supernova

It's already been stated that 2010 was a 1 in 100 year event and, as much as we'd like it not to be the case, we're unlikely to see a repeat next week (more's the pity - we were buried in Lincs). Synoptical comparison (variable dependent on which model output and date you choose obvs but I've selected something tasty from the GFS just as a guide). Lot's of fundamental differences. Just managing expectations, although anything could still happen obvs (including rain Ed)! Basically suggesting that we shouldn't be looking back to 2010 as any sort of guide or expectation, and should instead be focusing on what the models are portraying in the current output, not least in this thread.

If memory serves me correctly, Battleground, there was considerable agreement from a long way out. GFS in particular dropped the theme a few times but reverted quickly. What none of the models saw was the intense Polar low that buried Lincs (amongst other areas) into a snowy playground over a very short period of time. That was the year I lost some pretty old trees (and my central heating!) to temperatures of -19C. In all honesty we tend not to do so well from Northerlies up here for some reason, it's either NE or Easterlies that have historically produced, but I'm happy to be pleasantly surprised this year if it delivers. What interests me most tonight is the cross model commonality for a Greenie high which is rare as hen's teeth, even in FI.

Whatever happens in ten days time, the start of the chase proper for coldies is always fun as the forums begin to thrum and my Weather Experts list on Twitter spikes with rumblings of "what ifs" and "interesting" comments from the usual suspects. This from Gav who frames current goings on rather nicely, as ever.

Oh go on then.... ECM at 240hrs

Interest abounds in tonight's output but a word of caution re GFS Op - one of the colder solutions in the ensembles which have overall trended slightly warmer across the last three runs (not by much but warmer nonetheless). Previous GEFS for reference.

GEM is magnificent. GFS isn't. UKMO is magnificent. GFS isn't. UKMO freezes the entire country in -8 to -10 uppers until the end of the run and then looks set to slide the upstream low. GFS doesn't. GEM picks up intense streamers and delivers significant snow not just in the east but right across to the west of the country in many areas before a major snow event next weekend which could be temporarily marginal for the southern-most counties but too far out to even bother speculating. GFS doesn't (too progressive as always). ECM will hopefully follow the UKMO/GEM later. GFS probably won't. And even if it does I still won't care. GEM streamers and snow event. GFS Op significantly above the mean as it tries to break down the cold progressively. Might be right. Probably isn't.

@johnholmesDo you remember this John?! V interesting read. I wonder whether that historic Humber streamer will return this week? North Sea not quite as warm but uppers are colder this time. Maybe.... Looking forward to seeing the faxes next 24 hours. Dec 1 2010

Don't show @sheikhy the GEM. V snowy in his manor!

UKMO ejects the limpet low cleanly east and slides the upstream system beneath long-fetch easterlies for a spectacular synoptic set up with long-term potential. Perfection. GFS holds the limpet low slightly further north (than the 06z) and the coldest uppers are delayed into the SE BUT upstream low sliding more readily - short term pain might bring long term gain. Edit: Blows up the dart-board low upstream (as always). That's as far as I'm going.

Icon...limpet low further south and colder uppers down to the SE faster as a result. Upgrade!

Crikey, the naysayers are out in force this morning. For anyone in the south worried about the upcoming cold spell....yes things could all look very different on the models tomorrow. They could be colder!!! Ha ha ha ha. PS I can’t wait for @nick sussex to post later....he’ll be convening a full on COBRA meeting. And when do we start debating mesoscale and Polar lows?

Oh Lordy, this could turn into a classic spell. These snow depth charts are useless, especially in a convective Easterly set up, but it highlights the potential for most places. Anyway, snow depth in 10 days? No idea. The suggestion that there might even still be snow in ten days time interests me more!

And the colder uppers quickly return so surely worst case back edge snow as the low disrupts east?

GFS Op goes onto be an outlier later on in the GEFS as it tries to keep the cold in for longer rather than a snowy breakdown from the South West as some other models are suggesting but is firmly supported until then (also raising the prospect of building Scandi heights and extending the cold). We have cross model agreement guys, meaningful Easterly at 96hrs with pretty similar placement for the limpet low from all. The whole country swathed in -8 or better by Monday night and significantly earlier than that the further north you go. Finally. My first BOOOM!

Trigger low positioning absolutely crucial to achieve a lasting and expansive result for coldies and as one might expect at this range, we're really none the wiser. Irrespective of whether the West or Central/Northern regions have had any snow or not this winter (and accepting that Lincs/EA/SE have largely had bugger all), there's still plenty of time for the low to transition to hero or, sadly, zero. Nothing unusual in these "classic" Easterly set ups - often so fickle. The mean is mostly our friend, at least, not just on the ECM but also the GEM, and the UKMO/Met remains fully on board. That the hi-res Det and Control are bang in the middle of the ensembles until FI also gives me more than a crumb of comfort. Keep the faith. We'll know soon.

Classic! As suspected, Op above the mean from start to finish (so far) and Control almost as warm.

Don't even need to look at the GEFS to understand whether GFS Op is an outlier. If that chart verifies I'll buy everyone on here a beer. Twice.

Can't take my eyes off the GEM. Slider incoming, robust Greenie high, Easterly firmly established with notable convective snow showers/streamers and bloody cold!

No only the GFS runs four times a day (at least for the general public to access as @MattStoke and others rightly note above, and which is too many runs in my humble opinion!)

For public consumption, ECMF rolls twice a day, 0z and 12z. Between 6pm and 7pm for the next run. ICON first of this afternoon's runs (sometime after 3pm), then UKMO and the GFS a bit later along with the GEM. No doubt someone can give you exact times but that's a rough and ready guide.

06z GFS Para ejects the limpet low slightly faster without blowing it up which allows the incoming system to slide like the UKMO and ECM. Bingo...the whole country but especially the east side of the UK gets plastered.

Gonna really stick my neck out here....the low is slightly more north and therefore it's going to be....really hard to work out what actually happens until the run is several frames on if not entirely complete. And then, even if it's a complete dog's dinner, I'm still going to ignore it until there's an element of conversion between all the main models or one or other of them waves the white flag and totally jumps camp! For any new members reading, try not to get hung up on every post on every frame as you'll find the commentary confusing if not downright contradictory. The stakes may be high (even if it's only us nutters who attach such importance to the weather) but, in the end, as has been said many, many times on here, not one single comment on this thread or a prediction by any of the models' will make the slightest bit of difference to what actually happens outside. The models are a speculative (often highly speculative) preview of what may happen in coming days...nothing more...even if watching events unfold are, for most of us, much more entertaining than anything on the telly. Enjoy! Edit: For what it's worth, the longer the limpet low is allowed to sit around over the UK rather than eject readily to the south/south east, the more chance the incoming system racing across the Atlantic has to phase rather messily with it which thwarts a clean fetch of the coldest uppers from northern Europe which by Friday is already frozen.

ICON blowing the low up in situ a little rather than clearing it SE which leads to a slight delay in dragging the coolest uppers west compared to its previous run but looks like it would go on to produce the goods soon afterwards. Slightly delayed (if correct!) but by no means awful. . 00z vs 06z

Slideeeeerrrrrrr! Come on ECM. Don’t think anyone in the SE will be upset this morning just as long as they ignore the GFS in its entirety. Big ask but, well just look....

GEFS meaningful step backwards on the 18z. See what the morning brings.