Winter Model Discussion 18Z 13/1/13 onwards.

[Froze were the Days]

Warm Air Advection anyone?? Might keep that Scandinavian block well in place. Right where she deserves..

Robbie we need to see that block more amplified so the WAA goes up steeply towards Iceland and the trough near NW Spain develop so we get a stronger southern arm to the jet, on this chart anyway. What you've shown looks like only a break down of the HP.

[Zenarcher]

My take on the models this evening using the GFS, UKMO, ECM, JMA, GEM and NOGAPS,

96 hours Friday - The UKMO, GFS, GEM and NOGAPS all look similar here out in the Atlantic they have two low pressure systems in the same place although the deepness of them varies.

The JMA and ECM don't look like the other models here they do give one low some support but don't agree on a low to be near or over Iceland instead they send the low more South East,

This little image shows the difference between the UKMO and ECM with the low,

120 hours Saturday - This where the confusion really starts for the models they all agree on a large area of low pressure out in the Atlantic although what they are not sure on yet is how far South it will dig and how much pressure builds up to our North.

Firstly the UKMO and NOGAPS show something similar here with good high pressure to our North and the low starts to undercut it,

The rest of the models show the big low to be even bigger, deeper and further West in the Atlantic but they do agree on high pressure building up to our North. Remember the likes of the ECM and GFS yesterday weren't keen on bringing high pressure to our North but the UKMO did. Today the ECM and GFS have moved to a similar idea the UKMO has although not exact it is a interesting change from them.

Is the GFS overdoing the low in the Atlantic here? It shows a deep 945mb and GEM agree's but the rest go for something slightly weaker it's difficult to say most models do over cook lows at the long range and GFS is famous for doing that the problem is with PV out there and the jet stream as well it is possible to have a low that deep but at the moment not many show something that deep.

144 hours Sunday - Despite the large differences we do see the models come up with a similar idea at this point the high pressure appears to just make it over our North and into Greenland,

And they show the low that was at 120 hours weaken down slowly but surely.

Overall -

24 hours ago most of the models didn't seem keen on building up high pressure to our North and that the Atlantic lows would go over the top of things giving us a flat pattern the UKMO kept saying no,

ECM Yesterday

And Today

This goes to show the changes that can be made in just a day but this evening the models do look better than what they did yesterday, disagreement is as always big but at least most of the models this evening show and end up with a similar picture despite all their differences.

[Carlrg]

Atlantic not breaking through on the BOM next Saturday. Batleground UK (not in the North) then the jet is deflected SSE.

http://www.meteociel...ode=5&archive=0

Its changed slightly has it just updated!

Edited January 14, 2013 by Carlrg

[ChartViewer]

One day that model might just get something close to being right on the off-chance all other models fail or break.

To be honest ive found it right now to be more on the mark than any wild swing gfs........roll back to what it predicted for now 7 days ago and it hasnt done bad and actually right now it isnt performing to bad at all...JMA/BOM/GFS...Hmmm swinging rapidly as they try to get hold of whats going on upstream......verification stats needed but i think you will find when we look back this particular model has shown itself to be more stable than a few of the other so called models of choice including NOGAPS.. .we shall see....

Edited January 14, 2013 by ChartViewer

[phil nw.]

Just flicking through the 850hPa ens graphs on the GFS run and we can see how the mean and therefore evidence of any less cold blip varies.

I just picked 4 locations South to North with my own for the middle of England .

As we would expect with the coldest air further north and east any Atlantic inroad of milder air shown at the end of the week by the models would impact Devon the most being nearest to the boundary.

It`s a rather simplistic way of looking at things but sometimes when we have these differences in the operationals the ens. gives an idea of how far north and east this milder air might advance.

Indications of a less cold spell are showing at the weekend- but still 2-4C below average based on these it seems with only Devon getting close to 0C.

One thing we cant see is any mild spell in the outlook.

Hopefully we can see a gradual trend for more defined undercutting of the block continue to flatten out the upward curve in those graphs as we go through the week.

[allenar]

Warm Air Advection anyone?? Might keep that Scandinavian block well in place. Right where she deserves..

The following in the MetOffice forecast really does sum up how bad things could get for the UK, and how special it could to witness something in our lifetime.

UK Outlook for Tuesday 29 Jan 2013 to Tuesday 12 Feb 2013

may be. Not will be, also the key to that statement is this winter. We haven't had many snow events this winter. So four or five would be more..

[Polar Maritime]

This http://www.myweather2.com/activity/play-weather-maps.aspx?mapid=3&id=66646&maptype=UPPER_TEMP shows the battle between the Atlantic and the cold block very well.

