Yeti
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Yes, ironically as some have said, it looks like the East may actually be in a better position for Monday/Tuesday's snow event than the West, because the low looks like tracking too far west for anywhere, in England/Wales at least, to pick up a northerly flow but at the same time this could draw a SE'ly flow off the continent up the eastern flank:
http://www.wetterzentrale.de/pics/Rtavn1202.png
http://www.wetterzentrale.de/pics/Rtavn12010.png
So the North and East currently look most likely to see snow from this event although this is obviously still subject to change. A small shift W may actually help keep DPs lower further W, but it requires a pretty big shift E now to get the full effects of the N'ly and this looks unlikely.
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Sorry but have to agree with Lewis. He has a good point and thats how he sees the models and what he thinks will happen. If the ECM shows the same I think Lewis will have his trend.
If the whole of the UK is sitting under the high on Thursday/Friday as Lewis seems to be suggesting then I will eat my hat. Sorry but this is really getting quite annoying, what "point" is actually being made here? That we're all in for a big disappointment if we don't listen to what he says? The only reason that anybody should be disappointed is if they took those tasty FI charts at face value a few days back. In fact I remember certain individuals were already talking about snow for most of the week in Yorkshire. FI is, and always will be, UNRELIABLE, especially wrt details such as where snow will fall! Honestly, if anyone is disappointed at that 12z they have themselves to blame!
The UKMO and ECM still have the high slightly further N anyway (and the 12z is marginally better than the 6z, so quite what this new "trend" is I've no idea). There's no reason to think that this is all going to be a flop -
http://www.wetterzentrale.de/pics/Rtavn961.png
http://www.wetterzentrale.de/pics/Rukm961.gif
http://www.wetterzentrale.de/pics/Recm961.gif
All in all an excellent selection of charts, with cold for all and snow for most places S of the Wash and even N of it at times.
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There you go;
Really I don't see what the big issue is at the moment - this was always going to be more of an event for SE/E Anglia as soon as it appeared within the more reliable timeframe and I don't see much output to change that?
Easterlies rarely affect the whole of the UK - in fact they are usually severest in the SE - and people were warned of this a few days ago but as usual, many seemed intent on ramping it up: blizzard this, Feb 86 that. There has been a SLIGHT shunt Swards but this is almost always the case with the models, and often they readjust (upgrade) later on to reach a halfway house. Besides, the difference this will actually make at the surface, as TEITS says, is really very small indeed. Snow showers could still crop up in most areas with more and more the further S and E you go.
It still looks an exciting week for many, and even if it doesn't snow, at least it will be relatively settled, cold and sunny.
http://www.wetterzentrale.de/pics/Rtavn961.png
Doesn't seem a bad chart to me considering we were looking at raging SW'lies just a week ago!
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This is very much following my script with +192/+216 showing stage 3 that I mentioned.
Clearly see this cold spell isn't going to arrive with a bang. This could well differ to the last cold spells as this has more potential for being even more prolonged. I feel Steve M summed it up perfectly by saying slow to start slow to end.
Yes, I seem to remember that during previous cold spells this winter the models were already showing breakdowns which kept being put back over and over again. However this time the ops just keep it cold all the way through, even to T384. This can only be a good sign - and we should bear in mind also that although good synoptics are difficult to get, they are also very difficult to get rid of, rather like mild patterns. With the SSW kicking in later, we could be in for a very cold February overall.
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The extra solar input won't make the showers off the sea any heavier but it will allow us to 'grow our own' over land during the day to a limited extent. Best example is during the summer months where the showers fall inland whilst coastal areas can stay sunny all day.
Being early Feb the sun won't have a lot of strengh, but i suspect it will be just enough to cause some activity inland (as long as there isn't a sheet a grey low cloud).
Eh? If the sun enhances land convection then it must also enhance sea convection... both involve exactly the same mechanism, except that the sea has a lot more water so it produces a lot more activity.
Similarly, if the sun is strong enough, as some people are suggesting, to make a difference to daytime temps by heating the ground more, then it cannot NOT have effects in other areas... that just doesn't make sense. It's certainly true, though, that cold uppers are vital to decent convection which is why I suspect there won't be that much around before midweek. In fact, the upper profile doesn't look brilliant, all things taken into account - the core of the cold pool is now trending further S into Germany with more S and E areas still seeing some really decent 850 temps - still subject to upgrades/downgrades.
