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

[Roger J Smith]

I don't see the usual update today but will post it if needed (around 10 p.m.), it's 5.6 C like the previous day. (-1.2 rel 1961-90). 

The 12z GFS run is about the same as the past two days, some intervals of near average temperatures mingled with cooler spells, can't see the overall average for today to 30th being much warmer than 7.5 overall, which would bring us in around 6.7 C. Also it looks quite dry in England and Wales, a bit wetter in parts of Ireland and Scotland although even there below average. We are going to be challenged to reach either our lowest CET or EWP forecasts. 

Edited April 14, 2021 by Roger J Smith

[damianslaw]

Looking odds on we will return a below average finish, how low is the question? Certainly a very cold first half to the month. Only a slow rise expected in the outlook, can't see anything especially mild on the cards, nightime minima will keep means low.

Today has brought widespread double digit maxima but after another very chilly night, and it still feels more akin to late Feb/early march, rather than mid-April. Still waiting for that true spring feeling.. very different to this time last year.

 

[Frigid]

I wonder when the last time we had a very dry cold April. All the precip I’ve seen fallen this month has been snow showers. Ground is rock solid.

[Roger J Smith]

For continuity ...

5.6c to the 13th

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

(2.6 below the 91 to 20 average)

___________________________

Current high this month 8.8c on the 1st
Current low this month 5.6c on the 12th and 13th

[Weather-history]

Temperature wise, this year has been following a similiar path to 1966, so far. 

1966 2.9  5.7  6.5  7.2

2021 3.1  5.1  7.2

[The PIT]

Sunny Sheffield still at 5.2C -2.4C below avergae. Rainfall unchanged at 3.3mm 5.9% of the monthly average.

So cold first half as recent trend will we get a milder 2nd half ?

[Summer Sun]

5.7c to the 14th

1.2c below the 61 to 90 average
2.0c below the 81 to 10 average

___________________________

Current high this month 8.8c on the 1st
Current low this month 5.6c on the 12th and 13th

[Roger J Smith]

EWP is only 4 mm and the next ten days will add almost nothing to that according to the GFS, the grid average is barely 2 mm and large parts of the south and east will see near zero amounts. The maps for days 11 to 15 are showing a bit of rain (or sleet) from a disturbance that is supposed to move southwest across the country near the end of the month. That looks like about 5-10 mm, so we have evidence for a grand total of 10-15 mm, quite a ways below the minimum forecast from Polar Gael of 36 mm. I could pretty much score the contest now if this model forecast is even 20 mm out. 

On the CET front, I see a few days later next week that look slightly warmer than average, but it's a brief interval and the most likely outcome for CET remains high 6 to around 7 range. 

[damianslaw]

An unusual combination a dry cold April.. most drier April's recently have also been warm, think last year, 2007, 2011.

[The PIT]

Sunny Sheffield up to 5.3C -2.4C below normal. Rainfall unchanged.

ECM this morning has gone for a colder outlook whether the other models go with this idea remains to be seen

[BornFromTheVoid]

Latest projections

 

The chances of finishing:
Close to average (8.5C to 9.5C) is  to 0.4% (2 days ago 2.4%)
Above average (>9.5C) remains at 0.0% (2 days ago 0.0%)
Below average (<8.5C) is  to 99.6% (2 days ago 97.6%)

The period of the 16th to the 21st is forecast to average 7.5C, which is 1.5C below the 91-20 average.

[Summer Sun]

5.6c to the 15th

1.3c below the 61 to 90 average
2.1c below the 81 to 10 average

___________________________

Current high this month 8.8c on the 1st
Current low this month 5.6c on the 12th, 13th & 15th

[Relativistic]

On 08/04/2021 at 16:52, Relativistic said:

Recent first halves (1st-15th) of April to beat are:

2013: 5.8C
2008: 6.7C
2000: 5.6C
1998: 6.6C
1996: 6.5C
1994: 5.8C
1990: 6.7C
1989: 6.5C
1986: 4.4C
1984: 5.6C
1983: 5.6C
1978: 5.4C
1977: 6.2C
1975: 5.6C
1973: 6.3C
1970: 4.7C

We stand a chance of beating all those since 1986, although that's far from nailed on. A slim possibility we end up third coldest since 1970.

With the provisional figure sitting at 5.6C then a modest downward correction of 0.2C at month's end would see us tie 1978 as the third-coldest first half since 1970. A larger downward correction would give us outright third, with zero chance of beating 1970 and 1986.

The mean minimum CET is worth keeping an eye on. To the 16th the provisional figure is 1.2C, which becomes 1.0C with our modest correction. If the remaining 14 days averaged a little over 3.0C we'd still end up fifth-coldest on record; 4.0C lands us at around 10th and 5.0C around 20th.  For context, the coldest is 1.4C from 1917.

