Rain All Night

12z deterministic runs, Wed 28th to Tue 5th (day 7) 12z ensemble means, Wed 28th to Wed 13th (day 15) Earlier on I'd take the GEFS as it looks drier, but later on, we've got a new signal - the demise of the block to our east, and in the case of the GEFS, a significant flattening of the heights profile. ECM and GEM prefer to hint that the heights may be moving over to our west side. Bonus The mean zonal winds bottom out at around -18m/s on around 10th March (day 12) on this morning's EC46. That's certainly much more significant than the previous two reversals.

0z/6z deterministic runs, Tue 27th to Tue 5th (day 7) All looking pretty much as expected up to the final day or so, when the ensemble means leave me optimistic that the GEM solution without the high over Portugal will not verify. 0z/6z ensemble means, Tue 27th to Wed 13th (day 15) I'm liking this! It seems our fortunes may be changing for the drier around 6th March (day 8). The mean surface low does start to look a bit more iffy around 11th March perhaps, but that's way out at day 13 so we can disregard it for now.

12z deterministic runs, Tue 27th to Mon 4th (day 7) It looks like a case of things getting worse before they get better... though at least these charts are a reminder that high pressure over Europe can yield, when it wants to. 12z ensemble means, Tue 27th to Tue 12th (day 15) Similar to this morning, but with that low signal to the southwest from the 8th not quite as strong.

0z/6z deterministic runs, Mon 26th to Mon 4th (day 7) I see that in the 36 hours or so since my last post, the immediate aftermath of the arrival of the next trough over the UK has been revealed to us: it will be sucked back into the Atlantic, while a part of it splits off to the southeast into Europe. 0z/6z ensemble means, Mon 26th to Tue 12th (day 15) Once that next trough has departed, we might be able to swing a dry spell from the build of heights to our east, perhaps even a brief southerly airflow. Then, there is a signal for a new trough perhaps becoming a cut-off low to our southwest from around 8th March (day 11) onwards. Depending on how close that sits to us, we could either get a nice dry continental air flow, or buckets of Atlantic rain. Oddly there was no GEM ensemble out on Meteociel this morning.

12z/18z deterministic runs, Sun 25th to Sat 2nd (day 7) 12z ensemble means, Sun 25th to Sun 10th (day 15) The point at which this next trough drops over the UK, which is now crossing into "week 1", and which by now feels like we've known it's coming for an age, really does seem to be quite a fork in the road for the models; it remains completely unclear what will follow this event. Heights to the east and mild air flows from south of west remain modestly signalled. It still seems there will be a moving of the furniture upstairs in the stratosphere throughout the first week of March. Whether or not this has anything to do with the model uncertainty beginning at around the same time is above my pay grade.

0z/6z deterministic runs, Sat 24th to Sat 2nd (day 7) Am I to be encouraged by the amplification, or concerned that the trough at the turn of the month may be getting trapped over the UK? 0z/6z ensemble means, Sat 24th to Sun 10th (day 15) This morning's means start to diverge quite early (2nd Mar, day 7) as the little trough drops over the UK. ECM, which not quite as impressive as yesterday's 12z, still offers hope of high pressure subsequently in a protective role for the UK, as does the GEFS.

Even more amplification being found now?

12z deterministic runs, Sat 24th to Fri 1st (day 7) The models seem to be finding more amplification this afternoon (GEM excepted), which gives me some hope for drier times ahead. 12z ensemble means, Sat 24th to Sat 9th (day 15) The ECM ensemble mean is nice to see, with a mean Atlantic shutdown from 3rd March through to the end of the run. The other two models look like they need a little more convincing, though the GEFS mean is still a good one (unless you're only interested in a cold outcome, which is not on the table in this timeframe).

0z deterministic runs, Fri 23rd to Fri 1st (day 7) 0z ensemble means, Fri 23rd to Sat 9th (day 15) Still a slow learning process. From 3rd March (day 9), the ensemble means tell us that a lot of member runs feature raised heights to our east, but the means remain too blurry to indicate what pattern might be setting up just yet, and by 7th March (day 13), the signal fades back to noise. None of the ECM ensemble cluster representative members at day 10 convince me that a strong blocking pattern is emerging, but perhaps there could be some opportunities for drier weather ahead:

12z/18z deterministic runs, Fri 23rd to Thu 29th (day 7) 12z/18z ensemble means, Fri 23rd to Fri 8th (day 15) Seeing more of that signal for heights to build to the east or even northeast after that next trough comes in at the turn of the month, kind of interesting.

