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

[BornFromTheVoid]

Minimum today is 10.9C, while maxima look like being close to 15C, so an increase to 9.9C is likely on tomorrows update.

After that, the 12z GFS has the CET at:

9.9C to the 20th (11.3: +7.6) [Record High: 11.1C]
9.9C to the 21st (9.9: +5.7)
10.0C to the 22nd (10.6: +6.1) [Record High: 11.6C]
9.9C to the 23rd (8.5: +3.8]
9.9C to the 24th (9.3: +4.6)
9.7C to the 25th (6.4: +1.9)
9.6C to the 26th (5.9: +1.6)
9.4C to the 27th (5.5: +1.6)
9.3C to the 28th (6.5: 2.4)

To beat the record high average for the 19th, the maximum only needs to be 12.5C, which is pretty much guaranteed. To set the first December day of 13.0C or more, the max needs to be at least 15.0C, which is possible but not certain.
The cooler Christmas period is looking more likely now, which means a good chance to the CET dipping to the low 9s as we approach the last few days. At this stage, I'd say 8.7C to 9.7C is likely before corrections, and 8.2 to 9.7C after. Best guess is probably the high 8s.

[Roger J Smith]

Here's another record under threat this month:

From 1772 to 2014, every December managed at least one below normal day (either vs 1981-2010 averages or against the mean of all data which tend to be about 0.5 lower). Also, in absolute terms, every December has had one day of 4.2 or lower (that was set in 2013). These are the current top five that will now have to move over for 2015 which has managed a low of only 5.6 on 13th. Two dates are listed for 2013 as one is the absolute low but another is the lowest anomaly of its date. The mean of "all data" was a statistic that I generated from the 1772-2011 CET daily values and it has not been adjusted for 2012-14 yet. That adjustment will probably add 0.1 to a few days, then when 2015 gets into the set, to most days very likely (even a day that is 12 deg above normal adds only .05 deg to an average of 240 years).

 

YEAR ___________ MIN (date) ____ ANOMALY (all data) ___ ANOMALY (1981-2010)

01 2015 ___________ 5.6 (13th) _______ +1.1 __ (rank 1st) ____________ +1.0

02 2013 ___________ 4.2 (11th) ________ 0.0 __________________________ 0.0

........... (2013) ______ 4.6 (6th) ________ --0.2 __ (rank 3rd) ____________ --0.4

03 1934 ___________ 3.8 (22nd) ______ --0.1 __ (rank 2nd) ____________ --0.7

04 1806 ___________ 3.7 (2nd) _______ --1.3 __________________________ --2.1

05 1959 ___________ 3.4 (2nd) _______ --1.6 __________________________ --2.4

06 1924 ___________ 3.3 (11th) ______ --0.9 __ (rank t 5th) ____________ --0.9

06 1974 ___________ 3.3 (11th) ______ --0.9 __ (rank t 5th) ____________ --0.9

xx 1953 ___________ 2.9 (31st) ______ --0.5 __ (rank 4th) ______________ --1.5

The third ranked anomaly from 31st 1953 looks a lot less significant against modern averages, the mean for the 31st long-term being only 3.4 ... the coldest days long-term in December are all 3.4, 25th to 28th and 31st.

Since some might find this interesting, the following is the change from the mean of all data (1772-2011) to the mean of 1981-2010, listed from 1st to 31st:

7, 8,10,10,10, 2, 2, 0, 3, 0, 0, -1, 1, 0, 2, 3, 1, 1, 3, -2, 3, 5, 9,10,11, 9, 5, 7, 3, 6,10

(numbers are multiples of +0.1 C, e.g., 1st has risen 0.7 C deg, 2nd 0.8, and 12th, 20th have fallen 0.1, 0.2).

It is interesting to note that from 6th to 21st December looks about the same as it did long-term, but both ends of the month have warmed up in the recent 30-year normal period.

 

Edited January 1, 2016 by Roger J Smith

[The PIT]

Sunny Sheffield up to 8.6C which maybe the high point of the month.

[Summer Sun]

9.9c to the 19th

5.1c above the 61 to 90 average

5.0c above the 81 to 10 average

[Weather-history]

33 minutes ago, Summer Sun said:

9.9c to the 19th

5.1c above the 61 to 90 average

5.0c above the 81 to 10 average

The CET by the 19th May of 1996 was just 7.3C.

