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Roger J Smith

The "new normals" for 1991-2020 (CET)

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Posted (edited)

This thread will track the emerging next set of 30-year normals to replace the 1981-2010 CET values, which are shown below, followed by what we have to date (1991-2019 for Jan to July and 1991-2018 for Aug-Dec and annual). The July 2019 value is projected from current tracking as 17.5 and this will be adjusted in edits later this month. 

What follows the list of almost completed 1991-2020 averages will be final values that would occur for ranges of plausible values in 2020 (for Jan-July) or average of 2019-20 for Aug-Dec and annual. The thread will be maintained and edited so that these ranges shrink down to 2020 values by January, and we welcome in the new normals one by one during 2020 (subject to official verification when close to the rounding boundaries). 

(18 Oct 2019 _ updated with July to October 2019 confirmed values in the 1991-2019 averages)

_______ Jan _ Feb _ Mar _ Apr _ May _ Jun _ Jul _ Aug _ Sep _ Oct _ Nov _ Dec __ YEAR

1981-2010 _ 4.4 _ 4.4 _ 6.6 _ 8.5 _11.7 _14.4 _16.7 _16.4 _14.0 _10.7 _7.1 _ 4.6 ___ 10.0

1991-2019*_ 4.6 _ 4.8 _ 6.7 _ 8.9 _11.9 _14.7 _16.8 _16.5 _14.2 _10.9 _7.4 _ 4.9 ___ 10.2

* 1991-2018 Dec and annual

JAN will end up 4.6 if Jan 2020 is 3.0 to 5.9. It will end up 4.7 for 6.0 to higher than record max, and 4.5 for zero to 2.9 in Jan 2020 (4.4 for a neg value).

FEB will end up 4.8 if Feb 2020 is 2.2 to 5.1. It would end up 4.9 for any value 5.2 to current max 7.9 or even 8.1, and 4.7 for anything -1 to 2.1.

MAR will end up 6.7 if Mar 2020 is 4.2 to 7.1. It would end up 6.8 for any value 7.2 to record 10.0, and would drop to 6.6 for a cold 1.3 to 4.1 (last seen 2013).

APR will end up 8.9 if Apr 2020 is 7.4 to 10.3. It would end up 9.0 for any value 10.4 to beyond current record max, and would drop to 8.8 at 7.3 or lower.

MAY will end up 11.9 if May 2020 is 11 to 14, only 1833 was warmer than that (for 12.0 avg). Any plausible value 10.9 or below would yield 11.8 as new value.

JUN will end up 14.7 if June 2020 is 14.1 to 17.0. A very warm 17.1+ would change it to 14.8, and a cool 14.0 or lower would drop it to 14.6.

JUL will end up 16.8 if July 2020 is 14.6 to 17.5. Warmer (17.6-20.5) would yield 16.9. Unlikely to be below 14.6 (to drop back to 16.7).

AUG will end up 16.5 if 2020 averages 15.5 to 18.4. It would drop to 16.4 for 15.4 or lower, and would rise to 15.6 for 18.5 or higher..

SEP will end up 14.2 if 2020 averages 13.3 to 16.2. From 13.2 down to 10.3, the new September average would be 14.1.A near-record high 16.3 or higher would increase September to 14.3.

OCT will end up 11.0 if 2020 averages 11.5 to 14.4, otherwise (11.4 or colder to 8.5) the new normal is 10.9. The cold value for 2019 shifted the range for 2020 and makes it somewhat less likely now that October will reach 11.0.

NOV will end up 7.4 if 2020 averages 6.6 to 9.5. It would go to 7.5 if November 2020 is milder than current third place 9.5, and would go down to 7.3 if another colder than normal November occurs (3.6 to 6.5).