There's still a way to go yet, but it's nice to be able to talk about what might be a notably cold month.

Edited April 16, 2021 by Relativistic

[Derecho]

I notice the coldest CET estimate for this month is 6.8C by a few members, I went for 7.3C which I thought was a bit of a risk but there is a chance it may come in lower then everyone's guess!

A lot of people are going to be a long way out for this month. I still remember December 2015 when lettucing gutted won 

[feb1991blizzard]

15 minutes ago, Quicksilver1989 said:

I notice the coldest CET estimate for this month is 6.8C by a few members, I went for 7.3C which I thought was a bit of a risk but there is a chance it may come in lower then everyone's guess!

A lot of people are going to be a long way out for this month. I still remember December 2015 when lettucing gutted won 

Must admit ive finally come around to that way of thinking now, there was a brief period where the ECM eps best data was showing a good run of 16c max's with 6 or 7 mins post 20th, thought i might get away with my comments earlier on the thread but they're down to 12 and 13's now so its goodnight vienna, damaged limitation now for me and with rainfall, just hope i don't fall too far behind in the annual, think your 7.3 still has a very decent chance, ruling out 8c+ now, still would be very surprised if it finished below 6.5c, as even below average days will still raise it in the last 3rd, any above average days will raise it by 0.2 or 0.3 because it is so low.

[Roger J Smith]

EWP still looking quite low for the rest of the month, same estimate as yesterday (25 mm) which is lower than all forecasts. 

I updated the scoring file using that estimate although any number below 40 mm has the same scoring outcome (with slight changes to scores as one parameter in play is percentage error differential from the leader, and that spreads out to include slightly better scores for the dry half of the field as the outcome approaches 40). Those differentials would be only .02-.03 and would likely not change any annual scoring ranks. Will post these estimates over the weekend if I don't see any large changes in the guidance. A brief overview is that virtualsphere moves into first place in the annual contest with Feb91blizzard moving up to a close second. There are slight changes in the rest of the top ten, Blast from the Past moves back in at ninth. 

You can see your April rank by counting from the dry end of the forecasts (page three), the top three were Polar Gael, weather26 and myself. 

No change to my CET outlook from today's guidance, near 7 C before corrections. 

[damianslaw]

Good chance we might return a mean at least 1 degree below the 61-90 mean, we're not used to seeing such low returns nowadays.. A finish above the mean looks a very tall order now.

Edited April 16, 2021 by damianslaw

[feb1991blizzard]

18 minutes ago, damianslaw said:

Good chance we might return a mean at least 1 degree below the 61-90 mean, we're not used to seeing such low returns nowadays.. A finish above the mean looks a very tall order now.

Especially in April.

[Don]

Hmm, is it safe to say yet my guess of 9.1C will be too high?! 

[damianslaw]

11 minutes ago, Don said:

Hmm, is it safe to say yet my guess of 9.1C will be too high?! 

In a word yes!

[Don]

15 minutes ago, damianslaw said:

In a word yes!

Lol, I think so now!  Both my temperature and precipitation guesses are going to be a bust this month!  Still, never mind.

[Frigid]

This is turning out to be a March 2013 or December 2015 moment, not as extreme as those months were but I don’t think we expected this April to be as cold as it’s been so far. We haven’t really seen a significantly cool April since the 80s so our minds are skewed into thinking we will be in for a mild April given how many we’ve had in the last decade. Coolest April I’ve experienced was in 2012 which was wet and dull, so to see a bone dry, cold April is very notable. Still there’s 2 weeks left for things to change, maybe a warm spell at months end perhaps. 

[Don]

9 minutes ago, Frigid said:

This is turning out to be a March 2013 or December 2015 moment, not as extreme as those months were but I don’t think we expected this April to be as cold as it’s been so far. We haven’t really seen a significantly cool April since the 80s so our minds are skewed into thinking we will be in for a mild April given how many we’ve had in the last decade. Coolest April I’ve experienced was in 2012 which was wet and dull, so to see a bone dry, cold April is very notable. Still there’s 2 weeks left for things to change, maybe a warm spell at months end perhaps. 

It's been a somewhat different April to what we were experiencing 10 years ago!  That would have been good for the pubs reopening.....

[The PIT]

Sunny Sheffield still at 5.3C -2.5C below normal. Rainfall unchanged. 

ECM moved to less cold outlook however then develops cold pool over Europe. Deep in LALA land so can't be taken seriously at the moment.

A slow steady rise next is on the cards though.

[Summer Sun]

5.6c to the 16th

1.5c below the 61 to 90 average
2.1c below the 81 to 10 average

___________________________

Current high this month 8.8c on the 1st
Current low this month 5.6c on the 12th, 13th, 15th & 16th