wellington boot

Initially I thought you were comparing the NOAA anomaly charts with the EC/GFS ones, but none of those have high pressure over the UK. Looking, however, at the anomaly charts, once again they might be moving in the right direction... the EC/GFS charts both broadly have the UK in a neutral zone between positive anomalies to the North and SW and a negative anomaly over Europe, while the 6-10 day NOAA still has variable negative anomalies strung out W-E across the Atlantic. However, the NOAA 8-14 day is significantly more promising, and not just a diluted version of the 6-10 day. Large, positive anomaly spread across the Atlantic, neutrality over the UK, positive anomalies close on all sides. Importantly, the shape of the EC-GFS charts particularly and even the 8-14 day NOAA chart are pretty consistent with the negatively oriented low diving into Europe shown on the GFS and ECM 00z runs at t192-240, with HP building behind. From that position, a more settled spell is quite possible. Obviously I was wrong last time... http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html https://www.cpc.ncep.noaa.gov/products/predictions/814day/500mb.php..

Apologies for the belated response to this. I obviously bow to your infinitely greater knowledge and experience, and I recognise that I probably exaggerated somewhat. I also realise that my language was sloppy, talking of high pressure and low pressure - it was a quick post in a snatched moment and unfortunately I wasn't clear. And "promising" was definitely an overreach... Equally, to suggest that high pressure was moving closer was highly contentious. I was looking at the Greenland positive anomaly shifting slowly SE and at the Azores positive anomaly drifting slowly E towards Europe, but truthfully there was little to suggest significant and relevant height rises even by the end of the 6-10 day period. With that said... I would defend my original comment up to a point. I observed at the time and still observe that the focus of the negative anomaly is shifting gradually towards the NE, while the extent of the negative anomaly over the UK seems to be gradually declining. It's not dramatic, but as you explained a few days ago, this is a five day average, so you would expect the changes day to day to be subtle most of the time. It seems to me there is a trend towards more average conditions at least. I should add that I didn't mean to suggest settled weather was necessarily on the way within the 6-10 period itself, just that there was a trend in the right direction... Here are the last 5 charts in order: The chart from the evening after my original comment (18th Aug) actually did me no favours, but given today's much better chart, I'm reasonably comfortable making my case above...

I think the NOAA charts are at least somewhat promising. Still showing low pressure over us, but showing signs of migration to NE, plus intensity waning, plus high pressure moving closer day by day.

Yes this was my interpretation also. Unusually erratic output, although Tamara's posts from recent days predicted just such difficulties for the models (as well as potentially a less unsettled outcome than currently shown). Will be interesting to see how this resolves.

I understood your point the other day about successful interpretation of these charts requiring a good dose of experience, as well as your point about it being a moving average and needing to be understood in that context. With that in mind, do today's charts not show a striking shift from yesterday's? Seems quite a dramatic shift North and East by that low pressure. Separately, I wonder if you can shed any light on how these NOAA anomaly charts are actually produced? Is there another suite of model runs which is aggregated and summarised this way? Or is the underlying data/method completely different?

Temperature here, near Tunbridge Wells, is 34.5C under hazy sun and feels more humid than it supposedly is

OK, but don't the contours always necessarily show a broadly westerly flow everywhere, albeit with southerly and northerly tilts in places? The dashed anomalies on the NOAA charts clearly show positive anomalies stationed over and just to the north of us.

@Tamara Thank you for noticing my message and responding so thoroughly. Your response clarifies some issues that have been persistently bothering me. My intuitive sense of the dynamics under discussion has been immeasurably enhanced, which I always feel is a good indicator of understanding. I do have further questions - several about the apparent consistency of the twin low frequency tropical convection signal over around a year up to June, even as we saw major changes to average synoptics and conditions here and across Europe. But I will aim to ask more when appropriate in response to your frequent, excellent updates. For now, can you say more about how you would expect that signal to evolve? Are long periods of stability typical? And is that why you use the term 'default', because at any given moment there is a relatively stable configuration driving default conditions. Or could we realistically see the current standing wave arrangement disrupted or shifted at any moment? And a big thank you again.

Your interpretation of these maps is really interesting. I am seeing positive anomalies over and to the north of the UK on all three charts, including the 8-14 day NOAA that you say shows a general westerly flow. Would you mind clarifying why you see those as showing a return of westerlies?

For what it's worth, temperature here appears to be 89f or just shy of 32C at 1130. Should note the thermometer is on the east side of the house but in shade on a North facing wall. Currently Arome cloud cover charts looking accurate incidentally.

@Tamara I wonder if you might answer a couple of questions I have about this. - You note the inevitability of the low frequency tropical signal returning (which you have previously described as "default") and promoting upstream amplification etc. - You also later refer to the default pattern and seasonal wavelength changes in August. I wonder if you could flesh this out a little more. Firstly I'm interested in what you mean by the default pattern. Do you mean on a global basis, or are you specifically referring to default patterns for a UK summer, because there seems to be an implication regarding the effects of this change on UK conditions? I understand that there are more and less typical broader patterns, so an Azores high is typical while a Scandinavian high is less so, but even if you imagine a default Azores high in place, there are many ways for the UK to retain a warm/continental flow, for instance, just as there are ways to be cool and wet with warm southerly or easterly draws. So what is the implication when you say the default pattern will return? Do you just mean, default broader patterns will return, accompanied by relatively moderate conditions and all the usual uncertainty, or are you implying specific conditions in the UK? I suppose I'm asking here because if default broader conditions are to be significant (as you suggest they are) in this context they must imply specific effects for local weather. And yet looking through recent summers we have had prolonged spells of both warm, settled weather (probably majority overall) as well as wetter, cooler weather, such that it is not clear to me what our default summer weather is. So it's not clear to me either what default conditions locally are, or that globally default conditions have predictable effects on weather locally... Secondly, can you add any further detail about seasonal wavelength changes? Is this to do with the jet firing up? Does this mean August should actually be expected to be a less summery month overall than June/July? My understanding was that our recent run of our Augusts was anomalous set against long term averages. A few questions in there I know. I hope you can pick that apart...

