General Model Output Discussion

[Thundery wintry showers]

Looking at the 18Z, it is already falling into line with the ECM. There is still scope for things to change and for a breakdown to reappear in 6 days' time, but I think the ECMWF has most likely latched onto the correct sort of trend here.

Sunshine, with snow showers for the east tomorrow and Saturday, and a strengthening easterly wind. Then for Sunday and Monday, we'll get that area of cloud and more persistent sleet and snow moving in from the east, affecting eastern and central England, while other areas stay dry, quite sunny, and cold. Although 850-1000mb thicknesses and 850hPa temperatures support snow, my eye is drawn towards those 2m temperature maps which suggest temperatures hovering just above freezing in most places, and 2 or 3C along some of those eastern coasts, suggesting that it will be marginal wet snow, and probably sleet near the east coast, especially in north-east England.

Tuesday looks like being dry and cloudy for most, with some sleety showers and a thaw near the coasts of E Scotland and NE England, then into Wednesday/Thursday I am 80% confident that this low to the SW will not initiate a breakdown but will instead slide east to the south of the block. This will allow a pulse of colder 850s to come in from the northeast, which may well bring back the theme of sunshine and snow showers for eastern districts, albeit probably still sleety along coastal fringes of the northeast. As the GFS hasn't picked up on this yet (although moving towards it on the 18Z) I will have to see more detailed outputs regarding this before I can be certain of a return of the sunshine and snow showers regime.

Beyond that, who knows...

[andymusic]

Who is this Joe B...Keep hearing about him.

Anyway and WRT Sunday...I do wonder how much the models are downplaying the precipitation considering the potential that came from the event this Tuesday and Wednesday. I really do think it will be all eyes to the NAE.

Our area never does too well out of Easterlys ironicaly (home counties)I do think the modification of the airmass over London does affect this though I have no doubt that we will see a shower or two.

Models not showing any sign of a breakdown until i go skiing now....imagine that off on the 16th and if BFTP is correct about lows from the 14th i may head to Gatwick early, in fact I might just get a placement at EGKK for a week

Joe B - check out accuweather.com (uk & ireland section) you'll find his blog there!

[chionomaniac]

chuckle Wasn't a whole bunch of people slating the GFS only 6 hours ago ?? Now its backed down from the mild invasion next week, suddenly its a reliable model again..

I don't really understand this comment because the fact that the GFS changes from run to run, still suggests that unreliability exists and for that reason any criticism is still valid. The fact that this run is more in line with the ECM and background teleconnections suggests though that this run may be closer to the mark in the higher resolution section. The ensembles from this point should give an idea of the possibilities from the lower resolution section of the run.

[damianslaw]

I'm siding with the ECM outlook for next week as opposed to GFS, the main reason being that the energy of the jet looks locked towards the south which will help steer the projected low on course to develop to the SW and head towards the SW of the country to quickly retreat south into France - with those heights to the NE advecting further west again through next week - the AO is a major player and it looks like staying very negative.

Whether the high advects towards iceland and greenland or decides to sit over Scandanavia next week remains to be seen, if we see heights descending down from the arctic courtesy of any arctic high building we are likely to see a reload pattern as to where we were at New Year - this cold spell has a lot of mileage in it yet, and even if we see a breakdown of sorts within the next 2 weeks I can see this being very similiar in nature to what happened just after christmas i.e. it will be temporary.

[Thundery wintry showers]

Yes, people are saying this run is more likely to be near the mark purely because it agrees more with what the ECMWF is showing, and nothing to do with the GFS being reliable. The ECMWF is not bulletproof, but since its wobble over the start of the cold spell around 17 December, it has been stunningly accurate out to T+144 for much of the time, and I think many people are just taking this into consideration when arguing that the ECM evolution is the more likely.

I saved a few ECMWF runs to my hard drive around mid to late December and all of them were almost spot on out to T+168, and only veered off course as we headed towards T+240.

[Don]

Then for Sunday and Monday, we'll get that area of cloud and more persistent sleet and snow moving in from the east, affecting eastern and central England, while other areas stay dry, quite sunny, and cold. Although 850-1000mb thicknesses and 850hPa temperatures support snow, my eye is drawn towards those 2m temperature maps which suggest temperatures hovering just above freezing in most places, and 2 or 3C along some of those eastern coasts, suggesting that it will be marginal wet snow, and probably sleet near the east coast, especially in north-east England.

