kold weather

Trough coming through quicker than the models are predicting (the GFS from a few days ago timing looks better). Probably means most will end up just on the wrong side of marginal unless the showers strengthen to a similar level as those in the NW, which is unlikely. Maybe the Downs might may have a shot above 150m but we will see, for most I'm thinking probably rain/sleet.

In al lfairness to the Met office, I've been looking at the forecast from the 4th January for this week, this is what it reads: Got to say, that sounds pretty good in terms of general pattern, but if anything they have slightly overdone the MILD air, not the cold...

Even without snow this is quite a pleasant day so far,wonderful sunshine, something that has been a little lacing so far this month.

There is an awful lot of uncertainties within the ensembles and giving the set-up we are in a small shift here and there will make quite a large difference to our actual weather. As has been said there are basically 21 different solutions from the GFS ensembles, though two generally broadly differening views of how things evolve to our north past day-8: 1: pressure generally rises along with a more southerly jet. 2: PV strengthens and shifts towards Greenland and jet lifts north. As can be seen, some rather big differences to our weather would be expected. The 06z GFS op run more or less fell into the 2nd camp, though it does give a cold spell beforehand. My guess though is the idea of a re-strengthening PV is unlikely at this point, we'd be badly unlucky to get that to shift have not had any real impact from the SSW. What is interesting is there is more than a hint again of possible snow event around the 29-31st. This was also highlighted yesterday on the 12z ECM ensembles, though I've not seen the 00z ECM ensembles to see whether that has held. So as you can see, a rather 180 contrast from the GFS ensembles

Yes fair play to the UKMO ikt did clock that change to the 144hrs, and now we are around 120hrs out the models are starting to shift towards the UKMO.

GFS looks decent upto day 10, and indeed even the progression after that looks reasonable, but I'm not convinced we are going to get a resurgent PV over Greenland like that 06z wants later in the run , aka +ve AO/NAO pattern deep in the run which destroys our chances of sustained cold. Very odd presentation.

Well another run and another utterly different Arctic profile past 216hrs, that's probably about as far as we can go with even a slight amount of confidence. 06z GFS version of the Arctic is to ramp up the PV again over Greenland...GFS looks like its going back to a phase MJO look. Total contrast to the 00z which blew up strong upper highs over Greenland...so yeah, confidence very very low!

Agreed, I think as you've said before the diving troughs are still the main feature, though that is increasingly being aided by a mid Atlantic ridge helping to keep the cold air coming down rather then getting cutoff. any ridging though will probably end up being forced SE and I wouldn't be shocked if we need one more bite of the cherry before we get that proper northern blocking. But its getting there steadily. Down the line, need to watch what the arctic does, I'm still going for a 5-10th Feb date for some decent northern blocking to emerge...I'm praying I'm right!

Further east should be better purely because the timing is better, more time for cooling from peak daytime temperatures, Surrey is probably going to get the trough only just after peak warmth so they will be more dependent on there being strong enough showers to bring the snow level down (quite possible)

Lower thickness across the Arctic so far on the 06z, but the trend looks broadly similar. Slightly colder flow from the NW at 168hrs as well.

Certainly is a lot of uncertainty out there in terms of certain key features. The GFS ensembles in particular are all a mess bar maybe two key things: 1: still plenty of LP's coming from the NW 2: General trend of some rising pressure to our north, to some extent. Other than that, seems like the models really are struggling with the various somewhat conflicting set-ups due that stubborn PV lobe but tropical forcing/strat forcing suggesting pressure should be rising quite close by with ridging from the Atlantic. Stewfox, I think people jus don't believe anything the models are showing at the moment, huge amounts of apathy here.

For you guys up here away from higher ground the intensity of any showers is going to be key as to whether the snow settles or not. In lighter falls probably going to struggle, but heavier falls I would think be condusive for decent settling at lower levels. Of course questions to be had over how much it holds on after the shower has passed through. Not surprised Buxton is getting hammered, I suspect most towns above 200M on the western side of the Pennies will get hammered, same for most places in Lake District, etc.