I know what you're getting at and I think that's right, but I was probably getting at something slightly different. The suggestion was that the 12z UKMO from yesterday was dramatically different from this morning's, and in the context of model analysis on here, you would expect that to signify a dramatic, visually obvious synoptic shift. So lows that weren't there in the last run, or highs rejigged to pull the air from an entirely different direction. My view, however, is that this morning's UKMO and yesterday afternoon's look very similar on heights, SLP, and overall shape of evolution. Of course, as I acknowledge in my second paragraph above, even subtle shifts can have significant effects on details like airmass temperature.

I think it would be tropical more than simply wet. Heat, storms, torrential downpours... Many on here would find it exciting I think. And we could do with the rain around here.

A lot on here describing the UKMO as wildly different today and I'm not seeing it. The 850s might look quite different, but overall the synoptics are very similar and honestly this morning's version looks like a pretty natural 12 hour evolution of yesterday's 12z. The effect these subtle shifts can have on 850s is of course to be carefully noted, as this potential remains going forward and will affect predicted temperatures from run to run.

This is exactly the point. Saturday was written off by so many on here a couple of days ago and yesterday's ECM taken as gospel when temperatures looked a little suppressed. Now, with minor tweaks, look at the 850s on this morning's UKMO. Record breaking potential over several days, and hot from Friday right through the weekend...

And I would contest that the GFS/ECM 8-10 day shows the HP retreating back to the Atlantic. If anything, both show HP dominant over Scandinavia and generally close to us, no real LP anomaly in our vicinity, and both suggest a good chance of a warm flow for the British Isles. The ECM in particular, which is better and therefore more important, shows a promising arrangement for mid-late next week. ECM vs GFS: http://mp1.met.psu.edu/~fxg1/ECMWF_0z/test8.gif

Hope I'm not treading on any toes here... 6-10 day NOAA chart: 8-14 day NOAA chart: Both excellent really, particularly when you consider how the summer has been for many on here. Suggest ongoing potential for warm, settled weather at least.

Bizarre logic... So a model which is demonstrably less reliable is preferred because it fires out so many different scenarios that somewhere along the line you can always (retrospectively) find the right one... Ok... But perhaps I'm just the beneficiary of a summer that is increasingly looking like quite a lovely affair overall down here. And I'm therefore lucky enough not to have lost my mind.

The 12z output is overall very close to the 00z output. One model is 12 hours later than the other. The charts you're referring to are approximately six days out. Not sure why this is suddenly considered to be the final verdict... Is it just because it allows you to wallow...?

Sorry?? It's barely different to its 00z run...

Let me preface this by acknowledging as ever that I live in the far South East and i realise this may not be everyone's experience.... BUT... It does seem weird that everyone has been complaining so bitterly about the poor weather coming soon for such a long time. We had three pleasant, sunny days last week, Saturday was glorious, and now Monday through Wednesday has also been beautiful. Given the level of uncertainty beyond the weekend, and the fact that the best model (recently), the UKMO, recently had things decent for next week and is showing far greater inconsistency than usual, I'd advise people enjoy the current weather and have some patience... and read Tamara's post...

Last couple of runs follow a similar path, which is nice, but... difficult to ignore the fact that every single run forecasts almost exactly the same rise in AAM, so it's a challenge to take it at all seriously...

You imply "pleasant" is disappointing and I'm scraping the barrel as it has been so underwhelming. Unremarkable maybe, less warm than recent Julys, and there was a 7-10 day period recently which was meh, but frankly either side of that I can't really complain. i find blue skies and 20-23C to be genuinely pleasant/lovely/summery. And for the record, while i actually enjoy very hot weather, southern Spain is currently around 40C every day, and I can honestly say that beyond novelty value, i prefer current conditions in SE UK. Anyhow, I do feel for those currently experiencing a washout summer. Fortunately the models show some decent weather for many parts over the next 4-5 days, and beyond that I look forward to further in-depth analysis from Tamara and John Holmes, whose input is wholly more interesting and valuable than hundreds of longer term NWP perturbations, all of which generally serve merely to illustrate and exemplify Butterfly Effect theory.

Truly we live in a sun-drenched paradise down here.

I can only advise more of you move south (although cant say we really want you here...). Most of the last week to ten days has been pretty pleasant - mostly pleasantly warm, plenty of sunshine. In fact, Friday up to today, 5 days out of 6 have been sunny, except for yesterday, which was still perfectly warm. With that in mind, the models look fine to me. Plenty more sunny weather on the way over the next week, and teleconnections mixed and complicated enough that many possibilities exist beyond that. Given June was also fine, it feels to me like we're getting away with one down here given questionable underlying conditions for summer weather...