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Roger J Smith

June 2019 CET & EWP forecast contests

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12.9c to the 16th

0.9c below the 61 to 90 average

1.0c below the 81 to 10 average

__________________________________

Current high this month 17.1c to the 1st & 2nd

Current low this month 12.8c to the 13th & 14th

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Sunny Sheffield up 12.8C -0.4C below normal. The coming warm days and nights should push us to normal probably. Rainfall 100.6mm 137.8% of the monthly average.

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Trevor Harley refers to the June's of 1901 and 1902 as "very cold".  June 2019 will have to warm up a bit to warrant that description by the look of things!

I'm sure it will warm up in the second half.  If it were to stay as it were. it would be what I define as a cold month  (ie within the coldest 10% mean CETs for the respective month) .

So far this century (taken from Jan 2000) we've only had 2 such cold months, less than one per cent of all months. By contrast nearly 30% of the months have been warm ones. But despite the predominance of warm months, only 4 of the Junes this century have been warm and that includes the two previous years!  In the last two years warm June months this century have gone from 12.5% to 22.22%, but still languish comfortably behind the average for this century.. 

It's remarkable that, in these days of warming temperatures, up until 2017 the predominance of warm Junes this century was less than it was in the 18th Century (14%). And that the 18th Century had more warm Junes than the 19th Century (9%) and 20th century (6%) . Where ever did the reputation for "blazing June" come from??!! 🙂 

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23 minutes ago, Timmytour said:

Where ever did the reputation for "blazing June" come from??!! 🙂 

It’s flaming June and that has a suitable double meaning ..! 

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June is the only month whose highest running 30-year CET was not in the recent past (it was 1822 to 1851). We were within striking distance after last June but this one will prolong the inevitable to about 2021 when cool June 1991 is out of the interval. If June 2020 and 2021 are just average, the 30-year running mean will likely reach the same value as its maximum back in the 1822-51 interval (which was 14.72). December's highest 30-year mean goes back a bit to 1971-2000, otherwise all other months max out in some very recent 30-year interval.

I have been number crunching the historical EWP values too, and there was a marked rise in June EWP about the same time, the 30-year running average reached a peak value of 79 mm for 1828 to 1857. It then dropped off gradually to values below 60 mm and the minimum was 52 mm (1913-42) but has recently been increasing again, peaking recently at 69 mm (1987 to 2016) and last seen at 67 mm for 1989 to 2018. That will be back up again for 1990 to 2019 perhaps to 69 mm as 1989 was a little under the average (the mean will change by 1/30 the difference of 2019 minus 1989). 

Edited by Roger J Smith

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13.0c to the 17th

0.8c below the 61 to 90 average

0.9c below the 81 to 10 average

__________________________________

Current high this month 17.1c to the 1st & 2nd

Current low this month 12.8c to the 13th & 14th

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

image.thumb.png.3a368ab19fd341998ebde4aa9360084b.png

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.

image.thumb.png.c591fdc0fcfc5d6d8f1816ccfedc3c56.pngimage.thumb.png.09cc6a07b15fdacf40f5d375d22c4293.png  

The numbers and graphs speak for themselves really. Little change over the next 6 days, before a big warm up with daily records coming under threat too. Nothing certain that far out, but an above average month is clearly not out of the running just yet.

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It is probably worth adding that the Euro produces about 2 days of high CET means so right now the GFS is the upper boundary with its direct plume.

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Warmest June day on record is 23.0 on 3rd (1947) which is low-hanging fruit for this climate, almost everywhere else with a temperate climate would expect to set its all-time June record near the end of the month adjacent to July. Normal values are certainly higher at end of June than start of the month. In a way it was surprising that June 1976 didn't manage to dislodge the early June mark from 1947, there was a full week of heat wave conditions at end of June and values above 24 were recorded by early July. 

It would be a bit of a laugher if this month managed to set the all-time record, but it matches what happened at end of July 1948 which was otherwise quite a cool month. Even a four-day heat wave at end failed to move it past 16 C. 

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By the way, worth mentioning that the upper parameters shown on the GFS are extreme values for southern England (around 26th-27th), 850 mb temperatures as high as 24 C and 576 thickness contour into Midlands suggesting 578-579 for southeast England. That's almost desert heat. You could imagine readings of 36 to 38 (and 40 in parts of France) with these parameters. Given how wet it has been any fronts would have a lot of moisture available too. The air mass might be trying to dessicate but with that surface moisture dew points would be sure to get close to 20 C, making it a very oppressive heat. I would not be the least bit surprised if this output proves overcooked because otherwise it will be many of the readers of this thread being overcooked. The full heat would not spread into Wales or Ireland or most of Scotland, it would get warm (23-27 C) but not that hot. Remarkable maps anyway, whether true or false (perhaps the summer version of some of the 10-day maps we had last January). 

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Sunny Sheffield at 12.8C still -0.5C below normal. Rainfall unchanged.

The uppers shown on the 26th only seem to generate heat in the far south and south east suggesting a cloudy outcome so it should feel like a sauna. Hopefully it's stay away in Europe and understands Brexit properly. 🙂

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The 12z GFS backed away from the extreme warmth scenario and all guidance seems to converge now on a solution where the continental heat stays just the other side of the Channel but fires up an active frontal wave around Tuesday into Wednesday of next week, that might produce some vigorous thunderstorms in southeast England and Midlands. Some of the warmer days might approach 20 for average CET from a 23/17 sort of max/min but I think any chance of record warmth would be across the far southeast if it gets onto land anywhere in the UK. Still, guidance could wobble back to the extreme warmth option again before this is settled. 

