Man With Beard

Looking at the ECM ensembles again... the ray of hope for the turn of the month has been snuffed out in the last couple of ensemble sets. Not as many warmer runs between July 31 and August 5, and the duration of warmer weather has been shortened where it is shown. In addition, a new period of rainfall between 31st July and 2nd August is firming up fast.

Bit of a backtrack on the ECM ensembles tonight for the D11-15 period - ridging towards UK not as strong - and now I'm worried the upcoming pattern change could plunge us into another summer killer pattern, the Azores High / UK trough / Scandi High sandwich...

And then they looked at the ECM 00Z and thought "Hmmm. Maybe those teleconnections guys have a chance after all"

12Z ECM ensembles mean, the signal for slightly warmer air getting in at the turn of the month getting stronger:

Well I'll continue looking for those green shoots! Once again, 36 out of 51 ECM ensembles (for London) go uppers above 12C at times between 31st July and 6th August - granted, some members have this warmer wave as short-lived, but some are not. Here is the table showing uppers for the next 15 days (better than a timestamp as it doesn't get skewed by timing issues) - the increase in yellows and oranges as we get to August tell the story better than I do: I'd suggest this chart is only possible if a pulse from a warmer source in the Atlantic is successful in getting through. Rainfall amounts tend to get more scattered during the start of August, too: I'd suggest at least some half-decent days based on this (at least for the south, I haven't checked the north). Bear in mind - if a short-term pulse of heights is moving in from the Atlantic, but there is variation on the arrival time, this signal will get squashed by the mean.

Following on from the chat on the GFS, well look at this - the 12Z had a deep low north of Scotland at D9 - on the 18Z, the low doesn't even exist!

I would remind you that the GFS FI has thrown out a few heatwave runs in recent days, too. Which one to trust!

That's a fair comment, I confess I am one of those who've talked about signals, but in truth these signals never got into the majority on the ensembles, hence the NOAA charts. But 36 out of 51 members tonight providing warmer air at some point in the first days of August (at least for the south east, I haven't checked for the north) is by far a better sign than anything I've seen since the one day heatwave at the start of July.

Now here's the best thing I've seen on the models for weeks On the ECM ensembles tonight, 36 out of the 51 members get the upper 850hpa air for London above 12C at some point between 1st and 5th August #warmer?

Yes that's the first real sign of improvement - the "neutral" anomaly line is approaching the south west of the UK, and the lines are flattening a bit. The hints of a recovery in the ECM extended are still there, and actually the "better" ensembles members are only slightly short of 50% by T300. Quite a good number of successful Azores High intrusions on this one with the source being more WSWly on many members: Definitely a "chance" of something hotter by the first weekend of August, based on that - but the overall signal is still weakish when considering the less settled runs.

I checked the members individually at T360 - to my eyes 23 out of 51 members had high pressure in the ascendancy for most of the UK. Not bad for D15 (6 August) but I feel we've had a few false dawns at that far out, so I'm still on the fence myself...

The ECM, however, continues unsettled right out to the end of July. Recent ensembles give a little hope to projections such as the GFS 00Z, but the balay of members on all suited remain on the less settled side even through the first week of August. I always feel the window on the hottest weather closes by about 15th August, so there is an increasing risk that we are going to completely miss the main period of summer this year.

It's going to be interesting tracking this ECM D15 mean over the next few weeks to see if the recent upgrade leads to better outcomes. Your chart is a really good match. I looked up the D15 chart from the 1st July on vedur.is (couldn't find archives on Meteociel). Slightly underdone in strength of the trough, understandably for a mean chart, but the overall shape isn't bad - troughing centred north UK / north sea. Here's this morning's D15 chart. Will this one verify to some degree?

They have been superb recently, yes. I feel they do particularly well when things are stable. The 6-10 chart I feel pretty confident about. During some recent summers the 8-14 has missed a couple of heatwaves. But it's usually a good guide. The problem is probably us - we desire concrete predictions as far into the future as possible, and we're perhaps not as close to that as we'd like especially beyond D10.

ECM ensembles update for the end of the month ... still less than half of members suggesting a clear-cut change of pattern to something more settled, generally through the Azores High. However, things generally flatter out west (which is a start), and less unsettled to the NE than of late: The clusters format shows the rather high numbers of possibilities more clearly - the one that continues to elude is the one which might have the best chance of leading to a heatwave - a strong build of heights through central Europe

Continuing to monitor the ECM ensembles for the end of the month ... it continues to promote two paths almost equally, one involving the Azores High pushing in and the other giving more of the what we've been having recently. Which one will win out?

Only issue for me is it looks like the "dislike" symbol on other social media. Is it possible to use a question mark symbol instead?

The ECM also continues to leave the carrot dangling for the turn of the month - a look at the members for 31st July reveals what appears a fairly equal split between the Azores High building in, and troughs remaining stuck in the flow. The dominance of the Scandi trough looks to be waning in most ensembles, thankfully:

I'll keep trying to pump some optimism in here! For the first time in weeks, a majority in the ECM clusters going for an Azores High build towards the UK in the D11-15 period (clusters 1 and 3, which represent perhaps 60% of members):

This may justifiably be called clutching at straws ... but I did have a bit of a "hold on a moment" with the T144 on the ECM What if the developing trough to the west digs a bit further west than expected and separates from the trough in the North Sea, attracting euro heights just a touch further north? The south-east, on the face of it, has got close to joining in the heat from Europe a couple of times in the past week, and I'm just wondering if a slight twist could happen to push the heat a bit closer before too long. Unlikely, sure, but such things have happened before. This current pattern is a bit anomalous, and anomalous patterns sometimes end a bit surprisingly - which is why I was a little surprised at the Met Office announcing "no heatwave for 4 weeks".

It's telling that I keep looking for tentative signs at D15 ... there's not much else to look at in terms of summer weather Anyway, as with the previous days, the D15 mean on the ECM keeps hinting that we could get a change. Interestingly, though, it's not punting for the change that the teleconnections appear to support? Instead of pulling the trough westwards, this morning it tries to bring the Azores High towards us by pushing the trough eastwards instead. The mean is fairly representative of the individual members I looked at, obviously with more settled/less settled variations:

ECM 10 day rain chart - pretty wet everywhere except the SE which somehow remains relatively dry, whether it turns out that way, I'm not banking on it:

There were more members like this on the ECM ensembles at D14 than the mean would suggest:

Not so bad in the south on Tuesday?

GFS this morning looks pretty mad for Sardinia - 8 straight days of 44C or more starting on Monday.