July 2015 CET forecasts

[damianslaw]

CET taking a bit of a tumble, another very near average month now looks likely, the theme of 2015 apart from April, quite a contrast to 2014 and its theme of well above average months.

[Don]

CET taking a bit of a tumble, another very near average month now looks likely, the theme of 2015 apart from April, quite a contrast to 2014 and its theme of well above average months.

 

Indeed, 2015 has been pretty average so far temperature wise.  However, it's notable that we recorded the hottest July temperature ever in what looks to be an average month temperature wise overall.  In fact, if anything July will probably finish slightly below the 61-90 average! 

Edited July 25, 2015 by Don

[draztik]

CET taking a bit of a tumble, another very near average month now looks likely, the theme of 2015 apart from April, quite a contrast to 2014 and its theme of well above average months.

 

 

Pretty much. Heat bottled up across the heart of Europe.

Edited July 26, 2015 by draztik

[The PIT]

Sunny Sheffield down to 16.1C -0.7C below average

[March Blizzard]

 

Pretty much. Heat bottled up across the heart of Europe.

Western Russia in the freezer. The Alps on fire!

[BornFromTheVoid]

The minimum today is 8.7C (lowest of the month so far) while maxima look like reaching the mid 17s, so a drop to 16.5C is likely on tomorrows update.

 

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

 

16.5C to the 27th (16.0: -1.2)

16.4C to the 28th (14.3: -3.1)

16.3C to the 29th (13.1: -4.6)

16.2C to the 30th (13.0: -4.4)

16.1C to the 31st (13.8: -3.4)

 

 

Latest run has the final 10 days average 14.2C. If correct, we'd have to go back to 1920 to find a colder end to July.

[Milhouse]

So a pretty rubbish month tbh after such a promising start. Will go down as nothing special, totally masking the impressive heat right at the start.

[Summer Sun]

16.6c to the 25th

 

0.7c above the 61 to 90 average

 

Bang on the 81 to 10 average

[Eugene]

Pretty normal July then and the warmest month of the year so far, been a humid month too.

[Milhouse]

Pretty normal July then and the warmest month of the year so far, been a humid month too.

 

First of all you would expect July to be the warmest month out of the first 7 months. The last time June was warmer than July was 1970. And theres still more of this cool rubbish to go so it will end up below average.

[Don]

So a pretty rubbish month tbh after such a promising start. Will go down as nothing special, totally masking the impressive heat right at the start.

 

In some ways, this month has reminded me of a Summer version of February 2009.  Although we didn't break any cold temperature records at the start of that month, it did start very cold and a cold to very cold month overall was looking very likely. However, the second half of the month became very mild and the overall CET finished slightly above the 61-90 average at 4.1C.

Edited July 26, 2015 by Don

[Weather-history]

I notice that the last occasion, May, June and July had CET values less than the 1971-2000 CET average values was 1987

[hillbilly]

Just to note there is only one summer in the last 20 years averaging below 15 deg,yet the previous 20 years had eight !!

[damianslaw]

Have we jumped into October? my guess of 18 degrees has quickly gone down the pan, I think many are probably surprised how much of a cooldown we are seeing, a significant one, likely to end up possibly the greater fall in CET values from start to finish since I don't know how long - any stats?

[BornFromTheVoid]

Have we jumped into October? my guess of 18 degrees has quickly gone down the pan, I think many are probably surprised how much of a cooldown we are seeing, a significant one, likely to end up possibly the greater fall in CET values from start to finish since I don't know how long - any stats?

 

I looked at something like that on the last page https://forum.netweather.tv/topic/83389-july-2015-cet-forecasts/?p=3238311

[Yarmy]

Just to note there is only one summer in the last 20 years averaging below 15 deg,yet the previous 20 years had eight !!

 

Combination of GW and AMO phase, presumably. But a discussion for another thread.

[The PIT]

Sunny Sheffield down to 16C good chance of 15.9C by tomorrow.

[BornFromTheVoid]

Just to note there is only one summer in the last 20 years averaging below 15 deg,yet the previous 20 years had eight !!

 

[Summer Sun]

16.5c to the 26th

 

0.5c above the 61 to 90 average

 

0.1c below the 81 to 10 average

[Lettucing Gutted]

Have we jumped into October? my guess of 18 degrees has quickly gone down the pan, I think many are probably surprised how much of a cooldown we are seeing, a significant one, likely to end up possibly the greater fall in CET values from start to finish since I don't know how long - any stats?