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There is lots of talk about longer days and a stronger sun which is certainly true, but we ought to remember that this also increases convection potential. A stronger sun than in Jan, shining over a comparatively cold N Sea should result in a lot of beefy snow showers - the question is will these make it far inland. The flow isn't great if we're honest, but it's better than a lot we've had where snow showers have formed in many areas, so I think it would be fair to say that some places could see a good amount of snow even this week - particularly parts of East Anglia and the SE from Wednesday onwards - the risk zone being a bit further N prior to this.
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524 DAM thickness in the SE at monday Lunchtime---- Low heights, low thickness = snow showers---
Allignment of flow is Thames Streamer territory..
S
Nice to see you back Steve, your input is always v. popular - I see you are as excited as many other members are!!
Now that is a nice NE'ly from the ECM at 120!
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Wow and if I thought the 120hrs was a good un, the 144hrs is quite unreal, thicknesses a good bit below 510 in the SE, would be a very snowy evolution for a good part of the country I'm pretty sure!
Indeed - and with the sun that bit stronger, and the North Sea that bit colder than the last cold spell, these charts would produce some very impressive convection. On the GFS and UKMO 12z the high is also in such a position that the whole of the eastern side would be affected.
I remember last cold spell people were complaining about the precip charts being too dry and that it was going to be a cold dry spell. When it came to it that was far from the case - but look at this already:
http://www.wetterzentrale.de/pics/Rtavn1504.png
For the GFS to pick up on that convection so far out, it's difficult to imagine how awesome the activity would be if that 144 chart actually verified!
Still a long way to go though yet, but things trending in the right direction. And obviously, those precip charts are only useful as an indication of the sort of pattern we're looking at atm, i.e. sunshine and snow showers.
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Well there's reasonable model agreement tonight on the future synoptic evolution which is obvious because people are starting to argue about where the snow is going to fall!! The truth is that the SE and EA will nearly always be the favoured spots for snow showers in these easterly setups, but as we know, snow would crop up in most places IF the charts were to verify, as fine detail is a long way from being modelled atm.
Let's hope things firm up in the right direction more and more, otherwise I think any backtracks to mild tomorrow will be too much for some members to cope with emotionally!
If this does turn out to be a notable easterly spell, this winter really will go down as one where luck has been very much on the side of the cold ramper, after years of misfortunes.
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I certainly would not want to make a forcast for next week based on the runs
I have seen tonight. The ECM at t168 showing promise again with what looks
like troughing trying to undercut although on Meteociel it is sometimes hard to
tell.
Tbh CC I think things are looking pretty clear now; it doesn't look like there is going to be a cold spell in the near future. The fabled easterly has once again disappeared from all the models. This time I fear it is too late for it to reappear.
There was hope this morning from the UKMO but this, too, has now turned into mild SW'lies and I believe the first truly mild spell of winter is nearly upon us. The problem is that the west based NAO is almost more than a help rather than a hindrance as we just end up trapped on the wrong side of the trough with the block holding the unfavourable pattern in position, and whilst it wouldn't take much to bring us a colder flow, these small changes would actually be quite stubborn to occur.
I have refrained from posting until things firmed up somewhat but tonight it seems things have done exactly that. The writing was on the wall a couple of days ago when the easterly appeared only on certain models, and each time that particular model was "the favourite" for some reason or other; for example until this morning the UKMO was written off by most but when it showed the desired undercut this morning it was clearly a "trend setter". For the newbies on here, this is a good indication that a cold spell isn't on the cards.
Hopefully things will be more favourable mid-month as the SSW pumps up the height rises over the Arctic - this may be a more promising period for a cold spell to occur. Until then, the background signals were looking pretty mixed, with conflicting cold/mild signs that in the end look like giving us a frustrating near miss!
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As far as I can see the main problem is the new trend for a ridge to develop over Europe; GP hinted at this a while back but unfortunately, rather than low heights over Europe sucking in undercutting LPs we end up with the ridge deflecting them N at the worst moment. Of course the west based NAO actually helps to lock in the mild for a time as lows struggle to make much eastward progress but then on the other hand, as others have said, it only takes relatively small changes to move the pattern eastwards into a more favourable position for the UK.
Certainly though nobody can honestly deny that there is a trend for milder weather now on all of the major models, and the ECM ensembles have taken a dramatic turn for the worse. So this has to be the most favoured outcome IMO, however annoying that is!
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We have a covering here in Cambridge atm after a little fall last night... a nice surprise, as I wasn't expecting anything.
Looks like that's it for showers in the E though now except the extreme E of E Anglia.
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Slightly improved NAO forecasts.