[Robbie Garrett]

Robbie we need to see that block more amplified so the WAA goes up steeply towards Iceland and the trough near NW Spain develop so we get a stronger southern arm to the jet, on this chart anyway. What you've shown looks like only a break down of the HP.

Not with a Polar Vortex sitting where it is, with low pressure over central Europe, is is very unlikely the high sinks with a jet at that angle either. The net result of warm advection is to make a region warmer. Warm advection creates a localised area of high pressure, in this case the Scandinavian High which is already there, the WAA is only likely to strengthen and allow the block to last longer.

Edited January 14, 2013 by Robbie Garrett

[IDO]

No surprise the op run is with the coldest members of the ensembles with the flow coming from the NE late in the ECM 12z (De Bilt):

The mean rises late on which is surprising as the op cools. However the control is on board so pretty impressive if we can get the cold from that direction.

Edited January 14, 2013 by i'm dreaming of...

[nick sussex]

Looking at the ECM ensemble spreads a clustering keep high pressure in the Scandi area influencing Europe right out to 240hrs with the jet sinking south.

A cluster look to develop a deep trough in the Atlantic, looking at these and the expected upstream pattern from the NOAA discussions I can't see a proper Greenland high setting up but high pressure more likely to be centred to the ne.

[Sawel]

Interestingly on the ECM ensemble means for the entirety of its run, most of Scotland is kept under the -5C isotherm.

Edited January 14, 2013 by Sawel

[bradymk]

ECM means quite impressive again along with the short term de bilt charts. High to our NE quite strong throughout, poor old atlantic struggling to make inroads across whole of UK for sure.

[phil nw.]

No surprise the op run is with the coldest members of the ensembles with the flow coming from the NE late in the ECM 12z (De Bilt):

The mean rises late on which is surprising as the op cools. However the control is on board so pretty impressive if we can get the cold from that direction.

They continue to look bitterly cold for Holland.It will interesting to see the London ones later and how they compare with the GEFs temps.

[musicman2000]

Matthew Hugo â€@MattHugo81

Impossible to summarise on twitter but the EC ENS from the 12z run are distinctly cold and blocked. The Atlantic could struggle to 'get in'

[ChartViewer]

CMA T144....Not to dis simliar to its European counterparts....scand heights holding on, atlantic attack, battleground scenarios possible..Sure they have all fallen in line with this model

Energy going south

[kold weather]

Looking at the mean charts from the ECM, they do suggest the atlantic does have the strength to push through, though the angle of the jet looks primed for another slidder and cold spell probably kicking in by say the 23-25th of Jan and its only a less cold spell, certainly not mild by any means!

[Jason T]

Off Topic ,But lovely.

Cheers Ian.

Ian Fergusson â€@fergieweather

"@MattHugo81: Spotted this link earlier and it's a brilliant visualisation of the recent stratospheric warming. http://i50.tinypic.com/1zwgkmd.gif"

[Panayiotis]

Looking at the mean charts from the ECM, they do suggest the atlantic does have the strength to push through, though the angle of the jet looks primed for another slidder and cold spell probably kicking in by say the 23-25th of Jan and its only a less cold spell, certainly not mild by any means!

Yes we want the Atlantic to push through, but only if the lows go under the high! By no means mild neither! Edited January 14, 2013 by Panayiotis

[Carlrg]

The 2m temps stay cool right through the run right up to Jan 24 then seem to tail off so you could be right K.W.

http://www.meteociel...ode=8&archive=0

Edited January 14, 2013 by Carlrg

[NorthernRab]

Interestingly on the ECM ensemble means for the entirety of its run, most of Scotland is kept under the -5C isotherm.

Yes the recent model developments have been largely positive for Scotland. Up until now we've been slightly left out of the loop to an extent, but our fortunes certainly look like changing with regards to deep cold and heavy snowfall.

[snowice]

Am I misreading this - wouldn't that be West and Northern Ireland in the firing line?

Yes if you notice, amounts are higher in the west, and this is because the front stalls, and where it hits the colder air, snow is produced.

west is rain east turns to snow on gfs! north west of Ireland you would be right!

Edited January 14, 2013 by snowice

[R.P. McMurphy]

That's totally wrong. The west would have a big snow event from the latest models.

[ChartViewer]

Well the CMA168 again is synoptically eye candy and could go on to be a stunner.....However could be a complete dud ...great model watching again though...

Edited January 14, 2013 by ChartViewer

[kold weather]

Some models do have a BIG snow event for the west/SW (possibly for the south as well, though less certainty about that one) for Friday. Whilst still too soon to have any confidence in this, its worth watching IMO.

Low confidence, high impact type set-up. Saturday is too far away but certainly a significant number of GFS ensemble members have a snow event on Saturday, though many do get less cold afterwards as the atlantic wins.

[Summer Sun]

ECM short ensemble