Model Output Discussion

[Mark Bayley]

Sorry if I am being stupid here but the way I am reading those colours and the numbers on them indicate that the SW will still have temperatures of 0 or lower which although milder than -10 is not really mild as far temperature is concerned.

If I am right then the maybe people should say it's turning less cold.

The charts aren't ground temperatures, if that's what your wondering. The colours represent the air temperature at the 850 hPa level. The chart shows milder air pushing into the South West

[Wilxy]

I think this cold spell will have a lot less widespread snowfall compaired to last

[Tristrame]

It's not just you mate, i spotted it earlier. It's the obvious sign, just a lot of people don't agree. I reckon come the 18z it will be even further South.

I hope not though.

Thats another thing I've not liked about this spell,the tendency for that high to meander around blocking an islands wide unsettled cold spell ie no widespread decent snow possibilities.

Everything seems to be so slow and pushed forward [except SE England I suppose to an extent],that it is my fear that we'll be well into march before a decent Easterly will have set up and by then the continent will have warmed up.

[PubliusEnigma]

It's not just you mate, i spotted it earlier. It's the obvious sign, just a lot of people don't agree. I reckon come the 18z it will be even further South.

I hope not though.

We need to post a comparison of Sat 13th Chart for ECM 00z and 12z for today. The visual will show whether or not the high

ia becoming something of an absorbatron. The central pressure may not be shifting much but if the outer concentric circles of pressure are moving ever outwards, it will have the same impact as if the HP it self was moving South.

[J10]

You can view the 0z on net weather data centre and the 850hpas here

http://www.meteogroup.co.uk/uk/home/weather/latest_model_forecasts/ecmwf/archiv/NSea/thgt850/2010020812/seethumb/ch/b1b094b7d4.html

Cheers for that, I have bookmarked the links. The ECM really goes for the retrogrssion in a big way, and leaves us in what looks like a west based -NAO pattern. Saying that that low pressure could be very interesting with the low 850HPA over us at that time. Especially as the winds could come from the SE and that is where the cold air is forecast to be just before this weekend. Perhaps a mix between the ECM and the GFS is the most likely outcome, certainly very interesting synoptically once again.

[karyo]

The ECM from 168hrs looks very strange to me, normally once that negative western NAO sets up you'd expect to see low pressure stuck to the nw not sinking again, perhaps that trough in the eastern USA is doing the UK a favour by stopping the high from retrogressing further west.

Also it becomes more complicated, as the low heads south a feed of se'rlies come in from the continent towards the UK, how much cold air will be left over Europe at that stage?

The ECM this evening looks a bit of a mess to me past 168hrs.

If the 12z ECM FI was to verify, then there would be loads of snow for many places next week, before less cold/mild weather moved in from the south. However, it is a worrying trend as the 12z has pushed the -NAO further west than the 0z.

I hope this trend stops and ideally reverses to an extend! The GEFS ensembles keep it cold for much longer!

Karyo

[nick sussex]

Thats another thing I've not liked about this spell,the tendency for that high to meander around blocking an islands wide unsettled cold spell ie no widespread decent snow possibilities.

Everything seems to be so slow and pushed forward [except SE England I suppose to an extent],that it is my fear that we'll be well into march before a decent Easterly will have set up and by then the continent will have warmed up.

This is what i posted earlier and i think might go some way to explaining the problem with the modelling of easterlies this winter.

Unfortunately we seem to be seeing a recurring pattern with the models and easterlies, I've noticed this with looking at the ensembles for southern Europe, when the easterly was reinstated initially there wasn't much support for the main cold in these regions, however with time a cluster of colder members appear but the operational is reluctant to go with these, the models then already start retrogressing the pattern so the core of the high starts forming to the nw and the ridge to the east takes a back seat. This then takes the coldest air into Europe, although there is still some -10 air getting into the se. In previous winters the problem has been the jet roaring over the top and causing the coldest air to go into mainland Europe, this winter the problem for easterlies has been the continually evolving pattern to retrogression, so that the ridge to the east is already being squeezed out by the troughing in Scandi.

I still think theres a little more room for manouevre but IMO any main snow for areas away from the east and se is more likely to come from a northerly as the pattern retrogresses.

[snowspotter]

I have been looking only occasionally the last few days but the impression I am getting is that the high pressure is flabbier and heading more over us. Thus any easterly has in effect been diluted and there are no very cold 850's to tap into.

All in all a coldish mainly dry spell , cloudy with a few snow showers in the east but nothing major . After about mid month its a warm up and then I think we will be looking to spring.

I've notcied the ensembles on the GFS have been warming up the last few runs .

Not looking good if you like cold and snow

[ANYWEATHER]

If you like the cold certainly pleasing out from gfs and ecm. Settled and cold for NorthWest Uk and less settled with some snow for southeast Uk in the short term...and it looks very unlikely that the Atlantic will have any play in the forseeable future!

[nick sussex]

If the 12z ECM FI was to verify, then there would be loads of snow for many places next week, before less cold/mild weather moved in from the south. However, it is a worrying trend as the 12z has pushed the -NAO further west than the 0z.

