December 2021 C.E.T. and EWP forecast contests -- start of the new contest year for 2021-2022

[BLAST FROM THE PAST]

Glad I didn’t adjust down, pace a-gathering for a milding up for middle sector of December.  Will be interesting to see how mild and for how long.

 BFTP

[Summer Sun]

7.3c to the 1st

2.5c above the 61 to 90 average
1.5c above the 81 to 10 average

___________________________

Current high this month 7.3c on the 1st
Current low this month 7.3con the 1st

[BLAST FROM THE PAST]

43 minutes ago, Summer Sun said:

7.3c to the 1st

2.5c above the 61 to 90 average
1.5c above the 81 to 10 average

___________________________

Current high this month 7.3c on the 1st
Current low this month 7.3con the 1st

It wasn’t 7.3c minimum here this morning?

 

BFTP

[Roger J Smith]

That 7.3 is the average for the first (yesterday), but will probably be more like 5.5 in the final numbers as it was a lot colder by evening. Lows were around -1 C on average in the CET zone last night, recovering to around 5-6 today. Would expect tomorrow's update to drop significantly. 

Model runs are showing outcomes near 5 C to mid-month with what looks like a 3-4 day mild spell signal so could be closer to 6 C by 20th perhaps, if that verifies. EWP looks about average in general. 

 

[Don]

8 hours ago, Roger J Smith said:

That 7.3 is the average for the first (yesterday), but will probably be more like 5.5 in the final numbers as it was a lot colder by evening. Lows were around -1 C on average in the CET zone last night, recovering to around 5-6 today. Would expect tomorrow's update to drop significantly. 

Model runs are showing outcomes near 5 C to mid-month with what looks like a 3-4 day mild spell signal so could be closer to 6 C by 20th perhaps, if that verifies. EWP looks about average in general. 

 

Are you wishing you stuck to your 5.4C guess Roger?

[Roger J Smith]

Are the models flip-flopping again? They weren't even able to form a consensus for next week's development until recently so we'll have to wait and see how long and strong the warming proves to be. I was expecting a warmer spike and a stormy interval before Christmas, possibly quite a bit colder after that (over the horizon still). 

[Summer Sun]

5.4c to the 2nd

0.4c above the 61 to 90 average
0.4c below the 81 to 10 average

___________________________

Current high this month 7.3c on the 1st
Current low this month 5.4c on the 2nd

[Roger J Smith]

First report on the EWP ... after two days it is around 8 mm. The ten day GFS grid average is about 35 mm with heavy falls depicted over parts of southwest England and Wales. This is dependent on the actual track of the Tuesday-Wednesday 7th-8th storm which the 06z model run stalls off southwest coast with long duration rainfalls reaching 60-100 mm in Cornwall, Devon and Somerset. A track further north might distribute rainfall from this storm in a different pattern but it might still have roughly the same overall impact on the grid, so the total of about 40 mm by the 13th looks fairly reliable regardless of the distribution. Beyond day ten there would be another 10-20 mm likely by the 19th. The pace is generally near normal in this guidance with a bit of uncertainty suggesting the potential for almost any forecast to do well so far. 

Although the models have probably shifted a bit towards milder outcomes, there is enough uncertainty and transient cold to suggest that the CET should remain fairly close to normal values as well, which in the 1991-2020 averages stay in the mid 5s well into the third week of the month and reach 5.2 around Christmas, 5.0 end of month. Not seeing strong signals to take the CET very far off that timetable so far. Then there's the adjustment, won't even touch that one. 

[Roger J Smith]

(The first three days of December Almanac reports were in the November thread ... will continue here now to end of December ... I post them around 00h to 02h of the day in question).

 

Almanac for 4th December

Worth mentioning that in 1952 around this time of year, a deadly smog episode was underway in London that led to hundreds or possibly thousands of deaths and led to calls for changes in air quality standards. The meteorological situation of stagnant high pressure will be addressed in tomorrow's link to maps. 

