September 2022 C.E.T. and EWP forecast contests

[Roger J Smith]

EWP update, currently at about 56.7 mm, GFS estimates are very low for most of the grid to 30th, in fact zero for London and Hampshire, 2 mm in the Midlands, and only above 10 mm in parts of north Wales and northwest England. The grid average is close to the 3.3 mm required to maintain the previous estimate of 60 mm for a finish. This would give current leader The PIT (60 mm, second entry) a second place score behind Ed Stone with 60 mm first entry, and with closest challengers freeze (76 mm) and Feb91Blizzard (81 mm) set to drop back a bit. That low estimate could of course change, there have been a few runs in recent days showing up to 15-20 mm additional rainfall that will certainly be available over parts of Ireland and Scotland when the flow becomes more southwest late in the month. 

As to the CET projection, it stays quite cool for several days, warms somewhat towards Thursday 22nd, then falls back again, net result looks to be into the range of 14.5 to 15.0. 

[damianslaw]

0.3 degree drop, expect at least the same tomorrow's update and quite probably through until Monday. Could well be in the 15s as soon as the equinox. 

Edited September 16, 2022 by damianslaw

[Summer Sun]

16.5c to the 16th

3.0c above the 61 to 90 average
1.8c above the 81 to 10 average

[The PIT]

Sunny Sheffield down to 16.5C +1.1C above normal. Rainfall 41.1mm 62.5%of the monthly average

[damianslaw]

4 hours ago, Summer Sun said:

16.5c to the 16th

3.0c above the 61 to 90 average
1.8c above the 81 to 10 average

As expected another 0.3 degree drop. Tomorrow should be the same at least.

[Roger J Smith]

Yes, today could produce a drop of 0.4 as the minimum looks to be as low as 2-3 C. Further steady drops to about Tuesday then a few milder days will produce a flat line for the CET (at around 15 C) but several rather chilly days near the end of the month and results could be well down into the 14s. EWP continues to look very dry now to end, current estimate for a finish is 62 mm. 

[The PIT]

Sunny Sheffield down to 16.2C +0.8C above normal. Rainfall unchanged.

Looks like slow down in the drop for the next five days but still a downward pressure.

[Summer Sun]

16.2c to the 17th

2.6c above the 61 to 90 average
1.6c above the 81 to 10 average

[Don]

10 minutes ago, Summer Sun said:

16.2c to the 17th

2.6c above the 61 to 90 average
1.6c above the 81 to 10 average

Almost a 1C drop in 3 days.  Another decline tomorrow before stabilising for a number of days?

Edited September 18, 2022 by Don

[richie3846]

2 minutes ago, Don said:

Almost a 1C drop in 3 days.  Another decline tomorrow before stabilising for a number of days?

I would expect so, nights are looking much milder from tonight onwards, and last night wasn't that cold (not sure if that goes into tomorrow's figure or already calculated?). Another above average month methinks, unless the last week drags down some much cooler air.

[Don]

31 minutes ago, richie3846 said:

I would expect so, nights are looking much milder from tonight onwards, and last night wasn't that cold (not sure if that goes into tomorrow's figure or already calculated?). Another above average month methinks, unless the last week drags down some much cooler air.

I think an above average month has pretty much been in the bag since early in the month.  The question has really always been, how much above average will it be?  Last night's model output suggested something in the 14's, today however, not sure, it really hinges on the final week.  I believe last night's minimum will be factored into tomorrow's update, so I suspect the CET will be 16.0 tomorrow?

Edited September 18, 2022 by Don

[richie3846]

27 minutes ago, Don said:

I think an above average month has pretty much been in the bag since early in the month.  The question has really always been, how above average will it be?  Last night's model output suggested something in the 14's, today however, not sure, it really hinges on the final week.  I believe last night's minimum will be factored into tomorrow's update, so I suspect the CET will be 16.0 tomorrow?

Thanks for clarifying the date/min temp. I wasn't aware it was factored in a day later than I incorrectly assumed.

[LetItSnow!]

