August 2019 C.E.T. and EWP forecast contests

[summer blizzard]

Gavin is estimating 16.6C to the 24th so certainly after adjustments we still can’t rule out a 15.x finish.

[Roger J Smith]

EWP up to 24 mm after eight days, the 9th likely added 8-10 mm (blend of small amounts in three quarters of the grid and quite large amounts in parts of Wales and northern England). The 10-day GFS estimate looks to be close to 50 mm, once again blending amounts like 20 mm near London and 80 mm in northern England. That all combines to totals near 83 mm and that's only out to 20th, the next six days on the GFS not part of the projection appear moderate for further rainfall, so creeping up towards that 100 mm estimate by 26th. 

Not quite as sold on the cooling trend, charts have a lot of westerly flow that can sometimes prove to be overdone especially well out into the future, so the downturn while inevitable may be a bit less dramatic than some projections, I would estimate 17.2 by end of the 16-day run based on average of 16.5 for the period blended with current 18.5 (estimating today at around 17).

(18.4x10 + 16.5x16) / 26

(184 + 264)/26

448/26 = 17.23

then that should be reduced to 16.9 or 17.0 probably.

Trends have been towards warmer output near end of GFS run, hmm a warm spell near end of a month, how surprising is that? 

 

[damianslaw]

A very warm August so far, despite any very warm maxima - indeed I don't think anywhere has breached the 80f mark so far.. 

[Don]

28 minutes ago, damianslaw said:

A very warm August so far, despite any very warm maxima - indeed I don't think anywhere has breached the 80f mark so far.. 

Yes indeed.  I think this has been mainly due to little diurnal variation so far?

[Roger J Smith]

The synoptics are more or less like a mild November with a higher sun angle and longer days. 

[The PIT]

Sunny Sheffield done to 18.3C +1.7C above normal. Rainfall 36.7mm 55,5% of the monthly average

[Summer Sun]

18.4 to the 10th

2.4c above the 61 to 90 average

1.5c above the 81 to 10 average

________________________________

Current high this month 18.8 to the 4th

Current low this month 18.1 to the 1st

[Roger J Smith]

EWP 33 mm after 9 days, add about 5 mm for 10th (large areas nil but heavy in north), and at least 50 mm shown for next ten days, heavy amounts both north and south coast, less in Midlands. That brings the estimate close to 90 mm by just the 21st with ten days additional. May need to do a provisional for 120 mm at this rate. 

[summer blizzard]

1 hour ago, Roger J Smith said:

EWP 33 mm after 9 days, add about 5 mm for 10th (large areas nil but heavy in north), and at least 50 mm shown for next ten days, heavy amounts both north and south coast, less in Midlands. That brings the estimate close to 90 mm by just the 21st with ten days additional. May need to do a provisional for 120 mm at this rate. 

While it may prove an extreme example you did in June point out to me that historically very wet June's are followed by a less wet July but much wetter August. 

This summer seems to be following that pattern. 

What is the June total for us to chase?

[Roger J Smith]

Did you mean, what is the summer total? Here's the current top twelve (only two were recent) and what we need this August to match them. The August record is 192.9 mm (1912) so that rather dire August was both coldest and wettest.

(June 2019 EWP was 115.9 mm and July 2019 was 72.2, total was 188.1 mm).

Wettest summers (EWP) 1766 to 2018

Rank __ Year ___ Total rainfall ___ Aug 2019 to match

_01 ___ 1912 ____ 409.7 ________ 221.6

_02 ___ 1879 ____ 409.2 ________ 221.1

_03 ___ 1829 ____ 396.3 ________ 208.2

_04 ___ 2012 ____ 375.0 ________ 186.9

_05 ___ 1860 ____ 370.8 ________ 182.7

_06 ___ 1768 ____ 362.2 ________ 174.1

_07 ___ 1828 ____ 355.9 ________ 167.8

_08 ___ 1839 ____ 351.2 ________ 163.1

_09 ___ 1775 ____ 347.3 ________ 159.2

_10 ___ 1817 ____ 345.7 ________ 157.6

_11 ___ 1848 ____ 344.3 ________ 156.2

_12 ___ 2007 ____ 343.5 ________ 155.4

___________________________________________________

Most of these would seem to be out of reach, but you never know.

The next entry that occurred since 1981 was 36th wettest 1985 (293.0) for which 104.9 mm is needed, and at 39th is 2004 (290.4) for which 102.3 mm is required. So with 100 mm this would be the fifth wettest summer in the past 40 since 99.9 mm would tie with 1980 in 42nd place overall. 

For the Northwest England subgroup, the wettest summer (series begins 1873) was 2012 at 430.6 mm, so far they have seen 221 mm in June and July, 48 to 9th of August and probably another 20 or more yesterday into today, so sitting around 290 mm needing another 141 to break that record. 

