IDO

Alderc 2.0 I have been keeping an eye on the models and the mean has been the guiding star with the omnipresent underlying pattern of an Atlantic trough with the UK predominantly on the colder side of the jet, with system after system pushing west to east. So cool and wet. Looking at D8-16 mean: Still no change in this relentless pattern so proving the point that even multiple SSWs do not mean anything for certain regions if the macro pattern is the alpha.

damianslaw I. would not pay any attention to D10 charts as they have been worthless about pressure rises all this Winter, and 9 out of 10 times are outliers. Looking at the EC and GFS means, this is another case in point: Both are clear outliers, especially the GFS. We would need 4-5 consistent runs showing this before it would be worth taking it seriously, as these random op runs showing colder charts have been popping up regularly for the last few weeks without one verifying. The GEFS mean has been consistently good this year, and there is no change here; more of the same. D8-16:

I am not seeing any changes from what the mean has been saying over the last eight days for the upcoming period. A west-based Atlantic trough means any cold is pushed away, and scraps are the best we can expect. EC for the next ten days, but GEM and GFS are similar: We are still getting random outlier colder runs but not supported by the mean, so they are best ignored until they gain support and consistency. The 2m London ens: Nothing cold or snowy there. The Bering Sea surface high is still evident on the mean D8-16 and has been for a few days on the GEFS: But the mean tPV looks like it is splitting, so I am not sure this will take the UK out of no man's land, caught between an Atlantic and Scandi trough. The mean defines this well as a mean out in FI. It looks like March is going out with a whimper, assuming we do not get any forcing of the pattern, being tropical waves or SSW sPV impacts.

I don't know what happened with yesterday's EC 12z. It was one of the biggest outliers I have ever seen. So, it is no surprise that the 0z is different and more representative of the mean. The model op runs are all struggling with the next ten days (post-D5), but none offer anything freezing, just run-of-the-mill March changeable weather. There is still a chance post-D5 for the UK to be clipped by some transient colder uppers, but nothing remotely blocked or sustainable for anything worthwhile for snow and ice. London GFS ens: We can see the border between the Atlantic and the Euro high via accumulated rainfall on the GFS op: A NW-SE split. Post D9 on the GFS mean and a mean Bering Sea HP forms, which could mean a change in the pattern as the tPV still appears to be driving the NH pattern: Though no tropical forcing is evident, the SSW does not get any help from upstream waves to speed up the cold moving south. There have been three SSWs this year, and if we want any proof that they are not as big a deal as hyped, then this winter bangs that home.

The mean still wants to have nothing of the cold, and in fact, the 2m temps are on the rise in FI for London: It does look like any SSW pattern will not bring cold to the UK before the last third of March. There is still some random cold outlier op runs, and even the ensembles have a few brief colder runs for D7-8: But maybe more runs above the mean, so even that brief cold looks less likely with each run. GEM and EC agree that the UK will miss the cold to D10 after a few random cold runs that did not align with the means. The GEFS D8-16 850s sums it up: With no tropical forcing, we are at the beck and call of the meandering tPV, and that means the UK is caught in no man's land despite sitting north of the jet in the colder potential. Maybe things will change, but the mean has been relatively reliable recently.

KTtom The trend, if anything, for the south is less cold 850s and milder 2m temps. In fact, after this brief colder few days the 2m max mean in London stays above 10c until D16 with some members going close to 15c. If we want to pluck a few cold runs out, we should also look at the milder ones. Hence why we use the mean: There is a clear rise in temps over the next 16 days. We need to see the trend of moving in the opposite direction to be hopeful of a cold finish to winter. Gem to D10 and even less keen on any significant UK cold: We remain on the cold side of the jet but the NH pattern needs a little nudge as any harsh cold is falling to our east and west^^^. EC to D9: I do not post D10 EC charts for obvious reasons! So it looks like decreasing chances for the UK to see any of the cold spilling from the Arctic without a reset from tropical forcing or the models to change the current predicted pattern.

