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

[Scorcher]

5 hours ago, damianslaw said:

If today's models verify the CET should take a rapid fall.. on average latter part of the month does see a significant drop. 

Not until the 2nd half of next week at the earliest. Don't forget that in a cyclonic regime the minima will be held up. 

It also doesn't change the fact that this has been one of the warmest first halves of September on record- no getting away from that.

Edited September 16, 2021 by Scorcher

[LetItSnow!]

On 16/09/2021 at 20:10, Scorcher said:

Not until the 2nd half of next week at the earliest. Don't forget that in a cyclonic regime the minima will be held up. 

It also doesn't change the fact that this has been one of the warmest first halves of September on record- no getting away from that.

I don’t think anyone is trying to get away from that. He’s just stating that a some steady drop is likely to occur and would probably take us below 16. 15s are my feel at the moment (as of what output I saw earlier)

[Roger J Smith]

EWP has reached 20 mm and ten-day forecast grid average is around 15 mm, taking it to 35 mm by 27th. Around 15 mm appears possible to end of month (with heavy rainfalls indicated Oct 1-3). That would be an end point of around 50 mm. 

There are a few colder days coming in about a week, but on average the downward pressure on CET is slight until then, and temperatures recover to somewhat above average near the end, so overall thinking that mid-15 range is most likely. 

[damianslaw]

First half of September a month too late.. had it happened first half of August a real scorcher would have ensued.. 

[The PIT]

Sunny Sheffield at 17.2C  +1.8C above normal. Rainfall 9mm 13.7%of the monthly average

[Summer Sun]

17.4c to the 16th

3.2c above the 61 to 90 average
2.7c above the 81 to 10 average

___________________________

Current high this month 18.1c on the 10th & 11th
Current low this month 14.4c on the 1st

[Roger J Smith]

The latest guidance has taken the colder turn pretty much out of the forecast and there isn't much rain in the outlook either. Currently stalled at 20 mm, EWP could be 30 mm by 28th and will take some late increases but looking like 40-50 mm the most likely finish. The CET will start a slow drop but the anomaly regime looks similar so it will only be a seasonal downturn and there is probably some chance again of remaining above 16 although mid 15s probably best bet at this point. 

[Shillitocettwo]

Come on 17.0.C you can do it!

 

Although a 2nd half of 16.6.C (and higher with downward correction) would be monumental!

Edited September 17, 2021 by Shillitocettwo

[Summer Sun]

17.3c to the 17th

3.2c above the 61 to 90 average
2.7c above the 81 to 10 average

___________________________

Current high this month 18.1c on the 10th & 11th
Current low this month 14.4c on the 1st

[damianslaw]

8 minutes ago, Summer Sun said:

17.3c to the 17th

3.2c above the 61 to 90 average
2.7c above the 81 to 10 average

___________________________

Current high this month 18.1c on the 10th & 11th
Current low this month 14.4c on the 1st

The very mild nights are certainly helping to keep CET levels up, and consistent maxima in the 19-22 degree range. Had the weather of the last 3 weeks occured first 3 in August - a major heatwave would have ensued.. 

Cooler conditions forecast from 22nd onwards, back down to the seasonal average, though I suspect southern parts could see slightly above average temps, nightime minima will be notably cooler in the north under chilly uppers. Might produce first air frost of the season.. 

[The PIT]

Sunny Sheffield at 17.1C +1.8C above normal. Rainfall unchanged.

A slow decline for the next five days.

[Stu_London]

If I was sitting on a 15.5C guess I would be quite happy.

However, I didn't enter the competition, so ambivalence for me 

[Don]

Mid to high 15's after corrections would be my guess currently for this month.

[Roger J Smith]

There has never been a 15.5 CET for September, almost as noteworthy as the missing 5.9 of December (especially given that September's mean for 1991-2020 is now almost as close to 15.5 as the December mean is to 5.9). Also there have not been any 15.8 or 15.9 finishers. 

If the month did finish on 15.5, then it would rank 10th warmest and that is the highest outcome for any month since April 2020 (10.4) finished tied fifth warmest. July 2018 finished third warmest (19.1). At the moment the month that had the highest rank since April 2020 is Aug 2020 (17.6 tied 12th warmest). 15.4 would rank tied tenth warmest with 1895. 

This is interesting too -- after Feb 1779 the intervals between warmest months was as follows:

54 yrs 3 mo to warmest May 1833

13 yrs 1 mo to warmest June 1846

69 yrs 7 mo to warmest Jan 1916

41 yrs 2 mo to warmest Mar 1957

37 yrs 8 mo to warmest Nov 1994

 0 yrs 9 mo to warmest Aug 1995

 6 yrs 2 mo to warmest Oct 2001

 4 yrs 9 mo to warmest July 2006

 0 yrs 2 mo to warmest Sep 2006

 5 yrs 1 mo to warmest Oct 2011

 5 yrs 2 mo to warmest Dec 2015

(the last six intervals averaged 3 years 8 mo)

The average interval from 1779 to 1994 on the other hand was 42 yrs 10 mo. 