The highest daily mean (1772-2020) was 12.1 in 1888. This replaced 11.1 from 1866 which had edged out 11.0 from 1836. Also quite mild were 1852 and 1868 at 10.9. The warmest since 1888 was 11.7 in 1986. Other notably mild days were 11.5 in 1934, 11.1 in 1898, 10.9 in 1985, and 10.7 in 1918 and 1931.

The lowest daily mean (1772-2020) was -3.8 in 1879, tied in 1925. Between those tied values was -1.9 in 1902. Those tied records replaced -1.4 from 1871. Other cold mean daily values for 4 Dec include -2.0 in 1976, -1.5 in 2010, -1.3 in 1796 and 1950, -1.0 in 1870.

The highest maximum (1878-2020) was 13.8 in both 1888 and 1979. Those were almost joined by 1931 and 1986 which hit 13.7. Other mild daily maxima include 13.4 in 2006 and 2007, 13.0 in 1904, 12.9 in 2000, 12.8 in 1898, 12.4 in 1918 and 1934, 12.2 in 1900 and 1985.   

The highest minimum (1878-2020) was 10.6 in 1934, which replaced 10.4 from 1888, it was also 9.4 in 1898 and 9.0 in 1918.  The highest value since 1934 has been 9.7 in 1986, with 9.5 in 1985. 

The lowest maximum (1878-2020) was -1.5 in 1925. That replaced -1.4 from 1879, in between was 0.2 in 1902. Since 1925 other cold values include 1.3 in 1950, 1.2 in 1976. (2010 moderated to 3.8) 

The lowest minimum (1878-2020) was -6.7 in 2010 which replaced -6.1 from 1879. Other cold minima include -6.0 in 1925, -5.1 in 1976, -4.0 in 1902, and -3.9 in 1957 as well as -3.8 in 1950.  

The wettest 4th of December (1931-2020) in the EWP data was 14.03 mm (1934). followed by 11.72 mm (1937), 10.71 mm (1961), then 10.61 mm (1965), 10.41 mm (1942) and 10.05 mm (2020). 

The wettest week ending 4th December (28th Nov -4th Dec) was 58.48 mm in 1992, followed by 55.58 mm (1960) and 50.53 mm (1965) .

The least amount falling in a week ending 4th December was 0.23 mm in 1962, then 0.41 mm in 1957, 0.51 mm in 1989, 0.58 mm in 1990, 0.84 mm in 1991, 0.92 mm in 2016, 1.25 mm in 1983 and 1.66 mm in 1958.

-----------------------------

(map for 04 Dec 1879,  very cold interval lasting about a week, snowstorms for 3rd-4th then mainly cold and dry.) 

https://www.wetterzentrale.de/reanalysis.php?map=1&model=noaa&var=1&jaar=1879&maand=12&dag=04&uur=0600&h=0&tr=360&nmaps=24#mapref

[LetItSnow!]

14 hours ago, Roger J Smith said:

First report on the EWP ... after two days it is around 8 mm. The ten day GFS grid average is about 35 mm with heavy falls depicted over parts of southwest England and Wales. This is dependent on the actual track of the Tuesday-Wednesday 7th-8th storm which the 06z model run stalls off southwest coast with long duration rainfalls reaching 60-100 mm in Cornwall, Devon and Somerset. A track further north might distribute rainfall from this storm in a different pattern but it might still have roughly the same overall impact on the grid, so the total of about 40 mm by the 13th looks fairly reliable regardless of the distribution. Beyond day ten there would be another 10-20 mm likely by the 19th. The pace is generally near normal in this guidance with a bit of uncertainty suggesting the potential for almost any forecast to do well so far. 

Although the models have probably shifted a bit towards milder outcomes, there is enough uncertainty and transient cold to suggest that the CET should remain fairly close to normal values as well, which in the 1991-2020 averages stay in the mid 5s well into the third week of the month and reach 5.2 around Christmas, 5.0 end of month. Not seeing strong signals to take the CET very far off that timetable so far. Then there's the adjustment, won't even touch that one. 

