April 2015 CET Forecasts

[Summer Sun]

In the brackets, they show the average from the 1st up to that point in the month (cumulative average), similar to what the MO show with the 61-90 average.

The value outside the brackets is the average for that individual day.

 

Thanks

 

[Summer Sun]

7.8c to the 4th

 

1.5c above the 61 to 90 average

 

0.1c above the 81 to 10 average

Edited April 5, 2015 by Summer Sun

[BornFromTheVoid]

The outlook is very mild. With a min today of 4.9C and maxima likely to climb over 13C, we'll probably see an increase to 8.1C on tomorrows update.

 

After that, the 06z GFS has the CET at:

 

8.5C to the 6th (10.3)

8.6C to the 7th (9.5)

8.8C to the 8th (10.0)

9.0C to the 9th (10.6)

9.3C to the 10th (11.6)

9.3C to the 11th (9.2)

9.4C to the 12th (10.7)

9.6C to the 13th (12.1)

9.8C to the 14th (13.0)

 

That would have us about 1.7C above the 81-10 average by the 10th, and more than 2C above by the 14th.

Potential for a top 20 warmest first halves of April on record.

[reef]

 

The outlook is very mild. With a min today of 4.9C and maxima likely to climb over 13C, we'll probably see an increase to 8.1C on tomorrows update.

 

After that, the 06z GFS has the CET at:

 

8.5C to the 6th (10.3)

8.6C to the 7th (9.5)

8.8C to the 8th (10.0)

9.0C to the 9th (10.6)

9.3C to the 10th (11.6)

9.3C to the 11th (9.2)

9.4C to the 12th (10.7)

9.6C to the 13th (12.1)

9.8C to the 14th (13.0)

 

That would have us about 1.7C above the 81-10 average by the 10th, and more than 2C above by the 14th.

Potential for a top 20 warmest first halves of April on record.

 

I wonder if we might record another double-digit CET April this year. Its a statistical oddity, but throughout the CET series they tend to come in bunches.

 

The last eight years have seen four such years (2007, 2009, 2011 and 2014), there were four in seven years in the 1940s (1943, 1944, 1945 and 1949) and another four in seven years in the 1790s (1792, 1794, 1796 and 1798).

 

Considering there are only 21 such Aprils in the CET series, its very unusual indeed.

[BlueSkies_do_I_see]

My 9.4C call is the 13th highest so a lot look to be going bust this month in the competition as it stands. If we retain high pressure for a prolonged length of time it will be how close we can get to 2007. I doubt 2011 will be beaten this year.

Edited April 5, 2015 by BlueSkies_do_I_see

[Don]

My 9.4C call is the 13th highest so a lot look to be going bust this month in the competition as it stands. If we retain high pressure for a prolonged length of time it will be how close we can get to 2007. I doubt 2011 will be beaten this year.

 

Yes, my 8.4C prediction is looking a little shaky at the moment.  Obviously though, with it still being early in the month, plenty of twists and turns to come yet.

[BlueSkies_do_I_see]

Yes, you are right of course. A mild first half doesn't point to a mild second half of the month. I don't know how rare it is for CET at mid point of a Spring month to already have a high figure. What was 2011 running at by the 15th out of interest? From memory the first 10 days of the month were incredibly mild.

Aprils are getting milder though and I do enjoy these warmer springs. It's my favourite time of the year. Longer day, greener landscape, explosion of new life in animal kingdom and of course the warmer and warmer avg temps. This is true through April, May and June. July and August can be too hot and the days getting shorter again so for me the build-up to the solstice is what I live for.

Edited April 5, 2015 by BlueSkies_do_I_see

[Summer Sun]

8.1c to the 5th

 

1.7c above the 61 to 90 average

 

0.5c above the 81 to 10 average

[Summer Sun]

8.3c to the 6th

 

1.9c above the 61 to 90 average

 

0.7c above the 81 to 10 average

[BornFromTheVoid]

Minimum today of 3.9C while maxima look like hitting the high 16s, so an increase to 8.6C is likely on tomorrows update.

 

After that, the 06z GFS has the CET at:

 

8.8C to the 8th (10.2)

9.1C to the 9th (11.4)

9.4C to the 10th (12.1)

9.4C to the 11th (9.4)

9.2C to the 12th (7.5)

9.3C to the 13th (9.9)

9.5C to the 14th (12.2)

9.8C to the 15th (14.3)

10.1C to the 16th (15.2)

 

While it's quite far away, it's interesting to see a 15C or higher CET mean so early. It it did occur on the 16th, it would be the 9th earliest to achieve it of any year on record (though some had more than 1 by the 16th).

