April 2024 C.E.T. and EWP contests

[snowray]

 Roger J Smith I'm getting the feeling this could be one of them years Roger.

[Metwatch]

15 minutes ago, snowray said:

April can be the most unpredictable of all of the months of the year, like early summer one day and like late winter the next.

That's what facinates me a lot about April. The sun is as strong as late summer, so don't need a particularly warm airmass to see temperatures shoot up, but at the same time there's still a lot of cold air left in the Arctic from the winter so that can easily spill down to the UK, well into the end of month, such as that was the case in April 2016. Cold spells are more common than many ordinary folk may think for this month.

Searching through the forum ( can be done like this: ( https://community.netweather.tv/search/?&q=april&type=forums_topic&quick=1&nodes=40&search_and_or=and&search_in=titles&sortby=relevancy ) and it seems April 1892 had the most insane warm to cold contrast: April 1966 had some potent spells too which if a repeat was to happen in modern days I think would be quite the shock.

Also a few topics on April cold and snow falls in more recent years:

 

 

Edited April 17 by Metwatch

[Derecho]

EC 12z control has the CET finishing on 9.6C. Pretty close to the ensemble mean overall with the monthly CET dipping below 10C on the 23rd.

According to this, first half CET would be 11.1C, second half would be 8.0C so quite a contrast. 

[Roger J Smith]

1778 as already discussed went from near-record warmth 1-13 Apr to near-record cold 14-27 Apr, and had a daily average of only 2.9 on 24th which was broken in 1908 so it isn't in list of records now, but 22 April is still there (3.4 C). 1873 also had very cold days near 3 C not staying as records after 1908. 

I had a look to verify that no colder readings than 2.9 were broken by the 1908 and 1856 records. The 2.7 mean daily on 30 April 1945 is another case of a record low following warm April weather (record highs set 15-16 Apr). 

After 2.5 on 23 April 1908 the second coldest average was 3.2 in 1857 (also 3.4 in 1827). 

After 0.6 on 24 April 1908 the second coldest average was 2.9 in 1778 (also 3.2 in 1873). 

After 1.8 on 25 April 1908 the second coldest average was 3.2 in 1816, 1873 and 1950. (also 3.5 in 1829). 

After 0.7 on 29 April 1856 the second coldest average was 3.1 in 1782. 

The -0.2 of 19 April 1772 was not further ahead of 1.7 in 1849 (also 2.3 in 1793, 2.4 in 1838 and 2.5 in 1809).

 

Edited April 17 by Roger J Smith

[Summer Sun]

10.8c to the 17th

2.9c above the 61 to 90 average
3.0c above the 81 to 10 average

[The PIT]

Sunny Sheffield down to 9.7C +1.9C above average. Rainfall 66.2mm 118% of average

[Summer Sun]

10.6c to the 18th

2.7c above the 61 to 90 average
2.8c above the 81 to 10 average

[damianslaw]

 Summer Sun Nearly a 1 degree drop in 5 days. A finish in the 9s increasingly likely based on current output, a late sudden heat spike could pop up, but the theme is for a sustained cool northerly sourced airflow, possibly becoming cut off in the latter stages of the month to a more cyclonic near average flow. We shall see. We are seeing some notably chilly minima in sheltered spots presently colder than at first anticipated. 

[The PIT]

Sunny Sheffield down to 9.7C +1.8C above normal. Rainfall 66.4mm 118.4% of the monthly average.

[Don]

 damianslaw My guess is certainly looking better than it was a week or so ago!

[Summer Sun]

10.6c to the 19th

2.7c above the 61 to 90 average
2.8c above the 81 to 10 average

[damianslaw]

 Summer Sun Surprised CET held... should be a drop tomorrow, last night was quite cold for many.

[snowray]

There were some 0c and -1c temps last night but day time maxes seem very hard to peg down, 12c,13c  in many places.

[Roger J Smith]

In scoring estimates already posted, I added 95 mm as an option below original 75 mm tables. Anyway just a preview. 

Will be on a break for about two weeks, some internet access but I won't be on line for most of ten days now to 30 April, any data questions etc may not be answered in usual prompt timing but I may get on briefly ... posted next contest already, and will try to get some of usual end of contest posts up on 1st before disappearing again for about five days on return portion of trip (going down to UT and AZ). 

 

[WYorksWeather]

Just looking at the figures for this week so far in terms of how we're doing. This was supposed to be a relatively cold week, but just goes to show how difficult it is to get anything approaching cold these days on the 1961-1990 average. April is a rapidly warming month so given that we're towards the end (but not right at the end) I'm inclined to add half a degree to the 7.9C average for the whole of April to give us 8.4C as a comparator for this week - this seems to roughly align with an eyeballing of the Met Office CET chart as a sense check.

