June C.E.T

[West is Best]

Just thought I'd mention that we seem to be back to the warm minima syndrome of recent years. We are currently running 3.1C above average, which is really amazing.

Someone I think mentioned about westerlies being needed to peg back the CET? Despite the absence of really high maxima, this current tropical blanket syndrome we have is likely to keep the average well up. Very interesting to see the pronounced northerly blocking at the moment -

I really can't see the CET falling fast with that around.

[Glacier Point]

In order for the same magnitude of anomaly to persist, within a warming month, we should see the trend for temperatures to maintain an upward trend. No models currently show this, indeed, the ECM shows 00z operational, control and ensemble mean all heading slightly downward - not the upward trend needed to maintain the same anomaly for the remainder of the month.

We have to recognise a high degree of uncertainty with the pattern t144 onwards with the track of that big low projected in the Atlantic - this could be the decider somewhere between 15 and 16 C and something a lot more excessive.

Edited June 12, 2007 by Glacier Point

[West is Best]

I think that's just a little simplistic though GP. So many factors come into play: particularly cloud cover and the kind of set-up. But perhaps that's what you meant? Certainly a straight correlation from upper air temps to the CET average doesn't quite work. For instance, if one has warm nights under cloud such as tonight (probably around 13C in the CET zone) you only need maxima of 19C to maintain a 16C mean ...

[Stratos Ferric]

All the more likely to have values surpressed by low cloud last week then as west was definately best.

Definitely agree there. There was a marked E-W gradient at times last week. We're currently at 16.3, and I'd be surprised, with high minima last night, and again tonight, if we don't nudge up to around 16.5 by Wednesday c.o.b. Thereafter, as currently progged, something which is, if not cool, certainly less warm, before a month end that looks like more of the same as we have now: as WiB opines above, warm (though not hot) day time maxima off a W'ly are balanced by minima staying in double digits: there aren't any days looking like averaging less than 15C. On that basis 15.5-16 would be my narrow window at present, but it's still far too early to call the month end from the models. I still rather fancy something warmer and more settled than the models reckon, simply because we're slightly overdue, but that doesn't really count for much.

[beng]

I think the local warm sea surface temperatures (particularly over the N Sea where the wind has frequently been coming from) are holding temperatures up at nighttime (and boosting them relative to the long term average during the day). Anyway it's my assertion that the current relative 'warmth' on the CET scale is more a legacy effect of the previous very warm 12 months - than the current synoptic pattern.

15 years ago I suspect we might have been looking at a below average CET at this point in the month based on the patterns we've seen. If we record similar synoptics on and off for the next 6 months (big if) - then we should start to see CET months returning to more average values (or below) as we lose the local positive sea surface temperature anomalies.

For the moment though, it's going to be very tough to get a cool CET month this summer with those anomalies (that doesn't imply that it will be a great summer though).

Also worth noting that CET doesn't tell the whole story (someone correct me if I'm wrong on this) since it's the halfway point between the max and min temperature for a day - rather than a mean average temperature for the 24 hour period.

Edited June 12, 2007 by beng

[Stratos Ferric]

...Also worth noting that CET doesn't tell the whole story (someone correct me if I'm wrong on this) since it's the halfway point between the max and min temperature for a day - rather than a mean average temperature for the 24 hour period.

Not sure why "it's also worth noting...". The CET is not derived by integrating the area below the line of temperature plotted minute by minute, if that's what you mean: rather it's derived from the simple (and standard) [max+min]/2. That said, any error comapred to the more precise calculation will tend to be fairly small, and can, in any case, go in either direction.

Anyway, my extrapolation for the rest of the month. As ever, I'm far from convinced by the 18z run, which looks a little too cool to me. I'm still favouring 15.5-16 as the outturn.

[Joneseye]

Good Morning!

CET: (Jun 1-12): 16.4°C (+2.9 degC)

E&W Rain: (Jun 1-12): 4.4mm ( 16 per cent)

E&W Sun: (Jun 1-12): 75.8hr (100 per cent)

Figures taken from http://www.climate-uk.com/index.html

The current N-W UK tracker figure for June 2007 is: 15.86°C

(difference from average June CET is 1.76°C)

Interesting to see the big difference between the two figures here. My suspicion is that the Net-Weather Tracker has some stations further east than the CET zone..

[summer blizzard]

Hadley is 0.4C below the Manley estimate, so Net-Weather is simply closer to Hadley than Manley.

