nick sussex

Although there’s been some positive changes re the cold backing west the upstream troughing shows no sign of disrupting favourably at day 6. I know we’re coming up to Christmas but not sure the models are in the mood to deliver a miracle . The shape of that upstream troughing looks all wrong, the ECM ensembles aren’t interested at all bar the odd straggler . Give it to tomorrow morning but it really would be the mother of all turnarounds if the Atlantic is held at bay past day 6 .

True , it doesn’t go completely off the rails but we want the UKMO solution . The big question is whether that could stop the Atlantic at day 7. We still need a weakening of the low upstream at day 6 and the block even further west but you never know . If you compare last nights UKMO with tonights it’s a huge change.

Even with the GFS not building on it’s better start it’s still finding a bit more trough disruption at T120hrs.

The GFS after a better start starts to implode . The key is the upstream low exiting Newfoundland . The UKMO has a deeper feature which phases much earlier with the troughing to the west of the UK at T96 hrs. The early phase stops the forward momentum of the upstream troughing and helps to pivot some of the energy away from the Scandi block . If you follow both the UKMO and GFS you can clearly see between T72 hrs and T96 hrs the huge difference the phase timing makes .

A westwards correction already showing up on the GFS 06 hrs run at T60 hrs. Look our for the low exiting Newfoundland , that’s the one that develops more on the ECM and phases with troughing to the west , quicker phase is what you want to see.

The mean looks okay at day 4 and seeing as the UKMO has now backtracked towards the ECM you’d think that the others would . The Euros both wrong at day 4 is very rare .

It’s like musical chairs ! Now the UKMO has dumped last nights most progressive solution and the ECM has backed the pattern west . Unfortunately the same problem remains later the lack of sufficient trough disruption at day 6 . Theres just too much energy upstream and unless someone can deflate that ASAP then today’s Euro improvements are just delaying the inevitable . Looking at the De Bilt ensembles there are more colder solutions upto day ten than last night but these are still very much a minority .

I’d have rather the GFS had pulled that run out not the UKMO. Yes it looked fine at T72 hrs then hit the buffers . Looking at the GEFS the UKMO has little support , indeed it looks like just 2 out of 20 members are anything close to it at T120hrs .

I’ve gone to emergency code red straw clutching ! If it hadn’t been for the misery model tonight would have started okay . Thankfully Arsenal scraped a win so my mood has stabilized !

Models out so far , and in terms of trough disruption and favourable phase at the key timeframe . GFS GEM ARPEGE Pants phase ! Satans love child aka UKMO

Satans love child has appeared in the form of tonights UKMO. A horrible run which unravels as early as T96 hrs. The big problem is you can see the lack of phasing at the key timeframe of the two lows to the west and nw . The phase motion slows the earthwards progression and takes the energy ne then nw as the other Atlantic low phases at the base of the main trough . The UKMO just barrels everything east and it’s game over . We are talking at just day 4 and it’s very unusual for it to be that far out at that timeframe . We await the ECM but even if that’s still okay we’ll have to wait to tomorrow morning .

After the first shortwave which ejects from the upstream low what happens after that is still subject to change. Currently the GFS barrels the next low east with no disruption .The ECM has that runner low and is less progressive . In these set ups you often develop a momentum if the Scandi block is underestimated with the pattern continuing to back further west and south . We should have a better idea tonight if that’s going to happen . At this point next week is still up in the air , could get whiter or conversely turn into an anti-climax .

That’s often the case with these set ups . The lower resolution ensembles always struggle until closer in to the event .

Lots going on. Here are some of the highlights. The will it or won’t it cold undercut from the east meeting Atlantic fronts still no resolution . A possible runner low deepening quickly running east across more southern areas , snow on the northern flank possible but again no certainties . Later on the ECM develops an interesting looking NH pattern , the PV is located favourably with heights lifting over Greenland . The GFS tries to bring in a northerly . Overall it’s all finely balanced upto day 7 between a damp squib and a few snow events for favoured areas. Let’s hope it’s the latter!

Anything could happen next week and I’m not talking about the current political soap opera ! We had a few days where things were sliding the wrong way. Tonight there’s been an upturn in fortunes but the cold mild boundary could still be shunted too far east. These set ups are so difficult to forecast given the narrow margins between snow and rain .