I hope this trend stops and ideally reverses to an extend! The GEFS ensembles keep it cold for much longer!

Karyo

I think the ECM 12hrs run on face value is an upgrade on the 00hrs because it doesn't look like locking in the milder air, if you look at the trough orientation across the eastern USA and over Scandi, that has more of an Omega block look to it but just further north, you're not seeing that strong ne/sw alligned flow into the mid Atlantic.

However putting that aside I think its a complete mess trying to marry some conflicting signals.

[cooling climate]

Well I guess there could be a school of thought that if phase 1 and 2 dont materialise Dave, then perhaps you should

rename phase 3 to..perhaps phase 1 ;o). Some could argue that today could indeed be the coldest day of the week in the E and SE based on the 12z ECM.

Not according to this.

http://www.meteogroup.co.uk/uk/home/weather/latest_model_forecasts/ecmwf_popup/archiv/Europe/thgt850/2010020812/nothumb/on/168/ch/d65e5e7278.html

[Thundery wintry showers]

There is a little bit of an over-reaction on here, the Euro models still insist on having the HP a bit weaker and further north than the GFS (the stand-off continues, but with everything shifted towards the HP further south than before- so the GFS has done much better than it did last time, in early January with a similar setup). Eastern areas are still likely to see a fair amount of shower activity with the wind off the sea, but it does look like staying dry for most central and western parts.

[snowspotter]

I think if anything interesting is going to develop it will be from the North or syatems pushing into cold air. The upper pattern looks good but we don't know where the block will set-up, I think as we get towards the second half of Feb we should be looking for snow events rather than prolonged cold.

Think you may be right. I may be being unduly pessimisitc , charts are not a disaster by any means and I am in a favoured area.

[Duane S.]

perhaps that trough in the eastern USA is doing the UK a favour by stopping the high from retrogressing further west.

The ECM this evening looks a bit of a mess to me past 168hrs.

Hi Nick.

That's what I was getting at earlier. I think the -NAO signature won't be as west based as some are forecasting for that reason.

And I also agree with you about the ECM 168 - 192, it looks very peculiar.

[johnholmes]

Just some basic temperature comments from the GFS output for this week; the prediction for average max temp for this area (+2 added) is currently 5.6C, Mon-Fri; GFS has varied that value from a low of 3.4C on 12Z Thursday run to its current idea of 5.6C; most runs have suggested around 4C. At first glance that seems a fairly consistent line, apart from that of today. What it masks though is the dropping of any what you might call really cold days with corrected max temps of only 2 to 3C. Over the past 48 hours those numbers have disappeared completely with 4 being the lowest for any one day and most days, as per this run, barely below the normal for this time of the year (6.5C).

So to some extent I can understand and even empathise with those who feel that the initial 'real' cold has slowly been 'watered down shall we say. Its still a below normal prediction for the next 7-14 days but not by that much really.

It will be interesting to see what temperature values actually occur here over the next 7-14 days. I'll let you know 14 days from now!

I would so like to have some warm sunshine-sorry coldies.

[lukemc]

Hi,

I have read a lot of talk on here recently of a west based negative NAO pattern and the blocking high moving too far west allowing milder air from the Atlantic in? Is this why it turned milder in the second half of February 2009 after the cold and snowy first half of the month? And did it also happen in February 1991 as I believe the tail end of that month was milder (-NAO setup moving too far west?).

Also I hear a lot of talk on here of "downgrades" but surely it is just the precipitation that as been downgraded, and not the cold! Surely we could get some very cold temperatures this week in some areas? An example would be early January 2009 when some places got to -12 or below with little or no snowcover under a largely dry HP setup. Also some are saying that the downgrade has occurred because the high is further south meaning more stable high pressure dominance, but the teleconnection signals suggest it will move NW towards Greenland, so wouldn't the fact that the high is further south mean that the cold would last longer because the high would take longer to retrogress? Then we could say it is an upgrade in the longer term?

And also wouldn't that mean that the cold would embed itself for longer meaning that when say a breakdown from the Atlantic does occur we could get a very big snow event do you think that a February 1996 style event could be possible at the moment do you think that the synoptics shown in the charts are similar to early February 1996 I have read that thier was a lot of cold and dry weather before that event can anyone correct me on this?

Luke

[PubliusEnigma]

Not according to this.

http://www.meteogroup.co.uk/uk/home/weather/latest_model_forecasts/ecmwf_popup/archiv/Europe/thgt850/2010020812/nothumb/on/168/ch/d65e5e7278.html

But thats FI, it will be totally different by then.

A lot of talk on here everynight about the ensembles

Yet they are as innacurate as the models so why bother?

A week away from anything remotely interesting and the sun is getting higher and stronger

Game over re another severe cold spell methinks, though snow can and will fall upto April.

Just not the staying around stuff!