Despite an unsettled outlook the immediate outlook doesn’t look mild at any point now and then there’s the headache of the low pressure system and what comes after that. I’ve been caught out before by thinking this but I’m not certain of a mild December but we will see…

[Summer Sun]

5.1c to the 3rd

0.1c above the 61 to 90 average
0.8c below the 81 to 10 average

___________________________

Current high this month 7.3c on the 1st
Current low this month 5.1c on the 3rd

[emmett garland]

13 hours ago, Roger J Smith said:

(The first three days of December Almanac reports were in the November thread ... will continue here now to end of December ... I post them around 00h to 02h of the day in question).

 

Almanac for 4th December

Worth mentioning that in 1952 around this time of year, a deadly smog episode was underway in London that led to hundreds or possibly thousands of deaths and led to calls for changes in air quality standards. The meteorological situation of stagnant high pressure will be addressed in tomorrow's link to maps. 

The highest daily mean (1772-2020) was 12.1 in 1888. This replaced 11.1 from 1866 which had edged out 11.0 from 1836. Also quite mild were 1852 and 1868 at 10.9. The warmest since 1888 was 11.7 in 1986. Other notably mild days were 11.5 in 1934, 11.1 in 1898, 10.9 in 1985, and 10.7 in 1918 and 1931.

The lowest daily mean (1772-2020) was -3.8 in 1879, tied in 1925. Between those tied values was -1.9 in 1902. Those tied records replaced -1.4 from 1871. Other cold mean daily values for 4 Dec include -2.0 in 1976, -1.5 in 2010, -1.3 in 1796 and 1950, -1.0 in 1870.

The highest maximum (1878-2020) was 13.8 in both 1888 and 1979. Those were almost joined by 1931 and 1986 which hit 13.7. Other mild daily maxima include 13.4 in 2006 and 2007, 13.0 in 1904, 12.9 in 2000, 12.8 in 1898, 12.4 in 1918 and 1934, 12.2 in 1900 and 1985.   

The highest minimum (1878-2020) was 10.6 in 1934, which replaced 10.4 from 1888, it was also 9.4 in 1898 and 9.0 in 1918.  The highest value since 1934 has been 9.7 in 1986, with 9.5 in 1985. 

The lowest maximum (1878-2020) was -1.5 in 1925. That replaced -1.4 from 1879, in between was 0.2 in 1902. Since 1925 other cold values include 1.3 in 1950, 1.2 in 1976. (2010 moderated to 3.8) 

The lowest minimum (1878-2020) was -6.7 in 2010 which replaced -6.1 from 1879. Other cold minima include -6.0 in 1925, -5.1 in 1976, -4.0 in 1902, and -3.9 in 1957 as well as -3.8 in 1950.  

The wettest 4th of December (1931-2020) in the EWP data was 14.03 mm (1934). followed by 11.72 mm (1937), 10.71 mm (1961), then 10.61 mm (1965), 10.41 mm (1942) and 10.05 mm (2020). 

The wettest week ending 4th December (28th Nov -4th Dec) was 58.48 mm in 1992, followed by 55.58 mm (1960) and 50.53 mm (1965) .

The least amount falling in a week ending 4th December was 0.23 mm in 1962, then 0.41 mm in 1957, 0.51 mm in 1989, 0.58 mm in 1990, 0.84 mm in 1991, 0.92 mm in 2016, 1.25 mm in 1983 and 1.66 mm in 1958.

-----------------------------

(map for 04 Dec 1879,  very cold interval lasting about a week, snowstorms for 3rd-4th then mainly cold and dry.) 

https://www.wetterzentrale.de/reanalysis.php?map=1&model=noaa&var=1&jaar=1879&maand=12&dag=04&uur=0600&h=0&tr=360&nmaps=24#mapref

Absolutely loving the daily data Roger

[BornFromTheVoid]

Latest CET projection, based on the 06z GFS.

 

Before corrections, the chances of finishing:
Close to average (4.5C to 5.5C) is 41%
Above average (>5.5C) is 20%
Below average (<4.5C) is 39%

The period of the 4th to the 9th is forecast to average 4.4C, 1.1C below the 91-20 average.

