Duane S.

Guessing a lot of late risers out there because when I noticed we were still on page 8 here before viewing the model output, I assumed they were going to be a poor set! I think it's safe to say I was pleasantly surprised. This is looking increasing less and less like a toppler and more like a very interesting cold spell on the horizon. More runs needed as always but looking good.

This is very pertinent. I've been at this long enough to know GEFS just doesn't randomly produce -15c 850s member runs (lower than that still into tropical Dorset) if there isn't some genuine potential. People may be fed up of the 'P' word but better to have it than none (aka 95% of the time during winter 13/14) and right here, right now, we have oodles of it.

Sorry, not true I'm afraid. There are 'signs' if you are willing to broaden your horizons beyond the exact output of few op runs. By no means is anything set in stone but a decent cold spell looks a very good prospect going into Feb, thereafter HLB has to be a genuine contender as things currently stand. But of course, even HLB doesn't guarantee cold for the UK.

The Taiwanese model is where it's at. Plenty of support from other models of only a brief stay in the dreaded COD.

Oh you little tease ECM! A quick scan through GEFS and there is support for a similar idea with quite an amplified flow progged at that range. I think after a week or so of alternating average / cool for most of us, heading into Feb is starting to look very interesting indeed

Back on subject and zonal winds are forecast to be but a breeze through the mid Strat after a nice wind reversal over the pole...

As I understand it, past forecasts and their verifications are looked at along with the input/start data of the current run. Adjusting previous inaccuracies often improves the midrange (and I suppose subsequently longer range) forecasts as opposed to short range which wouldn't be that affected.

Hi, sorry just remembered I didn't get back ref this... This is copied and pasted from the wiki SSW page which cites the WMO as source... "Minor warmings are similar to major warmings however they are less dramatic, the westerly winds are slowed, however do not reverse. Therefore a breakdown of the vortex is never observed. Mclnturff states: a stratospheric warming is called minor if a significant temperature increase is observed (that is, at least 25 degrees in a period of week or less) at any stratospheric level in any area of winter time hemisphere. The polar vortex is not broken down and the wind reversal from westerly to easterly is less extensive." Which to my mind backs up my earlier comments that we did have an SSW but of the 'minor' variety. I think confusion comes from some (rightly or wrongly) only calling it an SSW if it is of the 'major' variety which specifically requires a U wind reversal at 10hpa / 60N, which although close, was not achieved earlier in the month.

Phase 6 would likely aid ridging northwards of the Azores High.

Absolutely Nick. I posted yesterday (and many times before) about these large blocks to our east. More often than not they serve to tease us throughout winter without ever extending westwards enough to directly feed continental to our shores. These smaller Scandi cells are often much more productive as often their duration with a propensity to ridge westwards through time is underplayed by the models. I think undercut could become the buzz word of the month (if it isn't already) Interesting times ahead I think...

Ref mobility, I can fully see why it is being touted as the formhorse for next weekend. A glance at upstream signals would confirm that the cold spell has got its work cut out to cling on but even if we do pull in a more mobile regime, I would be surprised to see it hanging around for long. The waxing waning ridging of the Azores High looks set to continue, watch an increased ridging northwards signal grow in the models as we get into the final week of the month. There will likely be a period of opportunity here for some more interesting looking heights to grow into Greenland.

Maybe a mile off but looking at the u winds charts through Jan and I am wondering if the E-QBO worked against us in a perverse way. There was quite a strong poleward surge of Easterlies at around mid strat level earlier this month, getting us far north as around 40N. This left a small area of persistent wind reversals around this area, still present. This has seemingly forced zonal winds downwards at higher latitude than may otherwise have occurred. Did this help scupper a full SSW I wonder? As it is forecast to finally abate so the finger of zonal wind drops back equatorwards allowing the more benign looking zonal profile where we want it.

Updated now. Wave1 incoming...

Why do iPads do that?? Type a lengthy post, pop over to another tab, come back to this one to finish typing the post, it refreshes and post gone! Anyway the gist was things looking a little rosier on the 00z suite or at least the 'downgrades' of yesterday have been halted. A much more pleasant environment on here this morning than yesterday. Yes I would say a more mobile weather is currently the favourite for this time next week but before we get there, we have plenty of fun and games. And who's to say a more continental influence isn't just around the corner thereafter? Forecasters nightmare though when these 'sliders' come into play. Ppn types, location, intensity, duration as energy passes down. Small mesoscale systems can often develop, hardly noticeable but as they meander down in the unstable flow they can be responsible for some big surprise falls in the lucky areas in these sort of setups. So the key word is potential for all. The great thing about living where I do is that expectations are always low, so anything that occurs of the fluffy white variety is always going to be a bonus! Also just because our hp cell currently over Northern Scandi isn't the most robust looking, it isn't necessarily a bad thing. I like them. Seen it many times before that they tend to linger longer (and often 'nose' westwards towards Iceland in time allowing continued undercutting) whilst those big strong blocks to the NE might look great, the reality is that almost always is their westerly influence stops well east of the UK and whilst it may hinder full on Atlantic mobility, what we often get is the dreaded 'no mans land scenario'. Especially around this time of year.

The 00z suite, if taken for granted, is not as good as some before but it isn't disastrous and there is plenty of scope for improvements.

All well and good but by virtue of it being more north the likelihood would be it would be deeper and with it more mixing and marginality. The snow band would potentially be less wide and whilst it may bring some a big dumping for those in the sweet spot, we ideally want it clearing sharpish off to our South / Southeast to aid longetivity of the cold spell

Absolutely. A quick glance through what is normally the semi reliable timeframe is enough to remind us what a myriad of options lie on the table. Never mind 3-5 days, T-6 hours will quite feasibly be when some of the details will start to get shored up as these mesoscale features travel down over us. All we do know is that it is going to get cold and there will be snow. Good luck Ian!