However if you take Nov 1994 as the end point then this changes (since the last six would not be in the list) to this:

Sep 1729 would be the start point (16.6, now 2nd)...

49 yrs 5 mo to warmest Feb 1779

54 yrs 3 mo to warmest May 1833

13 yrs 1 mo to warmest June 1846

18 yrs 10 mo to warmest April 1865 (now 3rd)

50 yrs 9 mo to warmest Jan 1916

18 yr 11 mo to tied warmest Dec 1934 (now tied 2nd)

22 yrs 3 mo to warmest Mar 1957

12 yrs 7 mo to warmest Oct 1969 (now tied 3rd)

__ (5 yrs 2 mo to tied warmest Dec 1974 -- now tied 2nd)

5 yrs 10 mo to warmest Aug 1975 (now third) (interval from the tied Dec just 8 months)

7 yr 11 mo to warmest July 1983 (now 2nd)

11 yrs 4 mo to warmest Nov 1994

____________________________________________

And if I took the warmest Nov out, then fourth warmest 1818 would replace it. 

 

Edited September 18, 2021 by Roger J Smith

[The PIT]

Sunny Sheffield still at 17.2C +2.0C above normal. Rainfall at 9mm 13.7% of the monthly average.

Probably around 16.9C to 17C by the end of the week.

[Scorcher]

Has anyone got the records for the warmest Septembers up to the 20th/21st? This must be up there for the warmest first two thirds of the month.

[Roger J Smith]

6 hours ago, Scorcher said:

Has anyone got the records for the warmest Septembers up to the 20th/21st? This must be up there for the warmest first two thirds of the month.

The highest running CET values were from 1865 in this part of the month, 17.8 on 19th and 20th, 17.5 on 21st, 17.2 on 22nd, then tied 17.1 with 2006 which led for the rest of the way gradually cooling to 16.8. Just looking at data for the 20th, the second to fifth highest values (1st to 20th) would be 17.4 in 1898, 17.0 in 1795, 16.9 in 2006, 16.7 in 2016. 

[Scorcher]

5 hours ago, Roger J Smith said:

The highest running CET values were from 1865 in this part of the month, 17.8 on 19th and 20th, 17.5 on 21st, 17.2 on 22nd, then tied 17.1 with 2006 which led for the rest of the way gradually cooling to 16.8. Just looking at data for the 20th, the second to fifth highest values (1st to 20th) would be 17.4 in 1898, 17.0 in 1795, 16.9 in 2006, 16.7 in 2016. 

Thanks Roger, all very interesting. Fair to say there haven't been many warmer up to this point.

[Roger J Smith]

Probably in the range of 3rd to 5th warmest so far (after we get the final values) ... 1898 was the only one of those which dropped significantly to end of the month (15.2). 

[Roger J Smith]

EWP currently around 25 mm, looks to add only 5-10 mm to 29th with some moderate rainfall on the 30th (day 11) so still on track for a 40-50 mm finish. The current model run stays quite warm to almost the end of the month then finishes with a shot of cooler air from the north, if that verified it would perhaps drag the CET down 0.2 from wherever it stood on 29th. A finish in the mid 15s still appears quite likely. 

[The PIT]

Sunny Sheffield at 17.1C +2C above normal. Rainfall up to 9.4mm 14.3% of the monthly average

Good chance on being in top ten driest months and the warmest on record.

[Derecho]

With the rest of the week and into next weekend looking above average, I can see the September CET finishing around 16.0-16.3C after corrections.

[Summer Sun]

17.2c to the 19th

3.2c above the 61 to 90 average
2.7c above the 81 to 10 average

___________________________

Current high this month 18.1c on the 10th & 11th
Current low this month 14.4c on the 1st

[Man With Beard]

11 hours ago, Quicksilver1989 said:

With the rest of the week and into next weekend looking above average, I can see the September CET finishing around 16.0-16.3C after corrections.

Just how much will it drop? Probably not much if tonight's runs are correct!

[Derecho]

11 minutes ago, Man Without Beard said:

Just how much will it drop? Probably not much if tonight's runs are correct!

Indeed and I think next weekend could be very warm for the time of year. If the warmth holds on till the end of the month that would make things interesting but the last few days are uncertain and that is what could send the CET on a late drop if it turns cooler then average.