[ItNeverSnowsInWindsor]

After a coldish start looks like getting milder by mid month with the models currently showing no stamina with the Scandi high

[Roger J Smith]

Almanac for 5th December

In 1952 around this time of year, a deadly smog episode was underway in London that led to hundreds or possibly thousands of deaths and led to calls for changes in air quality standards. It led to the Clean Air Act of 1956. The meteorological situation of stagnant high pressure is illustrated in today's map link. 

The highest daily mean (1772-2020) was 12.6 in 1898. This replaced 11.1 from 1888 which in turn had replaced 10.8 from 1852 and 1868. The warmest since 1898 was 11.5 in 2000. Other notably mild days were 11.4 in 1986,  and 10.5 in 1862 and 1918.

The lowest daily mean (1772-2020) was -3.7 in 1844. Other cold mean daily values for 5 Dec include -3.2 in 1879,  -2.4 in 1902, -1.8 in 1925 and 1950, -1.7 in 1875, -1.4 in 1962, and -1.1 in the 1952 smog. 

The highest maximum (1878-2020) was 13.9 in 1898 which replaced 12.9 from 1888; it was also 12.6 in 1895. Other mild daily maxima include 13.0 in 2007 and 2015, 12.9 in 2000, 12.6 in 1979, 12.3 in 1891 and 2009, 12.1 in 1924 and 12.0 in 1986. 

The highest minimum (1878-2020) was 11.3 in 1898. This replaced 9.3 from 1888. The highest value since 1898 has been 10.8 in 1986 then also 10.0 in 2000; it was also 9.1 in 1951, with 9.0 in 1956. 

The lowest maximum (1878-2020) was -0.6 in 1902. That replaced 1.4 from 1879, and since 1902 other cold values include 1.2 in 1950, and 1.5 in 1925 and 1933. 

The lowest minimum (1878-2020) was -7.8 in 1879. Other cold minima include -6.2 in 1962, -5.2 in 1952, -5.1 in 1925, -4.8 in 1950 and 1976, -4.1 in 1902 (2010 only -2.4 yet that was coldest since 1976).  

The wettest 5th of December (1931-2020) in the EWP data was 16.13 mm (1972). followed by 13.36 mm (2009) and 10.26 mm (1931). 

The wettest week ending 5th December (29th Nov - 5th Dec) was 64.84 mm in 1972, followed by 56.41 mm (1960), 52.43 mm in 1992, and 50.69 mm (1934) .

The least amount falling in a week ending 5th December was 0.14 mm in 1962, then 0.16 mm in 1991, 0.39 mm in 1990, 0.67 mm in 1989, 0.83 mm in 1957, 1.03 mm in 2016, 1.42 mm in 1958 and 1.47 mm in 1983.

-----------------------------

(map for 05 Dec 1952,  five-day London smog episode began, very slack gradients with high pressure over the south. A rather moderate west to northwest flow began around the 10th slowly clearing the fog away. As a person born in 1949 I guess I lived through this, in Brum, all I remember of my youth before emigrating in May 1957 was one snowfall probably Feb 1956, some heat quite possibly 1955 because we can rule out 1956, and the coronation arches over the streets in 1953 (and that's no mistake, I believe they waited a year for the event after Her Majesty took the throne in 1952). I can recall one Guy Fawkes night with the back garden fireworks, and one ill-advised five-mile journey around suburban Northfield and Rubery on my tricycle, parents wondering where the heck I was. Oh and I do recall when they showed me a hedge up the hill where snow had apparently drifted to the top during the severe winter of 1947, or so they claimed. The December fog of 1952 made no impression, and for all I know we were in London because we went there several times a year on the train to visit my mother's family, she was from east London and evacuated to near Tamworth in the war where they met, hence their marriage in 1946 ... The only thing I now have in my possession from their home in England is a barometer that I have checked most days since starting my weather station in 1964.) 

https://www.wetterzentrale.de/reanalysis.php?map=1&model=noaa&var=1&jaar=1952&maand=12&dag=05&uur=1200&h=0&tr=360&nmaps=24#mapref

Edited December 5, 2021 by Roger J Smith

[kold weather]

22 hours ago, BornFromTheVoid said:

Latest CET projection, based on the 06z GFS.