Well I was browsing over on MM and their long range forecaster seems to disagree with

something of a notable cold spell imminent.

http://www.null.co.uk/weather.forum/viewtopic.php?f=3&t=11316

I'm not so sure I agree, as the extent of the retrogression to the NW into NE Canada could spell curtains

for winter if the long wave manage to make inroads into the SW in around 8 days time.

[cooling climate]

I am still not convinced by this westerly based -NAO, certainly not to the extent that the

ECM is showing. Looking at the stratosphere charts I am under the impression that

there will be higher heights to the north of Iceland and we will see a trend in this direction

over the next two or three days.

I am convinced we will see a very potent north to northeasterly set up over the latter part

of the weekend and into next week. The models are not showing this at the moment and

I appreciate this is all conjecture on my part at this stage.

So slightly less cold tomorrow (perhaps) and then becoming cold to very cold over the

Midlands, east Anglia, central southern and southeast England wednesday onwards with

the likelyhood of perhaps some substanstial snowfall for the more eastern and southeastern

areas of the country.

Very cold and snowy across the UK next week.

[Cloud 10]

ecm>> ukmo>>

Both of the euro models very similar at +144 with the high retrogressing to greenland quite quickly which opens the door to a cold attack from the north.

The gfs has a much slower solution with the high loitering far longer.

Some very unusual charts from the later stages of the ECM,with that extreme southerly jet,really quite bizarre.

[cooling climate]

But thats FI, it will be totally different by then.

Sorry I do not understand your reply. You said in a earlier post that going by the ECM 12 run

it will not be that cold. I have just shown you the projected 850 temps for that run and they

are cold in anyones book.

[The Weather Dragon]

I've got a hunch that we will not see any significant/severe cold spell now. Was talking to a friend who works at METO Exeter. They are not expecting any major disruption with this cold spell. One look at the models tonight would seem to back this up. The colder pool of upper air slides into France this weekend - just brushing the far South East corner of England (hence the METO warnings for Kent). Any real significant cold keeps getting put back in the model runs - Time is running out.

[Cheese Rice]

I've got a hunch that we will not see any significant/severe cold spell now. Was talking to a friend who works at METO Exeter. They are not expecting any major disruption with this cold spell. One look at the models tonight would seem to back this up. The colder pool of upper air slides into France this weekend - just brushing the far South East corner of England (hence the METO warnings for Kent). Any real significant cold keeps getting put back in the model runs - Time is running out.

Time is running out till what? There is plenty of time for snow and cold, admittedly the upcoming week doesn't look particularly interesting for most but after that hopefully the fun and games will begin with the northerly.

Edited February 8, 2010 by 10123

[cooling climate]

I think that's a pretty optimistic assessment CC but whatever happens another testing time ahead for the models.

Sure its just the way I see it playing out but as I said no more than pure conjecture on my

part I know. Also as Chionomaniac has said it is hard to predict how the warming and propagating

easterlies in the stratosphere will play out near to the surface.

This chart for example tells me that the vortex may end up further east.

http://strat-www.met...0&forecast=f192

Then there is this chart although admittedly it is the 400k isentropic chart(roughly 50,000ft)

http://strat-www.met...0&forecast=f192

Add to this the MJO phase 8,in fact the way it is spread out it probably covers more than just

phase 8.

http://www.cawcr.gov...m/OLR/m.3d.html

I could be talking a load of old rubbish time will tell.

Edited February 8, 2010 by cooling climate

[TEITS]

What it masks though is the dropping of any what you might call really cold days with corrected max temps of only 2 to 3C. Over the past 48 hours those numbers have disappeared completely with 4 being the lowest for any one day and most days, as per this run, barely below the normal for this time of the year (6.5C).

Slightly confused by your post.

Temps suggested for Wed-Friday are around 2-3C.

http://www.wetterzentrale.de/pics/Rmgfs784.gif

http://www.wetterzentrale.de/pics/Rmgfs1024.gif

You then have to take into account the GFS tends to prog temps around 1-2C too high. For instance today the GFS predicted 3C for my region but the reality was 1C and Norwich remained at 0C this afternoon.

Some locations may well reach 4-5C but for parts of E Anglia/SE the temps will struggle to rise much above 2-3C. Any locations that are subject to frequent snow showers will struggle to rise above freezing.

[Jason T]

I've got a hunch that we will not see any significant/severe cold spell now. Was talking to a friend who works at METO Exeter. They are not expecting any major disruption with this cold spell. One look at the models tonight would seem to back this up. The colder pool of upper air slides into France this weekend - just brushing the far South East corner of England (hence the METO warnings for Kent). Any real significant cold keeps getting put back in the model runs - Time is running out.

Forgive me for saying this,but your comments appear flawed, signficant/severe cold spell now what are they comparing to, Major disruption what are they classing as major. One look at the models,I dont think we can class one look as gospel for the further outcome. I believe JOHN HOLMES posted earlier regarding temps that the Models were not stating true temps which alone i would have thought could make models give distorted outputs at times.As for the METO warnings well they can change within hours.

Kind Regards.

Edited February 8, 2010 by silver line