From a climatological standpoint the wet spell would suggest caution with any sharp warming trends, they are going to be under pressure to overcome a tendency for warmer air to become cloud laden and therefore not as warm as it could be potentially had there been a dry run up to the signals. 

Hadley EWP tracker was at 96 mm after 16th, is now very likely above 100 mm and there's a solid 20-30 mm more indicated on the charts to 30th, with potential for 40-50, so outcome now seems almost assured to be above all but the one or two forecasts. 

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Going by this morning’s model runs, a below average June looks unlikely now.

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13.1c to the 18th

0.7c below the 61 to 90 average

0.9c below the 81 to 10 average

__________________________________

Current high this month 17.1c to the 1st & 2nd

Current low this month 12.8c to the 13th & 14th

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53 minutes ago, Summer Sun said:

13.1c to the 18th

0.7c below the 61 to 90 average

0.9c below the 81 to 10 average

__________________________________

Current high this month 17.1c to the 1st & 2nd

Current low this month 12.8c to the 13th & 14th

Not likely to be below average for much longer....

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2 minutes ago, Don said:

Not likely to be below average for much longer....

Perhaps, depends if any heat becomes widespread next week and not concentrated in the se.

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The 06z GFS continues to be more aggressive with the heat 25th-26th than the 12z which just rolled out, but either way, it would likely return to normal values by 29th-30th, so the outcome is beginning to converge on a narrow range of about 14.4 to 15.0 before adjustments. From the 12z GFS I am seeing 14.66 ((3x13.1 +2x17)/5)=(73.3/5) while from the 06z it would be 15.0. Would estimate 0.2 as correction so 14.4 to 14.8 there for final value. 

If heavy rainfalls accompany the warmth we might be looking at a top ten or even top five outcome for EWP. 

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Sunny Sheffield up to 13C -0.4C below average. Rainfall 102.1mm 139.9% of the monthly average. First uptick on the temperatures another rise tomorrow then probably another pause. Then if the heat arrives that should make dints in the averages.

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13.3c to the 19th

0.6c below the 61 to 90 average

0.8c below the 81 to 10 average

__________________________________

Current high this month 17.1c to the 1st & 2nd

Current low this month 12.8c to the 13th & 14th

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

image.thumb.png.060fdea1f511bba97ce536cb099351d2.png

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.

image.thumb.png.8eb6ce0974131a4c5daa3131ea1e531a.png   image.thumb.png.6c51b938220c2f24753bd1f0b794e902.png

Recent runs have become more bullish in a hot spell occurring next week, with several runs offering the warmest June day on record, and by a long margin. Also the chance of the warmest or second warmest 5 day June average since 1976. What the eventual outcome is, remains to be seen.
Whatever happens, we have another few days of slightly below average temperatures to get through before the warm up begins. Depending on how the hot/warm spell goes, a 15C+ finish may even be possible.

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EWP tracker had reached 100 mm after 18th, likely around 103 mm now. The ten day GFS precip forecast map shows an average of 25 mm more by 06z June 30th, with potential for perhaps 5 mm the rest of that day, so most likely outcome is now around 133 mm. Compared to the provisional scoring for 120 mm, the only change would be LG moving up to 4.2 points and tied 26th out of 44 (same error as 66 mm), while all who had been 28th to T42nd would move down one rank and lose 0.2 or 0.3 points. (former 27th now 28th but same points as calculated from second entry at 66 mm).

Those changes and a scoring line for the "what if" for Stewfox's late entry (line 335) are shown in this updated version of scoring. Further slight changes would occur depending on how far up or down the result is -- LG would move past all the other forecasts this month if we reached the June record of 160 mm.

EWP20182019Jun.xlsx

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I'll do a full update for the 06z, but for now, the 00z has us setting daily mean records from the 25th to the 29th. It breaks the June record (23.0C) 4 times from the 26th to the 29th, and the all time CET record twice (24.9C) on the 27th and 28th with 25.5C and 25.3C respectively. All before finishing the month off with a below average day on the 30th!

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13.3c to the 20th

0.6c below the 61 to 90 average

0.8c below the 81 to 10 average

__________________________________

Current high this month 17.1c to the 1st & 2nd

Current low this month 12.8c to the 13th & 14th

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

image.thumb.png.42c1805406cb70960e7f503b0e32a6b4.png

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.

 image.thumb.png.3ae796b4f04c1e56c6d1ed3c3e44a416.png  image.thumb.png.60eb45811bbf620ee2361fc01c3e62a1.png

The beginning of the hot spell now entering the reliable time-frame of just 3 days ahead, while the exceptional heat is almost there, at 5 days ahead. Very likely to break some daily records, a chance at breaking the June record and a small chance at setting an all time record also. Remarkably, an above average month now seems quite likely too!

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Sunny Sheffield at 13.2C -0.4C below normal. Rainfall at 103.3mm 141.5% of the monthly average. If the severe heatwave comes off that will push us into the mild category.

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