 

Before corrections, the chances of finishing:
Close to average (4.5C to 5.5C) is 41%
Above average (>5.5C) is 20%
Below average (<4.5C) is 39%

The period of the 4th to the 9th is forecast to average 4.4C, 1.1C below the 91-20 average.

I wonder what that would look like if you just used the last 30 years?

Since those are climatically far more relevant than the CET from say 1940s. IE is there a skewing more towards the top end of the dataset or not?

My guess is with the world that bit warmer its also that bit easier to have an exceptional warm spell which obviously the long term averages simply won't reflect.

[Summer Sun]

5.2c to the 4th

0.1c above the 61 to 90 average
0.7c below the 81 to 10 average

___________________________

Current high this month 7.3c on the 1st
Current low this month 5.1c on the 3rd

[Roger J Smith]

Almanac for 6th December

The highest daily mean (1772-2020) was 12.3 in 1898. This replaced 11.4 from 1888 which in turn had replaced 10.7 in 1866 and 1868, before that came 10.6 from 1865. The warmest since 1898 was 11.8 in 2015. Other notably mild days were 11.2 in 2007, and 10.5 in 1964.

The lowest daily mean (1772-2020) was -5.5 in 1844. Other cold mean daily values for 6 Dec include -3.8 in 2010, -3.6 in 1879,  -2.3 in 1902, -2.1 in 1962, -1.8 in 1796, -1.5 in 1803, -1.4 in 1962, and -1.1 in 1916.

The highest maximum (1878-2020) was 14.0 in 2007 replacing 13.8 from 1898. Other mild daily maxima include 13.3 in 2015, 13.1 in 1888, 12.9 in 1948, 12.5 in 1979, 12.4 in 2018, 12.3 in 1956 and 1964, 12.2 in 2019, 12.1 in 1899 and 12.0 in 1921.

The highest minimum (1878-2020) was 10.8 in 1898. This replaced 9.7 from 1888 . The highest value since 1898 has been 10.3 in 2015. Other high minima include 8.8 in 1900 and 1918, with 8.7 in 1956 and 8.6 in 2000.

The lowest maximum (1878-2020) was -1.8 in 2010 which replaced -1.1 from 1902. Other cold values include 1.0 in 1879, 1.5 in 1995, 1.8 in 1916, and 1.9 in 1903. 

The lowest minimum (1878-2020) was -8.1 in 1879. Other cold minima include -6.8 in 1962, -6.3 in 1950, -5.8 in 2010, -5.7 in 1925, -4.8 in 1952, -3.9 in 1916 and 1998, and -3.7 in 1892 with -3.6 in 2012.  

The wettest 6th of December (1931-2020) in the EWP data was 13.51 mm (1941), followed by 13.33 mm (1985), 12.95 mm (1934), 12.85 mm (1959) and 12.56 mm (1992), 11.90 mm (2007), 11.64 mm (1972), 10.91 mm (2012), 10.64 mm (2006), 10.26 mm (2018) and 10.08 mm (1993). 

The wettest week ending 6th December (30th Nov - 6th Dec) was 70.52 mm in 1972, followed by 63.48 mm (1934), 56.81 mm (1992), and 56.20 mm (1960).

The least amount falling in a week ending 6th December was 0.04 mm in 1962, then 0.16 mm in 1991, 0.69 mm in 1989, 1.32 mm in 1952, 1.35 mm in 1958 and 1.41 mm in 1983.

-----------------------------

(map for 06 Dec 1898,  very mild spell.) 

https://www.wetterzentrale.de/reanalysis.php?jaar=1898&maand=12&dag=6&uur=1200&var=1&map=1&model=noaa

 

 

Edited December 6, 2021 by Roger J Smith

[The PIT]

Sunny Sheffield at 4.5C -2.2C below normal. Rainfall 18.8mm 21.5% of the monthly average.

