May 2021 C.E.T. and EWP forecast contests

[LetItSnow!]

 

 

This mornings output really has me that mid-to-high 9s are on the cards this month... just a question of how low can we go!

[Summer Sun]

9.6c to the 18th

1.1c below the 61 to 90 average
1.4c below the 81 to 10 average

___________________________

Current high this month 9.6c on the 18th
Current low this month 6.6c on the 1st

[Froze were the Days]

Seriously how is the anomaly going down on the 61-90 series and to that 81-10?...I know I'm only talking about my backyard but temps here should max out around 17-18c presently and we haven't been near this (maybe 17c the other day) and night days are still rather supressed so why the continued rise?

This strikes me a bit like late April when we experienced the same thing only for the CET then to be corrected downwards, the next few days we should definitely see this go back down if temp predictions are to be correct.

Edited May 19, 2021 by Froze were the Days

[Roger J Smith]

12 minutes ago, Froze were the Days said:

Seriously how is the anomaly going down on the 61-90 series and to that 81-10?...I know I'm only talking about my backyard but temps here should max out around 17-18c presently and we haven't been near this (maybe 17c the other day) and night days are still rather supressed so why the continued rise?

This strikes me a bit like late April when we experienced the same thing only for the CET then to be corrected downwards, the next few days we should definitely see this go back down if temp predictions are to be correct.

What's happened is that these daily reports use actual rather than smoothed cumulative (or "running") values and as shown by the 1981-2010 averages there is a flat spot mid-month where several days in a row fail to advance the running CET. It must be similar for the 1961-90 averages and I notice it also happens in 1991-2020 which have stalled out also (at a similar value, the 1991-2020 normals mid-May are very similar to the 1981-2010, then they pick up and finish off at 11.9 compared to 11.7). 

date ___ CET avg _CET cum

___ 15 ___ 11.7 ___ 11.0 

___ 16 ___ 11.5 ___ 11.0 

___ 17 ___ 11.3 ___ 11.0 

___ 18 ___ 11.4 ___ 11.0 

These will begin to warm again starting with today's numbers in tomorrow's report (CET cum 11.1) heading for the final value of 11.7. 

 

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

EWP update, now at abour 83 mm (78 to 17th, est 5 mm yesterday) with 30 mm shown to 29th. 00z guidance had a rather heavy rainfall event from the east for 30th-31st but 06z GFS has only a weaker version of that (beyond the ten-day GFS estimates). Still looks like 110-120 mm for an outcome.

The CET estimate is close to 10.0 now, some further rises to about Sunday then some backtracking, we may well end up with something in the 9s at this rate, after adjustments. 

[Relativistic]

Unless there's a 2012-style warm-up, we look to be heading towards our first season below the 1961-90 average since Autumn 2019, and our first Spring to achieve the same feat since 2013. There's zero chance we'll match 2013 (the coldest since the 1800s and a full degree below this year if May finishes on 10.0C).

Edited May 19, 2021 by Relativistic

[The PIT]

Sunny Sheffield up to 9.1C -1.6C degrees below average. No change in the rainfall.

A cool outlook suggests a stall in rising after today and possible a slight fall.

[Earthshine]

3 hours ago, Relativistic said:

Unless there's a 2012-style warm-up, we look to be heading towards our first season below the 1961-90 average since Autumn 2019, and our first Spring to achieve the same feat since 2013. There's zero chance we'll match 2013 (the coldest since the 1800s and a full degree below this year if May finishes on 10.0C).

That really was a frigid spring.  A hot July and decent August saved that year for me in terms of pleasantness.

[damianslaw]

2 hours ago, Earthshine said:

That really was a frigid spring.  A hot July and decent August saved that year for me in terms of pleasantness.

It was a year of contrasting halves by and large, a much colder first half and much milder second half with a blip in November, December was very mild and Sept and Oct 2013 were generally mild and quite wet. 

[The PIT]

Sunny Sheffield up to 9.2C -1.6C below normal. Rainfall 102.8mm 172.5% above average

So there goes the 100mm mark however still a bit more needed to bring Spring up to average rainfall.

[Stevew]

Interesting to note the predominance of low temperatures for much of the spring. How might 2021 CET for March-May compare to other cold springs?

 

[Timmytour]

1 hour ago, Stevew said:

Interesting to note the predominance of low temperatures for much of the spring. How might 2021 CET for March-May compare to other cold springs?

 

The warm up in March probably saves it from records.   The aggregate monthly mean CET for the three months has only fallen below 17C five times since 1900.  If we get a mean CET of 10.5C for May, this year will make it six times.  It will be the first time since 1986 and using this measure no Spring  since 1941 would have been colder.

Incidentally, if we get a mean CET of 10.6C for May, the aggregate for the three months will be exactly 17C.   This hasn't occurred since 1680..... we could get it for the first time in 341 years!  

[Derecho]

I think the CET for this month will finish in the high 9s or low 10s. It'd be nice if we could get a month cooler then December 2015 but that is probably a stretch.

It has been an odd Spring this year with the warmest temps possibly occurring at the end of March. If a cool northerly flow had followed behind that low pressure after the weekend after the bank holiday, we could have ended up with a seriously low CET for the month.