I would have thought November 2010 would have had the biggest fall from start to finish.  Recently March 2013 also had a big fall from start to finish.  Since late winter through midsummer months are usually "warming months" its very unusual to get any significant drop let alone a big drop in these months.

Edited July 27, 2015 by Goodbye Cold Weather! :(

[Gael_Force]

I would have thought November 2010 would have had the biggest fall from start to finish.  Recently March 2013 also had a big fall from start to finish.  Since late winter through midsummer months are usually "warming months" its very unusual to get any significant drop let alone a big drop in these months.

These months are seasonal cusp months, big swings are expected; they are not to be expected in the true heart of summer.        

[BornFromTheVoid]

Yesterday was a particular cold day for the CET region at 12.8C. Keeping in mind that it's a provisional value, to find a colder day in the last week of July, we have to go back to July 30th 1986, which recorded 12.4C. In fact, since 1930, only 8 days during the last week of July have been as cold or colder than yesterday

[Roger J Smith]

These are the current record values for the statistic being discussed here today, namely, drop in CET from 1st to monthly average value. Where they exist, any other values greater than 8 deg are also shown, which is about what this month might produce (24 to 16) ... edit, final numbers blew away the previous July record from 1968 which was 6.8 (21.8 to 15.0).

 

JAN _ 1917 ___ 8.8 ___ from 10.4  to  1.6

JAN _ 1880 ___ 8.7 ___ from 9.6  to  0.9

JAN _ 1838 ___ 8.3 ___ from 6.8  to  -1.5

 

FEB _ 1929 ___ 8.6 ___ from 9.0 to 0.4

 

MAR _ 1799 ___ 6.0 ___ from 9.4 to 3.4

 

APR _ 1815 ___ 4.9 ___ from 13.0 to 8.1

 

MAY _ 1958 ___ 4.8 ___ from 15.9 to 11.1

 

JUN _ 1978 ___ 5.9 ___ from 19.6 to 13.7

 

JUL _ 2015 ___ 8.7 ___ from 24.6 to 15.9

 

AUG _ 2013 ___ 5.8 ___ from 22.7 to 16.9

 

SEP _ 1906 ___ 7.9 ___ from 21.8 to 13.9

 

OCT _ 1985 ___ 9.2 ___ from 20.2 to 11.0

OCT _ 1895 ___ 8.5 ___ from 15.6 to 7.1

 

NOV _ 1801 ___ 7.7 ___ from 12.5 to 4.8 .... 2010 was only 5.0 from 10.2 to 5.2

 

DEC _ 1939 ___ 8.8 ___ from 12.0 to 3.2

DEC _ 1840 ___ 8.1 ___ from 9.4 to 1.3

______________________________________________________

 

While Nov 2010 did not make the list, the drop from 13.6 on 5th to 5.2 at end of month was 8.4 and accomplished in 25 days. The only other within-month value that is easily noted is from 2nd to 30th in September 1906 (see above) which was a further 0.8 or 22.6 to 13.9, 8.7 degrees.

 

Of course that is not quite the right comparison, we need to take the cumulative CET at any point and compare that to month end. In Nov 2010, the cumulative on 5th was 12.2 so that dropped 7.0 to end of the month. And in Sep 1906 the cumulative on 2nd was 22,2 which then dropped 8.3 to 13.9 C.

 

There may be other cases of monthly records from within the month rather than first of month to average, it would be a lot of computer time required to find them but I may skim through record highs in first third of months to see if anything jumps out. March 2013 was never very close, the first was almost as cold as the month (3.8 vs 2.7) and the biggest drop I can find there is an absolute drop of 4.1 from 8th, but from a cumulative of 5.0 this reduces to only 2.3. As some have noted, the spring months are at a disadvantage and you might expect November to be a favourite but it has never broken 8, the record high values are from October, then all three winter months, and then quite possibly this month, which is quite remarkable given the rising tendency and the smaller variance of midsummer.

Edited August 2, 2015 by Roger J Smith

[BornFromTheVoid]

These are the current record values for the statistic being discussed here today, namely, drop in CET from 1st to monthly average value. Where they exist, any other values greater than 8 deg are also shown, which is about what this month might produce (24 to 16).