[beng]

The CET is not derived by integrating the area below the line of temperature plotted minute by minute, if that's what you mean: rather it's derived from the simple (and standard) [max+min]/2. That said, any error comapred to the more precise calculation will tend to be fairly small, and can, in any case, go in either direction.

Thanks SF.

[Snowly does it]

Hadley is 0.4C below the Manley estimate, so Net-Weather is simply closer to Hadley than Manley.

Gap is closing - Hadley stands at 16.2 to the 12th so now 0.2 adrift

Minima a real problem for low CET hunters despite what looks a more average spell of weather for the south (temp wise) - outside the CET zone June a little closer to normal but temps everywhere well up.

CET should start to drop after today for a while and may be more restricted than previously today as the heat transfers away from a western bias to the SE corner. After today nothing of note temp wise for a while but little to drop the CET dramatically either, perhaps 15.2 - 15.6 by this time next week?

[DR Hosking]

I am right in thinking that the 3 stations for measuring CET are all in urban areas and as such the average could be a fair bit higher than in rural areas within the CET zone? I expect rural areas could be as much as a degree different, mainly because of lower night time temperatures. For example if you see the forecast for the bbc temperatures are always for urban areas, so they have been consistantly giving temperatures at nightime for my area of 13,14 or 15 degrees for the last week or more, my local weather station which is rural has been recording nightime temperatures between 9 and 12 degrees for this period.

[Nick H]

I am right in thinking that the 3 stations for measuring CET are all in urban areas and as such the average could be a fair bit higher than in rural areas within the CET zone? I expect rural areas could be as much as a degree different, mainly because of lower night time temperatures. For example if you see the forecast for the bbc temperatures are always for urban areas, so they have been consistantly giving temperatures at nightime for my area of 13,14 or 15 degrees for the last week or more, my local weather station which is rural has been recording nightime temperatures between 9 and 12 degrees for this period.

No, they all in rural areas actually. One is Pershore nr Worcester, one is in Stonyhurst on the Lancashire Plain and the other is at Rothamsted in Hertfordshire at the foot of the Chilterns (about 10 miles NE of my location).

Edited June 13, 2007 by Nick H

[Stu_London]

Shockingly cool output from the 12z GFS

Max temps in the CET zone average about 16C (and don't exceed 21C for the whole run)

Min temps average 10C

14.3C for the month anyone?

[Duncan McAlister]

Shockingly cool output from the 12z GFS

Max temps in the CET zone average about 16C (and don't exceed 21C for the whole run)

Min temps average 10C

14.3C for the month anyone?

I think it's very unlikely even if the cool 12z comes off. 15.5C-16C would still be my bet.

I don't however think we'll see a 30C this month anywhere in the UK.

[Stu_London]

I think it's very unlikely even if the cool 12z comes off. 15.5C-16C would still be my bet.

I don't however think we'll see a 30C this month anywhere in the UK.

I agree temps progged by the 12z do seem unrealistic - 2nd half of the month looks cooler than the 1st half again though.

I also agree we wont see 30C this month and may struggle to see the temps top 25C again this month.

[Stratos Ferric]

Shockingly cool output from the 12z GFS

Max temps in the CET zone average about 16C (and don't exceed 21C for the whole run)

Min temps average 10C

14.3C for the month anyone?

Didn't see the run Stu, but I do hope you weren't just reading the GFS max-min numbers. They are a fairly crude indicator at the best of times. Today, for example, as of yesterday, GFS was showing 19s and 20s at best. The central S Midlands generally reached 22-23.

[Duncan McAlister]

The ensembles are remarkably consistent at around average to slightly below, however as we've seen recently minima in particular can still stay up in below average upper-airs.

Edited June 13, 2007 by Duncan McAlister

[Stratos Ferric]

...

14.3C for the month anyone?

At this stage anything, theoretically, is possible, but I'd be very surprised if it comes in below 15C now. Even that would require an average of 14C from here. Daytime maxes, in tropical air, will easily nudge 20 plus, and they aren't going to fall readily below 10C overnight in a moist flow. 14.5C is far too low unless we get a dramatic change in the progged set-up. Scotland may get some cooler stuff, but CETland is likely to have far more mild days than cool ones.

[Stu_London]

Didn't see the run Stu, but I do hope you weren't just reading the GFS max-min numbers. They are a fairly crude indicator at the best of times. Today, for example, as of yesterday, GFS was showing 19s and 20s at best. The central S Midlands generally reached 22-23.