Mike Poole Yes, colder easterly or less cold (SE flow). But you could have something in between, as you imply, an easterly that never really bites. The mean suggests that the colder uppers are insignificant in the ensembles, suggesting the last few wild ECM, GEM and GFS cold easterlies are low risk. These op runs are superseded by runs closer to the mean, so I would 100% use the mean as a starting point for FI rather than a random cold op run. Scandinavian High. We shall see. As we get closer to FI, hopefully, we will see a firming up of the pattern either way. My main concern is that we are still not seeing any forcing either upstream or local, so the mean NH tPV pattern being tempered with the tPV settling in the Arctic makes getting cold south harder, D8-16 mean 0z:

The Scandi high is sinking from D9, so by D11:

Lukesluckybunch Yes, returning to the mean profile.No shocker. Versus 0z: 06z: 0z: It is not mild but is a missed opportunity if the mean verifies.

I have no idea what is going on with the ops. This morning, the GFS op is on a wild outlier. For London: When many of the GEFS ens are moving milder than recent runs, the op produces a cold run! The mean remains similar to yesterday as the op has minimal support, D10: The GEM mean is similar, but the op is not like the GFS. We see this morning's EC revert closer to its mean after the outlier 12z from yesterday: We have learnt much this year about wintry charts in FI from the various ops to know that they have a habit of leading us up and down the garden path. Although solid mean support exists for the next ten days, we await if these random colder charts can gain some footing with consistency and ens support.

stodge The D10 op versus the mean from the EC are very different: The GEM and GFS means: They are solid means from the three suggesting a high level of certainty, so random ops that show otherwise, that are massive outliers and disappear by the next run (e.g. GEM) are best treated with sceptisism.

EC is off on one this evening with a whopper of an outlier. For London, the ens: There is nominal hope of verifying that!

It looks like we still remain west-based, so any Scandi high will have minimal impact on dragging any extreme cold to our shores. The GEFS mean from D8-16 highlights this: There was no sub-tropical forcing to help, and the mean tPV returned to the Arctic region in that timeframe. The 850s cold bottled up over the Arctic with no split tPV. The London ens (850s) looking average from next week: EC also keeping the cold away from our shores due to the trough to our west, next week (to D10 850s): As for the nearer time frame, a colder 2-3 days, though nothing unusual, may bring snow to some, but hills and mountains most likely: And, of course, M4 North! We remain on the cold side of the jet, so any forcing could bring cold in quicker than we usually have to wait, but at the moment, we are outside the periphery of where we need to be for a snowy end to the winter.

The GEFS mean has been solid for FI, and it really looks like up to mid-March, nothing interesting for the UK, snow-wise. The 0z: We are on the cold side of the jet but only scraps of colder 850s for the UK. The obvious negative is that there is no amplification of the NH, which is a sign of winter, so we are relying on the tPV to create something. The mean suggests it moves from our NW to the Arctic, which is invariably useless for the UK. The other negative is the omnipresent Russian/Siberian high, which has meant the latest cold push has been west-based, hence the washed-out uppers. GEM at D10, for example: So even when a wedge of heights (all models around D6-7) breaks through the UK trough and heads east through Scandi, the resulting pattern is west-based for the UK. There are some colder uppers but little of note for snow for most. London: The 850s and 2m temps are all, rather meh. Sums up this winter.

A west-based trough is the worst kind of weather at this time of year (EC 850s): It is a waste of a potential cold spell. So from D6-7 GEFS for London highlights average 850s as the trough moves in and dominates the FI to D16: That Russian/Siberian block to the east has been a killer this year for our winter. Rubbish end to another very poor winter (snow-wise).

The GEFS mean supports the initial west-based dropping of the trough, from around D7-8: So for the South a wishy-washy affair with 850s bringing mostly cold rain (London 2m temps): The temperatures are below average at points, but there is nothing like a cold spell. GEM also supports the initial drop, and it looks like post-D10, it will support the GFS op second drop. GFS op D8-16: The EC run this morning has a spoiler low off the ESB that kills the oscillating Azores high. D10 0z -v- 12z (yesterday): So, is EC having a blip or the op in another cluster? No northern blocking, maybe just a slowdown of the NH pattern and the Azores high oscillating to send the trough over the UK. For most of us, this setup in the last third of February is a waste. But looking like it will take us into Spring.