MJO excites me the most with some considerable stalling looking likely around phases 7 and 8.
Still looking odds on for a continental feed (of some desription) from around next weekend IMO. Increasing signs of blocking to the NW later on and with that Siberian block likely to try and muscle Westwards, could we get goalside of a much fabled link up in about 10 days time?? Not beyond the realms of possibilities, if unlikey by its very nature.
Yes the NAO is forecast to go slightly negative but perhaps we shouldn't worry too much about just how negative it actually goes:
http://www.wetterzentrale.de/pics/Recm1441.gif
If you look at the ECM - so far the best of the models today - the NAO is only slightly negative, with the Azores high not displaced very much and the block more E based than GL based. A strongly -ve NAO will be recorded when there is a large GL block forcing low pressure over the Azores. But this setup, as we know, isn't necessary to produce long, deep cold...
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The data was there a week ago, MMW, MJO,convection building over the date line, ridging into the Arctic,
hights moving across the pole and linking with the Siberian high, GLAAM and mountain torques predicted to
rise which you could see on the northern hemisphere charts,hints of fast downward propagation of easterly
winds in the stratosphere together with the warming and also remembering the initial response last year to a
sudden stratosphere warming (MMW)plus looking at the developing circulation pattern in the northern
hemisphere which I kept asking people to look at.
With the greatest of respect CC, if my memory serves me correctly you have been calling a return to cold ever since the end of the last cold spell - so, inevitably if/when it does return you will obviously be the first to have called it! As Tamara has already pointed out, the signs for a cold spell have not been (and still aren't) concrete, and February could quite easily have gone either way even though now a cold month is certainly favoured. IMO it is far too early to be celebrating forecasting victories, so let's just sit tight and see how things pan out. Even the northerly hasn't arrived yet, never mind any potential reloads from the East. This thread has, IMO, become quite polarised recently with two clear camps, which is a shame because judging by the comparative lack of posting with December, it is not just me who's decided to "lurk" instead of post.
As for the 12z, the HP doesn't get as far N as the 6z although I suspect that - as usual - the GFS is overdoing cyclogenesis and deepening those Atlantic depressions.
http://www.wetterzentrale.de/pics/Rtavn2041.png
Still, this is such a long way out that tiny changes in the short term will give rise to enormous long term changes, so it's almost useless looking at the 850 profiles as in the scheme of things these are small details that will become firmer later. Best keep an eye on the short to mid-term, particularly how the models are handling the troughing in Europe and upstream as this will be crucial to correct HP placement...
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UK Outlook for Sunday 31 Jan 2010 to Tuesday 9 Feb 2010:
Cold at first, with overnight frosts. Wintry showers likely on exposed northern and eastern coasts, but it should be drier and brighter elsewhere, particularly inland. Rain expected to spread from the west on Monday, with snow possible, particularly over hills and in the far north. Turning less cold in the west on Tuesday, with bright or sunny spells and wintry showers in the northeast. Drier conditions are likely further south, extending to most parts by Wednesday (3rd), with lighter winds but cold to near normal temperatures. The mainly dry weather with frost and fog is likely to continue for much of the rest of the period, with temperatures mostly below normal. However, a low risk of much colder conditions with wintry showers may develop at the end of the period.
Updated: 1234 on Tue 26 Jan 2010
The met office update today is looking more promising after this evening's runs.
where is steve murr? has he done a lord lucan?
Unsuprisingly the ecm operational was one of the colder solutions but not without support.Quite stunning ensembles actually.
Interestingly the control is also extremely cold so the op and the control (the highest resolutions?) both go for extensive and prolonged northern blocking.
Incredible charts tonight especially considering the doom and gloom that has been almost non-stop on here since the last flake of snow fell; we even had "winter's over" posts a few days back.
We're still a long way from the real deal but things are looking more and more positive every day, and what we are seeing is a trend for an initial northerly (the synoptics of which are remarkable in themselves considering recent winters) followed by the high toppling N and E above the trough over Europe, not only sustaining the cold spell but potentially delivering some really deep cold associated with the offshoot of the PV being advected west.
...Which I believe is what BFTP pointed out quite a while ago now!
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Hats off too TEITS and Nick Sussex for predicting this!!
Tbh I think BFTP may end up deserving a lot of credit; he went against even GP wrt a cold February and the Atlantic high eventually toppling into Scandi well before the models even hinted at this. Of course, we're still a long way from this happening but the signs are increasing that this may occur and if it does, then hats off to him
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Although Coastal areas are favoured, Im sure there will be troughs associated with the flow, which would bring snow to inland areas
And indeed some showers will penetrate further inland, especially in places like northern Scotland and here for us in EA (hopefully!). There is a period (Friday) where winds may swing more NNE as well, which would only help matters.
