)
 

Odds now in favour of recording a record mild December methinks. That forecast value of 13.3C on the 17th would be the warmest December day on record, and the first to exceed the 13C mark, so definitely on to keep an eye on.

When you have the daily anomalies laid out like that it gives you an idea of just how exceptionally mild this spell is. Bearing in mind we're already on 9.6C, the next 9 days based on your figures above have an anomaly of +5.4C. Absolutely bonkers.

9.5C to the 22nd would also only require an average of 4.8C over the remaining 9 days to give a finishing value of 8.2C. Its looking like a case of how much we'll beat the record by rather than if. We could well be up there with May 1833 and April 2011 by the end of the month for largest gap to 2nd warmest.

Edited December 13, 2015 by reef

[Summer Sun]

Looking at GFS I can see some daily records going later on in the week

[Methuselah]

I've a sneaky feeling that my guess (5.5 or 5.6C) might be a tad 'on the low side'?

[Gustywind]

Yep I reckon 9c minimum for finishing value would be my current guess, quite astonishing and scary. The pattern is well and truly locked in for at least 2 weeks, possible fleeting PM blast for the north, but that won't impact on the CET.

i actually can't see the pattern properly breaking till last third of January to be honest,  it's so entrenched and the polar vortex is only likely to strengthen further for a few weeks yet.

 

[Evening thunder]

Pretty remarkable.. I wonder if some southern parts could have even higher positive anomalies than the CET zone? Down here we haven't been affected at all by the 'cooler' stuff slightly affecting the CET zone at the moment.. with double figure mins last night. Here I am on a mean of 11.0C so far (though that is an average of all readings not min+max), and that doesn't look like dropping over the next week..

Have parts of the UK ever recorded a month approaching 5C above average? as that's what we're talking about at least down here if the last week of December isn't significantly cooler.

[BornFromTheVoid]

14 minutes ago, reef said:

When you have the daily anomalies laid out like that it gives you an idea of just how exceptionally mild this spell is. Bearing in mind we're already on 9.6C, the next 9 days based on your figures above have an anomaly of +5.4C. Absolutely bonkers.

9.5C to the 22nd would also only require an average of 4.8C over the remaining 9 days to give a finishing value of 8.2C. Its looking like a case of how much we'll beat the record by rather than if. We could well be up there with May 1833 and April 2011 by the end of the month for largest gap to 2nd warmest.

It really is a remarkable spell of weather. With the finishing value, we also have to consider corrections, which recently, have been anything from less than 0.1C up to 0.4C.
The anomaly of +8.9C forecast, if accurate, for the 17th would also be the 3rd most positive daily anomaly in a record of over 89,000 days! (The largest +ve daily anomaly is +9.8C from April 29th, 1775, which has a daily value of 19.7C)

[Weather-history]

If this December becomes the warmest on record, it would be exceptionally mild for November never mind December, it would be exceptionally warm for March. Warmest March is 1957 with 9.2C. It would be staggering if it beats this. 

[I remember Atlantic 252]

Yes Mr D, Craig Evans the closest here, even I underestimated the mildness, but I didn't underestimate the westerlies, my prediction was 'westerlies the whole month to dominate at 7.1C CET

[Gustywind]

Ha ha I tell you what that March record is definitely under threat! Incredible.

[Gustywind]

Annoyingly it really hasn't felt that great, mainly due to the persistent cloud, rain and wind here. I'm really struggling with SAD at the moment, just wish it could be sunny and mild, but that seems very hard to achieve in winter months.

[J10]

1 hour ago, Ed Stone said:

I've a sneaky feeling that my guess (5.5 or 5.6C) might be a tad 'on the low side'?

 

It is too late to change it now.

I went 4.7c

Edited December 13, 2015 by J10

[summer blizzard]

The incredible thing at the moment is the margin of victory over the potential record if we are above 9C to the 20th. This looks like a April 07/11 figure whereby the record is not inched but potentially thrashed.

That raises another point though, we've seen records in one month being followed a few months later by others so who knows.

[Captain Shortwave]

22 minutes ago, J10 said:

 

It is too late to change it now.

I went 4.7c

The output changed pretty much when I lowered my value from well above normal to slightly above normal.

My bad.... sorry guys 

[Don]

Well, looking at the CFSv2 outlook for the next few months, the remarkable mildness is only only going to continue.  I know some don't rate this model but it has been ultra consistent for months now with its exceptional mild signal for winter and so far, it's being proved correct.  Wouldn't be at all surprised to see that 70f recorded before winter's out.  I think Winter 2015/16 could well be a real eye opener.......

[March Blizzard]

4 hours ago, Weather-history said:

If this December becomes the warmest on record, it would be exceptionally mild for November never mind December, it would be exceptionally warm for March. Warmest March is 1957 with 9.2C. It would be staggering if it beats this. 

I mentioned this somewhere recently, a Decemeber warmer than the warmest March. 9.3C or higher...we couldn't, could we?!!

Anyway, in regards to the CET comp, it looks I'll get off to a good start with third place (7.2C) barring any serious cool-down late in the month. Craig Evans has pretty much already won this month- wouldn't it be funny if he went too low! 

[I remember Atlantic 252]

8 hours ago, March Blizzard said:

I mentioned this somewhere recently, a Decemeber warmer than the warmest March. 9.3C or higher...we couldn't, could we?!!

Anyway, in regards to the CET comp, it looks I'll get off to a good start with third place (7.2C) barring any serious cool-down late in the month. Craig Evans has pretty much already won this month- wouldn't it be funny if he went too low! 

I'll be closer in Jan! but yes Craig could have guessed too low!

[Summer Sun]

9.3c to the 13th

4.4c above the 61 to 90 average

4.2c above the 81 to 10 average

Daily high 9.7c set in 2000

[BornFromTheVoid]

Minimum today is 3.7C, while maxima look like reaching the high 8s, so a drop to 9.1C is likely on tomorrows update.

After that, the 06z GFS has the CET at:

9.2C to the 15th (10.3: +5.7) [Record High: 11.2C]
9.3C to the 16th (11.0: +6.4) [Record High: 10.8C]
9.5C to the 17th (13.3: +8.9) [Record High: 11.6C]
9.7C to the 18th (11.9: +7.5) [Record High: 11.8C]
9.8C to the 19th (12.3: +8.0) [Record High: 11.6C]
9.8C to the 20th (10.8: +7.1) [Record High: 11.1C]
9.8C to the 21st (9.7: +5.5)
9.9C to the 22nd (11.3: +6.8) [Record High: 11.6C]
9.8C to the 23rd (7.2: +2.5)
 

Just when you think the outlook can't get any milder...

Some remarkable records possible over the next week. That 13.3C for the 17th would be the warmest daily CET for December on record, and would also be the latest in the year both a >12C and >13C CET day has been record (the previous latest >13C day was Nov 23rd, and the latest >12C day was December 12th (though we have exactly 12.0C for Dec 29th)). But it looks like the record for the latest >12C day could be broken 2 days later again.

Being conservative, and guessing that the GFS is overestimating temps a tad, if we are on 9.7C to the 21st, we'd need the last 10 days to average 4.9C to drop back to 8.1C, the warmest December on record. To drop back to 8.6C, where we'd likely be safe from end of month corrections, we'd need to average 6.4C for the remainder of the month.
To drop back to the 81-10 average of 4.6C, we'd need to he last 10 days to average -6.1C!