Mike Poole

Good run from the GFS 12z, following on from the 6z earlier. But the uncertainty with this is huge, the spread on GEFS at T228: Spot the UK! Not for the first time, it is the one place in the NH that the model hasn’t got a clue about! This one is not getting resolved any time soon.

I agree the 6z is plausible. I have said for a while that wedges of high pressure rather than a big block look to be a more likely evolution to a colder outlook for the UK. Of course, any detail on such an evolution will only firm up much closer to T0, so at the moment it is just about seeing these runs crop up, and noting whether the signal grows over the next few days. It is consistent also with more confidence (I think) from the EPS and 46 in lower heights taking hold to our south, but less confidence on where any blocking to the northwest might set up.

Shock horror! Models fail to show cold in the timeframe it is not expected in! It remains beyond day 10 and the vagaries of the op runs at the moment. ECM clusters T192-T240: Largely Atlantic dominated, with a transient ridge most notable on cluster 2, but not really a shift in pattern. T264+: This is the change timeframe, and a fair few options here. The theme to lower heights to our south by day 15 is present across all clusters, as I’ve mentioned before, less clear is what blocking patterns might develop. Cluster 4 builds heights into Scandi which we’ve not seen recently, but only has 6 members. Clusters 2, 3 and 5 look best for developing something colder, cluster 1 has things a bit too far west. The potential in this timeframe is still there this morning, but the output is rather messy at the moment, as while a pattern change is suggested, the models are not clear on what to…

Much improved 46 tonight, as others have said. Zonal winds at 10hPA interesting, this is quite a recent signal to put the brakes back on, there was a hint of it yesterday: The MJO plot is fascinating as well, the actual track of it progresses nicely into Phase 7 (grey line) despite the model telling it that it has to then go round the houses back to 6 - will be interested to see what the eventual track through 7 actually looks like - and, more importantly, whether we make it into 8 at decent amplitude, which would, I expect, put the cat among the pigeons for an interesting second half of February.

ECM clusters, don’t really get going with cold potential until the extended T264+: Cluster 1 has a very southerly jet with a trough in southern Europe, options here, and it has 19 members. Cluster 2 looks wedge, I think the -NAO regime comes from the southern low pressure rather than high pressure further north with this setup. It’s something I’ve commented on re the 46, the stronger signal seems to be for a trough in Europe to our southeast, rather than for a massive block to the northwest. Clusters 3 and 4 flirt with ridging in the Atlantic, perhaps too close to the UK on the representative members shown in this instance.

Good slider on the ECM at T240: Probably not cold enough for the south, but will be for snow in the north. This sort of wedge scenario looks plausible quite soon, I think. But, seeing the posts berating the other models, I don’t think it is reasonable to expect too much earlier than day 10 yet, the MJO is a) possibly being under modelled, and b) has a lag time with it anyway. So I’m actually expecting the model output to improve as that comes in range and it counts down.

ECM clusters this morning has the signal for cold firming up, T192-T240: A tendency to build heights to our W on both clusters, cluster 2 has potential for cold by day 10. Euro heights dissipating on both, quicker on cluster 2. T264+: Which leads on to the consistent theme clusters 1, 2 and 3 (totalling 35 members) being the Euro trough. What is upstream of that varies with cluster 3 being the strong block, just west of Greenland on this suite. Cluster 1 is further west, but with a wedge closer to the UK, cluster 2 has a weaker ridge but closer, Cluster 4, the ridge encroaches the UK, and cluster 5 (just 7 members) is the more zonal one.

@sebastiaan1973 Yes, good sign. I wonder if actually that double back criss-cross that has been shown by the mean in phase 7 for days now is just an artefact of it being the mean of some runs that have the right signal and some that have it totally wrong. I bet it won’t pan out like that, it’ll either dive into the COD, or maintain amplitude through 7 - and given the way it is trending, maintaining high amplitude looks much the more likely outcome (for once).

ECM clusters T192-T240: No surprise having watched the recent op runs, that there is only the hint of a change in the 10 day range, with cluster 1 trying to put an upstream ridge up. T264+: Much more promising than this morning’s effort in the extended. Cluster 2 has a decent go at a Greenland high, actually ends up with the kind of height anomalies showing on the 46, with low heights to our south. Cluster 3 might tend to develop northerly incursions with more modest wedges of high pressure. Cluster 1 looks largely northwesterly flow.

No, we weren’t. If I recall correctly, we were avidly following the build up to the (well predicted in advance) SSW, with good reason to expect a favourable outcome - which, of course, there was. There are three good reasons why this chase is not gathering momentum: There are no really decent charts showing consistently on the operational models. While there are hints from teleconnections and the 46 of wintry potential from mid-February, we are all very well aware from the January chase that that is only at most half the battle for an island in our location. The stakes are lower. The January chase held the chance for a prolonged cold spell with reloads for the rest of winter. The upcoming spell cannot, time is already running out.

ECM clusters T192-T240: Zonal on cluster 1, weak ridge in the Atlantic on clusters 2 and 3, but nothing very substantial. T264+: I think the trend in this timeframe that is clear, is a trough developing in Europe to our SE on both clusters here. However, the signal for high heights to the NW to go along with that is much less clear now. There is no consistent sign of a big Greenland high, and the signal on the 46 for height rises to our NW is weak at best - but given the trough to the SE, it may be that well placed wedges could work very well, cluster 2 suggesting something like this, but such features will not be apparent until much much closer to T0. So I think we are headed towards a period of potential for colder weather, but the detail for that is some way away.