Quite an interesting set-up for Kent later tonight, as that LP forms in the flow the trough slows right down in its eastward progress. If it does slow down far enough west could see a surprise falling of snow tonight for Kent which could leave a 1-3cms. of course it may slow down when already too far east. Also good hints that the trough has been forcasted to move just that little bit slower which means its coming in a few hors AFTER peak daytime warmth, rather than during it. That may make a small temperature difference and help send it the right way of marginal, we will see...

Yeah, had these charts been fresh without the baggage of failure there would be plenty of excitement. As you say some good trends l. There is still some considerable amount of uncertainty With how the Atlantic responds. I'm am feeling more confident with regards to the blocking forming from the Atlantic with a slant to the east. Whether or not that's enough, we will see!

Got to treat each situation differently though, which I know really is difficult as many do rightly feel let down. I'm still going for a strong northern blocking 5-10th, if it comes earlier, then great!

Exactly Nick, it is somewhat of a high risk high reward thing, if the pieces do line up then we will get very snowy indeed and it maybe one of those rare cases that we get the snow cover BEFORE we get much deeper cold.

Amazing synoptically on this mornings 00z, they are going for northern blocking again. IMO given factors others have mentioned, it is quite plauseable solution. Biggest concern is lack of deep cold and we may require Abit of luck with LP placement but alot to be optimistic about this morning.. Not many people are bothered, looks like no one is willing to commit but this is many times more realistic than that easterly was with hindsight.

Yes the ECM ensembles are showing more in the way of NE via the Euro trough mainly. Also worth noting the 18z GFS ensembles are a total synotic flip from the last 12z suite. Many more northern blocks, though there are a fair number of the runs that have a huge lack of deep cold due to how we evolve into the pattern.

Yeah, I mean the GFS for example has been toying with making some good -ve AO action but each run has thrown up something different today so there can really be no confidence in that at all yet. I'm still sticking with 5-10th Feb for a decent burst of northern blocking. I'll probably be wrong, but I'll go down being wrong!

Well the 18z GFS control run looks a lot more realistic looking pattern in the Atlantic once we do get an attempt at a ridge and although it does bend to the east the set-up with regards to the ridging further NW looks FAR more realistic as well. The GFS op yet again did something different in the Arctic despite looking somewhat better in the Atlantic zone. Also a much better looking snow attempt between the 29-31st. Will be interesting to see how it reflecs on the GFS ensembles overall, as it was quite marked on the ECM ensembles.

Well the 18z control seems much more realistic in how it is handling everything, with the Azores high ridging towards Greenland but also getting slanted to the east by the PV over NE Canada.

Got to say the GFS is proving utterly useless when it comes to the Arctic at the moment. 4 runs today and 4 wildly different solutions. 00z has an arctic high that links to the Azores high ridge, the 06z attempts a cross polar flow from US+Russia then pumps up a strong high from Russia, the 12z doesn't even bother at all with the first arctic high, then eventually creates one at the death of the run and the 18z develops 2 highs via ridges in the Pacific. Just about covered every possible solution in the space of 4 runs, so I'd probably suggest that alone hints at quite a highly uncertain set-up. GFS 18z basically is an exact rerun of this weekend in FI, to the point where the storm I the US takes an identical track and this causes the ridging to collapse eastwards and we reset into the classic default GFS +ve NAO dirge. On balance I'm still expect some more significant blocking to arise between the 5-10th Feb, though where would have a large impact of course. I did originally think Greenland area but its starting to look like the only way to get rid of that PV is to fire several nukes at it! So maybe we will have to focus further east in a hope for something to take hold strong enough to disrupt the current pattern.

Well we get a GFS special from 300hrs onwards with about a textbook +ve NAO look as you can get. I'm not convinced by the way the GFS is handling the arctic at all on this run though... Also, the pattern its showing from 300hts is vastly different from the 12z GFS ensembles and also very different than most of the ECM ensembles as well, so GFS probably going off on one of its occasional wanderings to default so to speak.

Possibly good news as the GEFS have been getting more and more keen on that Atlantic low taking hold and rotating in SW air in early Feb despite upper ridging occurring further north.. There is the same signal on the ECM but its a much weaker signal compared to the 12z GFS

Fairly similar 18z to the 12z on a broad scale out to 192hrs, though obviously there is a weather difference to the locations of all the LP features. Maybe a touch flatter?