[The PIT]

It's smashing our highest ever December by 1.1C which was 7.5C in 1988  Strangely it may not be a wet month here 67% of rainfall and most of that fell on one day. Yet we've only had one dry day so far today may be next one.

[BornFromTheVoid]

Min today is 9.4C while maxima look like being in the high 11s, so remaining on 9.9C on tomorrows update.

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

9.9C to the 21st (9.8: +5.6)
9.9C to the 22nd (10.5: +6.0)
9.9C to the 23rd (8.5: 3.8]
9.8C to the 24th (8.9: +4.2)
9.7C to the 25th (7.5: +3.0)
9.7C to the 26th (8.5: +4.2)
9.6C to the 27th (8.8: +4.9)
9.6C to the 28th (8.7: +4.6)
9.6C to the 29th (9.9: +6.0)

Yesterday "only" averaged 12.7C, so we failed to reach the 13.0C mark, but did set the 3rd consecutive record for the latest date >12.0C.
This could be the end of the record daily averages with temperatures dipping back into the very mild, rather than exceptionally mild, category. The cooler spell around Christmas has largely gone too. This means a likely finishing CET of between 8.8C ad 9.8C before corrections, and 8.3C to 9.8C after.

[I remember Atlantic 252]

1 hour ago, Thunderbolt_ said:

I actually don't even think it's yet sunk in on me just how exceptional this month is turning out to be. Just to put this into perspective, that is 0.7C warmer than the warmest March on record and just 0.2C off being as warm as the warmest November on record.

9.9C wouldn't be bad for April either...

 

Just hope we don't have to pay for this!  we will do, I'm going for a lousy April/May with constant southerly tracking jet, little sun and below average temps, and who knows it may cost us a lousy June as well

[Optimus Prime]

Wow I thought April 2011 was exceptional in terms of anomalous warmth. This one does a pretty good job of marginalising it. Not a single night anywhere near freezing here and no ground frost, remarkable mid-late December warmth. T-shirt and shorts weather. The last few nights have been the warmest I have ever known it (in terms of the warm gusty wind) inside the Dec-Feb period (if not for March 2012 I'd include March in this as well)

Lets compare;

December 2010 here;

Mean Maximum 3.3c; 4.8c below normal

Mean Min -1.5c; 4.6c below normal

Mean +0.9c; 4.7c below normal

Current December to the 19th;

Mean Max 13.0c (4.9c above average)

Mean Minimum 10.2c (7.1c above average)

Mean Temperature; 11.6c (6.0 Above average)

Ok I'm comparing it to the 2003-2010 average which is on the cold side compared to the 61-90 (due to 2005 and 2008-2010) Mean Max against the long term is 4.2c above and 6.4c above for minimum

This is more memorable for me than Dec 2010 in terms of extremes.

 

Edited December 20, 2015 by Optimus Prime
Spacing

[March Blizzard]

1 hour ago, Optimus Prime said:

Wow I thought April 2011 was exceptional in terms of anomalous warmth. This one does a pretty good job of marginalising it. Not a single night anywhere near freezing here and no ground frost, remarkable mid-late December warmth. T-shirt and shorts weather. The last few nights have been the warmest I have ever known it (in terms of the warm gusty wind) inside the Dec-Feb period (if not for March 2012 I'd include March in this as well)

Lets compare;

December 2010 here;

Mean Maximum 3.3c; 4.8c below normal

Mean Min -1.5c; 4.6c below normal

Mean +0.9c; 4.7c below normal

Current December to the 19th;

Mean Max 13.0c (4.9c above average)

Mean Minimum 10.2c (7.1c above average)

Mean Temperature; 11.6c (6.0 Above average)

Ok I'm comparing it to the 2003-2010 average which is on the cold side compared to the 61-90 (due to 2005 and 2008-2010) Mean Max against the long term is 4.2c above and 6.4c above for minimum

This is more memorable for me than Dec 2010 in terms of extremes.

 

March 2012 generally had cool/cold, still and clear nights. Pretty much the opposite to now and is the reason it was cooler than this month up 'till now. 

[Optimus Prime]

You're right my highest minimum in March 2012 was 9.6c on the 10th. Still some 6c above average. I do remember the late evenings being notably warm that month though.

[The PIT]

A cooler night than expected kept the average temp on a warm 8.6C

Locally forecast shows a slow drift downwards so anywhere between 8.2C to 8.4C I reckon for us.

[BornFromTheVoid]

Min today is 5.8C, while maxima looking like hitting the 13s early tomorrow morning, so the CET should remain on 9.9C on tomorrows update.