[Summer Sun]

9.6c to the 19th

1.0c below the 61 to 90 average
1.5c below the 81 to 10 average

___________________________

Current high this month 9.6c on the 18th & 19th
Current low this month 6.6c on the 1st

[Relativistic]

3 hours ago, Timmytour said:

The warm up in March probably saves it from records.   The aggregate monthly mean CET for the three months has only fallen below 17C five times since 1900.  If we get a mean CET of 10.5C for May, this year will make it six times.  It will be the first time since 1986 and using this measure no Spring  since 1941 would have been colder.

Incidentally, if we get a mean CET of 10.6C for May, the aggregate for the three months will be exactly 17C.   This hasn't occurred since 1680..... we could get it for the first time in 341 years!  

I'm guessing you mean two months (being April and May). Over the entire record, only the Spring of 1837 has managed an aggregate below 17C.

[Timmytour]

10 minutes ago, Relativistic said:

I'm guessing you mean two months (being April and May). Over the entire record, only the Spring of 1837 has managed an aggregate below 17C.

Not my intention but that's what I did!  It's so obvious an error when pointed out, so my apologies!

So a CET of 10.5C would give us an aggregate of 24.1C for the three months.   The second coldest of this century after 2013 which contained that remarkably cold March, but also a May which only made 10.4C.

Before that such cold springs were not that uncommon.   Only 1996 in the nineties but there were four consecutive years in the 1980s that were colder

 

 

[Britneyfan]

What was the CET for spring 2013? I read that it was potentially cooler than this spring? Is that correct?

[Weather-history]

2 minutes ago, Britneyfan said:

What was the CET for spring 2013? I read that it was potentially cooler than this spring? Is that correct?

6.9C, no chance this spring will be colder. 

[Britneyfan]

29 minutes ago, Weather-history said:

6.9C, no chance this spring will be colder. 

Wow didn’t realise it was that chilly! What is this spring on? 9?

[Sunny76]

Barely scraped 14c today. And temps have recently struggled to even reach 16-17c, which is diabolical for mid to late May.

How anyone can enjoy this constant cool weather is beyond me. 

[Roger J Smith]

With 7.2 for March and 6.4 for April, this spring average will be as follows for the given values for May

9.5 _> 7.70 _____ 9.9 _> 7.83 ____ 10.3 _> 7.97

9.6 _> 7.73 ____10.0 _> 7.87 ____ 10.4 _> 8.00

9.7 _> 7.77 ____10.1 _> 7.90 ____ 10.5 _> 8.03

9.8 _> 7.80 ____10.2 _>7.93 ____ 10.6 _> 8.07

which will fit somewhere outside this list of cold spring averages since 1941:

6.87 __ 2013 __ t29st coldest 1659-2020

6.93 __ 1962 __ t32nd coldest

6.97 __ 1941 __ t35th coldest

7.00 __ 1951 __ t37th coldest

7.27 __ 1986 __ t50th coldest

7.30 __ 1969 __ t53rd coldest

7.37 __ 1986 __ t67th coldest

7.40 _ 1955,58 _ t71st coldest

7.50 __ 1979 __ t79th coldest

7.57 __ 1984 __ t88th coldest

7.67 __ 1975 __ t99th coldest

___________________________________________

It was that warm March that lifted 2021 up as high as it will finish, to match 2013 a March average of about 4 was needed. 

In the range 2021 is likely to finish, we find 1970 (7.80), 1983 (7.83) and 1985 (7.97). 1968 next at 8.07.

Edited May 20, 2021 by Roger J Smith

[Weather-history]

Given that April CET minimum was a record low, the CET minimum for April and May period could be heading for a notably low value. 

 

 

[feb1991blizzard]

Its a long shot but not completely out the equation that it could be the wettest May on record.

This current deluge could take it to 100mm (nearly 2 thirds of the record) with 2/3rds of the month gone.

Edited May 20, 2021 by feb1991blizzard

[Optimus Prime]

1 hour ago, Weather-history said:

Given that April CET minimum was a record low, the CET minimum for April and May period could be heading for a notably low value. 

 

 

A selection of chilly spring mean minimum temperatures;

(2021 - Assuming May has a theoretical average of 5.4 °C); thus the anomaly for 2021 (minimum) -1.7 °C below the most recent rolling 30 year average. 

Decadal averages since the 1880's

Pronounced warming trend since the late 1800's. 

[summer blizzard]

6 hours ago, Timmytour said:

Not my intention but that's what I did!  It's so obvious an error when pointed out, so my apologies!

So a CET of 10.5C would give us an aggregate of 24.1C for the three months.   The second coldest of this century after 2013 which contained that remarkably cold March, but also a May which only made 10.4C.

Before that such cold springs were not that uncommon.   Only 1996 in the nineties but there were four consecutive years in the 1980s that were colder

 

 

Must admit I’d not realised quite how cool spring as a whole has been relative to the prior 25 years.

5 hours ago, Britneyfan said:

Wow didn’t realise it was that chilly! What is this spring on? 9?

Remember that March 13 was about 4C below the 1991-2020 average. I’m not even sure that’s possible as we go deeper into spring and summer.

[damianslaw]

May is my favourite month, but not feeling it one bit this year..  feels a perpetual late winter.. year yet to get going especially after the misery of last 14 months. Really need June to kick things into touch.