A rather crude calculation - but using the model output for the next 10 days, I calcuated that the ECM and GFS get us to around: 

ECM 0z - 15.1 to the 28th

ECM 6z - 15.4 to the 25th

GFS 6z - 15.1 to the 28th (14.9 finish)

It's all about the minima I think. When the current ridge reasserts itself, if the air doesn't get too mixed up or cloudy, then we may hold on to some chilly nights which could nearly offset the days. The ECM had means of around 13-14 around the 22nd but the GFS is closer to 14-15, which would put the C.E.T. at a bit of a standstill and make it touch and go whether we go under 14. I think under 15 is at play, especially with some model output I've seen this morning, but it really hinges on the next few days. Once we get to the 24th then a possible plunge again. Upper 14s/low 15s looking good now I think.

Edited September 18, 2022 by LetItSnow!

[damianslaw]

A 1.3 degree drop in 5 days is preety impressive. Quite a cold spell for mid Sept. Based on current model output I"d say 60% change we will finish under 15 degrees, this could easily go up to about 75% by middle of next week. Going under 14 degrees would be a very tall order, a slim 10% chance. An above average almost a dead cert, an appreciably above average month 1.5 degrees or above, much less so. Still it will continue the run of above average months in 2022.Have we ever had a complete calandar year of above average months? 2014 probably has come closest. 

Edited September 18, 2022 by damianslaw

[richie3846]

6 minutes ago, damianslaw said:

A 1.3 degree drop in 5 days is preety impressive. Quite a cold spell for mid Sept. Based on current model output I"d say 60% change we will finish under 15 degrees, this could easily go up to about 75% by middle of next week. Going under 14 degrees would be a very tall order, a slim 10% chance. An above average almost a dead cert, an appreciably above average month 1.5 degrees or above, much less so. Still it will continue the run of above average months in 2022.Have we ever had a complete calandar year of above average months? 2014 probably has come closest. 

I wonder how much less the drop would be if the starting point 5 days ago was average? It doesn't feel like it's that much below average to me but I don't know what the exact figures are on the 30 year averages for the rolling month. My suspicion is that many people are perceiving this spell to be significantly below average when it may not be that far below. 

The drop is steep partly because the start point is high, rather than this being a notable cool spell for the time of year, this is my thinking but I don't have the numbers to back this up. I suspect it's only a slightly cool spell, maybe around 2c below the average for the stage in the month where we are at.

[damianslaw]

4 minutes ago, richie3846 said:

I wonder how much less the drop would be if the starting point 5 days ago was average? It doesn't feel like it's that much below average to me but I don't know what the exact figures are on the 30 year averages for the rolling month. My suspicion is that many people are perceiving this spell to be significantly below average when it may not be that far below. 

The drop is steep partly because the start point is high, rather than this being a notable cool spell for the time of year, this is my thinking but I don't have the numbers to back this up. I suspect it's only a slightly cool spell, maybe around 2c below the average for the stage in the month where we are at.

Yes we started from an exceptionally high benchmark. Anyone post the recent daily means. 

[LetItSnow!]

2 hours ago, damianslaw said:

Yes we started from an exceptionally high benchmark. Anyone post the recent daily means. 

The cool past few days have seen daily means of 10-11 so far - not record breaking, but notably cool.

In contrast, September 24-September 28, 2020 averaged 9.4degC.

[damianslaw]

3 hours ago, LetItSnow! said:

The cool past few days have seen daily means of 10-11 so far - not record breaking, but notably cool.

In contrast, September 24-September 28, 2020 averaged 9.4degC.

About 4.5 degrees below the norm, quite significantly lower than mid Sept mean.

 

[The PIT]

Sunny Sheffield down to 15.9C +0.8C above average. Rainfall unchanged.

We may even end up at average hard to tell as the modelling is a bit twitchy at the moment. Next few days should see a levelling off of the drop. Local forecast has some chilly nights at the end of the week so some smaller drops there.

 

[Summer Sun]

16.0c to the 18th

2.4c above the 61 to 90 average
1.4c above the 81 to 10 average

[Roger J Smith]

EWP estimates on GFS starting to increase a little, latest estimate would be 65-70 mm. 

CET estimate would be 14.5 to 14.8. 

[Summer Sun]

15.8c to the 19th

2.2c above the 61 to 90 average
1.3c above the 81 to 10 average

[damianslaw]

Looking increasingly will end in the 14s and comfortably so. 

[Summer Sun]

15.7c to the 20th

2.1c above the 61 to 90 average
1.2c above the 81 to 10 average

[Don]

55 minutes ago, Summer Sun said:

15.7c to the 20th

2.1c above the 61 to 90 average
1.2c above the 81 to 10 average

CET perhaps stabilising for the next couple of days before declining again from Saturday?