[snowspotter]

I have to question the netweather CET if I am honest . Try telling Joe Public that August is a scorcher 2.42c above an average August . Bearing in mind in simplistic terms taking the average maximum and minimum predicted for the next 10 days we would be looking at about 16c max which bearing in mind I am in the south east surely means the CET must come right down . I don’t buy this low diurnal range of temperature . I can’t even think we have had a warm first 10 days of August : something must surely be wrong 

[Roger J Smith]

Don't shoot the messenger (net-weather), the CET values and anomalies are direct from the official source, the UK Met Office. 

We are just reporting what they are saying (the 1981-2010 averages are calculated by our thread contributors from their data, the 1961-1990 averages come from the UK met office generated website, link is here)

http://hadobs.metoffice.com/hadcet/cet_info_mean.html

[ARTDEMOLE]

Met Office Hadley          18.2c.      Anomaly    2.3c.

Metcheck                       17.60c     Anomaly     1.58c

Mean of my 10 watched stations 18.25c. Anomaly 1.79c. Using a 6 year average. 2013 - 2019 

Edited August 12, 2019 by ARTDEMOLE

[Summer Sun]

18.2 to the 11th

2.3c above the 61 to 90 average

1.3c above the 81 to 10 average

________________________________

Current high this month 18.8 to the 4th

Current low this month 18.1 to the 1st

[The PIT]

Sunny Sheffield down to 18.1C +1.5C above normal. Rainfall unchanged.

A big drop tomorrow and possible the next few days before it slows.

[Roger J Smith]

EWP was 37 mm after ten days, added about 4 or 5 mm on 11th (only heavy in a few spots in north and Thames valley), but future projections on GFS have backed off somewhat to 20-30 mm in next ten days, and the charts for days 11 to 16 appear to have perhaps 10 mm potential. This gets us somewhere near 80 mm with a few days left in the month.

I already showed provisionals for 90.1 and 100.1 mm, here's 80.1 mm -- it seems that Reef would hold on to the annual contest lead with any outcome below 81 mm (he went for 72 mm in August, BFTV went for 90). 

EWP20182019AUG801.xlsx

[Summer Sun]

17.9 to the 12th

1.9c above the 61 to 90 average

1.0c above the 81 to 10 average

________________________________

Current high this month 18.8 to the 4th

Current low this month 17.9 to the 12th

[BornFromTheVoid]

Below is the estimate of the CET over the next 10 days based on the 06z GFS

The first graph is the provisional data and forecast with daily max, min, mean and the rolling CET, as well as the 81-10 rolling mean. The second graph is the daily mean in relation the the daily high and low mean record values.

   

After quite a warm first third, the CET looks like dropping steadily during the middle of the month, back down to the rolling average as we enter the final 10 days. As such, most guesses are still in with a shout.

[The PIT]

Sunny Sheffield down to 17.7C +1.1C above normal. Rainfall 37.3mm 56.4% of normal.

[Summer Sun]

17.6 to the 13th

1.6c above the 61 to 90 average

0.7c above the 81 to 10 average

________________________________

Current high this month 18.8 to the 4th

Current low this month 17.6 to the 13th

[Roger J Smith]

EWP 46 mm to 12th, likely added 2 mm on 13th, and GFS has about 30 mm on average for the grid over next ten days, then the maps for days 11 to 16 would suggest potential for only 5-10 mm in a blocked pattern. That altogether adds up to about 85 mm, similar to the last two estimates I posted. 

As to CET trends, once the average settles into the high 16s to near 17.0, it looks like very little pressure either way in the faintly warmish blocked pattern towards the end, but that could be first signs of a warm spell looming. 

[The PIT]

Sunny Sheffield down to 17.4C +0.9C above normal. Rainfall 38.5mm 58.2% of the monthly average.

The downward pressure should ease a little over the weekend and with the GFS showing a warm up next it still looks good for a +17C finish.

[Summer Sun]

17.4 to the 14th

1.4c above the 61 to 90 average

0.6c above the 81 to 10 average

________________________________

Current high this month 18.8 to the 4th

Current low this month 17.4 to the 14th

[summer blizzard]

Despite being an unremarkable month current model runs might actually produce the warmest August since 2004.

[Derecho]

On 11/08/2019 at 18:29, snowspotter said:

I have to question the netweather CET if I am honest . Try telling Joe Public that August is a scorcher 2.42c above an average August . Bearing in mind in simplistic terms taking the average maximum and minimum predicted for the next 10 days we would be looking at about 16c max which bearing in mind I am in the south east surely means the CET must come right down . I don’t buy this low diurnal range of temperature . I can’t even think we have had a warm first 10 days of August : something must surely be wrong 

So basically what you are saying is that the CET series is wrong?

Just because there has been no days above 30C so far, doesn't mean it hasn't been a warm month. The opening 10 days were consistently warm but at times unsettled as well. The last few days have been cooler hence the CET has started falling.