For Monday to Friday we have 8.0, 8.9, 7.1, 6.3 and 10.6. That gives an average of 8.2C. If we assume a  return of 6C for today and tomorrow which might even be too cold, then the average for the calendar week would fall to 7.6C, only just under 1C below the 1961-1990 average for the time of year.

Just goes to show - even with a whole week of winds blowing mostly from between NW and NE it has been difficult to get anything substantially below average. Which is of course why it's also so difficult to get a whole month below 1961-1990 at the moment.

[WYorksWeather]

 Roger J Smith I hope you enjoy your break!

In terms of the further look ahead having looked at GFS and ECM there's a bit of a last minute change as you say on EWP with potential further heavy rain next weekend probably meaning it will finish a bit wetter than we previously thought.

However, I also note a bit of a disagreement between the models tonight on temperature. GFS is keeping things chilly through the rest of April and would probably see CET fall into the 9s, but ECM has a warmup for the last three days with a return to southerly or south-westerly winds which probably means a finish in the 10s. Still a lot of uncertainty even at this stage.

 damianslaw Temperatures further west are holding up pretty well by day, and both Stonyhurst and Pershore benefit from that. If the pattern had been 100 miles further west this could have been quite a cold week overall, but it looks like the calendar week will only be a little below average on 1961-1990.

[Don]

1 hour ago, WYorksWeather said:

Just goes to show - even with a whole week of winds blowing mostly from between NW and NE it has been difficult to get anything substantially below average. Which is of course why it's also so difficult to get a whole month below 1961-1990 at the moment.

Yes and what is concerning is that we had an April only 3 years ago that was almost 1.5C below the 1961-90 average!  Has the climate changed that much in such a short space of time?!

Edited April 20 by Don

[The PIT]

Sunny Sheffield still at 9.4C +1.3C above average. Rainfall 68.1mm 121.4% of the monthly average.

[damianslaw]

 Don The difference with April 2021 is it was cold synoptics throughout. I've run the archives and on no one day was the airstream other than either between north and east or anticyclonic, a rare example of non atlantic influence, Feb 86 a good example. The clear anticyclonic conditions allowed for very low minima, and we had very cold arctic airstream.

The current cool spell, is neither clear anticyclonic - hence more cloud holding minima up, nor air of true arctic origin. 

[Dare i watch the GFS 06Z]

If you're feeling that April the most important spring month has gotten colder lately it's not a illusion, the peak of warm april's were in the late 00's since then it's gotten slowly colder on average.

[Summer Sun]

10.4c to the 20th

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

[WYorksWeather]

 Don My maths would probably suggest that April 2021 synoptics this year with warmer SSTs and higher overall global temperatures would probably still have managed below 1961-1990 average but only by around 1C.

In short, the synoptics now need to be either cool for the whole month with no other influences to counteract it, or a much colder than average spell which is then not counterbalanced by anything excessively mild. So your options in recent years for a cooler than 1961-1990 average month are either persistently chilly (April 2021) or a notable cold spell without a corresponding notably mild spell (December 2022). I think both those months would still be cooler than 1961-1990 if the synoptics reoccurred - it will happen again at some point.

I think currently I expect about 90% of months to come out above average on 1961-1990. If we don't see it happen this year I might have to revise that up to 95%, though. But as things stand I think it's probably as likely as not that it will happen at some point this year.

[Derecho]

Afternoon all, so after an unremarkable week of CET returns (even slightly above average with the last 7 days at 8.2C) it looks as though the CET may actually now be close to or even above 10C at the end of the month.

According to the 00z EC control, we have a few slightly chilly days up until the 26th which should take the CET down to around 9.7C. After that the daily CET returns are above 10C again.

00z EC control is slightly on the warmer side of the ensemble mean so something between 9.8C and 10.2C is probably in the right area. Another notably above average month yet again if this run comes off.

GFS handles the weekend low a bit differently so is cooler however to end the month.

[damianslaw]

 Dare i watch the GFS 06Z Is this graph for Sweden? The last below average April in 1987!!!

[damianslaw]

 WYorksWeather Dec 22 could have been a notably below average month but it was counterbalanced by a very mild 19-31st period.

When was the last 30 or 31 day running mean below 61-90 average, possibly hard to calculate Whilst July 23 nearly did it, I assume the 2 July to 1 Aug was below, and we will have had something more substantively i.e. 0.5 degrees below from say 7 July to 7 August... 

 

Edited April 21 by damianslaw