DEC will end up 4.9 for any average 3.6 to 5.05, from 5.1 to 6.5 it would end up 5.0, and for 6.6 or higher, 5.1 C. 

and the ANNUAL seems locked in to 10.2, the current value to two decimals is 10.22 (assuming Dec 2019 is 5.0). Some persistently warm anomalies now to Dec 2020 could push it to 10.3, but it would require about half the months to adjust upward. I see little chance of it falling back below 10.15. 

All of these stats will be updated by edit going forward. 

Edited by Roger J Smith

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Roger, do you have the Minimum and Maximum temps, as it is often mentioned that temps overnight  have risen quicker than Maximum temps.

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I have not been tracking that aspect, J10, maybe somebody reading this could provide some insights. I also had that perception about max rising a bit slower than min during this half century of warming. May be more applicable to warmer half of the year. 

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Posted (edited)

Here are the averages from London for 1989-2018, so the 1991-2020 averages should be very similar.

image.png.dd48bf52686533a7761c8032d1934a

Slightly warmer, wetter and cloudier than the 1981-2010 averages.

Edited by B87

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Posted (edited)

A brief glance at the annual data (lower graphs on the right) seems to suggest that the opposite is true, i.e. maxima are increasing more rapidly than minima.

https://www.metoffice.gov.uk/hadobs/hadcet/cet_info_max.html

https://www.metoffice.gov.uk/hadobs/hadcet/cet_info_min.html

Will do some quantitative analysis if I can find the time.

Edited by Relativistic

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Interesting that July, August and September have each only increased by 1C.

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Posted (edited)
27 minutes ago, J10 said:

Roger, do you have the Minimum and Maximum temps, as it is often mentioned that temps overnight  have risen quicker than Maximum temps.

In the UK it is the other way round at the official MetO observing network - maximum temperatures have generally increased faster than minimum temperatures.  I get a sense that this shift occurred in the 1990s and 2000s, associated with a decrease in cloud cover, and that we may see the maxima and minima both go up by a similar amount from 1981-2010 to 1991-2020.  That said, in many of the expanding populated areas of the UK the mean minimum temperature has risen more quickly due to the urban heat island effect.

Edit: I see Relativistic beat me to it!

Edited by Thundery wintry showers

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Posted (edited)

Trends.xlsxLooking into this further, Relativistic and Ian are both correct.

Max Temps have risen by an additional 0.1c (roughly) compared to Min Temps per decade.

At least though I have learnt something from my incorrect assumption.

MeanTempJAN  FEB  MAR APR  MAY  JUNE   JULY  AUG    SEP   OCT   NOV  DEC YEAR   INC
1961-1990 3.81  3.76  5.68  7.89  11.16  14.16  16.05  15.77  13.60  10.62  6.55  4.65    9.51
1971-2000 4.20  4.24  6.27  8.07  11.31  14.07  16.48  16.21  13.71  10.41  6.87  5.06    9.77      0.26
1981-2010 4.44  4.39  6.58  8.52  11.66  14.48  16.71  16.41  14.03  10.69  7.14  4.63  10.00      0.23
1991-2020 4.60  4.84  6.74  8.90  11.88  14.67  16.82  16.45  14.18  10.96  7.42  4.94  10.22      0.22

Min Temp JAN  FEB  MAR APR MAY  JUNE  JULY AUG  SEP  OCT  NOV DEC YEAR  INC
1961-1990 1.21  0.96  2.26  3.96  6.75    9.73  11.68 11.46   9.64  7.20  3.64  2.04  5.91
1971-2000 1.56  1.32  2.90  4.08  6.78    9.69  11.94 11.71   9.75  7.00  3.94  2.46  6.12     0.22
1981-2010 1.75  1.38  3.08  4.30  7.13  10.02  12.17 11.95 10.02  7.29  4.24  1.96  6.30     0.18
1991-2020 1.91  1.79  3.09  4.57  7.33  10.11  12.18 12.04 10.12  7.55  4.48  2.20  6.48     0.17