The earliest it's been recorded is in 1926 and 1946, with exactly 15.0C on the 3rd of April.

 

[summer blizzard]

Not breaking date records yet so not on par with 07 or 11 but it is looking pretty warm. 

[Summer Sun]

8.6c to the 7th

 

2.1c above the 61 to 90 average

 

1.1c above the 81 to 10 average

[Roger J Smith]

This will answer any questions about previous cases where April cooled off in the second half of the month. These are top 15% of cases of cooling 16th-30th relative to 1st-15th, in the data set from 1772 on. Quite a few additional years managed a slighter amount of cooling so it's not that unusual. In case you were looking for 1945, it only cooled from 10.4 to 9.8 (0.6) so not in the list.

 

 

YEAR __________ First half __ Second half ____ cooling

1778 ___________10.2 _______6.1 __________ 4.1

 

1884 ___________ 8.8 _______ 5.6 __________ 3.2

1981 ___________ 9.3 _______ 6.2 __________ 3.1

1815 ___________ 9.6 _______ 6.6 __________ 3.0

1906 ___________ 8.7 _______ 5.9 __________ 2.8

1808 ___________ 7.1 _______ 4.5 __________ 2.6

1835 ___________ 9.9 _______ 7.3 __________ 2.6

1991 ___________ 9.2 _______ 6.6 __________ 2.6

1859 ___________ 8.8 _______ 6.3 __________ 2.5

1826 ___________10.0 _______7.6 __________ 2.4

1838 ___________ 7.3 _______ 4.9 __________ 2.4

1877 ___________ 8.2 _______ 5.8 __________ 2.4

1926 ___________10.5 _______8.1 __________ 2.4

1803 ___________10.2 _______8.0 __________ 2.2

1995 ___________10.2 _______8.0 __________ 2.2

1827 ___________ 9.9 _______ 8.0 __________ 1.9

1974 ___________ 9.1 _______ 7.3 __________ 1.8

1892 ___________ 8.1 _______ 6.5 __________ 1.6

1894 ___________10.4 _______8.9 __________ 1.5

1850 ___________ 9.7 _______ 8.3 __________ 1.4

1857 ___________ 8.2 _______ 6.8 __________ 1.4

1933 ___________ 9.5 _______ 8.2 __________ 1.3

1856 ___________ 8.7 _______ 7.5 __________ 1.2

1939 ___________ 9.4 _______ 8.2 __________ 1.2

2001 ___________ 8.3 _______ 7.1 __________ 1.2

1805 ___________ 8.8 _______ 7.8 __________ 1.0

1848 ___________ 8.7 _______ 7.7 __________ 1.0

1923 ___________ 8.1 _______ 7.1 __________ 1.0

1960 ___________ 9.4 _______ 8.4 __________ 1.0

1985 ___________ 8.8 _______ 7.8 __________ 1.0

1846 ___________ 8.2 _______ 7.3 __________ 0.9

1772 ___________ 6.8 _______ 6.0 __________ 0.8

1813 ___________ 8.0 _______ 7.2 __________ 0.8

1819 ___________ 9.0 _______ 8.2 __________ 0.8

1908 ___________ 6.4 _______ 5.6 __________ 0.8

1972 ___________ 8.6 _______ 7.8 __________ 0.8

 

(In 1778, the mean was 11.3 C after 13 days then temperatures took a sharp dive)

 

 

Edited April 8, 2015 by Roger J Smith

[damianslaw]

8.3c to the 6th

 

1.9c above the 61 to 90 average

 

0.7c above the 81 to 10 average

 

 

I think these are based on the rolling average.. if so its a little misleading. Also as someone else pointed out the 61-90 average is far lower than the 80-10 average, and therefore comparing to 61-90 average is a bit of a misnomer as well.

 

Post above - it seems quite remarkable the second half of April can produce a mean below 5 degrees.. 1808 4.5 degrees! nearly as cold as an average January!

Edited April 8, 2015 by damianslaw

[Roger J Smith]

The rolling mean gives us at least some idea of how the pattern from first to date might compare to all other data. But of course it says nothing about what changes might lie ahead, BFTV shows that trend in his reports and you can go to the 1981-2010 table earlier in the thread to compare that projection with the running mean that exists at the end (or anywhere in between) of the projection. Models being somewhat imprecise, the range of uncertainty in these projections is often about half to one degree by day ten. Usually the first four or five days are going to be close enough to yield a small error. So I think the daily report is useful when taken in context of the projections.

