Rain All Night

0z/6z deterministic runs, Fri 2nd to Fri 9th (day 7) GEM is what we'd wish for, ECM/UKMO are what I suspect we will get. But you never know... 0z ensemble means, Fri 2nd to Sat 17th (day 15) We have slightly more agreement now on a (brief) mean northerly on 10th/11th Feb. Again the passage of the low through us is looking a little faster, it looks to be over with by the start of Monday 12th Feb. The later height rise has slipped east a bit on the ECM ensemble, making it less appealing, though it is still leaning against a trough downstream over Scandinavia and eastern Europe. GEM's version, while still further west, doesn't look quite as striking as in previous runs. Nonetheless, it's still a strong signal for high pressure to take back control in some form.

12z ensemble means, Fri 2nd to Fri 16th (day 15) ECM briefly gives us a mean northerly over the UK on 10th/11th Feb. I've noticed that these means are all showing the big low clearing away from us a little more quickly than had previously been suggested - it now looks likely that we will be out of its influence by Monday 12th Feb. The height rises that follow soon after it departs are really rather striking, particularly on the GEM, and though they may amount to nothing more than an Azores high extension over the UK, there is scope at this range for this signal to result in something altogether more interesting. Either way, it doesn't look like we need to brace ourselves for any more than about four or so days of wet weather late next week. 12z deterministic runs, Thu 8th (day 7) I'll show a broad selection of models this evening, since some of them are showing snow events at this timeframe.

0z/6z ensemble means, Thu 1st to Fri 16th (day 15) The ensembles are still broadly following the script we've established over the past few days: high pressure dominating to the south initially and deflecting the northerly blast around 6th Feb, then a large low pressure system crossing over the UK from roughly 8th to 12th Feb, and thereafter, late in the run, we still have the height rise signal, which appears to be focused just slightly to the west of us (especially if you ask the GEM), which might give it a colder flavour - but equally, it could simply indicate the eventual return of the Azores high. 0z/6z deterministic runs, Thu 8th (day 7) Just a few of the individual ideas for a week from today, when the large (and growing) low pressure system is expected to break through from the west, heralding the start of our change in weather pattern. 0z/6z deterministic runs, Sun 11th (day 10) I wouldn't normally post individual day 10 charts, but I'll make an exception this morning since they've generated a lot of conversation, for better or worse!

12z ensemble means, 1st Feb to 15th Feb (day 15) The most interesting piece of emerging information here is that the rise in heights from the south beginning around 13th Feb is starting to look like it has some potential to manifest as an Atlantic ridge - we'll want to keep an eye on that. For the five or so days before that, it's increasingly looking like we'll need to batten down the hatches. 12z deterministic runs, 7th Feb (day 7) These few charts are a fair representation of the spread of solutions seen at T+168h this afternoon.

BarnetBlizzard Just to nitpick, it's actually going due east, the hemispheric view makes it look like it's southeast:

0z/6z ensemble means, 31st Jan to 15th Feb (day 15) No change to the expectation of a switch to a cyclonic spell of weather from 8th/9th Feb, and it still appears that after about five days of this, pressure will start to rise again from the southwest. ECM's mean low pressure area is noticeably less intense than that shown by the GEFS (and still has a flatter top), implying that the ECM ensemble members might offer less miserable weather for the UK than the GEFS ensemble members. 0z/6z deterministic runs, 7th Feb (day 7) The end of the semi-reliable timeframe is still a day or two before the expected pattern change, so the appearance of any "saviour wedges" would still lie just beyond this - unless you ask the ICON.

12z ensemble means, Wed 31st to Tue 13th (day 14) GFS is still determined to scrape us with the northerly on 5th/6th Feb. At face value, the ensemble means are showing us a cyclonic period of weather from the 8th to 12th, as the high pressure to our south yields. But check out the northern flank of the mean low pressure area on the ECM ensemble... rather flat, isn't it? Now granted, the mean easterly is aimed at Iceland, but the deterministic run (further down this post) shows us that it's possible that it could end up further south. At the end of week 2, pressure seems to be rising again from the south. 12z deterministic runs, Tue 6th (day 7) The T+168h charts are messy around the UK, which I think is rather interesting to note in the circumstances. 12z deterministic runs, Fri 9th (day 10) I wouldn't normally show individual runs at day 10, but let's give ourselves an excuse to view those ECM and GFS wedges once more, alongside some less savoury suggestions of what we might see instead should those wedges fail to form.

0z/6z deterministic runs, Tue 30th to Tue 6th Still not a lot of variation between the models prior to Monday 5th. GFS and JMA are still trying to bring a taste of the northerly to northern Scotland. Otherwise, not a lot new to see for the next week. 0z/6z ensemble means, Tue 30th to Tue 13th We see suggestion of the arrival of an appreciable sphere of low heights from the west around 8th Feb, which coincides with the return of the precipitation signal on the ECM meteogram (Reading shown), as well as roughly coinciding with a signal for a drop in temperatures. Since this has been shown consistently for a few days now, I'd say we can reasonably expect a spell of unpleasant weather for most of us during the second week of February, so maybe don't go planning any outdoor activities for that week. Right at the end, on the 12th/13th, you can see hints of the low pressure perhaps progressing eastwards and pressure rising a little in the Atlantic behind it, but that's probably too far away to read much into.

Where's this going? Edit: Not here Edit 2: It's certainly keen to keep that HP there though!

12z deterministic runs, Tue 30th to Mon 5th This afternoon we see very little difference in the model outputs over the UK until day 6. All agree on a mostly dry week for the southeastern half of the UK. The system running to our north on Wednesday PM will provide some rain for those further north. 12z ensemble means, Tue 30th to Mon 12th What catches the eye here is the suggestion of a cooler, cyclonic spell of weather beginning around the 9th Feb (day 11). How long this might last is unclear. The high pressure to our southwest looks poised to return to our shores whenever it may feel like it. The signal for the return of precipitation to the southeastern half of the country (Reading used as a proxy) does not become significant until around 8th Feb on the ECM ensemble, over a week away.