Max Temp JAN  FEB  MAR  APR  MAY  JUNE  JULY  AUG   SEP   OCT   NOV  DEC YEAR  INC
1961-1990 6.44  6.56  9.08  11.82 15.56 18.57  20.41  20.08  17.56 14.02   9.45   7.29  13.11
1971-2000 6.86  7.13  9.63  12.06 15.81 18.41  20.98  20.71 17.68  13.80   9.80   7.69  13.41   0.30
1981-2010 7.15  7.36 10.07 12.72 16.16 18.91  21.23  20.85 18.05  14.08 10.06   7.32  13.70   0.29
1991-2020 7.31  7.86 10.38 13.22 16.40 19.22  21.45  20.86 18.25  14.37 10.36   7.68  13.97   0.27

 

 

Edited by J10

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Thanks for adding those details. Interesting. 

Meanwhile, the July CET was in fact 17.5 so no edits required to the tracking. It will take a warmer July than this year to produce a new normal of 16.9, otherwise it's likely to remain 16.8. 

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The tables have been updated for confirmed August and September values.

The commentary about projections for 1991-2020 have been updated now that we know the needed values for various outcomes for those months.

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On 31/07/2019 at 22:10, cheese said:

Interesting that July, August and September have each only increased by 1C.

hmmmmmmmmm yes, was just going to post something like that, more so no surprise that the 'snow possible' months have the biggest increase

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Here in Edmonton the warming seems to be confined to the winter...Dec-Mar has warmed by 1.5-2c ..yet the rest of the year has shown no real deviation from the 1937-90 data..the winters it seems have become drier and sunnier..where as the rest of the year precipitation and sunshine remains the same.

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I just remembered to update this thread for October. The rather cold (10.0) CET has shifted the range of Oct 2020 values now required to boost the current 29-year average of 10.9 into the 11.0 range. October 2020 will have to manage 11.5 to any record high value below 14.4 to reach 11.0 for the new normal. Otherwise if it can stay between 8.5 and 11.4, it will end up staying where it is now at 10.9. Next update after November CET is confirmed. 

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If I'm reading that correct, then we have only increased 0.71c in the last 60yrs?

 

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On 01/08/2019 at 20:07, J10 said:

Trends.xlsxLooking into this further, Relativistic and Ian are both correct.

Max Temps have risen by an additional 0.1c (roughly) compared to Min Temps per decade.

At least though I have learnt something from my incorrect assumption.

MeanTempJAN  FEB  MAR APR  MAY  JUNE   JULY  AUG    SEP   OCT   NOV  DEC YEAR   INC
1961-1990 3.81  3.76  5.68  7.89  11.16  14.16  16.05  15.77  13.60  10.62  6.55  4.65    9.51
1971-2000 4.20  4.24  6.27  8.07  11.31  14.07  16.48  16.21  13.71  10.41  6.87  5.06    9.77      0.26
1981-2010 4.44  4.39  6.58  8.52  11.66  14.48  16.71  16.41  14.03  10.69  7.14  4.63  10.00      0.23
1991-2020 4.60  4.84  6.74  8.90  11.88  14.67  16.82  16.45  14.18  10.96  7.42  4.94  10.22      0.22

Min Temp JAN  FEB  MAR APR MAY  JUNE  JULY AUG  SEP  OCT  NOV DEC YEAR  INC
1961-1990 1.21  0.96  2.26  3.96  6.75    9.73  11.68 11.46   9.64  7.20  3.64  2.04  5.91
1971-2000 1.56  1.32  2.90  4.08  6.78    9.69  11.94 11.71   9.75  7.00  3.94  2.46  6.12     0.22
1981-2010 1.75  1.38  3.08  4.30  7.13  10.02  12.17 11.95 10.02  7.29  4.24  1.96  6.30     0.18
1991-2020 1.91  1.79  3.09  4.57  7.33  10.11  12.18 12.04 10.12  7.55  4.48  2.20  6.48     0.17