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

9.9C to the 22nd (9.5: +5.0)
9.8C to the 23rd (8.2: +3.5)
9.7C to the 24th (8.7: +4.0)
9.7C to the 25th (8.1: +3.6)
9.6C to the 26th (8.6: +4.3)
9.7C to the 27th (11.9: +8.0) [Record High: 10.6C]
9.7C to the 28th (10.2: +6.1)
9.7C to the 29th (9.8: +5.9)
9.8C to the 30th (12.1: +7.9) [Record High: 11.0C]

Seems the GFS is flirting with the idea of more record breaking temps after Christmas. Perhaps a 10C+ finish shouldn't be ruled out just yet?

 

Edited December 21, 2015 by BornFromTheVoid

[Summer Sun]

9.9c to the 20th

5.1c above the 61 to 90 average

5.1c above the 81 to 10 average

[Milhouse]

Actually felt chilly today with lower upper temps and fairly brisk winds. Temps were still in double figures however.

Edited December 21, 2015 by Milhouse

[The PIT]

7 minutes ago, Milhouse said:

Actually felt chilly today with lower upper temps and fairly brisk winds. Temps were still in double figures however.

It's called being climatised. Spelt wrong I know. We are all used the mild weather so even it drops down mild from very mild it feels cold.

Sunny Sheffield should remain on 8.6C tomorrow unless tonight is colder than expected which is unlikely.

[March Blizzard]

10 hours ago, BornFromTheVoid said:

Min today is 5.8C, while maxima looking like hitting the 13s early tomorrow morning, so the CET should remain on 9.9C on tomorrows update.

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

9.9C to the 22nd (9.5: +5.0)
9.8C to the 23rd (8.2: +3.5)
9.7C to the 24th (8.7: +4.0)
9.7C to the 25th (8.1: +3.6)
9.6C to the 26th (8.6: +4.3)
9.7C to the 27th (11.9: +8.0) [Record High: 10.6C]
9.7C to the 28th (10.2: +6.1)
9.7C to the 29th (9.8: +5.9)
9.8C to the 30th (12.1: +7.9) [Record High: 11.0C]

Seems the GFS is flirting with the idea of more record breaking temps after Christmas. Perhaps a 10C+ finish shouldn't be ruled out just yet?

 

At this juncture, how likely would you consider a post-correction final figure of 9.2C or above, equalling or beating the warmest March on record?

 

 

[Scorcher]

Surely beating the March record is odds on now...if the downward correction is anything like November's, ie. non-existent. Those mild days now showing for after Christmas should seal it I'd have thought. The December record is all but gone now. Virtually impossible for it to drop that low now with the outlook as it is.

[BornFromTheVoid]

1 hour ago, March Blizzard said:

At this juncture, how likely would you consider a post-correction final figure of 9.2C or above, equalling or beating the warmest March on record?

 

The 18z would have the month finishing at about 9.4C before corrections. So based on that, I'd guess about 50/50 on at least equalling the March record after corrections are applied.

[Weather-history]

On 20 December 2015 at 11:46 AM, Summer Sun said:

9.9c to the 19th

5.1c above the 61 to 90 average

5.0c above the 81 to 10 average

December warmer than the April in the same year? Last time that happened was 1986.

 

[Timmytour]

A December CET of 9.4 would, I think, deliver an annual CET of around 10.3C and be the first time since record began that a December was within a degree of the Annual CET for the same year, and only the 4th time it was within 2C of it.

It would be a December with a higher CET than 60% of years on record have had!

[Weather-history]

Jeez look at these 

[The PIT]

Sunny Sheffield 8.7C matching November and the 6th time that December has matched or been milder than November here.

[Summer Sun]

9.9c to the 21st

5.1c above the 61 to 90 average

5.1c above the 81 to 10 average

[BornFromTheVoid]

The minimum today is 7.2C, while maxima look like being in the mid 13s, so remaining on 9.9C on tomorrows update.

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

9.8C to the 23rd (8.3: +3.6)
9.8C to the 24th (8.6: +3.9)
9.7C to the 25th (8.2: +3.7)
9.7C to the 26th (10.1: +5.8]
9.8C to the 27th (11.1: +7.2) [Record High: 10.6C]
9.8C to the 28th (9.0: +4.9)
9.8C to the 29th (10.8: +6.9)
9.9C to the 30th (12.3: +8.1) [Record High: 11.0C]
9.8C to the 31st (6.3: +1.9)