December 2024 C.E.T. and EWP forecast contests -- start of 2024-25 contest year -- all welcome

[Roger J Smith]

EWP is around 7 mm now and GFS predicts it will be 45-50 mm after 19 Dec. 

CET forecast would be in a range of 4.5 to 5.5 by 19th, several occasions where quite mild air makes either a brief visit or a glancing blow to south which increases uncertainty. 

[J10]

I plan to change the baseline in the CET comp to be 1991-2020 if no one has any objections.

[Summer Sun]

8.2 to the 3rd

3.7c above the 61 to 90 average

2.4c above the 91 to 20 average

[Summer Sun]

7.4 to the 4th

2.9c above the 61 to 90 average

1.7c above the 91 to 20 average

[Derecho]

Evening all, it looks like the latest EC has the CET stubborn to drop initially, with only a slow drop to colder temperatures mid month due to minima holding up. The EC is amongst the coldest ensemble members for the 14th and 15th so it wouldn't surprise me if we are still in the mid 6s halfway through this month.

After that is uncertain but there are signs of cold dipping into SE Europe mid December which ain't a good proxy for colder weather here. I'm beginning to think this could be another mild December but a large amount of uncertainty at this stage of course. 

[Don]

22 minutes ago, Derecho said:

After that is uncertain but there are signs of cold dipping into SE Europe mid December which ain't a good proxy for colder weather here. I'm beginning to think this could be another mild December but a large amount of uncertainty at this stage of course.

First of three mild months?! 

[Don]

24 minutes ago, Derecho said:

After that is uncertain but there are signs of cold dipping into SE Europe mid December which ain't a good proxy for colder weather here.

Unless you're considering a 'cold' winter break in that vicinity! 

[WYorksWeather]

 Derecho If we did go for a very mild second half, then perhaps the 11C CET finish could still be on the table? I still think it's very unlikely though for now, unless we see a strong signal for mild conditions start to ramp up in the next few days.

[Roger J Smith]

To end of NOV 2024 is running ahead of 2023 for EWP (1064.0 mm vs 1032.5 mm) but last year DEC was very wet (161.3 mm) to end year at 1193.8 mm, ranked 7th wettest. This month will need 130 mm to stay even with last year and only 82 mm is needed for 10th place. 

EWP ___ Jan _Feb _mar _ Apr _may _Jun _July _Aug _Sep _Oct _ Nov _ Dec _____ YEAR

2023 __ 97.6  16.5 136.7 76.8 43.8 49.3 130.5 85.7  91.1 177.5 127.1 161.3 __ 1193.8

2024 __ 97.2 151.8 111.9 95.8 91.7 33.7  90.6 48.8 154.3 102.5  85.7 

In the 259 years of EWP records, the wettest consecutive years prior to 2023-2024 by ranks exceeded were 2019-2020 ranking 20 and 19. Total precip was 2192.2 mm exceeded 4 times:

(4th_ 1768-69, 2198.2 mm) ... (1767-68 was also close at 2188.5 mm)

(3rd_ 1876-77, 2201.1 mm). ...

(2nd_ 2000-01, 2204.4 mm). ... We have already broken these totals (2260 and adding probably 50 more by 20 Dec).

(1st_ 1999-2000, 2268.5 mm). Now passing it later Friday probably, for a new 2-year record.

 

 

[damianslaw]

A cool down from tomorrow for the foreseeable but only back closer to average with nothing especially cold, we might struggle to get out of the 6s through mid month. 

[The PIT]

Sunny Sheffield at 7.1C

+1.2C above 1961- 1990 average

+0.4C above 1991 - 2020 average.

Rainfall 17.1mm

33.4% of the 1961 - 1990 Dec monthly average

31.7% of the 1991 -2020 Dec monthly average.

[Summer Sun]

7.8 to the 5th

3.3c above the 61 to 90 average

2.1c above the 91 to 20 average

[Don]

 damianslaw We need this month to do a December 2000, which had a CET of 5.4C.  Nothing to do with the fact I went for 5.4C this month though!