Max Temp JAN  FEB  MAR  APR  MAY  JUNE  JULY  AUG   SEP   OCT   NOV  DEC YEAR  INC
1961-1990 6.44  6.56  9.08  11.82 15.56 18.57  20.41  20.08  17.56 14.02   9.45   7.29  13.11
1971-2000 6.86  7.13  9.63  12.06 15.81 18.41  20.98  20.71 17.68  13.80   9.80   7.69  13.41   0.30
1981-2010 7.15  7.36 10.07 12.72 16.16 18.91  21.23  20.85 18.05  14.08 10.06   7.32  13.70   0.29
1991-2020 7.31  7.86 10.38 13.22 16.40 19.22  21.45  20.86 18.25  14.37 10.36   7.68  13.97   0.27

 

 

J10..

Any chance of sending out the updated xlsx file with the updated figures for Oct ?

Thanks

MIA

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I have updated the first post of the thread with data from Nov 2019 (6.2). This rather cold value now means that Nov 2020 will have to finish 6.6 to 9.5 to stay on 7.4, as we are now at about 7.36. Anything plausible colder than 6.6 will make 7.3 the new value. A really warm November could take us to 7.5. 

SteveB, here's the full breakdown of 30-year averages since 1901-30 for your interest. If you want to see earlier values, look in my historical CET thread in the historical weather section.

Some of my values may round 0.1 different from Met Office values because I think they derive them from an average of 30-year mean max and mean min. Also you get into third decimal issues about rounding from .x5 situations. But this gives the general picture of what's been happening in the recent past. 

Interval __________JAN __ FEB __ MAR _ APR _ MAY _ JUN __ JUL __ AUG __ SEP __ OCT _ NOV _ DEC __ YEAR

 

1901-1930________4.2 ___4.2 ___5.5 ___8.0 __ 11.3 __ 13.8 __ 15.8 __ 15.2 __ 13.1 ___9.8 ___5.8 ___4.5 ___ 9.2

1911-1940________4.2 ___4.3 ___5.7 ___8.2 __ 11.5 __ 14.2 __ 15.9 __ 15.6 __ 13.3 ___9.6 ___6.2 ___4.6 ___ 9.4

1921-1950________3.9 ___4.2 ___5.9 ___8.0 __ 11.3 __ 14.4 __ 16.3 __ 15.9 __ 13.6 __10.0 ___6.4 ___4.5 ___ 9.5

1931-1960________3.5 ___3.9 ___5.9 ___8.1 __ 11.5 __ 14.6 __ 16.2 __ 16.0 __ 13.7 __10.1 ___6.8 ___4.7 ___ 9.6

1941-1970________3.3 ___3.6 ___5.7 ___8.1 __ 11.4 __ 14.5 __ 16.0 __ 15.7 __ 13.7 __10.6 ___6.6 ___4.4 ___ 9.5

1951-1980________3.6 ___3.7 ___5.6 ___8.0 __ 11.3 __ 14.3 __ 15.9 __ 15.6 __ 13.6 __10.5 ___6.6 ___4.7 ___ 9.4

1961-1990________3.9 ___3.7 ___5.7 ___7.9 __ 11.1 __ 14.1 __ 16.1 __ 15.8 __ 13.6 __10.6 ___6.5 ___4.7 ___ 9.5

1971-2000________4.2 ___4.2 ___6.3 ___8.1 __ 11.3 __ 14.1 __ 16.5 __ 16.2 __ 13.7 __10.4 ___6.9 ___5.1 ___ 9.7

1981-2010________4.4 ___4.4 ___6.6 ___8.5 __ 11.7 __ 14.5 __ 16.7 __ 16.4 __ 14.0 __10.7 ___7.1 ___4.6 __ 10.0

=============================================================================================

Trends in the above data reveal that Jan and Feb were milder in the first half of the 20th century than around 1941-80, and we were only edging past those values by 1981-2010.

Spring, summer and autumn showed somewhat the opposite trend until the recent warming began. 

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