I think the GFS min-max numbers are generally ok, although the actual maximum each day generally falls midway between the 12Z and 18Z that each prediction is progged for. It probably was 20C at 12noon and 6pm but 22-23 at 3-4.

Generally I add a degree or so, or maybe a bit more if strong sunshine is predicted.

[Kentish Man]

For the period June 1-13 Manley stands at 16.4C , Hadley 16.2C and the NW tracker just 15.9C, which is quite a wide variance given we are almost mid month.

[Stratos Ferric]

I think the GFS min-max numbers are generally ok, although the actual maximum each day generally falls midway between the 12Z and 18Z that each prediction is progged for. It probably was 20C at 12noon and 6pm but 22-23 at 3-4.

Generally I add a degree or so, or maybe a bit more if strong sunshine is predicted.

I think you're being generous there. The problem GFS has is that it has to use linear extrapolation. It will work from projected depths and uppers, and it might make provision for air mass, but it is always going to produce the same output for the same input. In practice there are a lot of variables which I suspect will tend to be upside more than downside at all times of day: the presence, or not, of direct sunshine can easily make a 4-5C difference to the day's temperature. How does GFS accurately prog for this on a tropical flow? Answer, it can't. The double whammy being that the grid is very coarse, particularly in the LR portion of the model. Forward projection of temps from GFS is always going to be as much art as science.

By way of example, look at the projection I put up just two evenings back. My upside was well above the GFS max-min and even that is being exceeded by reality. Today, in the south, the progged maxes were 17-18: we're looking like going well above 20 fairly widely, whilst last night the minima were up around 13-14 generally across the country: again, well above the max-min values suggested by GFS.

GFS values put you in the ballpark, but let's be clear, that ballpark is approaching the size of a small country.

[Duncan McAlister]

Has that 28.4 record in Northern Ireland on Tuesday been discounted? It didn't appear on the Ceefax records p407, and betfair are still taking bets on 81F or lower for June :lol:

EDIT: It was actually Monday and BBC Weather have also not counted it.

http://www.bbc.co.uk/weather/ukweather/dai...007review.shtml

Edited June 14, 2007 by Duncan McAlister

[Kentish Man]

....Forward projection of temps from GFS is always going to be as much art as science.

By way of example, look at the projection I put up just two evenings back. My upside was well above the GFS max-min and even that is being exceeded by reality. Today, in the south, the progged maxes were 17-18: we're looking like going well above 20 fairly widely, whilst last night the minima were up around 13-14 generally across the country: again, well above the max-min values suggested by GFS.

To be fair to GFS our local BBC Kent and Sussex forecaster (Micahael Fish no less) was saying last night today would be wet and so we could expect depressed temps. Instead it is muggy, cloudy but essentially dry so far . A few brighter intervals have pushed the temps up to the levels you have mentioned.

[damianslaw]

Quite surprised to see the CET so high at this stage, however i now appreciate how mild the nights have been in the CET zone and the sustained above average maxima though nothing dramatic just sustained.

I can't help but feel cheated though by the figure as the first two weeks of June here in Tyne and Wear have been preety miserable and maxima really have been woeful.

It looks like the final CET for the month is not going to be a true reflection of conditions countrywide, maxima of about 11 and 12 is for June what we had yesterday and today and by the look of it tomorrow is useless...Perhaps the prospects of the azores high ridging polewards may ensure some cooler nights as we head into the second half of June, but who wouldn't bet at this stage of us perhaps recording a top 5 CET for June.

Does anyone know what the CET so far this month in Newcastle is? I would be very interested to compare with the national

[Snowly does it]

It looks like the final CET for the month is not going to be a true reflection of conditions countrywide, maxima of about 11 and 12 is for June what we had yesterday and today and by the look of it tomorrow is useless...Perhaps the prospects of the azores high ridging polewards may ensure some cooler nights as we head into the second half of June, but who wouldn't bet at this stage of us perhaps recording a top 5 CET for June.

I would bet against a top 5 June at this stage, it would need to be over 17 to be top 5 and therefore likely need an average of over 17.5 from here to reach that figure. This looks extremely unlikely. Top 50 (15.5) is a more likely target figure from here for me, the balance of the heat is transferring away from western areas.

Edited June 14, 2007 by snowmaiden