[The PIT]

Sunny Sheffield up to 7.3C

+1.5C above the 1961- 1990 average.

+0.7C above the 1991 - 2020 average.

Rainfall up to 33.2mm

40% of the 1961 - 1990 average

37.2% of the 1991- 2020 average.

[North-Easterly Blast]

 Don December 2000 had a CET of 5.8 in the legacy series.  5.4 is a huge downward adjustment on a now different series.  In my opinion the only way that you can have one dataset that says any month, or a day for that matter, has a different CET is if different stations are used to calculate it.  It is perfectly possible for two stations relatively close to one another to record a max or min temp for a day that is slightly different.

[Summer Sun]

7.7 to the 6th

3.1c above the 61 to 90 average

2.1c above the 91 to 20 average

[Metwatch]

Cooling down through to next week, but it won't be especially chilly so the CET shouldn't drop that fast or below around 5C. Then signs for the second half of December to turn milder again with a strong zonal flow.

Anywhere between 5-7C for December's overall CET is plausible i'd say. Unless there is a cold spell with decent duration in the second half, can't see the CET falling much below 5C currently.

[Summerlover2006]

What has been the longest rain duration this week because since like Friday night it feels like it hasn’t stop raining for more then an hour so surely some places have not stopped all weekend?

[The PIT]

Sunny Sheffield down to 7.2C

+1.4C above the 1961- 1990 average

+0.7C above the 1991 -2020 average

Rainfall 47.3mm

57.1% of the Monthly average 1961 - 1990

54.1% of the monthly average 1991- 2020

[Summer Sun]

7.7 to the 7th

3.1c above the 61 to 90 average

2.1c above the 91 to 20 average

[Roger J Smith]

Years since 1974 with a warmer start (1-7 Dec) than 7.7 ...

2015 _10.3

1979 _ 9.9

1985, 2000 _ 9.6

1974 _ 9.5

2006 _ 9.2

1986, 2007, 2018 _ 8.5

1993, 1994 _ 7.8

1984, 2024 _ 7.7

-----------

11 were warmer and one was equal in past fifty years. 

 

 

[Roger J Smith]

EWP is probably close to 60 now, a rather dry week will follow, but rain will resume towards 20 Dec and GFS indicates total by around 25 Dec could be 100 mm.

Rather than posting any EWP preliminary scoring ideas, I have added a "first approximation" scoring for Dec in the table of entries (on page 4). This will be updated as GFS changes projections, first approximation is set at 112.6 (one of the forecasts, and one which generates no ties). But I can see where any result 90 mm to 150 mm is quite plausible so all that's settled (I believe) is that lower third of forecasts are probably going to be lower third of scores as well (we're already not too far from consensus of 85.0 mm). 

If I see a different outcome emerging, we'll change the first approximation scoring as needed. 

[Summer Sun]

7.5 to the 8th

2.9c above the 61 to 90 average

2.0c above the 91 to 20 average

[The PIT]

Sunny Sheffield at 7C

+1.3C above the 1961- 1990 average

+0.6C above the 1991 - 2020 average

Rainfall at 54mm

65.1% of the Dec 1961 - 1990 average

61.7% of the Dec 1991 - 2020 average.

[Roger J Smith]

7.5 to 8th (CET) means you have to average as follows from 9th to 31st to hit given targets: 

8 C requires 8.2 C

7.5 C requires 7.5 C

7.0 C requires 6.8 C

6.5 C requires 6.2 C

6.0 C requires 5.5 C

5.5 C requires 4.8 C 

5.0 C requires 4.2 C

4.5 C requires 3.5 C

4.0 C requires 2.8 C

3.5 C requires 2.1 C

3.0 C requires 1.4 C

2.0 C requires 0.1 C

1.0 C requires -1.3 C

0.0 C requires -2.6 C

(to beat 2015 it would need close to record warmth every day, 10.4 C average)

(to beat 1890 it would require -3.7 C)