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Snowing here in Cambridge now - not expecting much but maybe a nice covering? Nearly everything has melted here from the last cold spell.
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The ECM 12z has a better tilt to the trough than the GFS - this is crucial because it helps to keep us in a continental flow, obviously helping ground temps but also the upper temps to a lesser degree. http://www.meteociel...CM1-96.GIF?09-0 . EDIT: 120 chart is not very good with the high ridging into France and Spain - more like the UKMO?
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A cold breakdown is certainly not concrete at all! On Wednesday Bristol was predicted 8C next Saturday and yesterday it was down to -1C. Everything can change from one model run to the other - we've already seen this twice this winter I'm sure.
To me this looks more like bitterly cold southeasterlies:
http://www.wetterzen.../Rtavn1201.html
http://www.wetterzen.../Rtavn1441.html
http://www.wetterzen.../Rtavn1681.html
Keeping pressure low to the south in the Med has to be the key to not letting a ridge extend into the Med. Interesting charts nonetheless. Let's not get worried just yet and take a mild breakdown as sudden as some are making out.
Regards
Those SE'lies are not bitterly cold at all. If that chart is to be believed we can expect 4c minima in the S by Thursday:
http://www.wetterzentrale.de/pics/Rtavn15017.png
Not saying it will happen at all, but people seem to assume that just because the flow is SE'ly it will be cold. Yes, parts of Europe are now bitterly cold and a surface flow from these areas would bring correspondingly cold temps. However the flow is now predicted to have a more southerly element bringing it off France rather than Germany, which is nowhere near as cold (see above chart). We need as much of an E'ly element as possible helped by undercutting low.
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Well there we are, our hope of extended cold seems almost to have vanished this morning. The GFS has stuck to its guns re the low slipping E rather than SE gradually giving rise to southerlies as the block is pushed E, but far more worryingly the UKMO and ECM are now all suggesting something similar. Ever since the GFS lost confidence in the undercutting scenario all the models have slowly downgraded the cold IMO but nothing compared to today! If it hadn't been for the previously cold-looking outlook a breakdown would be looking totally inevitable this morning. However there is still a chance that this is a wobble. That said, the GFS, ECM and UKMO all roughly agree on a similar evolution. But that isn't everything; I've dug out our only hope this morning which is the GEM! http://91.121.94.83/modeles/gem/run/gem-0-156.png - THAT is what we want to see back on the UKMO and ECM. One thing is for sure; if this turns out to be correct and the LP doesn't undercut, the GFS will have been the first to pick up on this. I wouldn't trust its post-180z output though as its switch to the euro high is far too quick to be trusted.Worrying trends this morning.
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If upper temps are too high at the time of any SW attack though, freezing rain rather than snow may result?
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Yes, those ensembles do suggest that the operationals, the GFS in particular, are being much too progressive.
A lot will depend on the amount of westerly winds added over the next 2-3 weeks Fred. The amount of tropical convection in the Indian Ocean this time round was low, and it doesn't look like the MJO over Indonesia will do much either so I'm thinking another significant notch down in angular momentum during Feb which if anything will take us towards a more Nina like pattern.
Thanks for these fantastic assessments - I have a question though!
You mention upper temps returning to milder (though still below average) values - this presumably being down to the cold air simply running out of steam underneath the Scandinavian ridge. If we were to see blocking retrogress to GL/Iceland, would this potentially allow another stream of cold air to leak out of the Arctic down the eastern side of the block once again and (perhaps) drive this towards the UK, hence creating another cold reload later on in January?
Thanks
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Well there's 6 centimetres here at the moment, seems to be slowing off a bit now. Would love to post some pics, but last time I tried they came out HUGE:oops:
If anyone has any tips on how to get them small enough to post I'd be grateful.
Thanks
One thing you could do and probably the easiest is just to set your camera to a smaller photo size, then they won't come out big!
Or you could upload them to facebook or something which downsizes them automatically and then just link them in from there.
Amazing just the amount of snow falling over the UK at the moment. Shame it's so dry here but at least it's very white.
3 Counties & Ea Cold Spell Discussion Part 10
in Spring Weather Discussion
Posted · Edited by Yeti
Fairly heavy snow here in Cambridge. Settling everywhere...