[Summer Sun]

5.3c to the 5th

Bang on the 61 to 90 average
0.7c below the 81 to 10 average

___________________________

Current high this month 7.3c on the 1st
Current low this month 5.1c on the 3rd

[damianslaw]

Looking a rather average first half to the month then a milder push before probably a colder end.. end result average probably disguising the mixed weather.

[BornFromTheVoid]

Latest CET projection, based on the 12z GFS.

 

Before corrections, the chances of finishing:
Close to average (4.5C to 5.5C) is 40% (2 days ago was 41%)
Above average (>5.5C) is 24% (2 days ago was 20%)
Below average (<4.5C) is 36% (2 days ago was 39%)

The period of the 6th to the 11th is forecast to average 4.8C, 0.4C below the 91-20 average.

 

On 05/12/2021 at 10:54, kold weather said:

I wonder what that would look like if you just used the last 30 years?

Since those are climatically far more relevant than the CET from say 1940s. IE is there a skewing more towards the top end of the dataset or not?

My guess is with the world that bit warmer its also that bit easier to have an exceptional warm spell which obviously the long term averages simply won't reflect.

2015 and 2010 sticking out like sore thumbs

Edited December 6, 2021 by BornFromTheVoid

[Roger J Smith]

Almanac for 7th December

The highest daily mean (1772-2020) was 12.3 in 1856. This replaced 10.2 from 1820 and 1848. The warmest since 1856 was 10.9 in both 1964 and 2015. The only other daily means above 10 were 10.8 in 1955, 10.3 in 1948 and 10.1 in 1979.

The lowest daily mean (1772-2020) was -5.7 in 1879 which replaced -2.5 from 1844. Other cold mean daily values for 7 Dec include -3.5 in 2010, -2.9 in 1902, -1.5 in 1803 and 1812, and -1.3 in 1796 and 1961.

The highest maximum (1878-2020) was 14.0 in 2015 replacing 13.4 from 1957. Other mild daily maxima include 13.6 in 2016, 12.9 in 1901, 12.8 in 1905, 12.6 in 1979, 12.4 in 2000, 12.3 in 1955, 1948 and 1964, and 12.0 in 1934 and 1974.

The highest minimum (1878-2020) was 9.5 in 1964. This replaced 9.3 from 1955, previously 8.3 in 1921. The highest value since 1964 has been 9.4 in 2018. 

The lowest maximum (1878-2020) was -0.4 in 2010 which replaced 0.0 from 1879. Other cold values include 0.4 in 1902, 1.2 in 1995, and 1.9 in 1967. 

The lowest minimum (1878-2020) was -11.4 in 1879. Other cold minima include -6.5 in 2010, -6.2 in 1902, -5.4 in 1962, -4.8 in 1961, and -4.4 in 1983. (Several cold spells from the 6th moderated on the 7th).

The wettest 7th of December (1931-2020) in the EWP data was 21.30 mm (2000), followed by 18.35 mm (1977), 17.59 mm (1982), 14.11 mm (1973), 13.25 mm (1994) and 13.17 mm (1978). 

The wettest week ending 7th December (1st - 7th Dec) was 72.24 mm in 1934 just ahead of 71.29 mm (1972) followed by 52.11 mm (1960) and 50.16 mm (2000).

The least amount falling in a week ending 7th December was 0.05 mm in 1991, 0.43 mm in 1989, 1.51 mm in 1962, 1.54 mm in 1952, 1.71 mm in 1968, 1.85 mm in 2004 and 1.93 mm in 1958.

-----------------------------

(map for 07 Dec 1856,  very mild spell.) 

https://www.wetterzentrale.de/reanalysis.php?jaar=1856&maand=12&dag=7&uur=1200&var=1&map=1&model=noaa

 

Edited December 7, 2021 by Roger J Smith

[The PIT]

Sunny Sheffield at 4.2C -2.4C below average, Rainfall 23.4mm 26.7% of the monthly average.

[Summer Sun]

5.0c to the 6th

0.2c below the 61 to 90 average
0.8c below the 81 to 10 average

___________________________

Current high this month 7.3c on the 1st
Current low this month 5.0c on the 6th