April 2013 CET Forecast Contest (2012-13 Competition)

[Roger J Smith]

I realize it is still the middle of winter, but here's the April forecast contest thread, and all the data from the past, irrelevant though that may be ...

April CET statistics and trivia

19.7 ... warmest April daily mean (29th, 1775)

16.3 ... warmest daily mean 1-15 April (15th, 1945)

11.8 ... warmest April (2011)

11.2 ... 2nd warmest April (2007)

10.6 ... 3rd warmest April (1865)

10.5 ... 4th warmest April (1943)

9.2 ... average for 2001-12

9.0 ... average for 14 yrs 1862-1875 (surprise?)

8.5 ... average for 1981-2010

8.1 ... average for 1971-2000 (and 20th century 1901-2000) (also 1971-2000)

8.0 ... average for 19th century 1801-1900

7.9 ... average for all data 1659-2012, also 1961-1990, also 18th century 1701-1800

7.3 ... average for 1659-1700

5.8 ... 18th coldest (tied) 1986 (coldest of past half century)

5.4 ... fifth coldest (tied) -- 1917 (coldest 20th century) also 1743,1770,1799)

5.2 ... third coldest (tied) -- 1782 and 1809

4.7 ... coldest Aprils (1701 and 1837)

-0.2 ... coldest April daily mean second half (19th, 1772)

-0.5 ... coldest April daily mean (2nd, 1917 and 3rd, 1799)

[summer blizzard]

-1C.

The ice age has begun.

[BornFromTheVoid]

For those hoping for a big turn around to spring warmth, here's a list of the 10 largest March to April CET increases (March and April values in brackets)

1865 ... 7.7 (2.9, 10.6)

1785 ... 7.2 (1.2, 8.4)

1783 ... 6.8 (3.3, 10.1)

1814 ... 6.7 (2.9, 9.6)

1845 ... 6.6 (2.0, 8.6)

1674 ... 6.5 (1.0, 7.5)

1762 ... 6.3 (3.7, 10.0)

1869 ... 6.3 (3.8,10.1)

1867 ... 6.2 (3.1, 9.3)

1987 ... 6.2 (4.1, 10.3)

It seems that there is a fairly strong auto-correlation between March and April though (0.3 over the series), so cold March CET values tend to be followed by cold April values.

[IanR]

7.8c

[Guest pjl20101]

7.1 to be honest. May revise it up next week.

[CongletonHeat]

6.5

[Bobd29]

....somewhere between 5 - 10 degs, will decide later; and judging by my 6.2 for March I am clearly an unsung expert!!!

[Portland Paul]

7. 2

Another (last for a while ) cold, wet month

[SteveB]

6.9c for me please

[SomeLikeItHot]

6 for me.

[jonboy]

7.3 for me cold start but warm last week

[Lettucing Gutted]

12C

[Bobd29]

12C

wouldn't it be great if Craig got right....if only

[Bobd29]

time to come off the fence, it just has to warm up eventually so I'll plump for a nice 8.9 please

[BornFromTheVoid]

Here's the April CET values since 1659, with the linear trend in black and the 10 year rolling mean in red.

Using the raw data, the auto-correlation is slightly positive +0.15 (meaning on average, warm Aprils tend to be followed by warm Aprils the next year, and cold Aprils by cold Aprils) but that may be due to the warming trend.

The April CET with the linear trend removed, shows a slight positive auto-correlation too, of 0.11. Overall, this indicated that there is a slight tendency to have periods where April CET values warm up, then periods where is cools down. This can actually be seen slightly in the graph, especially the 10 year mean showing numerous pronounced peaks and troughs.

Could we be about to enter another trough?

[Yarmy]

At this rate I might as well re-use my March value! So 279K (5.85C).

Rather hope I'm wrong though.

[summer blizzard]

wouldn't it be great if Craig got right....if only

Alarmingly he'd have only had to go for 11C before 2007 but we now have 2 April's which are miles ahead of anything else.

[Roger J Smith]

I'm tired of this cold weather and I don't even live there, so 9.4 what the hey.

[AWD]

5.7 please

[geoffw]

5.3

[Summer Sun]

Not so sure on April yet the first week or 2 could see a north south split mildest in the south and quite wet at times with some drier sunnier interludes but cooler still in the north with a snow risk on high ground at times but even here I expect sunshine at times making it feel pleasant but its mid April onwards when all the UK could see its first taste of some much needed and long over due warmth and sunshine with high pressure starting to influence our weather again

I'm gonna hold back for now on my CET prediction but steady improvements as we go through April hopefully with quite possibly our first above average month in a while

[Xyplode]

6.2

[Eugene]

Even the warmest April on record is still alot colder than the coldest July/August on record.

[BlueHedgehog074]

Will go for 9.0*C, with a mixture of everything.

[virtualsphere]

Tricky one this - as March 2006 demonstrates, at this time of the year a cold start can easily be scuppered by a few very mild days at the end, given the quickly lengthening days and strengthening sun. I've not looked into it but I would think therefore it is easier to get a cold April by ensuring the second half is cool rather than through having a very cold first half; certainly that's helped the current month to a low CET with the cold weather continuing as we head towards the end.

Enough rambling, I'll go for 8.1C - cold for the first half and warm for the second.