He does emphasise it was a minor SSW though, which by WMO definition, it was.

Shows how good a cold spell we have in prospect if a run we would have sold our grannies for 10 days ago, aka the the 12z ECM op, causes such an outpouring of grief and despair by some. A cold period is nailed. Yes a few signs it may be on its way out by next weekend but it is simply way too far away to start throwing toys out of prams.... It is on a bit of a knife edge, the swing to a milder scenario later on could easily flip back within 24 hours to an easterly solution. All to play for the end of the month and into January. Personally I think it is MJO assisted as per the Meto take when you consider we are currently running in high amplitude phase 6 and likely to make it through 7 before petering out well into the Pacific. But it is likely to be just as much down to the effects of the minor SSW that has been and gone which although didn't actually achieve full SSWness in terms of u wind reversal at 60N 10hpa, the temps at that level did hit a record warm temp in the strat polar cap. That arguably makes up for it only being a 'minor SSW' by definition and unlike the more direct MJO forcing on the troposphere( when there is a coupling as there seems to currently be), this strat event could spread its influence well into the month of February in terms of anomalous warm Arctic conditions and continued outflows of cold into lower latitudes (us if we get lucky)

The usual pre-cold spell madness on here ensues. Putting aside the usual 1 or 2 hellbent on delivering (unfounded) bad news to us snow starved UK snow hopers, why do others never learn in respect of snow chances? In my location, if I can refrain from the completely pointless task of micro analysing ever single op run for whether it may or may not snow in xx place in xx number of days, I'm sure most of you in more primed geographical locations can as well. The bigger picture for an at least 7 day cold spell is all that matters, that looks great at the moment. With good agreement on a slowly decreasing low pressure anomaly sat beneath us will stack the odds in our favour in respect of both increasing the longevity and severity of the cold spell, that's really all that matters. The will it snow, won't it snow in my town, as has always been the case, will have to wait for 24 hours prior at best, nowcasting at worst. It's worth remembering it is extremely rare to get one 'event' giving snow UK wide and I don't see that being any different with this setup. There will be losers and winners but the good news is, there looks to be a few 'events' in the offing with this impending setup, so chill out, relax and just enjoy the fact we are about to have a decent countrywide cold spell for the first time in nearly 2 years!? Where there is potential... And even if it does all go the way of the pear, it's still only mid January, plenty of winter left to go... Over to the ECM to deliver a beauty of an Easterly ??

'Sliders' rarely produce for the majority, Jan 13 was the the exception to the norm. What is more important is what potentially they set up thereafter. They often represent the start of a building cold spell. Look at it as a bonus if lower lying areas in the southern half benefit as energy travels SEwards / Swards towards the continent. It's all about whether, with lower pressure in underneath us and a quiter Atlantic, we can get the real thing with the window of opportunity this affords us, aka a proper cold spell(not snap) for the uk. This is the first time since late winter'13 we have genuine hope!

The hunt for cold will always be the underlying nature of the model thread in the winter and to remove that would rip the heart out of thread. The bickering goes on every winter on here but I have to say this year is the worst I can remember. I think it should left as it is but the moderating needs to get stricter. On the whole the moderating is very good but not enough posts are moved to the ramps / moans thread in my opinion, there are more posts than ever being made by those who seemingly can't hide their frustration as we edge towards the middle of winter and things have not panned out as well by now as many of us were expecting a month ago (snow / cold wise). If the mods get fed up moving the same posters posts across, ban them for a week. Most annoying to me are the few on here that constantly HAVE to find spoilers in any potential cold spell and when/if it becomes nailed on change tack to start posting about when it will breakdown and how short lived it will be. Personally, I find that sort of mentality very very difficult to comprehend. However, as nauseating as these posters are to me, as long as it is done with reasonable objectivity it is fine but there are plenty of times when they cross the line IMO (often just at the point when the cold spell is nailed and they then start looking for spoilers) and because they have posted a chart or 2 it is left. Although, I know that makes it a grey area as such. There is the world of difference between those (albeit, very few posters) I have described above and those who are just a bit more pragmatic and level headed than some and are simply pointing out pitfalls in an evolving potential cold spell. There is an ignore feature and it works to a degree but of course you inevitably get to see their posts when others quote them, so it's not perfect. As for those with little knowledge but keen to start posting on the model thread, there is a learning thread and many of the well respected posters on here now would have spent their early days beefing up their knowledge on there before venturing onto the model thread. If some can't be bothered to that as well, fine but keep to lingering on the model thread and posting in other threads, your choice. What the forum has very little of however is genuine trolling, remarkable for a forum of this size.

As others have mentioned, a quick route to HL blocking probably is an outsider but the ECM offers something of a (possibly more realistic?) slower evolution with a retreat westwards of the Azores High coupled with an increasingly favourable angle to the jet starting to slide energy out of Greenland on more of a NW-SE direction. What we want to see here is this passing through the SW quarter of the UK, or even better, to our SW. This would set up a great end to the month for sure!

Hi, it is my 3rd time here now and easily my favourite Alps resort. Despite the low snow base the skiing has been more than adequate this week although it could have been better obviously. We had a few cm above mid station this afternoon so were treated to some powder for our last session! Add to that we have had glorious cloudless skies for 4 days of the 6 and it has yet again been a great holiday all in all.

Seen enough output in recent days to believe it's a case of all roads lead to cold. The 00z reaffirms this. The nature and degree of the cold is the only thing up for grabs.