0z deterministic runs, Mon 29th to Mon 5th I'd take the GEM solution for an extension of the dry weather... the UKMO is quite a sorry sight as you can see the cold air really wants to pay us a visit, but can't quite make it through our high pressure shield... 0z ensemble means, Mon 29th to Mon 12th It looks like we could be heading for a period of cooler and more cyclonic weather in the second week of February as the high pressure to the south recedes.

12z deterministic runs, Mon 29th to Sun 4th There is scarcely any difference between the models for the UK up to day 7 this afternoon. 12z ensemble means, Mon 29th to Sun 11th It's now the ECM ensemble that is most willing to give us a shot of cold around 5th/6th Feb. I note with disappointment that the strong signal for dry weather ends on the 5th Feb on the ECM ensemble.

0z/6z deterministic runs, Sun 28th to Sun 4th It looks as though the disturbance running to our north on Wednesday will not be noticed by the southern half of the country. Most of the T+168h frames see us poised to be denied much impact from the anticipated PV surge by the high pressure to our south, though note the more ambitious 6z GEFS ensemble mean below. 0z/6z ensemble means, Sun 28th to Sun 11th The 6z GEFS is relatively generous with giving us a taste of the Scandi trough around the 5th of Feb. We then see suggestion of cooler mean surface winds from north of west into the second week of February, the influence of high pressure to our south seeming to have moved further west over the ocean rather than over the continent by this point.

12z deterministic runs, Sun 28th to Sat 3rd All I can say is I hope the high to the south can fend off the fronts from the west at day 7 and beyond. 12z ensemble means, Sun 28th to Sat 10th We have a monster vortex to our north. It may begin to relax a bit from around the second week of Feb, but otherwise, it is what it is.

0z/6z deterministic runs, Sat 27th to Sat 3rd This doesn't look like it will manage to be an uninterrupted dry period for all of us, with disturbances running over various parts on Monday and perhaps again on Wednesday (UKMO is most aggressive with that). 0z/6z ensemble means, Sat 27th to Sat 10th Some obvious interest emerging to the northwest from around 3rd Feb (beginning just after the T+168h frame of the op runs that I've presented above), peaking around 6th/7th. A week later and the signal has faded but it isn't gone completely, which at that range should be enough to sustain our interest.

0z deterministic runs, Fri 26th to Fri 2nd GEM continues its streak of maverick runs, this time sending some of the high pressure west into the Atlantic. On all the other models it's looking mostly settled down south, apart from possibly Monday/Tuesday. Would be interested to hear comments from anyone more knowledgeable about sunshine prospects? 0z ensemble means, Fri 26th to Fri 9th GEM wants to offer us some interest from the northwest around 3rd/4th Feb, but its two bigger brothers are not keen.

The pressure pattern over the Atlantic is pretty odd on that day:

12z deterministic runs, Fri 26th to Thu 1st The GEM again takes a different path, but still ends up at the same destination for the UK: high pressure tucking us in from the south. 12z ensemble means, Fri 26th to Thu 8th We could see some brief interest from the northwest around 3rd/4th Feb, by the looks of it. Right at the end there, it looks like the Atlantic trough might begin to flatten up, making our winds more westerly than southwesterly, and the ECM might even be said to be looking rather stormy again by day 14.

0z deterministic runs, Thu 25th to Thu 1st The end of the GEM is quite different to the others, with the low that forms over the Atlantic on Sunday flying upwards and kicking up a little high over Norway and Sweden. 0z ensemble means, Thu 1st to Thu 8th We almost see some interest around days 10-12 (Sun 4th & Mon 5th) on the ECM, perhaps a hint that a brief ridge could build in from the west, after the PV clears back out of northeast Europe. It doesn't show so much on the other two models.

Yeah. And they're run at a different resolution and with a different number of members (since June 2023).

12z deterministic runs, Thu 25th to Wed 31st In the last few frames here, we see that westward shift of the heights to the south that has been showing on the ensemble means for the past few days. Down south, we seem to be able to make a dry stretch last from Friday PM until Monday-ish. UKMO manages to get some modest high pressure to the north by the end of its run. 12z ensemble means, Thu 1st to Wed 7th ECM seems especially confident about the PV paying a visit to northeast Europe on the weekend after next, but it is equally bullish about high pressure remaining strong to our south, hopefully at least meaning that we continue to get some decent stretches of dry weather further south.

It's whether the probability of something unexpected like these two things occurring can be estimated that interests me, as if we can't do that, then I don't see how we can put a confidence level on a forecast. It was a surprise to me when the (earlier) SSW didn't occur and then again when the flattening occurred so quickly and stuck, just because the forecasts to the contrary had sounded so confident.

How can we assess the likelihood that this will occur, with respect to the earlier suggestions of high pressure to the north at an earlier timeframe (i.e. between the cold spell which has recently ended, and the timeframe of this new suggestion now being made) which it now appears will not occur?

Deterministic runs, Wed 24th to Wed 31st Each time it looks as though a sustained dry spell might build, something comes along to interfere with it. Still, there are plenty of shorter dry periods showing here, especially further south. Ensemble means, Wed 31st to Wed 7th The PV seems to go east, only to then possibly come back west again soon after. The heights to the south seem to gradually recede from their peak at the beginning of this period.

Also, the pattern we look to be getting in the next 10 days or so is better (in terms of immediate misery levels, rather than in terms of "cold prospects") than the one that we had to endure through December.