 

As to the report on April cooling events or cases, a quick check of the data reveals that this tendency has faded out of April climatology over the past century. The first half of the data (1772-1893) have almost twice as many hits as the second half (1894-2014). The tendency seemed to be even more frequent in the first third of data. I suppose having colder seas and closer arctic ice boundaries might have made April a bit more volatile in those decades long ago. At the same time, there have been very few modern Aprils that got off to as fast a start as 1778 although it all went for nothing in the end.

 

One other thing I noticed was a tendency for these topsy-turvy Aprils to occur near peak sunspot activity, but I have not subjected it to a rigorous analysis. Just noticed a lot of high sunspot years among the list.

[Roger J Smith]

Meanwhile, these are the Aprils since 1772 that managed 10.0 or higher as their first half CET ... I have listed them in chronological order with top five ranks in brackets. Ranks are based on second decimals where you see ties.

 

1778 _ 10.2

 

1783 _ 10.0

 

1792 _ 10.2

 

1798 _ 10.2

 

1803 _ 10.2

 

1826 _ 10.0

 

1865 _ 10.0

 

1869 _ 10.2

 

1894 _ 10.4 (4)

 

1926 _ 10.5 (2)

 

1943 _ 10.5 (3)

 

1945 _ 10.4 (5)

 

1946 _ 10.0

 

1995 _ 10.2

 

2007 _ 10.1

 

2011 _ 11.0 (1)

 

2014 _ 10.1

[Summer Sun]

8.8c to the 8th

 

2.3c above the 61 to 90 average

 

1.3c above the 81 to 10 average

[BornFromTheVoid]

The minimum today is 3.9C, while maxima look like reaching the low 16s, so an increase to 9.0C is likely on tomorrows update.

 

After that, the 06z GFS has the CET at:

 

9.3C to the 10th (12.2)

9.2C to the 11th (8.6)

9.2C to the 12th (8.

9.0C to the 13th (7.3)

9.0C to the 14th (9.0)

9.1C to the 15th (10.7)

9.4C to the 16th (12.

9.5C to the 17th (11.4)

9.5C to the 18th (12.2)

 

Remaining well above average overall, but no really exceptional days yet.

 

[cheeky_monkey]

Meanwhile, these are the Aprils since 1772 that managed 10.0 or higher as their first half CET ... I have listed them in chronological order with top five ranks in brackets. Ranks are based on second decimals where you see ties.

 

1778 _ 10.2

 

1783 _ 10.0

 

1792 _ 10.2

 

1798 _ 10.2

 

1803 _ 10.2

 

1826 _ 10.0

 

1865 _ 10.0

 

1869 _ 10.2

 

1894 _ 10.4 (4)

 

1926 _ 10.5 (2)

 

1943 _ 10.5 (3)

 

1945 _ 10.4 (5)

 

1946 _ 10.0

 

1995 _ 10.2

 

2007 _ 10.1

 

2011 _ 11.0 (1)

 

2014 _ 10.1

surprised 1997 is not on the list must have had a warm second half of the month?

[Roger J Smith]

1997 first half 9.1, second half 8.8 C

 

Closer misses in recent years were 1999 and 2009, 9.6 and 9.8 first half.

[The PIT]

Sunny Sheffield on 9c +0.6c above normal

[Roger J Smith]

... it seems quite remarkable the second half of April can produce a mean below 5 degrees.. 1808 4.5 degrees! nearly as cold as an average January!

 

Coldest first half values are even more wintry, 2.6 deg C in 1917 would have tied for 115th coldest January, 86th coldest February and 65th coldest December, and would have been the second coldest November or 12th coldest March, while 2.9 in 1837 was colder than 218 of 357 Januaries and 252 of 357 Februaries.

 

The coldest first half value since 1950 appears to be 4.4 C in 1986.

Edited April 9, 2015 by Roger J Smith

[ItNeverSnowsInWindsor]

Looking good for my 10.2 C prediction with a warm' week coming up.

[Summer Sun]

9.0c to the 9th

 

2.5c above the 61 to 90 average

 

1.5c above the 81 to 10 average

[BornFromTheVoid]

Latest GFS would have the CET at about 10.1C by the 15th, but still no daily records under threat.