 

JAN _ 1917 ___ 8.8 ___ from 10.4  to  1.6

JAN _ 1880 ___ 8.7 ___ from 9.6  to  0.9

JAN _ 1838 ___ 8.3 ___ from 6.8  to  -1.5

 

FEB _ 1929 ___ 8.6 ___ from 9.0 to 0.4

 

MAR _ 1799 ___ 6.0 ___ from 9.4 to 3.4

 

APR _ 1815 ___ 4.9 ___ from 13.0 to 8.1

 

MAY _ 1958 ___ 4.8 ___ from 15.9 to 11.1

 

JUN _ 1978 ___ 5.9 ___ from 19.6 to 13.7

 

JUL _ 1968 ___ 6.8 ___ from 21.8 to 15.0

 

AUG _ 2013 ___ 5.8 ___ from 22.7 to 16.9

 

SEP _ 1906 ___ 7.9 ___ from 21.8 to 13.9

 

OCT _ 1985 ___ 9.2 ___ from 20.2 to 11.0

OCT _ 1895 ___ 8.5 ___ from 15.6 to 7.1

 

NOV _ 1801 ___ 7.7 ___ from 12.5 to 4.8 .... 2010 was only 5.0 from 10.2 to 5.2

 

DEC _ 1939 ___ 8.8 ___ from 12.0 to 3.2

DEC _ 1840 ___ 8.1 ___ from 9.4 to 1.3

______________________________________________________

 

While Nov 2010 did not make the list, the drop from 13.6 on 5th to 5.2 at end of month was 8.4 and accomplished in 25 days. The only other within-month value that is easily noted is from 2nd to 30th in September 1906 (see above) which was a further 0.8 or 22.6 to 13.9, 8.7 degrees.

 

Of course that is not quite the right comparison, we need to take the cumulative CET at any point and compare that to month end. In Nov 2010, the cumulative on 5th was 12.2 so that dropped 7.0 to end of the month. And in Sep 1906 the cumulative on 2nd was 22,2 which then dropped 8.3 to 13.9 C.

 

There may be other cases of monthly records from within the month rather than first of month to average, it would be a lot of computer time required to find them but I may skim through record highs in first third of months to see if anything jumps out. March 2013 was never very close, the first was almost as cold as the month (3.8 vs 2.7) and the biggest drop I can find there is an absolute drop of 4.1 from 8th, but from a cumulative of 5.0 this reduces to only 2.3. As some have noted, the spring months are at a disadvantage and you might expect November to be a favourite but it has never broken 8, the record high values are from October, then all three winter months, and then quite possibly this month, which is quite remarkable given the rising tendency and the smaller variance of midsummer.

 

Hi RJS,

 

I've got the daily CET data arranged as a single column (about 89k rows!). I can send you a copy if you like, or maybe attach the excel file with it at some point.

 

Anyway, the the daily data as a single column, I can check the stats for within months too.

So the data below shows the biggest drops in the CET record from an individual day to the average of the next 30 days. 

 

 

Year......Month.....Day.....Drop... DayAvg..Next 30 Day Avg

1819....... 12....... .20...... 11.2...... 9.9......... -1.3

1819....... 12........ 22...... 11.1...... 9.4......... -1.7

1819....... 12.........19...... 10.9...... 9.9......... -1.0

1890....... 11........ 23...... 10.8...... 10.8........ 0.0

1813....... 12........ 25...... 10.8...... 8.1......... -2.7

1779....... 12........ 18...... 10.7...... 10.6....... -0.1

1813....... 12........ 24...... 10.5...... 8.3......... -2.2

1878....... 12........ 31...... 10.4...... 10.0....... -0.4

1819....... 12........ 18...... 10.4...... 9.7......... -0.7

2010....... 11......... 5....... 10.3...... 13.6........ 3.3

 

 

I'll give a more detailed look tomorrow when I have the time.

 

[Roger J Smith]

Thanks, I have a daily file downloaded that I have been updating manually since 2011. Just didn't think about the 30-day drop regardless of date. I suppose the real comparison is 30-day drop divided by the standard deviation in daily temperatures because I figure that summer must be about 2/3 of winter on that scale (s.d.) so 8 deg in July is comparable to 12 deg in January. Or if it was 4/5, then 8 is comparable to 10, etc.

 

This may in fact be the most significant 30-day differential on this scale when you consider that factor. The drop in October 1985  was larger in absolute terms but it would average about 2 deg at random (because temperatures are usually falling that much throughout October) so that should be subtracted, whereas July would average almost a degree up so that should be added for comparison, as well as the slightly larger spread of October means compared to July means.

Edited July 29, 2015 by Roger J Smith