GFS: The mean keeps something potentially cold in FI. D8-16 GEFS: The GFS op is woeful and brings Winter to an ignominious end. We still have Spring to get some cold, but I am not expecting much. Back to the mean, the ens may pick up on the currently discarded op runs of mid-high lat blocking and gradually shift back to the op. Assuming the trop is running the game, the issue for me is that the Alaskan high migrates to the Arctic and stalls with the tPV circulating it. With no tropical forcing in the NH, it will stagnate near the Arctic, becoming useless as a driver for cold to mid-lats. GEM: is different by D10: EC: Similar to GFS up to D10:

The GFS Control shows the cluster that gets the Alaskan ridge>Alaskan high>Arctic high direction of travel in the post D8 period: This is our best hope based on the current NH pattern of getting some cold. But even then we have to wait until post-D14. The GFS op shows what happens with an Alaskan ridge>Alaskan high>Pacific wedge>Arctic high passage: This has been cluster of late. Leading to a delay of several days with a UK high then retrogression post D16. That would take us close to March.

The GFS is a hard watch with its only intent to clear the cold further away from our shores, making it unlikely for cold pre-D14. D9-10: No upstream or Arctic help on this run in the semi-FI.

It does look like we have a small window pre-D10 to get a quick pattern change. Before D10 we have upstream amplification of an Alaskan Ridge that migrates into an Alaskan high and moves towards the Arctic. The GEFS mean highlights this (D8-16): The GEM (D10) and EC (D9) ops are similar: The GFS op cannot retrogress or build heights to the NW and we end up with a stinker of a run: The GFS mean supports EC/GEM so maybe the GFS is the worst-case option? The GFS control is more like GEM, but the London ens suggests the op has support ATM:

I think that split-retrogression of the Siberian high via Scandi/N Europe to a UK high is better than a high stuck in Eastern Europe, and both GEM and GFS have this: Though two days apart (GEM D9-GFS D11)! The models still fluid in this evolution, and this was the likely route 3-5 days ago deep in FI on the GFS though it keeps getting discarding and being resurrected. The GEFS mean to D14 are similar to the 06z. I think it's a case of letting the models sort themselves out. The Strat experts on here are hopeful that we get a coupling and a major reset in the NH trop so some good news.

Consistency with the GFS at D11-12 with the Iberian ridge firing up: 0z and 06z^^^ Pretty awful background signals forcing this.

Look how cold Europe is at D9: Even with a transient easterly flow there is little to tap into with a bloated Siberian high, as usual being a negative in setups like this. Could feel Spring-like between the frontal rain. In December this would be a hiatus, in mid-Feb this is a winter killer. Watch the cold block to the NE be sucked north over 48 hours:

The GFS and GEM means remain hopeful for the last week of Feb for a colder pattern (D8-16): But with the initial rise in heights being an Iberian ridge/UK heights, that means a long wait for cold. The London 2m temps: And, of course, in 16 days background signal could change. The lack of core cold in Europe and its distance to travel to reach the UK means a long wait: The mean ^^^ even at D16, only has -4c uppers just breaching N Scotland! All models have warmer air pumping up from the Iberian region, therefore preventing any cold air from the north. The EC at D10: The UK is caught between the Eastern block/high and the Atlantic, mediocrity at best. Hoping they are all wrong.

Ice Day The problem with a Siberian High is that the cold has do loop around the high and takes forever to get the main cold close to the UK: Some of the cold may break off for a cold pool, but then we have to hope it is signposted the UK. The above shows the progress of the very cold uppers over 4 days and to get to the UK, it may take another 4 days...a long time weather-wise. But, I am not even sure this is the correct longer term solution. The models remain fluid, and we may have to wait until the end of the week before we get a grip on post D5.GFS 12z shows how the Arctic high and Alaskan heights can block off good Atlantic/Europe cold.