Hi Ian. Do you think that Sunday/Monday's event may not amount to much in topping up the snow for inland areas, given the higher 2m temperatures of just above 0?

Edited January 7, 2010 by Don

[Thundery wintry showers]

A very difficult question and I'm afraid I can't make any promises either way. I haven't seen anything like this setup for Sunday/Monday since I started observing the models.

I'm reminded somewhat of the easterly of 26-27 January 1996. On the 26th most places had sunshine and snow showers, then on the 27th, a front, ahead of much warmer uppers coming in from the SE, brought heavy prolonged snowfalls to much of northern England. At first it fell as snow right out to the sea front, but late in the day, it turned sleety near the coast, and the snow at Cleadon was all gone by the next morning, while inland parts maintained snow cover for another few days.

However on that occasion the frontal zone was much further north, so the specifics may be a little different this time around.

[peterf]

Steady on. Francis is a legend in his own underpants. He has been around for ever and in the early 80's when on local Thames TV [yes a long time ago] he was the only forecaster one evening to predict heavy rain turning into 6" of Snow during the night!!!

Shortly afterwards he was snatched by SKY where he remains, older and as languid as ever.

Don't Diss the Wilson.

same here he is a ledgend lol.his style will never be replicated.

[Don]

A very difficult question and I'm afraid I can't make any promises either way. I haven't seen anything like this setup for Sunday/Monday since I started observing the models.

I'm reminded somewhat of the easterly of 26-27 January 1996. On the 26th most places had sunshine and snow showers, then on the 27th, a front, ahead of much warmer uppers coming in from the SE, brought heavy prolonged snowfalls to much of northern England. At first it fell as snow right out to the sea front, but late in the day, it turned sleety near the coast, and the snow at Cleadon was all gone by the next morning, while inland parts maintained snow cover for another few days.

However on that occasion the frontal zone was much further north, so the specifics may be a little different this time around.

Thanks for that, Ian. Very interesting times indeed!

[nick82]

You got a streamer on your way to north-east Kent by the looks of things!!!

Looking quite intense, just missing me at Felixstowe, enjoy!!!

[West is Best]

Morning all.

Well both GFS and UKMO are going for this breakdown middle of next week, with the Scandi high slipping south and introducing a mild southerly feed. I dismissed it yesterday but with both models holding firm overnight we need to consider it seriously, especially with the relatively short timeframe.

All eyes on ECM ... will it resist?!

[DEYS(Kent)]

GEM and DWD are great this morning at +144

ECM rollin' out soon.

[bluearmy]

GEM on its own in driving the trough into italy - however, not far from the GEFS mean. are the other ops a bit progressive or will the ens catch up?? given the depth of the cold, a slightly less progressive outcome culd be very snowy on the first push and possibly the second. we'll see as the weekend runs keep coming.

[Iceberg]

Horrendously complicated outlook from Wed to Sat next week. Certaintly more likelyhood on the milder breakdown, ECM follows the GFS to some degree, but does keep the cold air hanging around for an extra 2 or 3 days.

ECM also has the high retreating out to southern Russia.

GFS is a right dogs dinner IMO.

However I can't see anything that screams that the Atlantic wants to gear back to life. The 12Z ECM Ensembles really kept things cold, with a large scatter though from say the 18th onwards. Equally large scatter from the GFS ensembles.

The best advise I have on the models is to wait and see what happens over the next 24 hrs, there just are not any clear indications of what might happen.

The Snow in the south is still their btw on Sunday and the all models make more of the LP on Wed. With considerable frontal snow being shown by all models.

[Iceberg]

Snow mon morning and Tuesday night, but dry in the middle at the moment

[snowingman]

The End of this cold is now concrete!!

GFS slams milder air into us starting Monday, by Wednesday most of the country is melting!!! by Friday... t-shirt weather

ECM follows GFS, the first time they have paired up in 2 weeks

Ah well... of course the only question now is how much wet snow, sleet rain will occur during the transition?

We still have February to live through...

Fun while it lasted

Edited January 8, 2010 by snowingman

[Yeti]

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.