That was a LONG silence for this thread in winter!

0z deterministic runs, Thu 22nd to Thu 29th (day 7) Nothing new here really, though I note from other posts that there's some interest in whether the low on Sunday could miss us to the south entirely. Regardless, pressure contours looking slack over much of Britain for a while on Saturday and Sunday. 0z ensemble means, Thu 22nd to Fri 8th (day 15) It feels like we're learning ever so slowly at the moment. We've known about the next trough attack around 29th Feb/1st Mar for days, but still have little signal beyond that. My one concern, based on the raised heights to the east that have been showing up on some of the ensemble means into the first week of March, is that we could end up with troughs getting stuck over, or just to the west of, the UK with no way to exit. I hope the upcoming stratospheric event can do something to get rid of the tedious TPV to the northwest.

What does this actually mean?

0z deterministic runs, Wed 21st to Wed 28th (day 7) GFS has this morning 'capitulated' to the ECM's depiction of the toppling Atlantic ridge - but of course, nobody is paying much attention to that, since none of the suggested outcomes on either side have been especially interesting for the UK. 0z ensemble means, Wed 21st to Thu 7th (day 15) As with the op runs, the shift of the GFS ensemble towards the other two models is noticeable this morning. They're all now showing similar progressions into the first week of March. We have a new signal emerging in that first week of March, which is for a build of heights to our east. It's too early for me to guess at the possible impact of this at present. The GFS ensemble allows this signal to fade away into deep FI, but the ECM and GEM hold it in place.

Metwatch And why is that, I'm assuming the reduced solar input compared to mid-July?

Sod's law, the second strongest background driver after global warming!

Metwatch Do you not think 40C would be possible now in early August?

GFS continues to want to be different, its 18z run tries to link the Azores high to Scandinavia

raz.org.rain The SSW, and any subsequent impacts on us, will be in spring...

WYorksWeather That looks nice...

Is anyone else not looking forward to the consequences of this happening so late?

12z deterministic runs, Wed 21st to Tue 27th (day 7) Divergence after 96 hours (Sat 24th), though the difference between the outcomes on offer is not likely to be of great interest to many here since there are no deep cold air masses in the mix. 12z ensemble means, Wed 21st to Wed 6th (day 15) Looking back at my posts over the past week or so, I think our three 15-day ensembles have, as a team, given us good guidance on the progression through our upcoming battering: 21st Feb - round 1 25th Feb - round 1.5 (with GEFS making much more of the trough going into Europe after this point) 29th Feb - round 2 What happens beyond that (day 10+, the first days of March) remains unclear for now - as illustrated by the rather different directions each of the three ensemble means take after this point - but personally I'm not going to count on it being anything settled.

0z deterministic runs, Tue 20th to Tue 27th (day 7) GFS op runs, like its ensemble means, continue to make more of the trough going down into Europe, with the Atlantic high more reluctant to topple over it. 0z ensemble means, Tue 20th to Wed 6th (day 15) ECM and GEM still seem to send in a second big low behind the toppling Atlantic ridge by around 29th Feb (day 9), which may be followed by a second toppling ridge behind it. GFS continues to want to sink, rather than topple, the Atlantic ridge (and make more of the trough going into Europe), which appears to delay the arrival of the next big low by perhaps a day or two, and possibly hinder its progress through the UK.

RJBingham len You can get an annotated versions of ECMWF charts that are better for copying and pasting into your posts here: click the share button at the edge of the chart, choose "Copy link", paste the copied link into your browser's address bar, and the annotated version of the chart will load, which you can then right-click on and copy as normal, for pasting into your forum post.

I haven't in recent months been looking at height anomaly charts for the ensemble means like I used to, but this evening I did, and I'd forgotten how much the mean height anomalies from climate average can leave one with a different impression than the mean heights alone. "Lower than average heights over Iberia" was not one of my main takeaways from looking at the ensemble mean height charts from this afternoon's model runs on Meteociel, but that is one of the more prominent features highlighted by the anomaly charts for 5th March (day 15). And then, I look at all the members of the ECM ensemble on that day, and sure enough, I do indeed see more members than you'd typically expect to see showing lower than usual heights over Iberia, so the anomaly isn't misleading me (assuming that the ensemble members themselves are any good in the first place):