Very much so, I think! I’m not quite sure why that got so over-hyped (hold up my hand for my part in it), but we were all sucked in, and there’s understandably a reluctance to do that again, particularly as (and this may be IMBY in the south) it will be late season and therefore less likely to deliver even if the synoptics verify. At the moment, decent runs are becoming more prevalent in the GFS ops and in the ensemble suites for week 2. The spell has potential, but no more than that.

@feb1991blizzard The MJO has been modelled to cave into the COD for what seems like ages. But each day’s actual data verifies at higher amplitude than modelled just the day before, it seems. I think there does have to be a chance that it will sail through 7 at similar amplitude to currently. But you wouldn’t bet the house on it.

Extended clusters this morning have slightly less of a signal for a well placed block: Cluster 2 is where the signal lies, perhaps (putting faith in the teleconnections), and while it has more members (20) than yesterday’s similar cluster, it is a less well positioned high and weaker (on the representative member at any rate). Cluster 1 shows a -NAO but poorly aligned. Cluster 3 reverts to Atlantic driven.

A couple have people have made the connection to 2018 - where has this come from all of a sudden? I can’t see the similarity at all, apart from the time of year. 2018 was defined by a pretty much optimal split SSW with a very quick and striking trop response, it’s not just that we’re not in the same ballpark this year, we aren’t even in the same city! I’m optimistic we might see one final chase for the last period of winter, but am remaining cautious for now. A lot depends on the MJO, so almost by definition a lot can go wrong!

@sebastiaan1973 Yes, the 46 showing a strengthening signal for blocking in the Greenland area w/b 12th Feb, last 6 runs: The low pressure anomaly into Souther Europe is stronger too - that blue wasn't there yesterday. We need to see this signal start to show more strongly in the EPS over the next few days, building on the excellent cluster 4 in the extended on today’s 12z.

ECM clusters this evening are starting to develop something more interesting. T192-T240: While cluster 1 remains zonal, and cluster 2 shows a brief collapsing ridge, cluster 3 develops a much more substantial Atlantic ridge, albeit with only 5 members. T264+: Cluster 3 is the obligatory zonal cluster, but the others are more interesting, with some kind of ridging in the Atlantic on clusters 1 and 2, and the appearance of a proper Greenland block (for the first time) on cluster 4 (8 members) - one to watch…

Yes, it does seem from the modelling in this range that the force driving the westerlies peters out. But there doesn’t seem to be any strong blocking pattern to follow it. Nothing consistent that I’ve seen from the op runs and ensembles. We could drop lucky with a wedge, for sure. But I am still expecting to see more evidence in our sector of the +AAM and MJO into favourable phases than I’m seeing - it could just be a bit too early.

ECM clusters from T192 onwards: There is interest to develop an Atlantic ridge of some sorts from day 8, but the evolution thereafter is a bit of a mess. I’m not seeing a clear signal for a Greenland high here, rather the possibility that some clearer signal might develop once the trend to a more amplified pattern gets underway. Maybe a little soon for a response to the MJO. But time is tight now, particularly for the south, as the period of interest is now mid February.

An oddity from the 46 dayer tonight, from the regimes plot: On Monday 29th January, all members have no regime! Does this mean we aren’t getting any weather? More likely, the algorithm has given up the ghost for some reason!

The Strat profile has been very much in tandem with the trop profile all winter! With a strong vortex that would be a bad thing. But despite a very weak vortex, it has even so managed to thwart us at every turn. Maybe our luck about to change?

A little more cheer for coldies on the clusters this morning, T192-T240: Clusters 3, 4 and 5 all develop an Atlantic ridge extending into Greenland. Cluster 2 is the only really flat one, with clusters 1 and 6 hinting at height rises to the NW. T264+: +NAO not the favoured outcome here, a collapsing Atlantic ridge on cluster 2, clusters 1 and 3 maintain some ridging to the NW. I think the earlier timeframe needs nailing before giving too much credence to the scenarios in this one. I think the message that is most clear, is that the relentless zonal train is going to run out of steam. What is not clear (to me anyway) is what will replace it. There is no guarantee it will be a UK cold scenario, but the chances are there - think it will take a while before reality becomes clear.

@MJB That signal in Greenland for w/b 12th is the strongest since the runs go back to (9th Jan). Also, there are signs of a transition to it the week before which wasn’t previously evident.

@Singularity Well maybe, but I think there are too many possible pitfalls to be confident of the signal from mid-February to actually still be a thing by the time we get to mid February. An MJO fail certainly looks possible, and the strat vortex looks to be gathering in strength for the first time in winter, if that gets placed badly and starts to really rule the roost, then it could wipe out the rest of winter. We will see…

ECM clusters T264+: Well, there’s something still there in this timeframe, with various takes on an Atlantic ridge, cluster 3 looking the most convincing, but I’ll believe it when I see it, I think. The 46 dayer - the signal looks to be getting weaker there too. If all our eggs sit now in the MJO basket, then we really are up against it expecting that fickle beast to behave itself… The upcoming weather holds little interest for me, so I’ll take a break from model watching for a few days.