Edited January 8, 2010 by Yeti

[snowmadchrisuk]

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.  

Agreed , but it still doesn't mean that the Mild air will win at the first Attempt . I say a Snowy breakdown with Blizzards for most would be a very likely outcome . The GFS ensembles are actually better than yesterday this morning with most members keeping it cold or very cold until the 19th. This suggests the Ensembles don't think the Atlantic will win at the first attempt .

[coriolis]

The End of this cold is now concrete!!

Remind me not to ask you to come and do the foundations for my extension as your idea of concrete is a bit bizarre!

GFS sticks to its guns and wants the high to slip away (as does METO). I don't see a dramatic end to all of this just yet as there are so many different scenerios being played out. Next few runs 'may' give a better indication of a way forward.

[Shiny_Bottom_1]

Well, i'm going to completely contradict myself from the last few days.

The GFS, as it has done for around a week now, shows the 850's creeping above the -5oC for a 2-3 days period (all based on Derbyshire), with them returning below for a 3-4 day period.

Looking at the model comparison, we have a similar set up from the ECM.

However, look at the GFS T2M ensembles. For Derbyshire, it is not until the 18th/19th before we get above 0oC as a max temp.

Personally i'm sceptical about the snow potential, but those, such as Nick F, who have much more experience and knowledge than me (perhaps an understatement), disagree. So, you know who to listen to

Overall, remaining cold...potentially until the end of next weekend/early the following week.

[West is Best]

The ensembles certainly call into question any 'concreteness' of the end of cold. The operational is pretty much out on its own, with massive scatter especially on the air pressures.

So ... nothing definite yet about this. I still wouldn't be at all surprised to see a west vs east battle royal with the east winning. Seen this happen before, even when forecasters have confidently predicted the end of the cold.

[MP-R]

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.wetterzentrale.de/pics/Rtavn1201.html

http://www.wetterzentrale.de/pics/Rtavn1441.html

http://www.wetterzentrale.de/pics/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

[Optimus Prime]

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.

Regards

Spot on. Although the breakdown looks more likely the SE flow wouldn't be t-shirt weather (I ignored that post as it was just probably a joke) it would actually drag in some bitter weather from the SE with low level surface cold firmly embedded.

What we need to remember is ALL cold winters has this pattern come along. February 1963 a similar scenario brought 4 feet of snow to the SW and the temperatures rose above freezing before falling away throughout the month again. January 1979 was a subzero month and as Strattos Ferric has pointed out before, it was a very unsettled month with many incursions of westerly phases but with the continent (and the whole N.Hemisphere) brutally cold it never really warmed up. I can associate this month with that.

What we also need to remember is the GFS is threatening a ridge building from the SW which could build over us or to the west allowing northerlies to penetrate down.

The AO remains negative.

[Supacell]

Since I started looking at the models in 2004 it has always been a case of any very cold weather and snow being shown in the mid to long range, and it often has not happened. Usually the models revert back to zonality and mild, southwesterly muck after teasing us with fantastic winter weather.

This winter is different... the very cold weather in FI verified and hence we are now in the midst of what is, for me, the best winter cold spell I remember since I was a child in the 80's (maybe even better). I feel any mild weather in the mid to long ranges needs to appear over several runs and get into the reliable time frame before we can say that a breakdown is concrete!

Plus, as many have said, with such intense cold over us, any breakdown is going to bring very large amounts of snowfall to many people. Possibly more snow than anything we have seen so far this winter and in this cold spell.

[MR EXTREMES]

well its a shame to see a breakdown this morning but i must admit i was wrong.

lastnight i was convinced the gfs was over progressive well this morning the big guns are telling us the end is nearly here.

but id of thought it wont be over in a few hours i expect some brillant frontal snow lasting 24hour maybe 36hours.

but as some have noticed the alantic is not fired up like other milder years,

its only a matter of time before the next pulse of cold returns maybe within a week after the breakdown.

its been excellent event and id be very suprised if this is the end of winter.

and we do have the weekend to be excited about which is looking intresting already showers in the east are already kicking butt and starting to move inland its not over yet but will be soon.

but i reckon winter will bite back sooner than later.

Edited January 8, 2010 by badboy657